Make MessageCache use the immutable text cache during cache rebuilds

[mediawiki.git] / includes / parser / Parser.php

<?php
/**
 * PHP parser that converts wiki markup to HTML.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @ingroup Parser
 */
use MediaWiki\Linker\LinkRenderer;
use MediaWiki\MediaWikiServices;
use Wikimedia\ScopedCallback;

/**
 * @defgroup Parser Parser
 */

/**
 * PHP Parser - Processes wiki markup (which uses a more user-friendly
 * syntax, such as "[[link]]" for making links), and provides a one-way
 * transformation of that wiki markup it into (X)HTML output / markup
 * (which in turn the browser understands, and can display).
 *
 * There are seven main entry points into the Parser class:
 *
 * - Parser::parse()
 *     produces HTML output
 * - Parser::preSaveTransform()
 *     produces altered wiki markup
 * - Parser::preprocess()
 *     removes HTML comments and expands templates
 * - Parser::cleanSig() and Parser::cleanSigInSig()
 *     cleans a signature before saving it to preferences
 * - Parser::getSection()
 *     return the content of a section from an article for section editing
 * - Parser::replaceSection()
 *     replaces a section by number inside an article
 * - Parser::getPreloadText()
 *     removes <noinclude> sections and <includeonly> tags
 *
 * Globals used:
 *    object: $wgContLang
 *
 * @warning $wgUser or $wgTitle or $wgRequest or $wgLang. Keep them away!
 *
 * @par Settings:
 * $wgNamespacesWithSubpages
 *
 * @par Settings only within ParserOptions:
 * $wgAllowExternalImages
 * $wgAllowSpecialInclusion
 * $wgInterwikiMagic
 * $wgMaxArticleSize
 *
 * @ingroup Parser
 */
class Parser {
        /**
         * Update this version number when the ParserOutput format
         * changes in an incompatible way, so the parser cache
         * can automatically discard old data.
         */
        const VERSION = '1.6.4';

        /**
         * Update this version number when the output of serialiseHalfParsedText()
         * changes in an incompatible way
         */
        const HALF_PARSED_VERSION = 2;

        # Flags for Parser::setFunctionHook
        const SFH_NO_HASH = 1;
        const SFH_OBJECT_ARGS = 2;

        # Constants needed for external link processing
        # Everything except bracket, space, or control characters
        # \p{Zs} is unicode 'separator, space' category. It covers the space 0x20
        # as well as U+3000 is IDEOGRAPHIC SPACE for T21052
        # \x{FFFD} is the Unicode replacement character, which Preprocessor_DOM
        # uses to replace invalid HTML characters.
        const EXT_LINK_URL_CLASS = '[^][<>"\\x00-\\x20\\x7F\p{Zs}\x{FFFD}]';
        # Simplified expression to match an IPv4 or IPv6 address, or
        # at least one character of a host name (embeds EXT_LINK_URL_CLASS)
        const EXT_LINK_ADDR = '(?:[0-9.]+|\\[(?i:[0-9a-f:.]+)\\]|[^][<>"\\x00-\\x20\\x7F\p{Zs}\x{FFFD}])';
        # RegExp to make image URLs (embeds IPv6 part of EXT_LINK_ADDR)
        // @codingStandardsIgnoreStart Generic.Files.LineLength
        const EXT_IMAGE_REGEX = '/^(http:\/\/|https:\/\/)((?:\\[(?i:[0-9a-f:.]+)\\])?[^][<>"\\x00-\\x20\\x7F\p{Zs}\x{FFFD}]+)
                \\/([A-Za-z0-9_.,~%\\-+&;#*?!=()@\\x80-\\xFF]+)\\.((?i)gif|png|jpg|jpeg)$/Sxu';
        // @codingStandardsIgnoreEnd

        # Regular expression for a non-newline space
        const SPACE_NOT_NL = '(?:\t|&nbsp;|&\#0*160;|&\#[Xx]0*[Aa]0;|\p{Zs})';

        # Flags for preprocessToDom
        const PTD_FOR_INCLUSION = 1;

        # Allowed values for $this->mOutputType
        # Parameter to startExternalParse().
        const OT_HTML = 1; # like parse()
        const OT_WIKI = 2; # like preSaveTransform()
        const OT_PREPROCESS = 3; # like preprocess()
        const OT_MSG = 3;
        const OT_PLAIN = 4; # like extractSections() - portions of the original are returned unchanged.

        /**
         * @var string Prefix and suffix for temporary replacement strings
         * for the multipass parser.
         *
         * \x7f should never appear in input as it's disallowed in XML.
         * Using it at the front also gives us a little extra robustness
         * since it shouldn't match when butted up against identifier-like
         * string constructs.
         *
         * Must not consist of all title characters, or else it will change
         * the behavior of <nowiki> in a link.
         *
         * Must have a character that needs escaping in attributes, otherwise
         * someone could put a strip marker in an attribute, to get around
         * escaping quote marks, and break out of the attribute. Thus we add
         * `'".
         */
        const MARKER_SUFFIX = "-QINU`\"'\x7f";
        const MARKER_PREFIX = "\x7f'\"`UNIQ-";

        # Markers used for wrapping the table of contents
        const TOC_START = '<mw:toc>';
        const TOC_END = '</mw:toc>';

        # Persistent:
        public $mTagHooks = [];
        public $mTransparentTagHooks = [];
        public $mFunctionHooks = [];
        public $mFunctionSynonyms = [ 0 => [], 1 => [] ];
        public $mFunctionTagHooks = [];
        public $mStripList = [];
        public $mDefaultStripList = [];
        public $mVarCache = [];
        public $mImageParams = [];
        public $mImageParamsMagicArray = [];
        public $mMarkerIndex = 0;
        public $mFirstCall = true;

        # Initialised by initialiseVariables()

        /**
         * @var MagicWordArray
         */
        public $mVariables;

        /**
         * @var MagicWordArray
         */
        public $mSubstWords;
        # Initialised in constructor
        public $mConf, $mExtLinkBracketedRegex, $mUrlProtocols;

        # Initialized in getPreprocessor()
        /** @var Preprocessor */
        public $mPreprocessor;

        # Cleared with clearState():
        /**
         * @var ParserOutput
         */
        public $mOutput;
        public $mAutonumber;

        /**
         * @var StripState
         */
        public $mStripState;

        public $mIncludeCount;
        /**
         * @var LinkHolderArray
         */
        public $mLinkHolders;

        public $mLinkID;
        public $mIncludeSizes, $mPPNodeCount, $mGeneratedPPNodeCount, $mHighestExpansionDepth;
        public $mDefaultSort;
        public $mTplRedirCache, $mTplDomCache, $mHeadings, $mDoubleUnderscores;
        public $mExpensiveFunctionCount; # number of expensive parser function calls
        public $mShowToc, $mForceTocPosition;

        /**
         * @var User
         */
        public $mUser; # User object; only used when doing pre-save transform

        # Temporary
        # These are variables reset at least once per parse regardless of $clearState

        /**
         * @var ParserOptions
         */
        public $mOptions;

        /**
         * @var Title
         */
        public $mTitle;        # Title context, used for self-link rendering and similar things
        public $mOutputType;   # Output type, one of the OT_xxx constants
        public $ot;            # Shortcut alias, see setOutputType()
        public $mRevisionObject; # The revision object of the specified revision ID
        public $mRevisionId;   # ID to display in {{REVISIONID}} tags
        public $mRevisionTimestamp; # The timestamp of the specified revision ID
        public $mRevisionUser; # User to display in {{REVISIONUSER}} tag
        public $mRevisionSize; # Size to display in {{REVISIONSIZE}} variable
        public $mRevIdForTs;   # The revision ID which was used to fetch the timestamp
        public $mInputSize = false; # For {{PAGESIZE}} on current page.

        /**
         * @var string Deprecated accessor for the strip marker prefix.
         * @deprecated since 1.26; use Parser::MARKER_PREFIX instead.
         */
        public $mUniqPrefix = Parser::MARKER_PREFIX;

        /**
         * @var array Array with the language name of each language link (i.e. the
         * interwiki prefix) in the key, value arbitrary. Used to avoid sending
         * duplicate language links to the ParserOutput.
         */
        public $mLangLinkLanguages;

        /**
         * @var MapCacheLRU|null
         * @since 1.24
         *
         * A cache of the current revisions of titles. Keys are $title->getPrefixedDbKey()
         */
        public $currentRevisionCache;

        /**
         * @var bool Recursive call protection.
         * This variable should be treated as if it were private.
         */
        public $mInParse = false;

        /** @var SectionProfiler */
        protected $mProfiler;

        /**
         * @var LinkRenderer
         */
        protected $mLinkRenderer;

        /**
         * @param array $conf
         */
        public function __construct( $conf = [] ) {
                $this->mConf = $conf;
                $this->mUrlProtocols = wfUrlProtocols();
                $this->mExtLinkBracketedRegex = '/\[(((?i)' . $this->mUrlProtocols . ')' .
                        self::EXT_LINK_ADDR .
                        self::EXT_LINK_URL_CLASS . '*)\p{Zs}*([^\]\\x00-\\x08\\x0a-\\x1F\\x{FFFD}]*?)\]/Su';
                if ( isset( $conf['preprocessorClass'] ) ) {
                        $this->mPreprocessorClass = $conf['preprocessorClass'];
                } elseif ( defined( 'HPHP_VERSION' ) ) {
                        # Preprocessor_Hash is much faster than Preprocessor_DOM under HipHop
                        $this->mPreprocessorClass = 'Preprocessor_Hash';
                } elseif ( extension_loaded( 'domxml' ) ) {
                        # PECL extension that conflicts with the core DOM extension (T15770)
                        wfDebug( "Warning: you have the obsolete domxml extension for PHP. Please remove it!\n" );
                        $this->mPreprocessorClass = 'Preprocessor_Hash';
                } elseif ( extension_loaded( 'dom' ) ) {
                        $this->mPreprocessorClass = 'Preprocessor_DOM';
                } else {
                        $this->mPreprocessorClass = 'Preprocessor_Hash';
                }
                wfDebug( __CLASS__ . ": using preprocessor: {$this->mPreprocessorClass}\n" );
        }

        /**
         * Reduce memory usage to reduce the impact of circular references
         */
        public function __destruct() {
                if ( isset( $this->mLinkHolders ) ) {
                        unset( $this->mLinkHolders );
                }
                foreach ( $this as $name => $value ) {
                        unset( $this->$name );
                }
        }

        /**
         * Allow extensions to clean up when the parser is cloned
         */
        public function __clone() {
                $this->mInParse = false;

                // T58226: When you create a reference "to" an object field, that
                // makes the object field itself be a reference too (until the other
                // reference goes out of scope). When cloning, any field that's a
                // reference is copied as a reference in the new object. Both of these
                // are defined PHP5 behaviors, as inconvenient as it is for us when old
                // hooks from PHP4 days are passing fields by reference.
                foreach ( [ 'mStripState', 'mVarCache' ] as $k ) {
                        // Make a non-reference copy of the field, then rebind the field to
                        // reference the new copy.
                        $tmp = $this->$k;
                        $this->$k =& $tmp;
                        unset( $tmp );
                }

                Hooks::run( 'ParserCloned', [ $this ] );
        }

        /**
         * Do various kinds of initialisation on the first call of the parser
         */
        public function firstCallInit() {
                if ( !$this->mFirstCall ) {
                        return;
                }
                $this->mFirstCall = false;

                CoreParserFunctions::register( $this );
                CoreTagHooks::register( $this );
                $this->initialiseVariables();

                // Avoid PHP 7.1 warning from passing $this by reference
                $parser = $this;
                Hooks::run( 'ParserFirstCallInit', [ &$parser ] );
        }

        /**
         * Clear Parser state
         *
         * @private
         */
        public function clearState() {
                if ( $this->mFirstCall ) {
                        $this->firstCallInit();
                }
                $this->mOutput = new ParserOutput;
                $this->mOptions->registerWatcher( [ $this->mOutput, 'recordOption' ] );
                $this->mAutonumber = 0;
                $this->mIncludeCount = [];
                $this->mLinkHolders = new LinkHolderArray( $this );
                $this->mLinkID = 0;
                $this->mRevisionObject = $this->mRevisionTimestamp =
                        $this->mRevisionId = $this->mRevisionUser = $this->mRevisionSize = null;
                $this->mVarCache = [];
                $this->mUser = null;
                $this->mLangLinkLanguages = [];
                $this->currentRevisionCache = null;

                $this->mStripState = new StripState;

                # Clear these on every parse, T6549
                $this->mTplRedirCache = $this->mTplDomCache = [];

                $this->mShowToc = true;
                $this->mForceTocPosition = false;
                $this->mIncludeSizes = [
                        'post-expand' => 0,
                        'arg' => 0,
                ];
                $this->mPPNodeCount = 0;
                $this->mGeneratedPPNodeCount = 0;
                $this->mHighestExpansionDepth = 0;
                $this->mDefaultSort = false;
                $this->mHeadings = [];
                $this->mDoubleUnderscores = [];
                $this->mExpensiveFunctionCount = 0;

                # Fix cloning
                if ( isset( $this->mPreprocessor ) && $this->mPreprocessor->parser !== $this ) {
                        $this->mPreprocessor = null;
                }

                $this->mProfiler = new SectionProfiler();

                // Avoid PHP 7.1 warning from passing $this by reference
                $parser = $this;
                Hooks::run( 'ParserClearState', [ &$parser ] );
        }

        /**
         * Convert wikitext to HTML
         * Do not call this function recursively.
         *
         * @param string $text Text we want to parse
         * @param Title $title
         * @param ParserOptions $options
         * @param bool $linestart
         * @param bool $clearState
         * @param int $revid Number to pass in {{REVISIONID}}
         * @return ParserOutput A ParserOutput
         */
        public function parse(
                $text, Title $title, ParserOptions $options,
                $linestart = true, $clearState = true, $revid = null
        ) {
                /**
                 * First pass--just handle <nowiki> sections, pass the rest off
                 * to internalParse() which does all the real work.
                 */

                global $wgShowHostnames;

                if ( $clearState ) {
                        // We use U+007F DELETE to construct strip markers, so we have to make
                        // sure that this character does not occur in the input text.
                        $text = strtr( $text, "\x7f", "?" );
                        $magicScopeVariable = $this->lock();
                }
                // Strip U+0000 NULL (T159174)
                $text = str_replace( "\000", '', $text );

                $this->startParse( $title, $options, self::OT_HTML, $clearState );

                $this->currentRevisionCache = null;
                $this->mInputSize = strlen( $text );
                if ( $this->mOptions->getEnableLimitReport() ) {
                        $this->mOutput->resetParseStartTime();
                }

                $oldRevisionId = $this->mRevisionId;
                $oldRevisionObject = $this->mRevisionObject;
                $oldRevisionTimestamp = $this->mRevisionTimestamp;
                $oldRevisionUser = $this->mRevisionUser;
                $oldRevisionSize = $this->mRevisionSize;
                if ( $revid !== null ) {
                        $this->mRevisionId = $revid;
                        $this->mRevisionObject = null;
                        $this->mRevisionTimestamp = null;
                        $this->mRevisionUser = null;
                        $this->mRevisionSize = null;
                }

                // Avoid PHP 7.1 warning from passing $this by reference
                $parser = $this;
                Hooks::run( 'ParserBeforeStrip', [ &$parser, &$text, &$this->mStripState ] );
                # No more strip!
                Hooks::run( 'ParserAfterStrip', [ &$parser, &$text, &$this->mStripState ] );
                $text = $this->internalParse( $text );
                Hooks::run( 'ParserAfterParse', [ &$parser, &$text, &$this->mStripState ] );

                $text = $this->internalParseHalfParsed( $text, true, $linestart );

                /**
                 * A converted title will be provided in the output object if title and
                 * content conversion are enabled, the article text does not contain
                 * a conversion-suppressing double-underscore tag, and no
                 * {{DISPLAYTITLE:...}} is present. DISPLAYTITLE takes precedence over
                 * automatic link conversion.
                 */
                if ( !( $options->getDisableTitleConversion()
                        || isset( $this->mDoubleUnderscores['nocontentconvert'] )
                        || isset( $this->mDoubleUnderscores['notitleconvert'] )
                        || $this->mOutput->getDisplayTitle() !== false )
                ) {
                        $convruletitle = $this->getConverterLanguage()->getConvRuleTitle();
                        if ( $convruletitle ) {
                                $this->mOutput->setTitleText( $convruletitle );
                        } else {
                                $titleText = $this->getConverterLanguage()->convertTitle( $title );
                                $this->mOutput->setTitleText( $titleText );
                        }
                }

                # Done parsing! Compute runtime adaptive expiry if set
                $this->mOutput->finalizeAdaptiveCacheExpiry();

                # Warn if too many heavyweight parser functions were used
                if ( $this->mExpensiveFunctionCount > $this->mOptions->getExpensiveParserFunctionLimit() ) {
                        $this->limitationWarn( 'expensive-parserfunction',
                                $this->mExpensiveFunctionCount,
                                $this->mOptions->getExpensiveParserFunctionLimit()
                        );
                }

                # Information on include size limits, for the benefit of users who try to skirt them
                if ( $this->mOptions->getEnableLimitReport() ) {
                        $max = $this->mOptions->getMaxIncludeSize();

                        $cpuTime = $this->mOutput->getTimeSinceStart( 'cpu' );
                        if ( $cpuTime !== null ) {
                                $this->mOutput->setLimitReportData( 'limitreport-cputime',
                                        sprintf( "%.3f", $cpuTime )
                                );
                        }

                        $wallTime = $this->mOutput->getTimeSinceStart( 'wall' );
                        $this->mOutput->setLimitReportData( 'limitreport-walltime',
                                sprintf( "%.3f", $wallTime )
                        );

                        $this->mOutput->setLimitReportData( 'limitreport-ppvisitednodes',
                                [ $this->mPPNodeCount, $this->mOptions->getMaxPPNodeCount() ]
                        );
                        $this->mOutput->setLimitReportData( 'limitreport-ppgeneratednodes',
                                [ $this->mGeneratedPPNodeCount, $this->mOptions->getMaxGeneratedPPNodeCount() ]
                        );
                        $this->mOutput->setLimitReportData( 'limitreport-postexpandincludesize',
                                [ $this->mIncludeSizes['post-expand'], $max ]
                        );
                        $this->mOutput->setLimitReportData( 'limitreport-templateargumentsize',
                                [ $this->mIncludeSizes['arg'], $max ]
                        );
                        $this->mOutput->setLimitReportData( 'limitreport-expansiondepth',
                                [ $this->mHighestExpansionDepth, $this->mOptions->getMaxPPExpandDepth() ]
                        );
                        $this->mOutput->setLimitReportData( 'limitreport-expensivefunctioncount',
                                [ $this->mExpensiveFunctionCount, $this->mOptions->getExpensiveParserFunctionLimit() ]
                        );
                        Hooks::run( 'ParserLimitReportPrepare', [ $this, $this->mOutput ] );

                        $limitReport = "NewPP limit report\n";
                        if ( $wgShowHostnames ) {
                                $limitReport .= 'Parsed by ' . wfHostname() . "\n";
                        }
                        $limitReport .= 'Cached time: ' . $this->mOutput->getCacheTime() . "\n";
                        $limitReport .= 'Cache expiry: ' . $this->mOutput->getCacheExpiry() . "\n";
                        $limitReport .= 'Dynamic content: ' .
                                ( $this->mOutput->hasDynamicContent() ? 'true' : 'false' ) .
                                "\n";

                        foreach ( $this->mOutput->getLimitReportData() as $key => $value ) {
                                if ( Hooks::run( 'ParserLimitReportFormat',
                                        [ $key, &$value, &$limitReport, false, false ]
                                ) ) {
                                        $keyMsg = wfMessage( $key )->inLanguage( 'en' )->useDatabase( false );
                                        $valueMsg = wfMessage( [ "$key-value-text", "$key-value" ] )
                                                ->inLanguage( 'en' )->useDatabase( false );
                                        if ( !$valueMsg->exists() ) {
                                                $valueMsg = new RawMessage( '$1' );
                                        }
                                        if ( !$keyMsg->isDisabled() && !$valueMsg->isDisabled() ) {
                                                $valueMsg->params( $value );
                                                $limitReport .= "{$keyMsg->text()}: {$valueMsg->text()}\n";
                                        }
                                }
                        }
                        // Since we're not really outputting HTML, decode the entities and
                        // then re-encode the things that need hiding inside HTML comments.
                        $limitReport = htmlspecialchars_decode( $limitReport );
                        Hooks::run( 'ParserLimitReport', [ $this, &$limitReport ] );

                        // Sanitize for comment. Note '‐' in the replacement is U+2010,
                        // which looks much like the problematic '-'.
                        $limitReport = str_replace( [ '-', '&' ], [ '‐', '&amp;' ], $limitReport );
                        $text .= "\n<!-- \n$limitReport-->\n";

                        // Add on template profiling data in human/machine readable way
                        $dataByFunc = $this->mProfiler->getFunctionStats();
                        uasort( $dataByFunc, function ( $a, $b ) {
                                return $a['real'] < $b['real']; // descending order
                        } );
                        $profileReport = [];
                        foreach ( array_slice( $dataByFunc, 0, 10 ) as $item ) {
                                $profileReport[] = sprintf( "%6.2f%% %8.3f %6d %s",
                                        $item['%real'], $item['real'], $item['calls'],
                                        htmlspecialchars( $item['name'] ) );
                        }
                        $text .= "<!--\nTransclusion expansion time report (%,ms,calls,template)\n";
                        $text .= implode( "\n", $profileReport ) . "\n-->\n";

                        $this->mOutput->setLimitReportData( 'limitreport-timingprofile', $profileReport );

                        // Add other cache related metadata
                        if ( $wgShowHostnames ) {
                                $this->mOutput->setLimitReportData( 'cachereport-origin', wfHostname() );
                        }
                        $this->mOutput->setLimitReportData( 'cachereport-timestamp',
                                $this->mOutput->getCacheTime() );
                        $this->mOutput->setLimitReportData( 'cachereport-ttl',
                                $this->mOutput->getCacheExpiry() );
                        $this->mOutput->setLimitReportData( 'cachereport-transientcontent',
                                $this->mOutput->hasDynamicContent() );

                        if ( $this->mGeneratedPPNodeCount > $this->mOptions->getMaxGeneratedPPNodeCount() / 10 ) {
                                wfDebugLog( 'generated-pp-node-count', $this->mGeneratedPPNodeCount . ' ' .
                                        $this->mTitle->getPrefixedDBkey() );
                        }
                }
                $this->mOutput->setText( $text );

                $this->mRevisionId = $oldRevisionId;
                $this->mRevisionObject = $oldRevisionObject;
                $this->mRevisionTimestamp = $oldRevisionTimestamp;
                $this->mRevisionUser = $oldRevisionUser;
                $this->mRevisionSize = $oldRevisionSize;
                $this->mInputSize = false;
                $this->currentRevisionCache = null;

                return $this->mOutput;
        }

        /**
         * Half-parse wikitext to half-parsed HTML. This recursive parser entry point
         * can be called from an extension tag hook.
         *
         * The output of this function IS NOT SAFE PARSED HTML; it is "half-parsed"
         * instead, which means that lists and links have not been fully parsed yet,
         * and strip markers are still present.
         *
         * Use recursiveTagParseFully() to fully parse wikitext to output-safe HTML.
         *
         * Use this function if you're a parser tag hook and you want to parse
         * wikitext before or after applying additional transformations, and you
         * intend to *return the result as hook output*, which will cause it to go
         * through the rest of parsing process automatically.
         *
         * If $frame is not provided, then template variables (e.g., {{{1}}}) within
         * $text are not expanded
         *
         * @param string $text Text extension wants to have parsed
         * @param bool|PPFrame $frame The frame to use for expanding any template variables
         * @return string UNSAFE half-parsed HTML
         */
        public function recursiveTagParse( $text, $frame = false ) {
                // Avoid PHP 7.1 warning from passing $this by reference
                $parser = $this;
                Hooks::run( 'ParserBeforeStrip', [ &$parser, &$text, &$this->mStripState ] );
                Hooks::run( 'ParserAfterStrip', [ &$parser, &$text, &$this->mStripState ] );
                $text = $this->internalParse( $text, false, $frame );
                return $text;
        }

        /**
         * Fully parse wikitext to fully parsed HTML. This recursive parser entry
         * point can be called from an extension tag hook.
         *
         * The output of this function is fully-parsed HTML that is safe for output.
         * If you're a parser tag hook, you might want to use recursiveTagParse()
         * instead.
         *
         * If $frame is not provided, then template variables (e.g., {{{1}}}) within
         * $text are not expanded
         *
         * @since 1.25
         *
         * @param string $text Text extension wants to have parsed
         * @param bool|PPFrame $frame The frame to use for expanding any template variables
         * @return string Fully parsed HTML
         */
        public function recursiveTagParseFully( $text, $frame = false ) {
                $text = $this->recursiveTagParse( $text, $frame );
                $text = $this->internalParseHalfParsed( $text, false );
                return $text;
        }

        /**
         * Expand templates and variables in the text, producing valid, static wikitext.
         * Also removes comments.
         * Do not call this function recursively.
         * @param string $text
         * @param Title $title
         * @param ParserOptions $options
         * @param int|null $revid
         * @param bool|PPFrame $frame
         * @return mixed|string
         */
        public function preprocess( $text, Title $title = null,
                ParserOptions $options, $revid = null, $frame = false
        ) {
                $magicScopeVariable = $this->lock();
                $this->startParse( $title, $options, self::OT_PREPROCESS, true );
                if ( $revid !== null ) {
                        $this->mRevisionId = $revid;
                }
                // Avoid PHP 7.1 warning from passing $this by reference
                $parser = $this;
                Hooks::run( 'ParserBeforeStrip', [ &$parser, &$text, &$this->mStripState ] );
                Hooks::run( 'ParserAfterStrip', [ &$parser, &$text, &$this->mStripState ] );
                $text = $this->replaceVariables( $text, $frame );
                $text = $this->mStripState->unstripBoth( $text );
                return $text;
        }

        /**
         * Recursive parser entry point that can be called from an extension tag
         * hook.
         *
         * @param string $text Text to be expanded
         * @param bool|PPFrame $frame The frame to use for expanding any template variables
         * @return string
         * @since 1.19
         */
        public function recursivePreprocess( $text, $frame = false ) {
                $text = $this->replaceVariables( $text, $frame );
                $text = $this->mStripState->unstripBoth( $text );
                return $text;
        }

        /**
         * Process the wikitext for the "?preload=" feature. (T7210)
         *
         * "<noinclude>", "<includeonly>" etc. are parsed as for template
         * transclusion, comments, templates, arguments, tags hooks and parser
         * functions are untouched.
         *
         * @param string $text
         * @param Title $title
         * @param ParserOptions $options
         * @param array $params
         * @return string
         */
        public function getPreloadText( $text, Title $title, ParserOptions $options, $params = [] ) {
                $msg = new RawMessage( $text );
                $text = $msg->params( $params )->plain();

                # Parser (re)initialisation
                $magicScopeVariable = $this->lock();
                $this->startParse( $title, $options, self::OT_PLAIN, true );

                $flags = PPFrame::NO_ARGS | PPFrame::NO_TEMPLATES;
                $dom = $this->preprocessToDom( $text, self::PTD_FOR_INCLUSION );
                $text = $this->getPreprocessor()->newFrame()->expand( $dom, $flags );
                $text = $this->mStripState->unstripBoth( $text );
                return $text;
        }

        /**
         * Get a random string
         *
         * @return string
         * @deprecated since 1.26; use wfRandomString() instead.
         */
        public static function getRandomString() {
                wfDeprecated( __METHOD__, '1.26' );
                return wfRandomString( 16 );
        }

        /**
         * Set the current user.
         * Should only be used when doing pre-save transform.
         *
         * @param User|null $user User object or null (to reset)
         */
        public function setUser( $user ) {
                $this->mUser = $user;
        }

        /**
         * Accessor for mUniqPrefix.
         *
         * @return string
         * @deprecated since 1.26; use Parser::MARKER_PREFIX instead.
         */
        public function uniqPrefix() {
                wfDeprecated( __METHOD__, '1.26' );
                return self::MARKER_PREFIX;
        }

        /**
         * Set the context title
         *
         * @param Title $t
         */
        public function setTitle( $t ) {
                if ( !$t ) {
                        $t = Title::newFromText( 'NO TITLE' );
                }

                if ( $t->hasFragment() ) {
                        # Strip the fragment to avoid various odd effects
                        $this->mTitle = $t->createFragmentTarget( '' );
                } else {
                        $this->mTitle = $t;
                }
        }

        /**
         * Accessor for the Title object
         *
         * @return Title
         */
        public function getTitle() {
                return $this->mTitle;
        }

        /**
         * Accessor/mutator for the Title object
         *
         * @param Title $x Title object or null to just get the current one
         * @return Title
         */
        public function Title( $x = null ) {
                return wfSetVar( $this->mTitle, $x );
        }

        /**
         * Set the output type
         *
         * @param int $ot New value
         */
        public function setOutputType( $ot ) {
                $this->mOutputType = $ot;
                # Shortcut alias
                $this->ot = [
                        'html' => $ot == self::OT_HTML,
                        'wiki' => $ot == self::OT_WIKI,
                        'pre' => $ot == self::OT_PREPROCESS,
                        'plain' => $ot == self::OT_PLAIN,
                ];
        }

        /**
         * Accessor/mutator for the output type
         *
         * @param int|null $x New value or null to just get the current one
         * @return int
         */
        public function OutputType( $x = null ) {
                return wfSetVar( $this->mOutputType, $x );
        }

        /**
         * Get the ParserOutput object
         *
         * @return ParserOutput
         */
        public function getOutput() {
                return $this->mOutput;
        }

        /**
         * Get the ParserOptions object
         *
         * @return ParserOptions
         */
        public function getOptions() {
                return $this->mOptions;
        }

        /**
         * Accessor/mutator for the ParserOptions object
         *
         * @param ParserOptions $x New value or null to just get the current one
         * @return ParserOptions Current ParserOptions object
         */
        public function Options( $x = null ) {
                return wfSetVar( $this->mOptions, $x );
        }

        /**
         * @return int
         */
        public function nextLinkID() {
                return $this->mLinkID++;
        }

        /**
         * @param int $id
         */
        public function setLinkID( $id ) {
                $this->mLinkID = $id;
        }

        /**
         * Get a language object for use in parser functions such as {{FORMATNUM:}}
         * @return Language
         */
        public function getFunctionLang() {
                return $this->getTargetLanguage();
        }

        /**
         * Get the target language for the content being parsed. This is usually the
         * language that the content is in.
         *
         * @since 1.19
         *
         * @throws MWException
         * @return Language
         */
        public function getTargetLanguage() {
                $target = $this->mOptions->getTargetLanguage();

                if ( $target !== null ) {
                        return $target;
                } elseif ( $this->mOptions->getInterfaceMessage() ) {
                        return $this->mOptions->getUserLangObj();
                } elseif ( is_null( $this->mTitle ) ) {
                        throw new MWException( __METHOD__ . ': $this->mTitle is null' );
                }

                return $this->mTitle->getPageLanguage();
        }

        /**
         * Get the language object for language conversion
         * @return Language|null
         */
        public function getConverterLanguage() {
                return $this->getTargetLanguage();
        }

        /**
         * Get a User object either from $this->mUser, if set, or from the
         * ParserOptions object otherwise
         *
         * @return User
         */
        public function getUser() {
                if ( !is_null( $this->mUser ) ) {
                        return $this->mUser;
                }
                return $this->mOptions->getUser();
        }

        /**
         * Get a preprocessor object
         *
         * @return Preprocessor
         */
        public function getPreprocessor() {
                if ( !isset( $this->mPreprocessor ) ) {
                        $class = $this->mPreprocessorClass;
                        $this->mPreprocessor = new $class( $this );
                }
                return $this->mPreprocessor;
        }

        /**
         * Get a LinkRenderer instance to make links with
         *
         * @since 1.28
         * @return LinkRenderer
         */
        public function getLinkRenderer() {
                if ( !$this->mLinkRenderer ) {
                        $this->mLinkRenderer = MediaWikiServices::getInstance()
                                ->getLinkRendererFactory()->create();
                        $this->mLinkRenderer->setStubThreshold(
                                $this->getOptions()->getStubThreshold()
                        );
                }

                return $this->mLinkRenderer;
        }

        /**
         * Replaces all occurrences of HTML-style comments and the given tags
         * in the text with a random marker and returns the next text. The output
         * parameter $matches will be an associative array filled with data in
         * the form:
         *
         * @code
         *   'UNIQ-xxxxx' => [
         *     'element',
         *     'tag content',
         *     [ 'param' => 'x' ],
         *     '<element param="x">tag content</element>' ]
         * @endcode
         *
         * @param array $elements List of element names. Comments are always extracted.
         * @param string $text Source text string.
         * @param array $matches Out parameter, Array: extracted tags
         * @param string|null $uniq_prefix
         * @return string Stripped text
         * @since 1.26 The uniq_prefix argument is deprecated.
         */
        public static function extractTagsAndParams( $elements, $text, &$matches, $uniq_prefix = null ) {
                if ( $uniq_prefix !== null ) {
                        wfDeprecated( __METHOD__ . ' called with $prefix argument', '1.26' );
                }
                static $n = 1;
                $stripped = '';
                $matches = [];

                $taglist = implode( '|', $elements );
                $start = "/<($taglist)(\\s+[^>]*?|\\s*?)(\/?" . ">)|<(!--)/i";

                while ( $text != '' ) {
                        $p = preg_split( $start, $text, 2, PREG_SPLIT_DELIM_CAPTURE );
                        $stripped .= $p[0];
                        if ( count( $p ) < 5 ) {
                                break;
                        }
                        if ( count( $p ) > 5 ) {
                                # comment
                                $element = $p[4];
                                $attributes = '';
                                $close = '';
                                $inside = $p[5];
                        } else {
                                # tag
                                $element = $p[1];
                                $attributes = $p[2];
                                $close = $p[3];
                                $inside = $p[4];
                        }

                        $marker = self::MARKER_PREFIX . "-$element-" . sprintf( '%08X', $n++ ) . self::MARKER_SUFFIX;
                        $stripped .= $marker;

                        if ( $close === '/>' ) {
                                # Empty element tag, <tag />
                                $content = null;
                                $text = $inside;
                                $tail = null;
                        } else {
                                if ( $element === '!--' ) {
                                        $end = '/(-->)/';
                                } else {
                                        $end = "/(<\\/$element\\s*>)/i";
                                }
                                $q = preg_split( $end, $inside, 2, PREG_SPLIT_DELIM_CAPTURE );
                                $content = $q[0];
                                if ( count( $q ) < 3 ) {
                                        # No end tag -- let it run out to the end of the text.
                                        $tail = '';
                                        $text = '';
                                } else {
                                        $tail = $q[1];
                                        $text = $q[2];
                                }
                        }

                        $matches[$marker] = [ $element,
                                $content,
                                Sanitizer::decodeTagAttributes( $attributes ),
                                "<$element$attributes$close$content$tail" ];
                }
                return $stripped;
        }

        /**
         * Get a list of strippable XML-like elements
         *
         * @return array
         */
        public function getStripList() {
                return $this->mStripList;
        }

        /**
         * Add an item to the strip state
         * Returns the unique tag which must be inserted into the stripped text
         * The tag will be replaced with the original text in unstrip()
         *
         * @param string $text
         *
         * @return string
         */
        public function insertStripItem( $text ) {
                $marker = self::MARKER_PREFIX . "-item-{$this->mMarkerIndex}-" . self::MARKER_SUFFIX;
                $this->mMarkerIndex++;
                $this->mStripState->addGeneral( $marker, $text );
                return $marker;
        }

        /**
         * parse the wiki syntax used to render tables
         *
         * @private
         * @param string $text
         * @return string
         */
        public function doTableStuff( $text ) {

                $lines = StringUtils::explode( "\n", $text );
                $out = '';
                $td_history = []; # Is currently a td tag open?
                $last_tag_history = []; # Save history of last lag activated (td, th or caption)
                $tr_history = []; # Is currently a tr tag open?
                $tr_attributes = []; # history of tr attributes
                $has_opened_tr = []; # Did this table open a <tr> element?
                $indent_level = 0; # indent level of the table

                foreach ( $lines as $outLine ) {
                        $line = trim( $outLine );

                        if ( $line === '' ) { # empty line, go to next line
                                $out .= $outLine . "\n";
                                continue;
                        }

                        $first_character = $line[0];
                        $first_two = substr( $line, 0, 2 );
                        $matches = [];

                        if ( preg_match( '/^(:*)\s*\{\|(.*)$/', $line, $matches ) ) {
                                # First check if we are starting a new table
                                $indent_level = strlen( $matches[1] );

                                $attributes = $this->mStripState->unstripBoth( $matches[2] );
                                $attributes = Sanitizer::fixTagAttributes( $attributes, 'table' );

                                $outLine = str_repeat( '<dl><dd>', $indent_level ) . "<table{$attributes}>";
                                array_push( $td_history, false );
                                array_push( $last_tag_history, '' );
                                array_push( $tr_history, false );
                                array_push( $tr_attributes, '' );
                                array_push( $has_opened_tr, false );
                        } elseif ( count( $td_history ) == 0 ) {
                                # Don't do any of the following
                                $out .= $outLine . "\n";
                                continue;
                        } elseif ( $first_two === '|}' ) {
                                # We are ending a table
                                $line = '</table>' . substr( $line, 2 );
                                $last_tag = array_pop( $last_tag_history );

                                if ( !array_pop( $has_opened_tr ) ) {
                                        $line = "<tr><td></td></tr>{$line}";
                                }

                                if ( array_pop( $tr_history ) ) {
                                        $line = "</tr>{$line}";
                                }

                                if ( array_pop( $td_history ) ) {
                                        $line = "</{$last_tag}>{$line}";
                                }
                                array_pop( $tr_attributes );
                                $outLine = $line . str_repeat( '</dd></dl>', $indent_level );
                        } elseif ( $first_two === '|-' ) {
                                # Now we have a table row
                                $line = preg_replace( '#^\|-+#', '', $line );

                                # Whats after the tag is now only attributes
                                $attributes = $this->mStripState->unstripBoth( $line );
                                $attributes = Sanitizer::fixTagAttributes( $attributes, 'tr' );
                                array_pop( $tr_attributes );
                                array_push( $tr_attributes, $attributes );

                                $line = '';
                                $last_tag = array_pop( $last_tag_history );
                                array_pop( $has_opened_tr );
                                array_push( $has_opened_tr, true );

                                if ( array_pop( $tr_history ) ) {
                                        $line = '</tr>';
                                }

                                if ( array_pop( $td_history ) ) {
                                        $line = "</{$last_tag}>{$line}";
                                }

                                $outLine = $line;
                                array_push( $tr_history, false );
                                array_push( $td_history, false );
                                array_push( $last_tag_history, '' );
                        } elseif ( $first_character === '|'
                                || $first_character === '!'
                                || $first_two === '|+'
                        ) {
                                # This might be cell elements, td, th or captions
                                if ( $first_two === '|+' ) {
                                        $first_character = '+';
                                        $line = substr( $line, 2 );
                                } else {
                                        $line = substr( $line, 1 );
                                }

                                // Implies both are valid for table headings.
                                if ( $first_character === '!' ) {
                                        $line = StringUtils::replaceMarkup( '!!', '||', $line );
                                }

                                # Split up multiple cells on the same line.
                                # FIXME : This can result in improper nesting of tags processed
                                # by earlier parser steps.
                                $cells = explode( '||', $line );

                                $outLine = '';

                                # Loop through each table cell
                                foreach ( $cells as $cell ) {
                                        $previous = '';
                                        if ( $first_character !== '+' ) {
                                                $tr_after = array_pop( $tr_attributes );
                                                if ( !array_pop( $tr_history ) ) {
                                                        $previous = "<tr{$tr_after}>\n";
                                                }
                                                array_push( $tr_history, true );
                                                array_push( $tr_attributes, '' );
                                                array_pop( $has_opened_tr );
                                                array_push( $has_opened_tr, true );
                                        }

                                        $last_tag = array_pop( $last_tag_history );

                                        if ( array_pop( $td_history ) ) {
                                                $previous = "</{$last_tag}>\n{$previous}";
                                        }

                                        if ( $first_character === '|' ) {
                                                $last_tag = 'td';
                                        } elseif ( $first_character === '!' ) {
                                                $last_tag = 'th';
                                        } elseif ( $first_character === '+' ) {
                                                $last_tag = 'caption';
                                        } else {
                                                $last_tag = '';
                                        }

                                        array_push( $last_tag_history, $last_tag );

                                        # A cell could contain both parameters and data
                                        $cell_data = explode( '|', $cell, 2 );

                                        # T2553: Note that a '|' inside an invalid link should not
                                        # be mistaken as delimiting cell parameters
                                        # Bug T153140: Neither should language converter markup.
                                        if ( preg_match( '/\[\[|-\{/', $cell_data[0] ) === 1 ) {
                                                $cell = "{$previous}<{$last_tag}>{$cell}";
                                        } elseif ( count( $cell_data ) == 1 ) {
                                                $cell = "{$previous}<{$last_tag}>{$cell_data[0]}";
                                        } else {
                                                $attributes = $this->mStripState->unstripBoth( $cell_data[0] );
                                                $attributes = Sanitizer::fixTagAttributes( $attributes, $last_tag );
                                                $cell = "{$previous}<{$last_tag}{$attributes}>{$cell_data[1]}";
                                        }

                                        $outLine .= $cell;
                                        array_push( $td_history, true );
                                }
                        }
                        $out .= $outLine . "\n";
                }

                # Closing open td, tr && table
                while ( count( $td_history ) > 0 ) {
                        if ( array_pop( $td_history ) ) {
                                $out .= "</td>\n";
                        }
                        if ( array_pop( $tr_history ) ) {
                                $out .= "</tr>\n";
                        }
                        if ( !array_pop( $has_opened_tr ) ) {
                                $out .= "<tr><td></td></tr>\n";
                        }

                        $out .= "</table>\n";
                }

                # Remove trailing line-ending (b/c)
                if ( substr( $out, -1 ) === "\n" ) {
                        $out = substr( $out, 0, -1 );
                }

                # special case: don't return empty table
                if ( $out === "<table>\n<tr><td></td></tr>\n</table>" ) {
                        $out = '';
                }

                return $out;
        }

        /**
         * Helper function for parse() that transforms wiki markup into half-parsed
         * HTML. Only called for $mOutputType == self::OT_HTML.
         *
         * @private
         *
         * @param string $text The text to parse
         * @param bool $isMain Whether this is being called from the main parse() function
         * @param PPFrame|bool $frame A pre-processor frame
         *
         * @return string
         */
        public function internalParse( $text, $isMain = true, $frame = false ) {

                $origText = $text;

                // Avoid PHP 7.1 warning from passing $this by reference
                $parser = $this;

                # Hook to suspend the parser in this state
                if ( !Hooks::run( 'ParserBeforeInternalParse', [ &$parser, &$text, &$this->mStripState ] ) ) {
                        return $text;
                }

                # if $frame is provided, then use $frame for replacing any variables
                if ( $frame ) {
                        # use frame depth to infer how include/noinclude tags should be handled
                        # depth=0 means this is the top-level document; otherwise it's an included document
                        if ( !$frame->depth ) {
                                $flag = 0;
                        } else {
                                $flag = Parser::PTD_FOR_INCLUSION;
                        }
                        $dom = $this->preprocessToDom( $text, $flag );
                        $text = $frame->expand( $dom );
                } else {
                        # if $frame is not provided, then use old-style replaceVariables
                        $text = $this->replaceVariables( $text );
                }

                Hooks::run( 'InternalParseBeforeSanitize', [ &$parser, &$text, &$this->mStripState ] );
                $text = Sanitizer::removeHTMLtags(
                        $text,
                        [ $this, 'attributeStripCallback' ],
                        false,
                        array_keys( $this->mTransparentTagHooks ),
                        [],
                        [ $this, 'addTrackingCategory' ]
                );
                Hooks::run( 'InternalParseBeforeLinks', [ &$parser, &$text, &$this->mStripState ] );

                # Tables need to come after variable replacement for things to work
                # properly; putting them before other transformations should keep
                # exciting things like link expansions from showing up in surprising
                # places.
                $text = $this->doTableStuff( $text );

                $text = preg_replace( '/(^|\n)-----*/', '\\1<hr />', $text );

                $text = $this->doDoubleUnderscore( $text );

                $text = $this->doHeadings( $text );
                $text = $this->replaceInternalLinks( $text );
                $text = $this->doAllQuotes( $text );
                $text = $this->replaceExternalLinks( $text );

                # replaceInternalLinks may sometimes leave behind
                # absolute URLs, which have to be masked to hide them from replaceExternalLinks
                $text = str_replace( self::MARKER_PREFIX . 'NOPARSE', '', $text );

                $text = $this->doMagicLinks( $text );
                $text = $this->formatHeadings( $text, $origText, $isMain );

                return $text;
        }

        /**
         * Helper function for parse() that transforms half-parsed HTML into fully
         * parsed HTML.
         *
         * @param string $text
         * @param bool $isMain
         * @param bool $linestart
         * @return string
         */
        private function internalParseHalfParsed( $text, $isMain = true, $linestart = true ) {
                $text = $this->mStripState->unstripGeneral( $text );

                // Avoid PHP 7.1 warning from passing $this by reference
                $parser = $this;

                if ( $isMain ) {
                        Hooks::run( 'ParserAfterUnstrip', [ &$parser, &$text ] );
                }

                # Clean up special characters, only run once, next-to-last before doBlockLevels
                $fixtags = [
                        # French spaces, last one Guillemet-left
                        # only if there is something before the space
                        '/(.) (?=\\?|:|;|!|%|\\302\\273)/' => '\\1&#160;',
                        # french spaces, Guillemet-right
                        '/(\\302\\253) /' => '\\1&#160;',
                        '/&#160;(!\s*important)/' => ' \\1', # Beware of CSS magic word !important, T13874.
                ];
                $text = preg_replace( array_keys( $fixtags ), array_values( $fixtags ), $text );

                $text = $this->doBlockLevels( $text, $linestart );

                $this->replaceLinkHolders( $text );

                /**
                 * The input doesn't get language converted if
                 * a) It's disabled
                 * b) Content isn't converted
                 * c) It's a conversion table
                 * d) it is an interface message (which is in the user language)
                 */
                if ( !( $this->mOptions->getDisableContentConversion()
                        || isset( $this->mDoubleUnderscores['nocontentconvert'] ) )
                ) {
                        if ( !$this->mOptions->getInterfaceMessage() ) {
                                # The position of the convert() call should not be changed. it
                                # assumes that the links are all replaced and the only thing left
                                # is the <nowiki> mark.
                                $text = $this->getConverterLanguage()->convert( $text );
                        }
                }

                $text = $this->mStripState->unstripNoWiki( $text );

                if ( $isMain ) {
                        Hooks::run( 'ParserBeforeTidy', [ &$parser, &$text ] );
                }

                $text = $this->replaceTransparentTags( $text );
                $text = $this->mStripState->unstripGeneral( $text );

                $text = Sanitizer::normalizeCharReferences( $text );

                if ( MWTidy::isEnabled() ) {
                        if ( $this->mOptions->getTidy() ) {
                                $text = MWTidy::tidy( $text );
                        }
                } else {
                        # attempt to sanitize at least some nesting problems
                        # (T4702 and quite a few others)
                        $tidyregs = [
                                # ''Something [http://www.cool.com cool''] -->
                                # <i>Something</i><a href="http://www.cool.com"..><i>cool></i></a>
                                '/(<([bi])>)(<([bi])>)?([^<]*)(<\/?a[^<]*>)([^<]*)(<\/\\4>)?(<\/\\2>)/' =>
                                '\\1\\3\\5\\8\\9\\6\\1\\3\\7\\8\\9',
                                # fix up an anchor inside another anchor, only
                                # at least for a single single nested link (T5695)
                                '/(<a[^>]+>)([^<]*)(<a[^>]+>[^<]*)<\/a>(.*)<\/a>/' =>
                                '\\1\\2</a>\\3</a>\\1\\4</a>',
                                # fix div inside inline elements- doBlockLevels won't wrap a line which
                                # contains a div, so fix it up here; replace
                                # div with escaped text
                                '/(<([aib]) [^>]+>)([^<]*)(<div([^>]*)>)(.*)(<\/div>)([^<]*)(<\/\\2>)/' =>
                                '\\1\\3&lt;div\\5&gt;\\6&lt;/div&gt;\\8\\9',
                                # remove empty italic or bold tag pairs, some
                                # introduced by rules above
                                '/<([bi])><\/\\1>/' => '',
                        ];

                        $text = preg_replace(
                                array_keys( $tidyregs ),
                                array_values( $tidyregs ),
                                $text );
                }

                if ( $isMain ) {
                        Hooks::run( 'ParserAfterTidy', [ &$parser, &$text ] );
                }

                return $text;
        }

        /**
         * Replace special strings like "ISBN xxx" and "RFC xxx" with
         * magic external links.
         *
         * DML
         * @private
         *
         * @param string $text
         *
         * @return string
         */
        public function doMagicLinks( $text ) {
                $prots = wfUrlProtocolsWithoutProtRel();
                $urlChar = self::EXT_LINK_URL_CLASS;
                $addr = self::EXT_LINK_ADDR;
                $space = self::SPACE_NOT_NL; #  non-newline space
                $spdash = "(?:-|$space)"; # a dash or a non-newline space
                $spaces = "$space++"; # possessive match of 1 or more spaces
                $text = preg_replace_callback(
                        '!(?:                        # Start cases
                                (<a[ \t\r\n>].*?</a>) |    # m[1]: Skip link text
                                (<.*?>) |                  # m[2]: Skip stuff inside HTML elements' . "
                                (\b                        # m[3]: Free external links
                                        (?i:$prots)
                                        ($addr$urlChar*)         # m[4]: Post-protocol path
                                ) |
                                \b(?:RFC|PMID) $spaces     # m[5]: RFC or PMID, capture number
                                        ([0-9]+)\b |
                                \bISBN $spaces (           # m[6]: ISBN, capture number
                                        (?: 97[89] $spdash? )?   #  optional 13-digit ISBN prefix
                                        (?: [0-9]  $spdash? ){9} #  9 digits with opt. delimiters
                                        [0-9Xx]                  #  check digit
                                )\b
                        )!xu", [ $this, 'magicLinkCallback' ], $text );
                return $text;
        }

        /**
         * @throws MWException
         * @param array $m
         * @return HTML|string
         */
        public function magicLinkCallback( $m ) {
                if ( isset( $m[1] ) && $m[1] !== '' ) {
                        # Skip anchor
                        return $m[0];
                } elseif ( isset( $m[2] ) && $m[2] !== '' ) {
                        # Skip HTML element
                        return $m[0];
                } elseif ( isset( $m[3] ) && $m[3] !== '' ) {
                        # Free external link
                        return $this->makeFreeExternalLink( $m[0], strlen( $m[4] ) );
                } elseif ( isset( $m[5] ) && $m[5] !== '' ) {
                        # RFC or PMID
                        if ( substr( $m[0], 0, 3 ) === 'RFC' ) {
                                if ( !$this->mOptions->getMagicRFCLinks() ) {
                                        return $m[0];
                                }
                                $keyword = 'RFC';
                                $urlmsg = 'rfcurl';
                                $cssClass = 'mw-magiclink-rfc';
                                $trackingCat = 'magiclink-tracking-rfc';
                                $id = $m[5];
                        } elseif ( substr( $m[0], 0, 4 ) === 'PMID' ) {
                                if ( !$this->mOptions->getMagicPMIDLinks() ) {
                                        return $m[0];
                                }
                                $keyword = 'PMID';
                                $urlmsg = 'pubmedurl';
                                $cssClass = 'mw-magiclink-pmid';
                                $trackingCat = 'magiclink-tracking-pmid';
                                $id = $m[5];
                        } else {
                                throw new MWException( __METHOD__ . ': unrecognised match type "' .
                                        substr( $m[0], 0, 20 ) . '"' );
                        }
                        $url = wfMessage( $urlmsg, $id )->inContentLanguage()->text();
                        $this->addTrackingCategory( $trackingCat );
                        return Linker::makeExternalLink( $url, "{$keyword} {$id}", true, $cssClass, [], $this->mTitle );
                } elseif ( isset( $m[6] ) && $m[6] !== ''
                        && $this->mOptions->getMagicISBNLinks()
                ) {
                        # ISBN
                        $isbn = $m[6];
                        $space = self::SPACE_NOT_NL; #  non-newline space
                        $isbn = preg_replace( "/$space/", ' ', $isbn );
                        $num = strtr( $isbn, [
                                '-' => '',
                                ' ' => '',
                                'x' => 'X',
                        ] );
                        $this->addTrackingCategory( 'magiclink-tracking-isbn' );
                        return $this->getLinkRenderer()->makeKnownLink(
                                SpecialPage::getTitleFor( 'Booksources', $num ),
                                "ISBN $isbn",
                                [
                                        'class' => 'internal mw-magiclink-isbn',
                                        'title' => false // suppress title attribute
                                ]
                        );
                } else {
                        return $m[0];
                }
        }

        /**
         * Make a free external link, given a user-supplied URL
         *
         * @param string $url
         * @param int $numPostProto
         *   The number of characters after the protocol.
         * @return string HTML
         * @private
         */
        public function makeFreeExternalLink( $url, $numPostProto ) {
                $trail = '';

                # The characters '<' and '>' (which were escaped by
                # removeHTMLtags()) should not be included in
                # URLs, per RFC 2396.
                # Make &nbsp; terminate a URL as well (bug T84937)
                $m2 = [];
                if ( preg_match(
                        '/&(lt|gt|nbsp|#x0*(3[CcEe]|[Aa]0)|#0*(60|62|160));/',
                        $url,
                        $m2,
                        PREG_OFFSET_CAPTURE
                ) ) {
                        $trail = substr( $url, $m2[0][1] ) . $trail;
                        $url = substr( $url, 0, $m2[0][1] );
                }

                # Move trailing punctuation to $trail
                $sep = ',;\.:!?';
                # If there is no left bracket, then consider right brackets fair game too
                if ( strpos( $url, '(' ) === false ) {
                        $sep .= ')';
                }

                $urlRev = strrev( $url );
                $numSepChars = strspn( $urlRev, $sep );
                # Don't break a trailing HTML entity by moving the ; into $trail
                # This is in hot code, so use substr_compare to avoid having to
                # create a new string object for the comparison
                if ( $numSepChars && substr_compare( $url, ";", -$numSepChars, 1 ) === 0 ) {
                        # more optimization: instead of running preg_match with a $
                        # anchor, which can be slow, do the match on the reversed
                        # string starting at the desired offset.
                        # un-reversed regexp is: /&([a-z]+|#x[\da-f]+|#\d+)$/i
                        if ( preg_match( '/\G([a-z]+|[\da-f]+x#|\d+#)&/i', $urlRev, $m2, 0, $numSepChars ) ) {
                                $numSepChars--;
                        }
                }
                if ( $numSepChars ) {
                        $trail = substr( $url, -$numSepChars ) . $trail;
                        $url = substr( $url, 0, -$numSepChars );
                }

                # Verify that we still have a real URL after trail removal, and
                # not just lone protocol
                if ( strlen( $trail ) >= $numPostProto ) {
                        return $url . $trail;
                }

                $url = Sanitizer::cleanUrl( $url );

                # Is this an external image?
                $text = $this->maybeMakeExternalImage( $url );
                if ( $text === false ) {
                        # Not an image, make a link
                        $text = Linker::makeExternalLink( $url,
                                $this->getConverterLanguage()->markNoConversion( $url, true ),
                                true, 'free',
                                $this->getExternalLinkAttribs( $url ), $this->mTitle );
                        # Register it in the output object...
                        # Replace unnecessary URL escape codes with their equivalent characters
                        $pasteurized = self::normalizeLinkUrl( $url );
                        $this->mOutput->addExternalLink( $pasteurized );
                }
                return $text . $trail;
        }

        /**
         * Parse headers and return html
         *
         * @private
         *
         * @param string $text
         *
         * @return string
         */
        public function doHeadings( $text ) {
                for ( $i = 6; $i >= 1; --$i ) {
                        $h = str_repeat( '=', $i );
                        $text = preg_replace( "/^$h(.+)$h\\s*$/m", "<h$i>\\1</h$i>", $text );
                }
                return $text;
        }

        /**
         * Replace single quotes with HTML markup
         * @private
         *
         * @param string $text
         *
         * @return string The altered text
         */
        public function doAllQuotes( $text ) {
                $outtext = '';
                $lines = StringUtils::explode( "\n", $text );
                foreach ( $lines as $line ) {
                        $outtext .= $this->doQuotes( $line ) . "\n";
                }
                $outtext = substr( $outtext, 0, -1 );
                return $outtext;
        }

        /**
         * Helper function for doAllQuotes()
         *
         * @param string $text
         *
         * @return string
         */
        public function doQuotes( $text ) {
                $arr = preg_split( "/(''+)/", $text, -1, PREG_SPLIT_DELIM_CAPTURE );
                $countarr = count( $arr );
                if ( $countarr == 1 ) {
                        return $text;
                }

                // First, do some preliminary work. This may shift some apostrophes from
                // being mark-up to being text. It also counts the number of occurrences
                // of bold and italics mark-ups.
                $numbold = 0;
                $numitalics = 0;
                for ( $i = 1; $i < $countarr; $i += 2 ) {
                        $thislen = strlen( $arr[$i] );
                        // If there are ever four apostrophes, assume the first is supposed to
                        // be text, and the remaining three constitute mark-up for bold text.
                        // (T15227: ''''foo'''' turns into ' ''' foo ' ''')
                        if ( $thislen == 4 ) {
                                $arr[$i - 1] .= "'";
                                $arr[$i] = "'''";
                                $thislen = 3;
                        } elseif ( $thislen > 5 ) {
                                // If there are more than 5 apostrophes in a row, assume they're all
                                // text except for the last 5.
                                // (T15227: ''''''foo'''''' turns into ' ''''' foo ' ''''')
                                $arr[$i - 1] .= str_repeat( "'", $thislen - 5 );
                                $arr[$i] = "'''''";
                                $thislen = 5;
                        }
                        // Count the number of occurrences of bold and italics mark-ups.
                        if ( $thislen == 2 ) {
                                $numitalics++;
                        } elseif ( $thislen == 3 ) {
                                $numbold++;
                        } elseif ( $thislen == 5 ) {
                                $numitalics++;
                                $numbold++;
                        }
                }

                // If there is an odd number of both bold and italics, it is likely
                // that one of the bold ones was meant to be an apostrophe followed
                // by italics. Which one we cannot know for certain, but it is more
                // likely to be one that has a single-letter word before it.
                if ( ( $numbold % 2 == 1 ) && ( $numitalics % 2 == 1 ) ) {
                        $firstsingleletterword = -1;
                        $firstmultiletterword = -1;
                        $firstspace = -1;
                        for ( $i = 1; $i < $countarr; $i += 2 ) {
                                if ( strlen( $arr[$i] ) == 3 ) {
                                        $x1 = substr( $arr[$i - 1], -1 );
                                        $x2 = substr( $arr[$i - 1], -2, 1 );
                                        if ( $x1 === ' ' ) {
                                                if ( $firstspace == -1 ) {
                                                        $firstspace = $i;
                                                }
                                        } elseif ( $x2 === ' ' ) {
                                                $firstsingleletterword = $i;
                                                // if $firstsingleletterword is set, we don't
                                                // look at the other options, so we can bail early.
                                                break;
                                        } else {
                                                if ( $firstmultiletterword == -1 ) {
                                                        $firstmultiletterword = $i;
                                                }
                                        }
                                }
                        }

                        // If there is a single-letter word, use it!
                        if ( $firstsingleletterword > -1 ) {
                                $arr[$firstsingleletterword] = "''";
                                $arr[$firstsingleletterword - 1] .= "'";
                        } elseif ( $firstmultiletterword > -1 ) {
                                // If not, but there's a multi-letter word, use that one.
                                $arr[$firstmultiletterword] = "''";
                                $arr[$firstmultiletterword - 1] .= "'";
                        } elseif ( $firstspace > -1 ) {
                                // ... otherwise use the first one that has neither.
                                // (notice that it is possible for all three to be -1 if, for example,
                                // there is only one pentuple-apostrophe in the line)
                                $arr[$firstspace] = "''";
                                $arr[$firstspace - 1] .= "'";
                        }
                }

                // Now let's actually convert our apostrophic mush to HTML!
                $output = '';
                $buffer = '';
                $state = '';
                $i = 0;
                foreach ( $arr as $r ) {
                        if ( ( $i % 2 ) == 0 ) {
                                if ( $state === 'both' ) {
                                        $buffer .= $r;
                                } else {
                                        $output .= $r;
                                }
                        } else {
                                $thislen = strlen( $r );
                                if ( $thislen == 2 ) {
                                        if ( $state === 'i' ) {
                                                $output .= '</i>';
                                                $state = '';
                                        } elseif ( $state === 'bi' ) {
                                                $output .= '</i>';
                                                $state = 'b';
                                        } elseif ( $state === 'ib' ) {
                                                $output .= '</b></i><b>';
                                                $state = 'b';
                                        } elseif ( $state === 'both' ) {
                                                $output .= '<b><i>' . $buffer . '</i>';
                                                $state = 'b';
                                        } else { // $state can be 'b' or ''
                                                $output .= '<i>';
                                                $state .= 'i';
                                        }
                                } elseif ( $thislen == 3 ) {
                                        if ( $state === 'b' ) {
                                                $output .= '</b>';
                                                $state = '';
                                        } elseif ( $state === 'bi' ) {
                                                $output .= '</i></b><i>';
                                                $state = 'i';
                                        } elseif ( $state === 'ib' ) {
                                                $output .= '</b>';
                                                $state = 'i';
                                        } elseif ( $state === 'both' ) {
                                                $output .= '<i><b>' . $buffer . '</b>';
                                                $state = 'i';
                                        } else { // $state can be 'i' or ''
                                                $output .= '<b>';
                                                $state .= 'b';
                                        }
                                } elseif ( $thislen == 5 ) {
                                        if ( $state === 'b' ) {
                                                $output .= '</b><i>';
                                                $state = 'i';
                                        } elseif ( $state === 'i' ) {
                                                $output .= '</i><b>';
                                                $state = 'b';
                                        } elseif ( $state === 'bi' ) {
                                                $output .= '</i></b>';
                                                $state = '';
                                        } elseif ( $state === 'ib' ) {
                                                $output .= '</b></i>';
                                                $state = '';
                                        } elseif ( $state === 'both' ) {
                                                $output .= '<i><b>' . $buffer . '</b></i>';
                                                $state = '';
                                        } else { // ($state == '')
                                                $buffer = '';
                                                $state = 'both';
                                        }
                                }
                        }
                        $i++;
                }
                // Now close all remaining tags.  Notice that the order is important.
                if ( $state === 'b' || $state === 'ib' ) {
                        $output .= '</b>';
                }
                if ( $state === 'i' || $state === 'bi' || $state === 'ib' ) {
                        $output .= '</i>';
                }
                if ( $state === 'bi' ) {
                        $output .= '</b>';
                }
                // There might be lonely ''''', so make sure we have a buffer
                if ( $state === 'both' && $buffer ) {
                        $output .= '<b><i>' . $buffer . '</i></b>';
                }
                return $output;
        }

        /**
         * Replace external links (REL)
         *
         * Note: this is all very hackish and the order of execution matters a lot.
         * Make sure to run tests/parser/parserTests.php if you change this code.
         *
         * @private
         *
         * @param string $text
         *
         * @throws MWException
         * @return string
         */
        public function replaceExternalLinks( $text ) {

                $bits = preg_split( $this->mExtLinkBracketedRegex, $text, -1, PREG_SPLIT_DELIM_CAPTURE );
                if ( $bits === false ) {
                        throw new MWException( "PCRE needs to be compiled with "
                                . "--enable-unicode-properties in order for MediaWiki to function" );
                }
                $s = array_shift( $bits );

                $i = 0;
                while ( $i < count( $bits ) ) {
                        $url = $bits[$i++];
                        $i++; // protocol
                        $text = $bits[$i++];
                        $trail = $bits[$i++];

                        # The characters '<' and '>' (which were escaped by
                        # removeHTMLtags()) should not be included in
                        # URLs, per RFC 2396.
                        $m2 = [];
                        if ( preg_match( '/&(lt|gt);/', $url, $m2, PREG_OFFSET_CAPTURE ) ) {
                                $text = substr( $url, $m2[0][1] ) . ' ' . $text;
                                $url = substr( $url, 0, $m2[0][1] );
                        }

                        # If the link text is an image URL, replace it with an <img> tag
                        # This happened by accident in the original parser, but some people used it extensively
                        $img = $this->maybeMakeExternalImage( $text );
                        if ( $img !== false ) {
                                $text = $img;
                        }

                        $dtrail = '';

                        # Set linktype for CSS - if URL==text, link is essentially free
                        $linktype = ( $text === $url ) ? 'free' : 'text';

                        # No link text, e.g. [http://domain.tld/some.link]
                        if ( $text == '' ) {
                                # Autonumber
                                $langObj = $this->getTargetLanguage();
                                $text = '[' . $langObj->formatNum( ++$this->mAutonumber ) . ']';
                                $linktype = 'autonumber';
                        } else {
                                # Have link text, e.g. [http://domain.tld/some.link text]s
                                # Check for trail
                                list( $dtrail, $trail ) = Linker::splitTrail( $trail );
                        }

                        $text = $this->getConverterLanguage()->markNoConversion( $text );

                        $url = Sanitizer::cleanUrl( $url );

                        # Use the encoded URL
                        # This means that users can paste URLs directly into the text
                        # Funny characters like ö aren't valid in URLs anyway
                        # This was changed in August 2004
                        $s .= Linker::makeExternalLink( $url, $text, false, $linktype,
                                $this->getExternalLinkAttribs( $url ), $this->mTitle ) . $dtrail . $trail;

                        # Register link in the output object.
                        # Replace unnecessary URL escape codes with the referenced character
                        # This prevents spammers from hiding links from the filters
                        $pasteurized = self::normalizeLinkUrl( $url );
                        $this->mOutput->addExternalLink( $pasteurized );
                }

                return $s;
        }

        /**
         * Get the rel attribute for a particular external link.
         *
         * @since 1.21
         * @param string|bool $url Optional URL, to extract the domain from for rel =>
         *   nofollow if appropriate
         * @param Title $title Optional Title, for wgNoFollowNsExceptions lookups
         * @return string|null Rel attribute for $url
         */
        public static function getExternalLinkRel( $url = false, $title = null ) {
                global $wgNoFollowLinks, $wgNoFollowNsExceptions, $wgNoFollowDomainExceptions;
                $ns = $title ? $title->getNamespace() : false;
                if ( $wgNoFollowLinks && !in_array( $ns, $wgNoFollowNsExceptions )
                        && !wfMatchesDomainList( $url, $wgNoFollowDomainExceptions )
                ) {
                        return 'nofollow';
                }
                return null;
        }

        /**
         * Get an associative array of additional HTML attributes appropriate for a
         * particular external link.  This currently may include rel => nofollow
         * (depending on configuration, namespace, and the URL's domain) and/or a
         * target attribute (depending on configuration).
         *
         * @param string $url URL to extract the domain from for rel =>
         *   nofollow if appropriate
         * @return array Associative array of HTML attributes
         */
        public function getExternalLinkAttribs( $url ) {
                $attribs = [];
                $rel = self::getExternalLinkRel( $url, $this->mTitle );

                $target = $this->mOptions->getExternalLinkTarget();
                if ( $target ) {
                        $attribs['target'] = $target;
                        if ( !in_array( $target, [ '_self', '_parent', '_top' ] ) ) {
                                // T133507. New windows can navigate parent cross-origin.
                                // Including noreferrer due to lacking browser
                                // support of noopener. Eventually noreferrer should be removed.
                                if ( $rel !== '' ) {
                                        $rel .= ' ';
                                }
                                $rel .= 'noreferrer noopener';
                        }
                }
                $attribs['rel'] = $rel;
                return $attribs;
        }

        /**
         * Replace unusual escape codes in a URL with their equivalent characters
         *
         * This generally follows the syntax defined in RFC 3986, with special
         * consideration for HTTP query strings.
         *
         * @param string $url
         * @return string
         */
        public static function normalizeLinkUrl( $url ) {
                # First, make sure unsafe characters are encoded
                $url = preg_replace_callback( '/[\x00-\x20"<>\[\\\\\]^`{|}\x7F-\xFF]/',
                        function ( $m ) {
                                return rawurlencode( $m[0] );
                        },
                        $url
                );

                $ret = '';
                $end = strlen( $url );

                # Fragment part - 'fragment'
                $start = strpos( $url, '#' );
                if ( $start !== false && $start < $end ) {
                        $ret = self::normalizeUrlComponent(
                                substr( $url, $start, $end - $start ), '"#%<>[\]^`{|}' ) . $ret;
                        $end = $start;
                }

                # Query part - 'query' minus &=+;
                $start = strpos( $url, '?' );
                if ( $start !== false && $start < $end ) {
                        $ret = self::normalizeUrlComponent(
                                substr( $url, $start, $end - $start ), '"#%<>[\]^`{|}&=+;' ) . $ret;
                        $end = $start;
                }

                # Scheme and path part - 'pchar'
                # (we assume no userinfo or encoded colons in the host)
                $ret = self::normalizeUrlComponent(
                        substr( $url, 0, $end ), '"#%<>[\]^`{|}/?' ) . $ret;

                return $ret;
        }

        private static function normalizeUrlComponent( $component, $unsafe ) {
                $callback = function ( $matches ) use ( $unsafe ) {
                        $char = urldecode( $matches[0] );
                        $ord = ord( $char );
                        if ( $ord > 32 && $ord < 127 && strpos( $unsafe, $char ) === false ) {
                                # Unescape it
                                return $char;
                        } else {
                                # Leave it escaped, but use uppercase for a-f
                                return strtoupper( $matches[0] );
                        }
                };
                return preg_replace_callback( '/%[0-9A-Fa-f]{2}/', $callback, $component );
        }

        /**
         * make an image if it's allowed, either through the global
         * option, through the exception, or through the on-wiki whitelist
         *
         * @param string $url
         *
         * @return string
         */
        private function maybeMakeExternalImage( $url ) {
                $imagesfrom = $this->mOptions->getAllowExternalImagesFrom();
                $imagesexception = !empty( $imagesfrom );
                $text = false;
                # $imagesfrom could be either a single string or an array of strings, parse out the latter
                if ( $imagesexception && is_array( $imagesfrom ) ) {
                        $imagematch = false;
                        foreach ( $imagesfrom as $match ) {
                                if ( strpos( $url, $match ) === 0 ) {
                                        $imagematch = true;
                                        break;
                                }
                        }
                } elseif ( $imagesexception ) {
                        $imagematch = ( strpos( $url, $imagesfrom ) === 0 );
                } else {
                        $imagematch = false;
                }

                if ( $this->mOptions->getAllowExternalImages()
                        || ( $imagesexception && $imagematch )
                ) {
                        if ( preg_match( self::EXT_IMAGE_REGEX, $url ) ) {
                                # Image found
                                $text = Linker::makeExternalImage( $url );
                        }
                }
                if ( !$text && $this->mOptions->getEnableImageWhitelist()
                        && preg_match( self::EXT_IMAGE_REGEX, $url )
                ) {
                        $whitelist = explode(
                                "\n",
                                wfMessage( 'external_image_whitelist' )->inContentLanguage()->text()
                        );

                        foreach ( $whitelist as $entry ) {
                                # Sanitize the regex fragment, make it case-insensitive, ignore blank entries/comments
                                if ( strpos( $entry, '#' ) === 0 || $entry === '' ) {
                                        continue;
                                }
                                if ( preg_match( '/' . str_replace( '/', '\\/', $entry ) . '/i', $url ) ) {
                                        # Image matches a whitelist entry
                                        $text = Linker::makeExternalImage( $url );
                                        break;
                                }
                        }
                }
                return $text;
        }

        /**
         * Process [[ ]] wikilinks
         *
         * @param string $s
         *
         * @return string Processed text
         *
         * @private
         */
        public function replaceInternalLinks( $s ) {
                $this->mLinkHolders->merge( $this->replaceInternalLinks2( $s ) );
                return $s;
        }

        /**
         * Process [[ ]] wikilinks (RIL)
         * @param string $s
         * @throws MWException
         * @return LinkHolderArray
         *
         * @private
         */
        public function replaceInternalLinks2( &$s ) {
                global $wgExtraInterlanguageLinkPrefixes;

                static $tc = false, $e1, $e1_img;
                # the % is needed to support urlencoded titles as well
                if ( !$tc ) {
                        $tc = Title::legalChars() . '#%';
                        # Match a link having the form [[namespace:link|alternate]]trail
                        $e1 = "/^([{$tc}]+)(?:\\|(.+?))?]](.*)\$/sD";
                        # Match cases where there is no "]]", which might still be images
                        $e1_img = "/^([{$tc}]+)\\|(.*)\$/sD";
                }

                $holders = new LinkHolderArray( $this );

                # split the entire text string on occurrences of [[
                $a = StringUtils::explode( '[[', ' ' . $s );
                # get the first element (all text up to first [[), and remove the space we added
                $s = $a->current();
                $a->next();
                $line = $a->current(); # Workaround for broken ArrayIterator::next() that returns "void"
                $s = substr( $s, 1 );

                $useLinkPrefixExtension = $this->getTargetLanguage()->linkPrefixExtension();
                $e2 = null;
                if ( $useLinkPrefixExtension ) {
                        # Match the end of a line for a word that's not followed by whitespace,
                        # e.g. in the case of 'The Arab al[[Razi]]', 'al' will be matched
                        global $wgContLang;
                        $charset = $wgContLang->linkPrefixCharset();
                        $e2 = "/^((?>.*[^$charset]|))(.+)$/sDu";
                }

                if ( is_null( $this->mTitle ) ) {
                        throw new MWException( __METHOD__ . ": \$this->mTitle is null\n" );
                }
                $nottalk = !$this->mTitle->isTalkPage();

                if ( $useLinkPrefixExtension ) {
                        $m = [];
                        if ( preg_match( $e2, $s, $m ) ) {
                                $first_prefix = $m[2];
                        } else {
                                $first_prefix = false;
                        }
                } else {
                        $prefix = '';
                }

                $useSubpages = $this->areSubpagesAllowed();

                // @codingStandardsIgnoreStart Squiz.WhiteSpace.SemicolonSpacing.Incorrect
                # Loop for each link
                for ( ; $line !== false && $line !== null; $a->next(), $line = $a->current() ) {
                        // @codingStandardsIgnoreEnd

                        # Check for excessive memory usage
                        if ( $holders->isBig() ) {
                                # Too big
                                # Do the existence check, replace the link holders and clear the array
                                $holders->replace( $s );
                                $holders->clear();
                        }

                        if ( $useLinkPrefixExtension ) {
                                if ( preg_match( $e2, $s, $m ) ) {
                                        $prefix = $m[2];
                                        $s = $m[1];
                                } else {
                                        $prefix = '';
                                }
                                # first link
                                if ( $first_prefix ) {
                                        $prefix = $first_prefix;
                                        $first_prefix = false;
                                }
                        }

                        $might_be_img = false;

                        if ( preg_match( $e1, $line, $m ) ) { # page with normal text or alt
                                $text = $m[2];
                                # If we get a ] at the beginning of $m[3] that means we have a link that's something like:
                                # [[Image:Foo.jpg|[http://example.com desc]]] <- having three ] in a row fucks up,
                                # the real problem is with the $e1 regex
                                # See T1500.
                                # Still some problems for cases where the ] is meant to be outside punctuation,
                                # and no image is in sight. See T4095.
                                if ( $text !== ''
                                        && substr( $m[3], 0, 1 ) === ']'
                                        && strpos( $text, '[' ) !== false
                                ) {
                                        $text .= ']'; # so that replaceExternalLinks($text) works later
                                        $m[3] = substr( $m[3], 1 );
                                }
                                # fix up urlencoded title texts
                                if ( strpos( $m[1], '%' ) !== false ) {
                                        # Should anchors '#' also be rejected?
                                        $m[1] = str_replace( [ '<', '>' ], [ '&lt;', '&gt;' ], rawurldecode( $m[1] ) );
                                }
                                $trail = $m[3];
                        } elseif ( preg_match( $e1_img, $line, $m ) ) {
                                # Invalid, but might be an image with a link in its caption
                                $might_be_img = true;
                                $text = $m[2];
                                if ( strpos( $m[1], '%' ) !== false ) {
                                        $m[1] = str_replace( [ '<', '>' ], [ '&lt;', '&gt;' ], rawurldecode( $m[1] ) );
                                }
                                $trail = "";
                        } else { # Invalid form; output directly
                                $s .= $prefix . '[[' . $line;
                                continue;
                        }

                        $origLink = ltrim( $m[1], ' ' );

                        # Don't allow internal links to pages containing
                        # PROTO: where PROTO is a valid URL protocol; these
                        # should be external links.
                        if ( preg_match( '/^(?i:' . $this->mUrlProtocols . ')/', $origLink ) ) {
                                $s .= $prefix . '[[' . $line;
                                continue;
                        }

                        # Make subpage if necessary
                        if ( $useSubpages ) {
                                $link = $this->maybeDoSubpageLink( $origLink, $text );
                        } else {
                                $link = $origLink;
                        }

                        $noforce = ( substr( $origLink, 0, 1 ) !== ':' );
                        if ( !$noforce ) {
                                # Strip off leading ':'
                                $link = substr( $link, 1 );
                        }

                        $unstrip = $this->mStripState->unstripNoWiki( $link );
                        $nt = is_string( $unstrip ) ? Title::newFromText( $unstrip ) : null;
                        if ( $nt === null ) {
                                $s .= $prefix . '[[' . $line;
                                continue;
                        }

                        $ns = $nt->getNamespace();
                        $iw = $nt->getInterwiki();

                        if ( $might_be_img ) { # if this is actually an invalid link
                                if ( $ns == NS_FILE && $noforce ) { # but might be an image
                                        $found = false;
                                        while ( true ) {
                                                # look at the next 'line' to see if we can close it there
                                                $a->next();
                                                $next_line = $a->current();
                                                if ( $next_line === false || $next_line === null ) {
                                                        break;
                                                }
                                                $m = explode( ']]', $next_line, 3 );
                                                if ( count( $m ) == 3 ) {
                                                        # the first ]] closes the inner link, the second the image
                                                        $found = true;
                                                        $text .= "[[{$m[0]}]]{$m[1]}";
                                                        $trail = $m[2];
                                                        break;
                                                } elseif ( count( $m ) == 2 ) {
                                                        # if there's exactly one ]] that's fine, we'll keep looking
                                                        $text .= "[[{$m[0]}]]{$m[1]}";
                                                } else {
                                                        # if $next_line is invalid too, we need look no further
                                                        $text .= '[[' . $next_line;
                                                        break;
                                                }
                                        }
                                        if ( !$found ) {
                                                # we couldn't find the end of this imageLink, so output it raw
                                                # but don't ignore what might be perfectly normal links in the text we've examined
                                                $holders->merge( $this->replaceInternalLinks2( $text ) );
                                                $s .= "{$prefix}[[$link|$text";
                                                # note: no $trail, because without an end, there *is* no trail
                                                continue;
                                        }
                                } else { # it's not an image, so output it raw
                                        $s .= "{$prefix}[[$link|$text";
                                        # note: no $trail, because without an end, there *is* no trail
                                        continue;
                                }
                        }

                        $wasblank = ( $text == '' );
                        if ( $wasblank ) {
                                $text = $link;
                        } else {
                                # T6598 madness. Handle the quotes only if they come from the alternate part
                                # [[Lista d''e paise d''o munno]] -> <a href="...">Lista d''e paise d''o munno</a>
                                # [[Criticism of Harry Potter|Criticism of ''Harry Potter'']]
                                #    -> <a href="Criticism of Harry Potter">Criticism of <i>Harry Potter</i></a>
                                $text = $this->doQuotes( $text );
                        }

                        # Link not escaped by : , create the various objects
                        if ( $noforce && !$nt->wasLocalInterwiki() ) {
                                # Interwikis
                                if (
                                        $iw && $this->mOptions->getInterwikiMagic() && $nottalk && (
                                                Language::fetchLanguageName( $iw, null, 'mw' ) ||
                                                in_array( $iw, $wgExtraInterlanguageLinkPrefixes )
                                        )
                                ) {
                                        # T26502: filter duplicates
                                        if ( !isset( $this->mLangLinkLanguages[$iw] ) ) {
                                                $this->mLangLinkLanguages[$iw] = true;
                                                $this->mOutput->addLanguageLink( $nt->getFullText() );
                                        }

                                        $s = rtrim( $s . $prefix );
                                        $s .= trim( $trail, "\n" ) == '' ? '': $prefix . $trail;
                                        continue;
                                }

                                if ( $ns == NS_FILE ) {
                                        if ( !wfIsBadImage( $nt->getDBkey(), $this->mTitle ) ) {
                                                if ( $wasblank ) {
                                                        # if no parameters were passed, $text
                                                        # becomes something like "File:Foo.png",
                                                        # which we don't want to pass on to the
                                                        # image generator
                                                        $text = '';
                                                } else {
                                                        # recursively parse links inside the image caption
                                                        # actually, this will parse them in any other parameters, too,
                                                        # but it might be hard to fix that, and it doesn't matter ATM
                                                        $text = $this->replaceExternalLinks( $text );
                                                        $holders->merge( $this->replaceInternalLinks2( $text ) );
                                                }
                                                # cloak any absolute URLs inside the image markup, so replaceExternalLinks() won't touch them
                                                $s .= $prefix . $this->armorLinks(
                                                        $this->makeImage( $nt, $text, $holders ) ) . $trail;
                                                continue;
                                        }
                                } elseif ( $ns == NS_CATEGORY ) {
                                        $s = rtrim( $s . "\n" ); # T2087

                                        if ( $wasblank ) {
                                                $sortkey = $this->getDefaultSort();
                                        } else {
                                                $sortkey = $text;
                                        }
                                        $sortkey = Sanitizer::decodeCharReferences( $sortkey );
                                        $sortkey = str_replace( "\n", '', $sortkey );
                                        $sortkey = $this->getConverterLanguage()->convertCategoryKey( $sortkey );
                                        $this->mOutput->addCategory( $nt->getDBkey(), $sortkey );

                                        /**
                                         * Strip the whitespace Category links produce, see T2087
                                         */
                                        $s .= trim( $prefix . $trail, "\n" ) == '' ? '' : $prefix . $trail;

                                        continue;
                                }
                        }

                        # Self-link checking. For some languages, variants of the title are checked in
                        # LinkHolderArray::doVariants() to allow batching the existence checks necessary
                        # for linking to a different variant.
                        if ( $ns != NS_SPECIAL && $nt->equals( $this->mTitle ) && !$nt->hasFragment() ) {
                                $s .= $prefix . Linker::makeSelfLinkObj( $nt, $text, '', $trail );
                                continue;
                        }

                        # NS_MEDIA is a pseudo-namespace for linking directly to a file
                        # @todo FIXME: Should do batch file existence checks, see comment below
                        if ( $ns == NS_MEDIA ) {
                                # Give extensions a chance to select the file revision for us
                                $options = [];
                                $descQuery = false;
                                Hooks::run( 'BeforeParserFetchFileAndTitle',
                                        [ $this, $nt, &$options, &$descQuery ] );
                                # Fetch and register the file (file title may be different via hooks)
                                list( $file, $nt ) = $this->fetchFileAndTitle( $nt, $options );
                                # Cloak with NOPARSE to avoid replacement in replaceExternalLinks
                                $s .= $prefix . $this->armorLinks(
                                        Linker::makeMediaLinkFile( $nt, $file, $text ) ) . $trail;
                                continue;
                        }

                        # Some titles, such as valid special pages or files in foreign repos, should
                        # be shown as bluelinks even though they're not included in the page table
                        # @todo FIXME: isAlwaysKnown() can be expensive for file links; we should really do
                        # batch file existence checks for NS_FILE and NS_MEDIA
                        if ( $iw == '' && $nt->isAlwaysKnown() ) {
                                $this->mOutput->addLink( $nt );
                                $s .= $this->makeKnownLinkHolder( $nt, $text, $trail, $prefix );
                        } else {
                                # Links will be added to the output link list after checking
                                $s .= $holders->makeHolder( $nt, $text, [], $trail, $prefix );
                        }
                }
                return $holders;
        }

        /**
         * Render a forced-blue link inline; protect against double expansion of
         * URLs if we're in a mode that prepends full URL prefixes to internal links.
         * Since this little disaster has to split off the trail text to avoid
         * breaking URLs in the following text without breaking trails on the
         * wiki links, it's been made into a horrible function.
         *
         * @param Title $nt
         * @param string $text
         * @param string $trail
         * @param string $prefix
         * @return string HTML-wikitext mix oh yuck
         */
        protected function makeKnownLinkHolder( $nt, $text = '', $trail = '', $prefix = '' ) {
                list( $inside, $trail ) = Linker::splitTrail( $trail );

                if ( $text == '' ) {
                        $text = htmlspecialchars( $nt->getPrefixedText() );
                }

                $link = $this->getLinkRenderer()->makeKnownLink(
                        $nt, new HtmlArmor( "$prefix$text$inside" )
                );

                return $this->armorLinks( $link ) . $trail;
        }

        /**
         * Insert a NOPARSE hacky thing into any inline links in a chunk that's
         * going to go through further parsing steps before inline URL expansion.
         *
         * Not needed quite as much as it used to be since free links are a bit
         * more sensible these days. But bracketed links are still an issue.
         *
         * @param string $text More-or-less HTML
         * @return string Less-or-more HTML with NOPARSE bits
         */
        public function armorLinks( $text ) {
                return preg_replace( '/\b((?i)' . $this->mUrlProtocols . ')/',
                        self::MARKER_PREFIX . "NOPARSE$1", $text );
        }

        /**
         * Return true if subpage links should be expanded on this page.
         * @return bool
         */
        public function areSubpagesAllowed() {
                # Some namespaces don't allow subpages
                return MWNamespace::hasSubpages( $this->mTitle->getNamespace() );
        }

        /**
         * Handle link to subpage if necessary
         *
         * @param string $target The source of the link
         * @param string &$text The link text, modified as necessary
         * @return string The full name of the link
         * @private
         */
        public function maybeDoSubpageLink( $target, &$text ) {
                return Linker::normalizeSubpageLink( $this->mTitle, $target, $text );
        }

        /**
         * Make lists from lines starting with ':', '*', '#', etc. (DBL)
         *
         * @param string $text
         * @param bool $linestart Whether or not this is at the start of a line.
         * @private
         * @return string The lists rendered as HTML
         */
        public function doBlockLevels( $text, $linestart ) {
                return BlockLevelPass::doBlockLevels( $text, $linestart );
        }

        /**
         * Return value of a magic variable (like PAGENAME)
         *
         * @private
         *
         * @param string $index Magic variable identifier as mapped in MagicWord::$mVariableIDs
         * @param bool|PPFrame $frame
         *
         * @throws MWException
         * @return string
         */
        public function getVariableValue( $index, $frame = false ) {
                global $wgContLang, $wgSitename, $wgServer, $wgServerName;
                global $wgArticlePath, $wgScriptPath, $wgStylePath;

                if ( is_null( $this->mTitle ) ) {
                        // If no title set, bad things are going to happen
                        // later. Title should always be set since this
                        // should only be called in the middle of a parse
                        // operation (but the unit-tests do funky stuff)
                        throw new MWException( __METHOD__ . ' Should only be '
                                . ' called while parsing (no title set)' );
                }

                // Avoid PHP 7.1 warning from passing $this by reference
                $parser = $this;

                /**
                 * Some of these require message or data lookups and can be
                 * expensive to check many times.
                 */
                if ( Hooks::run( 'ParserGetVariableValueVarCache', [ &$parser, &$this->mVarCache ] ) ) {
                        if ( isset( $this->mVarCache[$index] ) ) {
                                return $this->mVarCache[$index];
                        }
                }

                $ts = wfTimestamp( TS_UNIX, $this->mOptions->getTimestamp() );
                Hooks::run( 'ParserGetVariableValueTs', [ &$parser, &$ts ] );

                $pageLang = $this->getFunctionLang();

                switch ( $index ) {
                        case '!':
                                $value = '|';
                                break;
                        case 'currentmonth':
                                $value = $pageLang->formatNum( MWTimestamp::getInstance( $ts )->format( 'm' ) );
                                break;
                        case 'currentmonth1':
                                $value = $pageLang->formatNum( MWTimestamp::getInstance( $ts )->format( 'n' ) );
                                break;
                        case 'currentmonthname':
                                $value = $pageLang->getMonthName( MWTimestamp::getInstance( $ts )->format( 'n' ) );
                                break;
                        case 'currentmonthnamegen':
                                $value = $pageLang->getMonthNameGen( MWTimestamp::getInstance( $ts )->format( 'n' ) );
                                break;
                        case 'currentmonthabbrev':
                                $value = $pageLang->getMonthAbbreviation( MWTimestamp::getInstance( $ts )->format( 'n' ) );
                                break;
                        case 'currentday':
                                $value = $pageLang->formatNum( MWTimestamp::getInstance( $ts )->format( 'j' ) );
                                break;
                        case 'currentday2':
                                $value = $pageLang->formatNum( MWTimestamp::getInstance( $ts )->format( 'd' ) );
                                break;
                        case 'localmonth':
                                $value = $pageLang->formatNum( MWTimestamp::getLocalInstance( $ts )->format( 'm' ) );
                                break;
                        case 'localmonth1':
                                $value = $pageLang->formatNum( MWTimestamp::getLocalInstance( $ts )->format( 'n' ) );
                                break;
                        case 'localmonthname':
                                $value = $pageLang->getMonthName( MWTimestamp::getLocalInstance( $ts )->format( 'n' ) );
                                break;
                        case 'localmonthnamegen':
                                $value = $pageLang->getMonthNameGen( MWTimestamp::getLocalInstance( $ts )->format( 'n' ) );
                                break;
                        case 'localmonthabbrev':
                                $value = $pageLang->getMonthAbbreviation( MWTimestamp::getLocalInstance( $ts )->format( 'n' ) );
                                break;
                        case 'localday':
                                $value = $pageLang->formatNum( MWTimestamp::getLocalInstance( $ts )->format( 'j' ) );
                                break;
                        case 'localday2':
                                $value = $pageLang->formatNum( MWTimestamp::getLocalInstance( $ts )->format( 'd' ) );
                                break;
                        case 'pagename':
                                $value = wfEscapeWikiText( $this->mTitle->getText() );
                                break;
                        case 'pagenamee':
                                $value = wfEscapeWikiText( $this->mTitle->getPartialURL() );
                                break;
                        case 'fullpagename':
                                $value = wfEscapeWikiText( $this->mTitle->getPrefixedText() );
                                break;
                        case 'fullpagenamee':
                                $value = wfEscapeWikiText( $this->mTitle->getPrefixedURL() );
                                break;
                        case 'subpagename':
                                $value = wfEscapeWikiText( $this->mTitle->getSubpageText() );
                                break;
                        case 'subpagenamee':
                                $value = wfEscapeWikiText( $this->mTitle->getSubpageUrlForm() );
                                break;
                        case 'rootpagename':
                                $value = wfEscapeWikiText( $this->mTitle->getRootText() );
                                break;
                        case 'rootpagenamee':
                                $value = wfEscapeWikiText( wfUrlencode( str_replace(
                                        ' ',
                                        '_',
                                        $this->mTitle->getRootText()
                                ) ) );
                                break;
                        case 'basepagename':
                                $value = wfEscapeWikiText( $this->mTitle->getBaseText() );
                                break;
                        case 'basepagenamee':
                                $value = wfEscapeWikiText( wfUrlencode( str_replace(
                                        ' ',
                                        '_',
                                        $this->mTitle->getBaseText()
                                ) ) );
                                break;
                        case 'talkpagename':
                                if ( $this->mTitle->canTalk() ) {
                                        $talkPage = $this->mTitle->getTalkPage();
                                        $value = wfEscapeWikiText( $talkPage->getPrefixedText() );
                                } else {
                                        $value = '';
                                }
                                break;
                        case 'talkpagenamee':
                                if ( $this->mTitle->canTalk() ) {
                                        $talkPage = $this->mTitle->getTalkPage();
                                        $value = wfEscapeWikiText( $talkPage->getPrefixedURL() );
                                } else {
                                        $value = '';
                                }
                                break;
                        case 'subjectpagename':
                                $subjPage = $this->mTitle->getSubjectPage();
                                $value = wfEscapeWikiText( $subjPage->getPrefixedText() );
                                break;
                        case 'subjectpagenamee':
                                $subjPage = $this->mTitle->getSubjectPage();
                                $value = wfEscapeWikiText( $subjPage->getPrefixedURL() );
                                break;
                        case 'pageid': // requested in T25427
                                $pageid = $this->getTitle()->getArticleID();
                                if ( $pageid == 0 ) {
                                        # 0 means the page doesn't exist in the database,
                                        # which means the user is previewing a new page.
                                        # The vary-revision flag must be set, because the magic word
                                        # will have a different value once the page is saved.
                                        $this->mOutput->setFlag( 'vary-revision' );
                                        wfDebug( __METHOD__ . ": {{PAGEID}} used in a new page, setting vary-revision...\n" );
                                }
                                $value = $pageid ? $pageid : null;
                                break;
                        case 'revisionid':
                                # Let the edit saving system know we should parse the page
                                # *after* a revision ID has been assigned.
                                $this->mOutput->setFlag( 'vary-revision-id' );
                                wfDebug( __METHOD__ . ": {{REVISIONID}} used, setting vary-revision-id...\n" );
                                $value = $this->mRevisionId;
                                if ( !$value && $this->mOptions->getSpeculativeRevIdCallback() ) {
                                        $value = call_user_func( $this->mOptions->getSpeculativeRevIdCallback() );
                                        $this->mOutput->setSpeculativeRevIdUsed( $value );
                                }
                                break;
                        case 'revisionday':
                                # Let the edit saving system know we should parse the page
                                # *after* a revision ID has been assigned. This is for null edits.
                                $this->mOutput->setFlag( 'vary-revision' );
                                wfDebug( __METHOD__ . ": {{REVISIONDAY}} used, setting vary-revision...\n" );
                                $value = intval( substr( $this->getRevisionTimestamp(), 6, 2 ) );
                                break;
                        case 'revisionday2':
                                # Let the edit saving system know we should parse the page
                                # *after* a revision ID has been assigned. This is for null edits.
                                $this->mOutput->setFlag( 'vary-revision' );
                                wfDebug( __METHOD__ . ": {{REVISIONDAY2}} used, setting vary-revision...\n" );
                                $value = substr( $this->getRevisionTimestamp(), 6, 2 );
                                break;
                        case 'revisionmonth':
                                # Let the edit saving system know we should parse the page
                                # *after* a revision ID has been assigned. This is for null edits.
                                $this->mOutput->setFlag( 'vary-revision' );
                                wfDebug( __METHOD__ . ": {{REVISIONMONTH}} used, setting vary-revision...\n" );
                                $value = substr( $this->getRevisionTimestamp(), 4, 2 );
                                break;
                        case 'revisionmonth1':
                                # Let the edit saving system know we should parse the page
                                # *after* a revision ID has been assigned. This is for null edits.
                                $this->mOutput->setFlag( 'vary-revision' );
                                wfDebug( __METHOD__ . ": {{REVISIONMONTH1}} used, setting vary-revision...\n" );
                                $value = intval( substr( $this->getRevisionTimestamp(), 4, 2 ) );
                                break;
                        case 'revisionyear':
                                # Let the edit saving system know we should parse the page
                                # *after* a revision ID has been assigned. This is for null edits.
                                $this->mOutput->setFlag( 'vary-revision' );
                                wfDebug( __METHOD__ . ": {{REVISIONYEAR}} used, setting vary-revision...\n" );
                                $value = substr( $this->getRevisionTimestamp(), 0, 4 );
                                break;
                        case 'revisiontimestamp':
                                # Let the edit saving system know we should parse the page
                                # *after* a revision ID has been assigned. This is for null edits.
                                $this->mOutput->setFlag( 'vary-revision' );
                                wfDebug( __METHOD__ . ": {{REVISIONTIMESTAMP}} used, setting vary-revision...\n" );
                                $value = $this->getRevisionTimestamp();
                                break;
                        case 'revisionuser':
                                # Let the edit saving system know we should parse the page
                                # *after* a revision ID has been assigned for null edits.
                                $this->mOutput->setFlag( 'vary-user' );
                                wfDebug( __METHOD__ . ": {{REVISIONUSER}} used, setting vary-user...\n" );
                                $value = $this->getRevisionUser();
                                break;
                        case 'revisionsize':
                                $value = $this->getRevisionSize();
                                break;
                        case 'namespace':
                                $value = str_replace( '_', ' ', $wgContLang->getNsText( $this->mTitle->getNamespace() ) );
                                break;
                        case 'namespacee':
                                $value = wfUrlencode( $wgContLang->getNsText( $this->mTitle->getNamespace() ) );
                                break;
                        case 'namespacenumber':
                                $value = $this->mTitle->getNamespace();
                                break;
                        case 'talkspace':
                                $value = $this->mTitle->canTalk()
                                        ? str_replace( '_', ' ', $this->mTitle->getTalkNsText() )
                                        : '';
                                break;
                        case 'talkspacee':
                                $value = $this->mTitle->canTalk() ? wfUrlencode( $this->mTitle->getTalkNsText() ) : '';
                                break;
                        case 'subjectspace':
                                $value = str_replace( '_', ' ', $this->mTitle->getSubjectNsText() );
                                break;
                        case 'subjectspacee':
                                $value = ( wfUrlencode( $this->mTitle->getSubjectNsText() ) );
                                break;
                        case 'currentdayname':
                                $value = $pageLang->getWeekdayName( (int)MWTimestamp::getInstance( $ts )->format( 'w' ) + 1 );
                                break;
                        case 'currentyear':
                                $value = $pageLang->formatNum( MWTimestamp::getInstance( $ts )->format( 'Y' ), true );
                                break;
                        case 'currenttime':
                                $value = $pageLang->time( wfTimestamp( TS_MW, $ts ), false, false );
                                break;
                        case 'currenthour':
                                $value = $pageLang->formatNum( MWTimestamp::getInstance( $ts )->format( 'H' ), true );
                                break;
                        case 'currentweek':
                                # @bug T6594 PHP5 has it zero padded, PHP4 does not, cast to
                                # int to remove the padding
                                $value = $pageLang->formatNum( (int)MWTimestamp::getInstance( $ts )->format( 'W' ) );
                                break;
                        case 'currentdow':
                                $value = $pageLang->formatNum( MWTimestamp::getInstance( $ts )->format( 'w' ) );
                                break;
                        case 'localdayname':
                                $value = $pageLang->getWeekdayName(
                                        (int)MWTimestamp::getLocalInstance( $ts )->format( 'w' ) + 1
                                );
                                break;
                        case 'localyear':
                                $value = $pageLang->formatNum( MWTimestamp::getLocalInstance( $ts )->format( 'Y' ), true );
                                break;
                        case 'localtime':
                                $value = $pageLang->time(
                                        MWTimestamp::getLocalInstance( $ts )->format( 'YmdHis' ),
                                        false,
                                        false
                                );
                                break;
                        case 'localhour':
                                $value = $pageLang->formatNum( MWTimestamp::getLocalInstance( $ts )->format( 'H' ), true );
                                break;
                        case 'localweek':
                                # @bug T6594 PHP5 has it zero padded, PHP4 does not, cast to
                                # int to remove the padding
                                $value = $pageLang->formatNum( (int)MWTimestamp::getLocalInstance( $ts )->format( 'W' ) );
                                break;
                        case 'localdow':
                                $value = $pageLang->formatNum( MWTimestamp::getLocalInstance( $ts )->format( 'w' ) );
                                break;
                        case 'numberofarticles':
                                $value = $pageLang->formatNum( SiteStats::articles() );
                                break;
                        case 'numberoffiles':
                                $value = $pageLang->formatNum( SiteStats::images() );
                                break;
                        case 'numberofusers':
                                $value = $pageLang->formatNum( SiteStats::users() );
                                break;
                        case 'numberofactiveusers':
                                $value = $pageLang->formatNum( SiteStats::activeUsers() );
                                break;
                        case 'numberofpages':
                                $value = $pageLang->formatNum( SiteStats::pages() );
                                break;
                        case 'numberofadmins':
                                $value = $pageLang->formatNum( SiteStats::numberingroup( 'sysop' ) );
                                break;
                        case 'numberofedits':
                                $value = $pageLang->formatNum( SiteStats::edits() );
                                break;
                        case 'currenttimestamp':
                                $value = wfTimestamp( TS_MW, $ts );
                                break;
                        case 'localtimestamp':
                                $value = MWTimestamp::getLocalInstance( $ts )->format( 'YmdHis' );
                                break;
                        case 'currentversion':
                                $value = SpecialVersion::getVersion();
                                break;
                        case 'articlepath':
                                return $wgArticlePath;
                        case 'sitename':
                                return $wgSitename;
                        case 'server':
                                return $wgServer;
                        case 'servername':
                                return $wgServerName;
                        case 'scriptpath':
                                return $wgScriptPath;
                        case 'stylepath':
                                return $wgStylePath;
                        case 'directionmark':
                                return $pageLang->getDirMark();
                        case 'contentlanguage':
                                global $wgLanguageCode;
                                return $wgLanguageCode;
                        case 'pagelanguage':
                                $value = $pageLang->getCode();
                                break;
                        case 'cascadingsources':
                                $value = CoreParserFunctions::cascadingsources( $this );
                                break;
                        default:
                                $ret = null;
                                Hooks::run(
                                        'ParserGetVariableValueSwitch',
                                        [ &$parser, &$this->mVarCache, &$index, &$ret, &$frame ]
                                );

                                return $ret;
                }

                if ( $index ) {
                        $this->mVarCache[$index] = $value;
                }

                return $value;
        }

        /**
         * initialise the magic variables (like CURRENTMONTHNAME) and substitution modifiers
         *
         * @private
         */
        public function initialiseVariables() {
                $variableIDs = MagicWord::getVariableIDs();
                $substIDs = MagicWord::getSubstIDs();

                $this->mVariables = new MagicWordArray( $variableIDs );
                $this->mSubstWords = new MagicWordArray( $substIDs );
        }

        /**
         * Preprocess some wikitext and return the document tree.
         * This is the ghost of replace_variables().
         *
         * @param string $text The text to parse
         * @param int $flags Bitwise combination of:
         *   - self::PTD_FOR_INCLUSION: Handle "<noinclude>" and "<includeonly>" as if the text is being
         *     included. Default is to assume a direct page view.
         *
         * The generated DOM tree must depend only on the input text and the flags.
         * The DOM tree must be the same in OT_HTML and OT_WIKI mode, to avoid a regression of T6899.
         *
         * Any flag added to the $flags parameter here, or any other parameter liable to cause a
         * change in the DOM tree for a given text, must be passed through the section identifier
         * in the section edit link and thus back to extractSections().
         *
         * The output of this function is currently only cached in process memory, but a persistent
         * cache may be implemented at a later date which takes further advantage of these strict
         * dependency requirements.
         *
         * @return PPNode
         */
        public function preprocessToDom( $text, $flags = 0 ) {
                $dom = $this->getPreprocessor()->preprocessToObj( $text, $flags );
                return $dom;
        }

        /**
         * Return a three-element array: leading whitespace, string contents, trailing whitespace
         *
         * @param string $s
         *
         * @return array
         */
        public static function splitWhitespace( $s ) {
                $ltrimmed = ltrim( $s );
                $w1 = substr( $s, 0, strlen( $s ) - strlen( $ltrimmed ) );
                $trimmed = rtrim( $ltrimmed );
                $diff = strlen( $ltrimmed ) - strlen( $trimmed );
                if ( $diff > 0 ) {
                        $w2 = substr( $ltrimmed, -$diff );
                } else {
                        $w2 = '';
                }
                return [ $w1, $trimmed, $w2 ];
        }

        /**
         * Replace magic variables, templates, and template arguments
         * with the appropriate text. Templates are substituted recursively,
         * taking care to avoid infinite loops.
         *
         * Note that the substitution depends on value of $mOutputType:
         *  self::OT_WIKI: only {{subst:}} templates
         *  self::OT_PREPROCESS: templates but not extension tags
         *  self::OT_HTML: all templates and extension tags
         *
         * @param string $text The text to transform
         * @param bool|PPFrame $frame Object describing the arguments passed to the
         *   template. Arguments may also be provided as an associative array, as
         *   was the usual case before MW1.12. Providing arguments this way may be
         *   useful for extensions wishing to perform variable replacement
         *   explicitly.
         * @param bool $argsOnly Only do argument (triple-brace) expansion, not
         *   double-brace expansion.
         * @return string
         */
        public function replaceVariables( $text, $frame = false, $argsOnly = false ) {
                # Is there any text? Also, Prevent too big inclusions!
                $textSize = strlen( $text );
                if ( $textSize < 1 || $textSize > $this->mOptions->getMaxIncludeSize() ) {
                        return $text;
                }

                if ( $frame === false ) {
                        $frame = $this->getPreprocessor()->newFrame();
                } elseif ( !( $frame instanceof PPFrame ) ) {
                        wfDebug( __METHOD__ . " called using plain parameters instead of "
                                . "a PPFrame instance. Creating custom frame.\n" );
                        $frame = $this->getPreprocessor()->newCustomFrame( $frame );
                }

                $dom = $this->preprocessToDom( $text );
                $flags = $argsOnly ? PPFrame::NO_TEMPLATES : 0;
                $text = $frame->expand( $dom, $flags );

                return $text;
        }

        /**
         * Clean up argument array - refactored in 1.9 so parserfunctions can use it, too.
         *
         * @param array $args
         *
         * @return array
         */
        public static function createAssocArgs( $args ) {
                $assocArgs = [];
                $index = 1;
                foreach ( $args as $arg ) {
                        $eqpos = strpos( $arg, '=' );
                        if ( $eqpos === false ) {
                                $assocArgs[$index++] = $arg;
                        } else {
                                $name = trim( substr( $arg, 0, $eqpos ) );
                                $value = trim( substr( $arg, $eqpos + 1 ) );
                                if ( $value === false ) {
                                        $value = '';
                                }
                                if ( $name !== false ) {
                                        $assocArgs[$name] = $value;
                                }
                        }
                }

                return $assocArgs;
        }

        /**
         * Warn the user when a parser limitation is reached
         * Will warn at most once the user per limitation type
         *
         * The results are shown during preview and run through the Parser (See EditPage.php)
         *
         * @param string $limitationType Should be one of:
         *   'expensive-parserfunction' (corresponding messages:
         *       'expensive-parserfunction-warning',
         *       'expensive-parserfunction-category')
         *   'post-expand-template-argument' (corresponding messages:
         *       'post-expand-template-argument-warning',
         *       'post-expand-template-argument-category')
         *   'post-expand-template-inclusion' (corresponding messages:
         *       'post-expand-template-inclusion-warning',
         *       'post-expand-template-inclusion-category')
         *   'node-count-exceeded' (corresponding messages:
         *       'node-count-exceeded-warning',
         *       'node-count-exceeded-category')
         *   'expansion-depth-exceeded' (corresponding messages:
         *       'expansion-depth-exceeded-warning',
         *       'expansion-depth-exceeded-category')
         * @param string|int|null $current Current value
         * @param string|int|null $max Maximum allowed, when an explicit limit has been
         *       exceeded, provide the values (optional)
         */
        public function limitationWarn( $limitationType, $current = '', $max = '' ) {
                # does no harm if $current and $max are present but are unnecessary for the message
                # Not doing ->inLanguage( $this->mOptions->getUserLangObj() ), since this is shown
                # only during preview, and that would split the parser cache unnecessarily.
                $warning = wfMessage( "$limitationType-warning" )->numParams( $current, $max )
                        ->text();
                $this->mOutput->addWarning( $warning );
                $this->addTrackingCategory( "$limitationType-category" );
        }

        /**
         * Return the text of a template, after recursively
         * replacing any variables or templates within the template.
         *
         * @param array $piece The parts of the template
         *   $piece['title']: the title, i.e. the part before the |
         *   $piece['parts']: the parameter array
         *   $piece['lineStart']: whether the brace was at the start of a line
         * @param PPFrame $frame The current frame, contains template arguments
         * @throws Exception
         * @return string The text of the template
         */
        public function braceSubstitution( $piece, $frame ) {

                // Flags

                // $text has been filled
                $found = false;
                // wiki markup in $text should be escaped
                $nowiki = false;
                // $text is HTML, armour it against wikitext transformation
                $isHTML = false;
                // Force interwiki transclusion to be done in raw mode not rendered
                $forceRawInterwiki = false;
                // $text is a DOM node needing expansion in a child frame
                $isChildObj = false;
                // $text is a DOM node needing expansion in the current frame
                $isLocalObj = false;

                # Title object, where $text came from
                $title = false;

                # $part1 is the bit before the first |, and must contain only title characters.
                # Various prefixes will be stripped from it later.
                $titleWithSpaces = $frame->expand( $piece['title'] );
                $part1 = trim( $titleWithSpaces );
                $titleText = false;

                # Original title text preserved for various purposes
                $originalTitle = $part1;

                # $args is a list of argument nodes, starting from index 0, not including $part1
                # @todo FIXME: If piece['parts'] is null then the call to getLength()
                # below won't work b/c this $args isn't an object
                $args = ( null == $piece['parts'] ) ? [] : $piece['parts'];

                $profileSection = null; // profile templates

                # SUBST
                if ( !$found ) {
                        $substMatch = $this->mSubstWords->matchStartAndRemove( $part1 );

                        # Possibilities for substMatch: "subst", "safesubst" or FALSE
                        # Decide whether to expand template or keep wikitext as-is.
                        if ( $this->ot['wiki'] ) {
                                if ( $substMatch === false ) {
                                        $literal = true;  # literal when in PST with no prefix
                                } else {
                                        $literal = false; # expand when in PST with subst: or safesubst:
                                }
                        } else {
                                if ( $substMatch == 'subst' ) {
                                        $literal = true;  # literal when not in PST with plain subst:
                                } else {
                                        $literal = false; # expand when not in PST with safesubst: or no prefix
                                }
                        }
                        if ( $literal ) {
                                $text = $frame->virtualBracketedImplode( '{{', '|', '}}', $titleWithSpaces, $args );
                                $isLocalObj = true;
                                $found = true;
                        }
                }

                # Variables
                if ( !$found && $args->getLength() == 0 ) {
                        $id = $this->mVariables->matchStartToEnd( $part1 );
                        if ( $id !== false ) {
                                $text = $this->getVariableValue( $id, $frame );
                                if ( MagicWord::getCacheTTL( $id ) > -1 ) {
                                        $this->mOutput->updateCacheExpiry( MagicWord::getCacheTTL( $id ) );
                                }
                                $found = true;
                        }
                }

                # MSG, MSGNW and RAW
                if ( !$found ) {
                        # Check for MSGNW:
                        $mwMsgnw = MagicWord::get( 'msgnw' );
                        if ( $mwMsgnw->matchStartAndRemove( $part1 ) ) {
                                $nowiki = true;
                        } else {
                                # Remove obsolete MSG:
                                $mwMsg = MagicWord::get( 'msg' );
                                $mwMsg->matchStartAndRemove( $part1 );
                        }

                        # Check for RAW:
                        $mwRaw = MagicWord::get( 'raw' );
                        if ( $mwRaw->matchStartAndRemove( $part1 ) ) {
                                $forceRawInterwiki = true;
                        }
                }

                # Parser functions
                if ( !$found ) {
                        $colonPos = strpos( $part1, ':' );
                        if ( $colonPos !== false ) {
                                $func = substr( $part1, 0, $colonPos );
                                $funcArgs = [ trim( substr( $part1, $colonPos + 1 ) ) ];
                                $argsLength = $args->getLength();
                                for ( $i = 0; $i < $argsLength; $i++ ) {
                                        $funcArgs[] = $args->item( $i );
                                }
                                try {
                                        $result = $this->callParserFunction( $frame, $func, $funcArgs );
                                } catch ( Exception $ex ) {
                                        throw $ex;
                                }

                                # The interface for parser functions allows for extracting
                                # flags into the local scope. Extract any forwarded flags
                                # here.
                                extract( $result );
                        }
                }

                # Finish mangling title and then check for loops.
                # Set $title to a Title object and $titleText to the PDBK
                if ( !$found ) {
                        $ns = NS_TEMPLATE;
                        # Split the title into page and subpage
                        $subpage = '';
                        $relative = $this->maybeDoSubpageLink( $part1, $subpage );
                        if ( $part1 !== $relative ) {
                                $part1 = $relative;
                                $ns = $this->mTitle->getNamespace();
                        }
                        $title = Title::newFromText( $part1, $ns );
                        if ( $title ) {
                                $titleText = $title->getPrefixedText();
                                # Check for language variants if the template is not found
                                if ( $this->getConverterLanguage()->hasVariants() && $title->getArticleID() == 0 ) {
                                        $this->getConverterLanguage()->findVariantLink( $part1, $title, true );
                                }
                                # Do recursion depth check
                                $limit = $this->mOptions->getMaxTemplateDepth();
                                if ( $frame->depth >= $limit ) {
                                        $found = true;
                                        $text = '<span class="error">'
                                                . wfMessage( 'parser-template-recursion-depth-warning' )
                                                        ->numParams( $limit )->inContentLanguage()->text()
                                                . '</span>';
                                }
                        }
                }

                # Load from database
                if ( !$found && $title ) {
                        $profileSection = $this->mProfiler->scopedProfileIn( $title->getPrefixedDBkey() );
                        if ( !$title->isExternal() ) {
                                if ( $title->isSpecialPage()
                                        && $this->mOptions->getAllowSpecialInclusion()
                                        && $this->ot['html']
                                ) {
                                        $specialPage = SpecialPageFactory::getPage( $title->getDBkey() );
                                        // Pass the template arguments as URL parameters.
                                        // "uselang" will have no effect since the Language object
                                        // is forced to the one defined in ParserOptions.
                                        $pageArgs = [];
                                        $argsLength = $args->getLength();
                                        for ( $i = 0; $i < $argsLength; $i++ ) {
                                                $bits = $args->item( $i )->splitArg();
                                                if ( strval( $bits['index'] ) === '' ) {
                                                        $name = trim( $frame->expand( $bits['name'], PPFrame::STRIP_COMMENTS ) );
                                                        $value = trim( $frame->expand( $bits['value'] ) );
                                                        $pageArgs[$name] = $value;
                                                }
                                        }

                                        // Create a new context to execute the special page
                                        $context = new RequestContext;
                                        $context->setTitle( $title );
                                        $context->setRequest( new FauxRequest( $pageArgs ) );
                                        if ( $specialPage && $specialPage->maxIncludeCacheTime() === 0 ) {
                                                $context->setUser( $this->getUser() );
                                        } else {
                                                // If this page is cached, then we better not be per user.
                                                $context->setUser( User::newFromName( '127.0.0.1', false ) );
                                        }
                                        $context->setLanguage( $this->mOptions->getUserLangObj() );
                                        $ret = SpecialPageFactory::capturePath(
                                                $title, $context, $this->getLinkRenderer() );
                                        if ( $ret ) {
                                                $text = $context->getOutput()->getHTML();
                                                $this->mOutput->addOutputPageMetadata( $context->getOutput() );
                                                $found = true;
                                                $isHTML = true;
                                                if ( $specialPage && $specialPage->maxIncludeCacheTime() !== false ) {
                                                        $this->mOutput->updateRuntimeAdaptiveExpiry(
                                                                $specialPage->maxIncludeCacheTime()
                                                        );
                                                }
                                        }
                                } elseif ( MWNamespace::isNonincludable( $title->getNamespace() ) ) {
                                        $found = false; # access denied
                                        wfDebug( __METHOD__ . ": template inclusion denied for " .
                                                $title->getPrefixedDBkey() . "\n" );
                                } else {
                                        list( $text, $title ) = $this->getTemplateDom( $title );
                                        if ( $text !== false ) {
                                                $found = true;
                                                $isChildObj = true;
                                        }
                                }

                                # If the title is valid but undisplayable, make a link to it
                                if ( !$found && ( $this->ot['html'] || $this->ot['pre'] ) ) {
                                        $text = "[[:$titleText]]";
                                        $found = true;
                                }
                        } elseif ( $title->isTrans() ) {
                                # Interwiki transclusion
                                if ( $this->ot['html'] && !$forceRawInterwiki ) {
                                        $text = $this->interwikiTransclude( $title, 'render' );
                                        $isHTML = true;
                                } else {
                                        $text = $this->interwikiTransclude( $title, 'raw' );
                                        # Preprocess it like a template
                                        $text = $this->preprocessToDom( $text, self::PTD_FOR_INCLUSION );
                                        $isChildObj = true;
                                }
                                $found = true;
                        }

                        # Do infinite loop check
                        # This has to be done after redirect resolution to avoid infinite loops via redirects
                        if ( !$frame->loopCheck( $title ) ) {
                                $found = true;
                                $text = '<span class="error">'
                                        . wfMessage( 'parser-template-loop-warning', $titleText )->inContentLanguage()->text()
                                        . '</span>';
                                wfDebug( __METHOD__ . ": template loop broken at '$titleText'\n" );
                        }
                }

                # If we haven't found text to substitute by now, we're done
                # Recover the source wikitext and return it
                if ( !$found ) {
                        $text = $frame->virtualBracketedImplode( '{{', '|', '}}', $titleWithSpaces, $args );
                        if ( $profileSection ) {
                                $this->mProfiler->scopedProfileOut( $profileSection );
                        }
                        return [ 'object' => $text ];
                }

                # Expand DOM-style return values in a child frame
                if ( $isChildObj ) {
                        # Clean up argument array
                        $newFrame = $frame->newChild( $args, $title );

                        if ( $nowiki ) {
                                $text = $newFrame->expand( $text, PPFrame::RECOVER_ORIG );
                        } elseif ( $titleText !== false && $newFrame->isEmpty() ) {
                                # Expansion is eligible for the empty-frame cache
                                $text = $newFrame->cachedExpand( $titleText, $text );
                        } else {
                                # Uncached expansion
                                $text = $newFrame->expand( $text );
                        }
                }
                if ( $isLocalObj && $nowiki ) {
                        $text = $frame->expand( $text, PPFrame::RECOVER_ORIG );
                        $isLocalObj = false;
                }

                if ( $profileSection ) {
                        $this->mProfiler->scopedProfileOut( $profileSection );
                }

                # Replace raw HTML by a placeholder
                if ( $isHTML ) {
                        $text = $this->insertStripItem( $text );
                } elseif ( $nowiki && ( $this->ot['html'] || $this->ot['pre'] ) ) {
                        # Escape nowiki-style return values
                        $text = wfEscapeWikiText( $text );
                } elseif ( is_string( $text )
                        && !$piece['lineStart']
                        && preg_match( '/^(?:{\\||:|;|#|\*)/', $text )
                ) {
                        # T2529: if the template begins with a table or block-level
                        # element, it should be treated as beginning a new line.
                        # This behavior is somewhat controversial.
                        $text = "\n" . $text;
                }

                if ( is_string( $text ) && !$this->incrementIncludeSize( 'post-expand', strlen( $text ) ) ) {
                        # Error, oversize inclusion
                        if ( $titleText !== false ) {
                                # Make a working, properly escaped link if possible (T25588)
                                $text = "[[:$titleText]]";
                        } else {
                                # This will probably not be a working link, but at least it may
                                # provide some hint of where the problem is
                                preg_replace( '/^:/', '', $originalTitle );
                                $text = "[[:$originalTitle]]";
                        }
                        $text .= $this->insertStripItem( '<!-- WARNING: template omitted, '
                                . 'post-expand include size too large -->' );
                        $this->limitationWarn( 'post-expand-template-inclusion' );
                }

                if ( $isLocalObj ) {
                        $ret = [ 'object' => $text ];
                } else {
                        $ret = [ 'text' => $text ];
                }

                return $ret;
        }

        /**
         * Call a parser function and return an array with text and flags.
         *
         * The returned array will always contain a boolean 'found', indicating
         * whether the parser function was found or not. It may also contain the
         * following:
         *  text: string|object, resulting wikitext or PP DOM object
         *  isHTML: bool, $text is HTML, armour it against wikitext transformation
         *  isChildObj: bool, $text is a DOM node needing expansion in a child frame
         *  isLocalObj: bool, $text is a DOM node needing expansion in the current frame
         *  nowiki: bool, wiki markup in $text should be escaped
         *
         * @since 1.21
         * @param PPFrame $frame The current frame, contains template arguments
         * @param string $function Function name
         * @param array $args Arguments to the function
         * @throws MWException
         * @return array
         */
        public function callParserFunction( $frame, $function, array $args = [] ) {
                global $wgContLang;

                # Case sensitive functions
                if ( isset( $this->mFunctionSynonyms[1][$function] ) ) {
                        $function = $this->mFunctionSynonyms[1][$function];
                } else {
                        # Case insensitive functions
                        $function = $wgContLang->lc( $function );
                        if ( isset( $this->mFunctionSynonyms[0][$function] ) ) {
                                $function = $this->mFunctionSynonyms[0][$function];
                        } else {
                                return [ 'found' => false ];
                        }
                }

                list( $callback, $flags ) = $this->mFunctionHooks[$function];

                # Workaround for PHP bug 35229 and similar
                if ( !is_callable( $callback ) ) {
                        throw new MWException( "Tag hook for $function is not callable\n" );
                }

                // Avoid PHP 7.1 warning from passing $this by reference
                $parser = $this;

                $allArgs = [ &$parser ];
                if ( $flags & self::SFH_OBJECT_ARGS ) {
                        # Convert arguments to PPNodes and collect for appending to $allArgs
                        $funcArgs = [];
                        foreach ( $args as $k => $v ) {
                                if ( $v instanceof PPNode || $k === 0 ) {
                                        $funcArgs[] = $v;
                                } else {
                                        $funcArgs[] = $this->mPreprocessor->newPartNodeArray( [ $k => $v ] )->item( 0 );
                                }
                        }

                        # Add a frame parameter, and pass the arguments as an array
                        $allArgs[] = $frame;
                        $allArgs[] = $funcArgs;
                } else {
                        # Convert arguments to plain text and append to $allArgs
                        foreach ( $args as $k => $v ) {
                                if ( $v instanceof PPNode ) {
                                        $allArgs[] = trim( $frame->expand( $v ) );
                                } elseif ( is_int( $k ) && $k >= 0 ) {
                                        $allArgs[] = trim( $v );
                                } else {
                                        $allArgs[] = trim( "$k=$v" );
                                }
                        }
                }

                $result = call_user_func_array( $callback, $allArgs );

                # The interface for function hooks allows them to return a wikitext
                # string or an array containing the string and any flags. This mungs
                # things around to match what this method should return.
                if ( !is_array( $result ) ) {
                        $result =[
                                'found' => true,
                                'text' => $result,
                        ];
                } else {
                        if ( isset( $result[0] ) && !isset( $result['text'] ) ) {
                                $result['text'] = $result[0];
                        }
                        unset( $result[0] );
                        $result += [
                                'found' => true,
                        ];
                }

                $noparse = true;
                $preprocessFlags = 0;
                if ( isset( $result['noparse'] ) ) {
                        $noparse = $result['noparse'];
                }
                if ( isset( $result['preprocessFlags'] ) ) {
                        $preprocessFlags = $result['preprocessFlags'];
                }

                if ( !$noparse ) {
                        $result['text'] = $this->preprocessToDom( $result['text'], $preprocessFlags );
                        $result['isChildObj'] = true;
                }

                return $result;
        }

        /**
         * Get the semi-parsed DOM representation of a template with a given title,
         * and its redirect destination title. Cached.
         *
         * @param Title $title
         *
         * @return array
         */
        public function getTemplateDom( $title ) {
                $cacheTitle = $title;
                $titleText = $title->getPrefixedDBkey();

                if ( isset( $this->mTplRedirCache[$titleText] ) ) {
                        list( $ns, $dbk ) = $this->mTplRedirCache[$titleText];
                        $title = Title::makeTitle( $ns, $dbk );
                        $titleText = $title->getPrefixedDBkey();
                }
                if ( isset( $this->mTplDomCache[$titleText] ) ) {
                        return [ $this->mTplDomCache[$titleText], $title ];
                }

                # Cache miss, go to the database
                list( $text, $title ) = $this->fetchTemplateAndTitle( $title );

                if ( $text === false ) {
                        $this->mTplDomCache[$titleText] = false;
                        return [ false, $title ];
                }

                $dom = $this->preprocessToDom( $text, self::PTD_FOR_INCLUSION );
                $this->mTplDomCache[$titleText] = $dom;

                if ( !$title->equals( $cacheTitle ) ) {
                        $this->mTplRedirCache[$cacheTitle->getPrefixedDBkey()] =
                                [ $title->getNamespace(), $cdb = $title->getDBkey() ];
                }

                return [ $dom, $title ];
        }

        /**
         * Fetch the current revision of a given title. Note that the revision
         * (and even the title) may not exist in the database, so everything
         * contributing to the output of the parser should use this method
         * where possible, rather than getting the revisions themselves. This
         * method also caches its results, so using it benefits performance.
         *
         * @since 1.24
         * @param Title $title
         * @return Revision
         */
        public function fetchCurrentRevisionOfTitle( $title ) {
                $cacheKey = $title->getPrefixedDBkey();
                if ( !$this->currentRevisionCache ) {
                        $this->currentRevisionCache = new MapCacheLRU( 100 );
                }
                if ( !$this->currentRevisionCache->has( $cacheKey ) ) {
                        $this->currentRevisionCache->set( $cacheKey,
                                // Defaults to Parser::statelessFetchRevision()
                                call_user_func( $this->mOptions->getCurrentRevisionCallback(), $title, $this )
                        );
                }
                return $this->currentRevisionCache->get( $cacheKey );
        }

        /**
         * Wrapper around Revision::newFromTitle to allow passing additional parameters
         * without passing them on to it.
         *
         * @since 1.24
         * @param Title $title
         * @param Parser|bool $parser
         * @return Revision|bool False if missing
         */
        public static function statelessFetchRevision( Title $title, $parser = false ) {
                $pageId = $title->getArticleID();
                $revId = $title->getLatestRevID();

                $rev = Revision::newKnownCurrent( wfGetDB( DB_REPLICA ), $pageId, $revId );
                if ( $rev ) {
                        $rev->setTitle( $title );
                }

                return $rev;
        }

        /**
         * Fetch the unparsed text of a template and register a reference to it.
         * @param Title $title
         * @return array ( string or false, Title )
         */
        public function fetchTemplateAndTitle( $title ) {
                // Defaults to Parser::statelessFetchTemplate()
                $templateCb = $this->mOptions->getTemplateCallback();
                $stuff = call_user_func( $templateCb, $title, $this );
                // We use U+007F DELETE to distinguish strip markers from regular text.
                $text = $stuff['text'];
                if ( is_string( $stuff['text'] ) ) {
                        $text = strtr( $text, "\x7f", "?" );
                }
                $finalTitle = isset( $stuff['finalTitle'] ) ? $stuff['finalTitle'] : $title;
                if ( isset( $stuff['deps'] ) ) {
                        foreach ( $stuff['deps'] as $dep ) {
                                $this->mOutput->addTemplate( $dep['title'], $dep['page_id'], $dep['rev_id'] );
                                if ( $dep['title']->equals( $this->getTitle() ) ) {
                                        // If we transclude ourselves, the final result
                                        // will change based on the new version of the page
                                        $this->mOutput->setFlag( 'vary-revision' );
                                }
                        }
                }
                return [ $text, $finalTitle ];
        }

        /**
         * Fetch the unparsed text of a template and register a reference to it.
         * @param Title $title
         * @return string|bool
         */
        public function fetchTemplate( $title ) {
                return $this->fetchTemplateAndTitle( $title )[0];
        }

        /**
         * Static function to get a template
         * Can be overridden via ParserOptions::setTemplateCallback().
         *
         * @param Title $title
         * @param bool|Parser $parser
         *
         * @return array
         */
        public static function statelessFetchTemplate( $title, $parser = false ) {
                $text = $skip = false;
                $finalTitle = $title;
                $deps = [];

                # Loop to fetch the article, with up to 1 redirect
                // @codingStandardsIgnoreStart Generic.CodeAnalysis.ForLoopWithTestFunctionCall.NotAllowed
                for ( $i = 0; $i < 2 && is_object( $title ); $i++ ) {
                        // @codingStandardsIgnoreEnd
                        # Give extensions a chance to select the revision instead
                        $id = false; # Assume current
                        Hooks::run( 'BeforeParserFetchTemplateAndtitle',
                                [ $parser, $title, &$skip, &$id ] );

                        if ( $skip ) {
                                $text = false;
                                $deps[] = [
                                        'title' => $title,
                                        'page_id' => $title->getArticleID(),
                                        'rev_id' => null
                                ];
                                break;
                        }
                        # Get the revision
                        if ( $id ) {
                                $rev = Revision::newFromId( $id );
                        } elseif ( $parser ) {
                                $rev = $parser->fetchCurrentRevisionOfTitle( $title );
                        } else {
                                $rev = Revision::newFromTitle( $title );
                        }
                        $rev_id = $rev ? $rev->getId() : 0;
                        # If there is no current revision, there is no page
                        if ( $id === false && !$rev ) {
                                $linkCache = LinkCache::singleton();
                                $linkCache->addBadLinkObj( $title );
                        }

                        $deps[] = [
                                'title' => $title,
                                'page_id' => $title->getArticleID(),
                                'rev_id' => $rev_id ];
                        if ( $rev && !$title->equals( $rev->getTitle() ) ) {
                                # We fetched a rev from a different title; register it too...
                                $deps[] = [
                                        'title' => $rev->getTitle(),
                                        'page_id' => $rev->getPage(),
                                        'rev_id' => $rev_id ];
                        }

                        if ( $rev ) {
                                $content = $rev->getContent();
                                $text = $content ? $content->getWikitextForTransclusion() : null;

                                Hooks::run( 'ParserFetchTemplate',
                                        [ $parser, $title, $rev, &$text, &$deps ] );

                                if ( $text === false || $text === null ) {
                                        $text = false;
                                        break;
                                }
                        } elseif ( $title->getNamespace() == NS_MEDIAWIKI ) {
                                global $wgContLang;
                                $message = wfMessage( $wgContLang->lcfirst( $title->getText() ) )->inContentLanguage();
                                if ( !$message->exists() ) {
                                        $text = false;
                                        break;
                                }
                                $content = $message->content();
                                $text = $message->plain();
                        } else {
                                break;
                        }
                        if ( !$content ) {
                                break;
                        }
                        # Redirect?
                        $finalTitle = $title;
                        $title = $content->getRedirectTarget();
                }
                return [
                        'text' => $text,
                        'finalTitle' => $finalTitle,
                        'deps' => $deps ];
        }

        /**
         * Fetch a file and its title and register a reference to it.
         * If 'broken' is a key in $options then the file will appear as a broken thumbnail.
         * @param Title $title
         * @param array $options Array of options to RepoGroup::findFile
         * @return File|bool
         */
        public function fetchFile( $title, $options = [] ) {
                return $this->fetchFileAndTitle( $title, $options )[0];
        }

        /**
         * Fetch a file and its title and register a reference to it.
         * If 'broken' is a key in $options then the file will appear as a broken thumbnail.
         * @param Title $title
         * @param array $options Array of options to RepoGroup::findFile
         * @return array ( File or false, Title of file )
         */
        public function fetchFileAndTitle( $title, $options = [] ) {
                $file = $this->fetchFileNoRegister( $title, $options );

                $time = $file ? $file->getTimestamp() : false;
                $sha1 = $file ? $file->getSha1() : false;
                # Register the file as a dependency...
                $this->mOutput->addImage( $title->getDBkey(), $time, $sha1 );
                if ( $file && !$title->equals( $file->getTitle() ) ) {
                        # Update fetched file title
                        $title = $file->getTitle();
                        $this->mOutput->addImage( $title->getDBkey(), $time, $sha1 );
                }
                return [ $file, $title ];
        }

        /**
         * Helper function for fetchFileAndTitle.
         *
         * Also useful if you need to fetch a file but not use it yet,
         * for example to get the file's handler.
         *
         * @param Title $title
         * @param array $options Array of options to RepoGroup::findFile
         * @return File|bool
         */
        protected function fetchFileNoRegister( $title, $options = [] ) {
                if ( isset( $options['broken'] ) ) {
                        $file = false; // broken thumbnail forced by hook
                } elseif ( isset( $options['sha1'] ) ) { // get by (sha1,timestamp)
                        $file = RepoGroup::singleton()->findFileFromKey( $options['sha1'], $options );
                } else { // get by (name,timestamp)
                        $file = wfFindFile( $title, $options );
                }
                return $file;
        }

        /**
         * Transclude an interwiki link.
         *
         * @param Title $title
         * @param string $action
         *
         * @return string
         */
        public function interwikiTransclude( $title, $action ) {
                global $wgEnableScaryTranscluding;

                if ( !$wgEnableScaryTranscluding ) {
                        return wfMessage( 'scarytranscludedisabled' )->inContentLanguage()->text();
                }

                $url = $title->getFullURL( [ 'action' => $action ] );

                if ( strlen( $url ) > 255 ) {
                        return wfMessage( 'scarytranscludetoolong' )->inContentLanguage()->text();
                }
                return $this->fetchScaryTemplateMaybeFromCache( $url );
        }

        /**
         * @param string $url
         * @return mixed|string
         */
        public function fetchScaryTemplateMaybeFromCache( $url ) {
                global $wgTranscludeCacheExpiry;
                $dbr = wfGetDB( DB_REPLICA );
                $tsCond = $dbr->timestamp( time() - $wgTranscludeCacheExpiry );
                $obj = $dbr->selectRow( 'transcache', [ 'tc_time', 'tc_contents' ],
                                [ 'tc_url' => $url, "tc_time >= " . $dbr->addQuotes( $tsCond ) ] );
                if ( $obj ) {
                        return $obj->tc_contents;
                }

                $req = MWHttpRequest::factory( $url, [], __METHOD__ );
                $status = $req->execute(); // Status object
                if ( $status->isOK() ) {
                        $text = $req->getContent();
                } elseif ( $req->getStatus() != 200 ) {
                        // Though we failed to fetch the content, this status is useless.
                        return wfMessage( 'scarytranscludefailed-httpstatus' )
                                ->params( $url, $req->getStatus() /* HTTP status */ )->inContentLanguage()->text();
                } else {
                        return wfMessage( 'scarytranscludefailed', $url )->inContentLanguage()->text();
                }

                $dbw = wfGetDB( DB_MASTER );
                $dbw->replace( 'transcache', [ 'tc_url' ], [
                        'tc_url' => $url,
                        'tc_time' => $dbw->timestamp( time() ),
                        'tc_contents' => $text
                ] );
                return $text;
        }

        /**
         * Triple brace replacement -- used for template arguments
         * @private
         *
         * @param array $piece
         * @param PPFrame $frame
         *
         * @return array
         */
        public function argSubstitution( $piece, $frame ) {

                $error = false;
                $parts = $piece['parts'];
                $nameWithSpaces = $frame->expand( $piece['title'] );
                $argName = trim( $nameWithSpaces );
                $object = false;
                $text = $frame->getArgument( $argName );
                if ( $text === false && $parts->getLength() > 0
                        && ( $this->ot['html']
                                || $this->ot['pre']
                                || ( $this->ot['wiki'] && $frame->isTemplate() )
                        )
                ) {
                        # No match in frame, use the supplied default
                        $object = $parts->item( 0 )->getChildren();
                }
                if ( !$this->incrementIncludeSize( 'arg', strlen( $text ) ) ) {
                        $error = '<!-- WARNING: argument omitted, expansion size too large -->';
                        $this->limitationWarn( 'post-expand-template-argument' );
                }

                if ( $text === false && $object === false ) {
                        # No match anywhere
                        $object = $frame->virtualBracketedImplode( '{{{', '|', '}}}', $nameWithSpaces, $parts );
                }
                if ( $error !== false ) {
                        $text .= $error;
                }
                if ( $object !== false ) {
                        $ret = [ 'object' => $object ];
                } else {
                        $ret = [ 'text' => $text ];
                }

                return $ret;
        }

        /**
         * Return the text to be used for a given extension tag.
         * This is the ghost of strip().
         *
         * @param array $params Associative array of parameters:
         *     name       PPNode for the tag name
         *     attr       PPNode for unparsed text where tag attributes are thought to be
         *     attributes Optional associative array of parsed attributes
         *     inner      Contents of extension element
         *     noClose    Original text did not have a close tag
         * @param PPFrame $frame
         *
         * @throws MWException
         * @return string
         */
        public function extensionSubstitution( $params, $frame ) {
                static $errorStr = '<span class="error">';
                static $errorLen = 20;

                $name = $frame->expand( $params['name'] );
                if ( substr( $name, 0, $errorLen ) === $errorStr ) {
                        // Probably expansion depth or node count exceeded. Just punt the
                        // error up.
                        return $name;
                }

                $attrText = !isset( $params['attr'] ) ? null : $frame->expand( $params['attr'] );
                if ( substr( $attrText, 0, $errorLen ) === $errorStr ) {
                        // See above
                        return $attrText;
                }

                // We can't safely check if the expansion for $content resulted in an
                // error, because the content could happen to be the error string
                // (T149622).
                $content = !isset( $params['inner'] ) ? null : $frame->expand( $params['inner'] );

                $marker = self::MARKER_PREFIX . "-$name-"
                        . sprintf( '%08X', $this->mMarkerIndex++ ) . self::MARKER_SUFFIX;

                $isFunctionTag = isset( $this->mFunctionTagHooks[strtolower( $name )] ) &&
                        ( $this->ot['html'] || $this->ot['pre'] );
                if ( $isFunctionTag ) {
                        $markerType = 'none';
                } else {
                        $markerType = 'general';
                }
                if ( $this->ot['html'] || $isFunctionTag ) {
                        $name = strtolower( $name );
                        $attributes = Sanitizer::decodeTagAttributes( $attrText );
                        if ( isset( $params['attributes'] ) ) {
                                $attributes = $attributes + $params['attributes'];
                        }

                        if ( isset( $this->mTagHooks[$name] ) ) {
                                # Workaround for PHP bug 35229 and similar
                                if ( !is_callable( $this->mTagHooks[$name] ) ) {
                                        throw new MWException( "Tag hook for $name is not callable\n" );
                                }
                                $output = call_user_func_array( $this->mTagHooks[$name],
                                        [ $content, $attributes, $this, $frame ] );
                        } elseif ( isset( $this->mFunctionTagHooks[$name] ) ) {
                                list( $callback, ) = $this->mFunctionTagHooks[$name];
                                if ( !is_callable( $callback ) ) {
                                        throw new MWException( "Tag hook for $name is not callable\n" );
                                }

                                // Avoid PHP 7.1 warning from passing $this by reference
                                $parser = $this;
                                $output = call_user_func_array( $callback, [ &$parser, $frame, $content, $attributes ] );
                        } else {
                                $output = '<span class="error">Invalid tag extension name: ' .
                                        htmlspecialchars( $name ) . '</span>';
                        }

                        if ( is_array( $output ) ) {
                                # Extract flags to local scope (to override $markerType)
                                $flags = $output;
                                $output = $flags[0];
                                unset( $flags[0] );
                                extract( $flags );
                        }
                } else {
                        if ( is_null( $attrText ) ) {
                                $attrText = '';
                        }
                        if ( isset( $params['attributes'] ) ) {
                                foreach ( $params['attributes'] as $attrName => $attrValue ) {
                                        $attrText .= ' ' . htmlspecialchars( $attrName ) . '="' .
                                                htmlspecialchars( $attrValue ) . '"';
                                }
                        }
                        if ( $content === null ) {
                                $output = "<$name$attrText/>";
                        } else {
                                $close = is_null( $params['close'] ) ? '' : $frame->expand( $params['close'] );
                                if ( substr( $close, 0, $errorLen ) === $errorStr ) {
                                        // See above
                                        return $close;
                                }
                                $output = "<$name$attrText>$content$close";
                        }
                }

                if ( $markerType === 'none' ) {
                        return $output;
                } elseif ( $markerType === 'nowiki' ) {
                        $this->mStripState->addNoWiki( $marker, $output );
                } elseif ( $markerType === 'general' ) {
                        $this->mStripState->addGeneral( $marker, $output );
                } else {
                        throw new MWException( __METHOD__ . ': invalid marker type' );
                }
                return $marker;
        }

        /**
         * Increment an include size counter
         *
         * @param string $type The type of expansion
         * @param int $size The size of the text
         * @return bool False if this inclusion would take it over the maximum, true otherwise
         */
        public function incrementIncludeSize( $type, $size ) {
                if ( $this->mIncludeSizes[$type] + $size > $this->mOptions->getMaxIncludeSize() ) {
                        return false;
                } else {
                        $this->mIncludeSizes[$type] += $size;
                        return true;
                }
        }

        /**
         * Increment the expensive function count
         *
         * @return bool False if the limit has been exceeded
         */
        public function incrementExpensiveFunctionCount() {
                $this->mExpensiveFunctionCount++;
                return $this->mExpensiveFunctionCount <= $this->mOptions->getExpensiveParserFunctionLimit();
        }

        /**
         * Strip double-underscore items like __NOGALLERY__ and __NOTOC__
         * Fills $this->mDoubleUnderscores, returns the modified text
         *
         * @param string $text
         *
         * @return string
         */
        public function doDoubleUnderscore( $text ) {

                # The position of __TOC__ needs to be recorded
                $mw = MagicWord::get( 'toc' );
                if ( $mw->match( $text ) ) {
                        $this->mShowToc = true;
                        $this->mForceTocPosition = true;

                        # Set a placeholder. At the end we'll fill it in with the TOC.
                        $text = $mw->replace( '<!--MWTOC-->', $text, 1 );

                        # Only keep the first one.
                        $text = $mw->replace( '', $text );
                }

                # Now match and remove the rest of them
                $mwa = MagicWord::getDoubleUnderscoreArray();
                $this->mDoubleUnderscores = $mwa->matchAndRemove( $text );

                if ( isset( $this->mDoubleUnderscores['nogallery'] ) ) {
                        $this->mOutput->mNoGallery = true;
                }
                if ( isset( $this->mDoubleUnderscores['notoc'] ) && !$this->mForceTocPosition ) {
                        $this->mShowToc = false;
                }
                if ( isset( $this->mDoubleUnderscores['hiddencat'] )
                        && $this->mTitle->getNamespace() == NS_CATEGORY
                ) {
                        $this->addTrackingCategory( 'hidden-category-category' );
                }
                # (T10068) Allow control over whether robots index a page.
                # __INDEX__ always overrides __NOINDEX__, see T16899
                if ( isset( $this->mDoubleUnderscores['noindex'] ) && $this->mTitle->canUseNoindex() ) {
                        $this->mOutput->setIndexPolicy( 'noindex' );
                        $this->addTrackingCategory( 'noindex-category' );
                }
                if ( isset( $this->mDoubleUnderscores['index'] ) && $this->mTitle->canUseNoindex() ) {
                        $this->mOutput->setIndexPolicy( 'index' );
                        $this->addTrackingCategory( 'index-category' );
                }

                # Cache all double underscores in the database
                foreach ( $this->mDoubleUnderscores as $key => $val ) {
                        $this->mOutput->setProperty( $key, '' );
                }

                return $text;
        }

        /**
         * @see ParserOutput::addTrackingCategory()
         * @param string $msg Message key
         * @return bool Whether the addition was successful
         */
        public function addTrackingCategory( $msg ) {
                return $this->mOutput->addTrackingCategory( $msg, $this->mTitle );
        }

        /**
         * This function accomplishes several tasks:
         * 1) Auto-number headings if that option is enabled
         * 2) Add an [edit] link to sections for users who have enabled the option and can edit the page
         * 3) Add a Table of contents on the top for users who have enabled the option
         * 4) Auto-anchor headings
         *
         * It loops through all headlines, collects the necessary data, then splits up the
         * string and re-inserts the newly formatted headlines.
         *
         * @param string $text
         * @param string $origText Original, untouched wikitext
         * @param bool $isMain
         * @return mixed|string
         * @private
         */
        public function formatHeadings( $text, $origText, $isMain = true ) {
                global $wgMaxTocLevel, $wgExperimentalHtmlIds;

                # Inhibit editsection links if requested in the page
                if ( isset( $this->mDoubleUnderscores['noeditsection'] ) ) {
                        $maybeShowEditLink = $showEditLink = false;
                } else {
                        $maybeShowEditLink = true; /* Actual presence will depend on ParserOptions option */
                        $showEditLink = $this->mOptions->getEditSection();
                }
                if ( $showEditLink ) {
                        $this->mOutput->setEditSectionTokens( true );
                }

                # Get all headlines for numbering them and adding funky stuff like [edit]
                # links - this is for later, but we need the number of headlines right now
                $matches = [];
                $numMatches = preg_match_all(
                        '/<H(?P<level>[1-6])(?P<attrib>.*?>)\s*(?P<header>[\s\S]*?)\s*<\/H[1-6] *>/i',
                        $text,
                        $matches
                );

                # if there are fewer than 4 headlines in the article, do not show TOC
                # unless it's been explicitly enabled.
                $enoughToc = $this->mShowToc &&
                        ( ( $numMatches >= 4 ) || $this->mForceTocPosition );

                # Allow user to stipulate that a page should have a "new section"
                # link added via __NEWSECTIONLINK__
                if ( isset( $this->mDoubleUnderscores['newsectionlink'] ) ) {
                        $this->mOutput->setNewSection( true );
                }

                # Allow user to remove the "new section"
                # link via __NONEWSECTIONLINK__
                if ( isset( $this->mDoubleUnderscores['nonewsectionlink'] ) ) {
                        $this->mOutput->hideNewSection( true );
                }

                # if the string __FORCETOC__ (not case-sensitive) occurs in the HTML,
                # override above conditions and always show TOC above first header
                if ( isset( $this->mDoubleUnderscores['forcetoc'] ) ) {
                        $this->mShowToc = true;
                        $enoughToc = true;
                }

                # headline counter
                $headlineCount = 0;
                $numVisible = 0;

                # Ugh .. the TOC should have neat indentation levels which can be
                # passed to the skin functions. These are determined here
                $toc = '';
                $full = '';
                $head = [];
                $sublevelCount = [];
                $levelCount = [];
                $level = 0;
                $prevlevel = 0;
                $toclevel = 0;
                $prevtoclevel = 0;
                $markerRegex = self::MARKER_PREFIX . "-h-(\d+)-" . self::MARKER_SUFFIX;
                $baseTitleText = $this->mTitle->getPrefixedDBkey();
                $oldType = $this->mOutputType;
                $this->setOutputType( self::OT_WIKI );
                $frame = $this->getPreprocessor()->newFrame();
                $root = $this->preprocessToDom( $origText );
                $node = $root->getFirstChild();
                $byteOffset = 0;
                $tocraw = [];
                $refers = [];

                $headlines = $numMatches !== false ? $matches[3] : [];

                foreach ( $headlines as $headline ) {
                        $isTemplate = false;
                        $titleText = false;
                        $sectionIndex = false;
                        $numbering = '';
                        $markerMatches = [];
                        if ( preg_match( "/^$markerRegex/", $headline, $markerMatches ) ) {
                                $serial = $markerMatches[1];
                                list( $titleText, $sectionIndex ) = $this->mHeadings[$serial];
                                $isTemplate = ( $titleText != $baseTitleText );
                                $headline = preg_replace( "/^$markerRegex\\s*/", "", $headline );
                        }

                        if ( $toclevel ) {
                                $prevlevel = $level;
                        }
                        $level = $matches[1][$headlineCount];

                        if ( $level > $prevlevel ) {
                                # Increase TOC level
                                $toclevel++;
                                $sublevelCount[$toclevel] = 0;
                                if ( $toclevel < $wgMaxTocLevel ) {
                                        $prevtoclevel = $toclevel;
                                        $toc .= Linker::tocIndent();
                                        $numVisible++;
                                }
                        } elseif ( $level < $prevlevel && $toclevel > 1 ) {
                                # Decrease TOC level, find level to jump to

                                for ( $i = $toclevel; $i > 0; $i-- ) {
                                        if ( $levelCount[$i] == $level ) {
                                                # Found last matching level
                                                $toclevel = $i;
                                                break;
                                        } elseif ( $levelCount[$i] < $level ) {
                                                # Found first matching level below current level
                                                $toclevel = $i + 1;
                                                break;
                                        }
                                }
                                if ( $i == 0 ) {
                                        $toclevel = 1;
                                }
                                if ( $toclevel < $wgMaxTocLevel ) {
                                        if ( $prevtoclevel < $wgMaxTocLevel ) {
                                                # Unindent only if the previous toc level was shown :p
                                                $toc .= Linker::tocUnindent( $prevtoclevel - $toclevel );
                                                $prevtoclevel = $toclevel;
                                        } else {
                                                $toc .= Linker::tocLineEnd();
                                        }
                                }
                        } else {
                                # No change in level, end TOC line
                                if ( $toclevel < $wgMaxTocLevel ) {
                                        $toc .= Linker::tocLineEnd();
                                }
                        }

                        $levelCount[$toclevel] = $level;

                        # count number of headlines for each level
                        $sublevelCount[$toclevel]++;
                        $dot = 0;
                        for ( $i = 1; $i <= $toclevel; $i++ ) {
                                if ( !empty( $sublevelCount[$i] ) ) {
                                        if ( $dot ) {
                                                $numbering .= '.';
                                        }
                                        $numbering .= $this->getTargetLanguage()->formatNum( $sublevelCount[$i] );
                                        $dot = 1;
                                }
                        }

                        # The safe header is a version of the header text safe to use for links

                        # Remove link placeholders by the link text.
                        #     <!--LINK number-->
                        # turns into
                        #     link text with suffix
                        # Do this before unstrip since link text can contain strip markers
                        $safeHeadline = $this->replaceLinkHoldersText( $headline );

                        # Avoid insertion of weird stuff like <math> by expanding the relevant sections
                        $safeHeadline = $this->mStripState->unstripBoth( $safeHeadline );

                        # Strip out HTML (first regex removes any tag not allowed)
                        # Allowed tags are:
                        # * <sup> and <sub> (T10393)
                        # * <i> (T28375)
                        # * <b> (r105284)
                        # * <bdi> (T74884)
                        # * <span dir="rtl"> and <span dir="ltr"> (T37167)
                        # * <s> and <strike> (T35715)
                        # We strip any parameter from accepted tags (second regex), except dir="rtl|ltr" from <span>,
                        # to allow setting directionality in toc items.
                        $tocline = preg_replace(
                                [
                                        '#<(?!/?(span|sup|sub|bdi|i|b|s|strike)(?: [^>]*)?>).*?>#',
                                        '#<(/?(?:span(?: dir="(?:rtl|ltr)")?|sup|sub|bdi|i|b|s|strike))(?: .*?)?>#'
                                ],
                                [ '', '<$1>' ],
                                $safeHeadline
                        );

                        # Strip '<span></span>', which is the result from the above if
                        # <span id="foo"></span> is used to produce an additional anchor
                        # for a section.
                        $tocline = str_replace( '<span></span>', '', $tocline );

                        $tocline = trim( $tocline );

                        # For the anchor, strip out HTML-y stuff period
                        $safeHeadline = preg_replace( '/<.*?>/', '', $safeHeadline );
                        $safeHeadline = Sanitizer::normalizeSectionNameWhitespace( $safeHeadline );

                        # Save headline for section edit hint before it's escaped
                        $headlineHint = $safeHeadline;

                        if ( $wgExperimentalHtmlIds ) {
                                # For reverse compatibility, provide an id that's
                                # HTML4-compatible, like we used to.
                                # It may be worth noting, academically, that it's possible for
                                # the legacy anchor to conflict with a non-legacy headline
                                # anchor on the page.  In this case likely the "correct" thing
                                # would be to either drop the legacy anchors or make sure
                                # they're numbered first.  However, this would require people
                                # to type in section names like "abc_.D7.93.D7.90.D7.A4"
                                # manually, so let's not bother worrying about it.
                                $legacyHeadline = Sanitizer::escapeId( $safeHeadline,
                                        [ 'noninitial', 'legacy' ] );
                                $safeHeadline = Sanitizer::escapeId( $safeHeadline );

                                if ( $legacyHeadline == $safeHeadline ) {
                                        # No reason to have both (in fact, we can't)
                                        $legacyHeadline = false;
                                }
                        } else {
                                $legacyHeadline = false;
                                $safeHeadline = Sanitizer::escapeId( $safeHeadline,
                                        'noninitial' );
                        }

                        # HTML names must be case-insensitively unique (T12721).
                        # This does not apply to Unicode characters per
                        # https://www.w3.org/TR/html5/infrastructure.html#case-sensitivity-and-string-comparison
                        # @todo FIXME: We may be changing them depending on the current locale.
                        $arrayKey = strtolower( $safeHeadline );
                        if ( $legacyHeadline === false ) {
                                $legacyArrayKey = false;
                        } else {
                                $legacyArrayKey = strtolower( $legacyHeadline );
                        }

                        # Create the anchor for linking from the TOC to the section
                        $anchor = $safeHeadline;
                        $legacyAnchor = $legacyHeadline;
                        if ( isset( $refers[$arrayKey] ) ) {
                                // @codingStandardsIgnoreStart
                                for ( $i = 2; isset( $refers["${arrayKey}_$i"] ); ++$i );
                                // @codingStandardsIgnoreEnd
                                $anchor .= "_$i";
                                $refers["${arrayKey}_$i"] = true;
                        } else {
                                $refers[$arrayKey] = true;
                        }
                        if ( $legacyHeadline !== false && isset( $refers[$legacyArrayKey] ) ) {
                                // @codingStandardsIgnoreStart
                                for ( $i = 2; isset( $refers["${legacyArrayKey}_$i"] ); ++$i );
                                // @codingStandardsIgnoreEnd
                                $legacyAnchor .= "_$i";
                                $refers["${legacyArrayKey}_$i"] = true;
                        } else {
                                $refers[$legacyArrayKey] = true;
                        }

                        # Don't number the heading if it is the only one (looks silly)
                        if ( count( $matches[3] ) > 1 && $this->mOptions->getNumberHeadings() ) {
                                # the two are different if the line contains a link
                                $headline = Html::element(
                                        'span',
                                        [ 'class' => 'mw-headline-number' ],
                                        $numbering
                                ) . ' ' . $headline;
                        }

                        if ( $enoughToc && ( !isset( $wgMaxTocLevel ) || $toclevel < $wgMaxTocLevel ) ) {
                                $toc .= Linker::tocLine( $anchor, $tocline,
                                        $numbering, $toclevel, ( $isTemplate ? false : $sectionIndex ) );
                        }

                        # Add the section to the section tree
                        # Find the DOM node for this header
                        $noOffset = ( $isTemplate || $sectionIndex === false );
                        while ( $node && !$noOffset ) {
                                if ( $node->getName() === 'h' ) {
                                        $bits = $node->splitHeading();
                                        if ( $bits['i'] == $sectionIndex ) {
                                                break;
                                        }
                                }
                                $byteOffset += mb_strlen( $this->mStripState->unstripBoth(
                                        $frame->expand( $node, PPFrame::RECOVER_ORIG ) ) );
                                $node = $node->getNextSibling();
                        }
                        $tocraw[] = [
                                'toclevel' => $toclevel,
                                'level' => $level,
                                'line' => $tocline,
                                'number' => $numbering,
                                'index' => ( $isTemplate ? 'T-' : '' ) . $sectionIndex,
                                'fromtitle' => $titleText,
                                'byteoffset' => ( $noOffset ? null : $byteOffset ),
                                'anchor' => $anchor,
                        ];

                        # give headline the correct <h#> tag
                        if ( $maybeShowEditLink && $sectionIndex !== false ) {
                                // Output edit section links as markers with styles that can be customized by skins
                                if ( $isTemplate ) {
                                        # Put a T flag in the section identifier, to indicate to extractSections()
                                        # that sections inside <includeonly> should be counted.
                                        $editsectionPage = $titleText;
                                        $editsectionSection = "T-$sectionIndex";
                                        $editsectionContent = null;
                                } else {
                                        $editsectionPage = $this->mTitle->getPrefixedText();
                                        $editsectionSection = $sectionIndex;
                                        $editsectionContent = $headlineHint;
                                }
                                // We use a bit of pesudo-xml for editsection markers. The
                                // language converter is run later on. Using a UNIQ style marker
                                // leads to the converter screwing up the tokens when it
                                // converts stuff. And trying to insert strip tags fails too. At
                                // this point all real inputted tags have already been escaped,
                                // so we don't have to worry about a user trying to input one of
                                // these markers directly. We use a page and section attribute
                                // to stop the language converter from converting these
                                // important bits of data, but put the headline hint inside a
                                // content block because the language converter is supposed to
                                // be able to convert that piece of data.
                                // Gets replaced with html in ParserOutput::getText
                                $editlink = '<mw:editsection page="' . htmlspecialchars( $editsectionPage );
                                $editlink .= '" section="' . htmlspecialchars( $editsectionSection ) . '"';
                                if ( $editsectionContent !== null ) {
                                        $editlink .= '>' . $editsectionContent . '</mw:editsection>';
                                } else {
                                        $editlink .= '/>';
                                }
                        } else {
                                $editlink = '';
                        }
                        $head[$headlineCount] = Linker::makeHeadline( $level,
                                $matches['attrib'][$headlineCount], $anchor, $headline,
                                $editlink, $legacyAnchor );

                        $headlineCount++;
                }

                $this->setOutputType( $oldType );

                # Never ever show TOC if no headers
                if ( $numVisible < 1 ) {
                        $enoughToc = false;
                }

                if ( $enoughToc ) {
                        if ( $prevtoclevel > 0 && $prevtoclevel < $wgMaxTocLevel ) {
                                $toc .= Linker::tocUnindent( $prevtoclevel - 1 );
                        }
                        $toc = Linker::tocList( $toc, $this->mOptions->getUserLangObj() );
                        $this->mOutput->setTOCHTML( $toc );
                        $toc = self::TOC_START . $toc . self::TOC_END;
                        $this->mOutput->addModules( 'mediawiki.toc' );
                }

                if ( $isMain ) {
                        $this->mOutput->setSections( $tocraw );
                }

                # split up and insert constructed headlines
                $blocks = preg_split( '/<H[1-6].*?>[\s\S]*?<\/H[1-6]>/i', $text );
                $i = 0;

                // build an array of document sections
                $sections = [];
                foreach ( $blocks as $block ) {
                        // $head is zero-based, sections aren't.
                        if ( empty( $head[$i - 1] ) ) {
                                $sections[$i] = $block;
                        } else {
                                $sections[$i] = $head[$i - 1] . $block;
                        }

                        /**
                         * Send a hook, one per section.
                         * The idea here is to be able to make section-level DIVs, but to do so in a
                         * lower-impact, more correct way than r50769
                         *
                         * $this : caller
                         * $section : the section number
                         * &$sectionContent : ref to the content of the section
                         * $showEditLinks : boolean describing whether this section has an edit link
                         */
                        Hooks::run( 'ParserSectionCreate', [ $this, $i, &$sections[$i], $showEditLink ] );

                        $i++;
                }

                if ( $enoughToc && $isMain && !$this->mForceTocPosition ) {
                        // append the TOC at the beginning
                        // Top anchor now in skin
                        $sections[0] = $sections[0] . $toc . "\n";
                }

                $full .= implode( '', $sections );

                if ( $this->mForceTocPosition ) {
                        return str_replace( '<!--MWTOC-->', $toc, $full );
                } else {
                        return $full;
                }
        }

        /**
         * Transform wiki markup when saving a page by doing "\r\n" -> "\n"
         * conversion, substituting signatures, {{subst:}} templates, etc.
         *
         * @param string $text The text to transform
         * @param Title $title The Title object for the current article
         * @param User $user The User object describing the current user
         * @param ParserOptions $options Parsing options
         * @param bool $clearState Whether to clear the parser state first
         * @return string The altered wiki markup
         */
        public function preSaveTransform( $text, Title $title, User $user,
                ParserOptions $options, $clearState = true
        ) {
                if ( $clearState ) {
                        $magicScopeVariable = $this->lock();
                }
                $this->startParse( $title, $options, self::OT_WIKI, $clearState );
                $this->setUser( $user );

                // Strip U+0000 NULL (T159174)
                $text = str_replace( "\000", '', $text );

                // We still normalize line endings for backwards-compatibility
                // with other code that just calls PST, but this should already
                // be handled in TextContent subclasses
                $text = TextContent::normalizeLineEndings( $text );

                if ( $options->getPreSaveTransform() ) {
                        $text = $this->pstPass2( $text, $user );
                }
                $text = $this->mStripState->unstripBoth( $text );

                $this->setUser( null ); # Reset

                return $text;
        }

        /**
         * Pre-save transform helper function
         *
         * @param string $text
         * @param User $user
         *
         * @return string
         */
        private function pstPass2( $text, $user ) {
                global $wgContLang;

                # Note: This is the timestamp saved as hardcoded wikitext to
                # the database, we use $wgContLang here in order to give
                # everyone the same signature and use the default one rather
                # than the one selected in each user's preferences.
                # (see also T14815)
                $ts = $this->mOptions->getTimestamp();
                $timestamp = MWTimestamp::getLocalInstance( $ts );
                $ts = $timestamp->format( 'YmdHis' );
                $tzMsg = $timestamp->getTimezoneMessage()->inContentLanguage()->text();

                $d = $wgContLang->timeanddate( $ts, false, false ) . " ($tzMsg)";

                # Variable replacement
                # Because mOutputType is OT_WIKI, this will only process {{subst:xxx}} type tags
                $text = $this->replaceVariables( $text );

                # This works almost by chance, as the replaceVariables are done before the getUserSig(),
                # which may corrupt this parser instance via its wfMessage()->text() call-

                # Signatures
                $sigText = $this->getUserSig( $user );
                $text = strtr( $text, [
                        '~~~~~' => $d,
                        '~~~~' => "$sigText $d",
                        '~~~' => $sigText
                ] );

                # Context links ("pipe tricks"): [[|name]] and [[name (context)|]]
                $tc = '[' . Title::legalChars() . ']';
                $nc = '[ _0-9A-Za-z\x80-\xff-]'; # Namespaces can use non-ascii!

                // [[ns:page (context)|]]
                $p1 = "/\[\[(:?$nc+:|:|)($tc+?)( ?\\($tc+\\))\\|]]/";
                // [[ns:page（context）|]] (double-width brackets, added in r40257)
                $p4 = "/\[\[(:?$nc+:|:|)($tc+?)( ?（$tc+）)\\|]]/";
                // [[ns:page (context), context|]] (using either single or double-width comma)
                $p3 = "/\[\[(:?$nc+:|:|)($tc+?)( ?\\($tc+\\)|)((?:, |，)$tc+|)\\|]]/";
                // [[|page]] (reverse pipe trick: add context from page title)
                $p2 = "/\[\[\\|($tc+)]]/";

                # try $p1 first, to turn "[[A, B (C)|]]" into "[[A, B (C)|A, B]]"
                $text = preg_replace( $p1, '[[\\1\\2\\3|\\2]]', $text );
                $text = preg_replace( $p4, '[[\\1\\2\\3|\\2]]', $text );
                $text = preg_replace( $p3, '[[\\1\\2\\3\\4|\\2]]', $text );

                $t = $this->mTitle->getText();
                $m = [];
                if ( preg_match( "/^($nc+:|)$tc+?( \\($tc+\\))$/", $t, $m ) ) {
                        $text = preg_replace( $p2, "[[$m[1]\\1$m[2]|\\1]]", $text );
                } elseif ( preg_match( "/^($nc+:|)$tc+?(, $tc+|)$/", $t, $m ) && "$m[1]$m[2]" != '' ) {
                        $text = preg_replace( $p2, "[[$m[1]\\1$m[2]|\\1]]", $text );
                } else {
                        # if there's no context, don't bother duplicating the title
                        $text = preg_replace( $p2, '[[\\1]]', $text );
                }

                return $text;
        }

        /**
         * Fetch the user's signature text, if any, and normalize to
         * validated, ready-to-insert wikitext.
         * If you have pre-fetched the nickname or the fancySig option, you can
         * specify them here to save a database query.
         * Do not reuse this parser instance after calling getUserSig(),
         * as it may have changed if it's the $wgParser.
         *
         * @param User $user
         * @param string|bool $nickname Nickname to use or false to use user's default nickname
         * @param bool|null $fancySig whether the nicknname is the complete signature
         *    or null to use default value
         * @return string
         */
        public function getUserSig( &$user, $nickname = false, $fancySig = null ) {
                global $wgMaxSigChars;

                $username = $user->getName();

                # If not given, retrieve from the user object.
                if ( $nickname === false ) {
                        $nickname = $user->getOption( 'nickname' );
                }

                if ( is_null( $fancySig ) ) {
                        $fancySig = $user->getBoolOption( 'fancysig' );
                }

                $nickname = $nickname == null ? $username : $nickname;

                if ( mb_strlen( $nickname ) > $wgMaxSigChars ) {
                        $nickname = $username;
                        wfDebug( __METHOD__ . ": $username has overlong signature.\n" );
                } elseif ( $fancySig !== false ) {
                        # Sig. might contain markup; validate this
                        if ( $this->validateSig( $nickname ) !== false ) {
                                # Validated; clean up (if needed) and return it
                                return $this->cleanSig( $nickname, true );
                        } else {
                                # Failed to validate; fall back to the default
                                $nickname = $username;
                                wfDebug( __METHOD__ . ": $username has bad XML tags in signature.\n" );
                        }
                }

                # Make sure nickname doesnt get a sig in a sig
                $nickname = self::cleanSigInSig( $nickname );

                # If we're still here, make it a link to the user page
                $userText = wfEscapeWikiText( $username );
                $nickText = wfEscapeWikiText( $nickname );
                $msgName = $user->isAnon() ? 'signature-anon' : 'signature';

                return wfMessage( $msgName, $userText, $nickText )->inContentLanguage()
                        ->title( $this->getTitle() )->text();
        }

        /**
         * Check that the user's signature contains no bad XML
         *
         * @param string $text
         * @return string|bool An expanded string, or false if invalid.
         */
        public function validateSig( $text ) {
                return Xml::isWellFormedXmlFragment( $text ) ? $text : false;
        }

        /**
         * Clean up signature text
         *
         * 1) Strip 3, 4 or 5 tildes out of signatures @see cleanSigInSig
         * 2) Substitute all transclusions
         *
         * @param string $text
         * @param bool $parsing Whether we're cleaning (preferences save) or parsing
         * @return string Signature text
         */
        public function cleanSig( $text, $parsing = false ) {
                if ( !$parsing ) {
                        global $wgTitle;
                        $magicScopeVariable = $this->lock();
                        $this->startParse( $wgTitle, new ParserOptions, self::OT_PREPROCESS, true );
                }

                # Option to disable this feature
                if ( !$this->mOptions->getCleanSignatures() ) {
                        return $text;
                }

                # @todo FIXME: Regex doesn't respect extension tags or nowiki
                #  => Move this logic to braceSubstitution()
                $substWord = MagicWord::get( 'subst' );
                $substRegex = '/\{\{(?!(?:' . $substWord->getBaseRegex() . '))/x' . $substWord->getRegexCase();
                $substText = '{{' . $substWord->getSynonym( 0 );

                $text = preg_replace( $substRegex, $substText, $text );
                $text = self::cleanSigInSig( $text );
                $dom = $this->preprocessToDom( $text );
                $frame = $this->getPreprocessor()->newFrame();
                $text = $frame->expand( $dom );

                if ( !$parsing ) {
                        $text = $this->mStripState->unstripBoth( $text );
                }

                return $text;
        }

        /**
         * Strip 3, 4 or 5 tildes out of signatures.
         *
         * @param string $text
         * @return string Signature text with /~{3,5}/ removed
         */
        public static function cleanSigInSig( $text ) {
                $text = preg_replace( '/~{3,5}/', '', $text );
                return $text;
        }

        /**
         * Set up some variables which are usually set up in parse()
         * so that an external function can call some class members with confidence
         *
         * @param Title|null $title
         * @param ParserOptions $options
         * @param int $outputType
         * @param bool $clearState
         */
        public function startExternalParse( Title $title = null, ParserOptions $options,
                $outputType, $clearState = true
        ) {
                $this->startParse( $title, $options, $outputType, $clearState );
        }

        /**
         * @param Title|null $title
         * @param ParserOptions $options
         * @param int $outputType
         * @param bool $clearState
         */
        private function startParse( Title $title = null, ParserOptions $options,
                $outputType, $clearState = true
        ) {
                $this->setTitle( $title );
                $this->mOptions = $options;
                $this->setOutputType( $outputType );
                if ( $clearState ) {
                        $this->clearState();
                }
        }

        /**
         * Wrapper for preprocess()
         *
         * @param string $text The text to preprocess
         * @param ParserOptions $options Options
         * @param Title|null $title Title object or null to use $wgTitle
         * @return string
         */
        public function transformMsg( $text, $options, $title = null ) {
                static $executing = false;

                # Guard against infinite recursion
                if ( $executing ) {
                        return $text;
                }
                $executing = true;

                if ( !$title ) {
                        global $wgTitle;
                        $title = $wgTitle;
                }

                $text = $this->preprocess( $text, $title, $options );

                $executing = false;
                return $text;
        }

        /**
         * Create an HTML-style tag, e.g. "<yourtag>special text</yourtag>"
         * The callback should have the following form:
         *    function myParserHook( $text, $params, $parser, $frame ) { ... }
         *
         * Transform and return $text. Use $parser for any required context, e.g. use
         * $parser->getTitle() and $parser->getOptions() not $wgTitle or $wgOut->mParserOptions
         *
         * Hooks may return extended information by returning an array, of which the
         * first numbered element (index 0) must be the return string, and all other
         * entries are extracted into local variables within an internal function
         * in the Parser class.
         *
         * This interface (introduced r61913) appears to be undocumented, but
         * 'markerType' is used by some core tag hooks to override which strip
         * array their results are placed in. **Use great caution if attempting
         * this interface, as it is not documented and injudicious use could smash
         * private variables.**
         *
         * @param string $tag The tag to use, e.g. 'hook' for "<hook>"
         * @param callable $callback The callback function (and object) to use for the tag
         * @throws MWException
         * @return callable|null The old value of the mTagHooks array associated with the hook
         */
        public function setHook( $tag, $callback ) {
                $tag = strtolower( $tag );
                if ( preg_match( '/[<>\r\n]/', $tag, $m ) ) {
                        throw new MWException( "Invalid character {$m[0]} in setHook('$tag', ...) call" );
                }
                $oldVal = isset( $this->mTagHooks[$tag] ) ? $this->mTagHooks[$tag] : null;
                $this->mTagHooks[$tag] = $callback;
                if ( !in_array( $tag, $this->mStripList ) ) {
                        $this->mStripList[] = $tag;
                }

                return $oldVal;
        }

        /**
         * As setHook(), but letting the contents be parsed.
         *
         * Transparent tag hooks are like regular XML-style tag hooks, except they
         * operate late in the transformation sequence, on HTML instead of wikitext.
         *
         * This is probably obsoleted by things dealing with parser frames?
         * The only extension currently using it is geoserver.
         *
         * @since 1.10
         * @todo better document or deprecate this
         *
         * @param string $tag The tag to use, e.g. 'hook' for "<hook>"
         * @param callable $callback The callback function (and object) to use for the tag
         * @throws MWException
         * @return callable|null The old value of the mTagHooks array associated with the hook
         */
        public function setTransparentTagHook( $tag, $callback ) {
                $tag = strtolower( $tag );
                if ( preg_match( '/[<>\r\n]/', $tag, $m ) ) {
                        throw new MWException( "Invalid character {$m[0]} in setTransparentHook('$tag', ...) call" );
                }
                $oldVal = isset( $this->mTransparentTagHooks[$tag] ) ? $this->mTransparentTagHooks[$tag] : null;
                $this->mTransparentTagHooks[$tag] = $callback;

                return $oldVal;
        }

        /**
         * Remove all tag hooks
         */
        public function clearTagHooks() {
                $this->mTagHooks = [];
                $this->mFunctionTagHooks = [];
                $this->mStripList = $this->mDefaultStripList;
        }

        /**
         * Create a function, e.g. {{sum:1|2|3}}
         * The callback function should have the form:
         *    function myParserFunction( &$parser, $arg1, $arg2, $arg3 ) { ... }
         *
         * Or with Parser::SFH_OBJECT_ARGS:
         *    function myParserFunction( $parser, $frame, $args ) { ... }
         *
         * The callback may either return the text result of the function, or an array with the text
         * in element 0, and a number of flags in the other elements. The names of the flags are
         * specified in the keys. Valid flags are:
         *   found                     The text returned is valid, stop processing the template. This
         *                             is on by default.
         *   nowiki                    Wiki markup in the return value should be escaped
         *   isHTML                    The returned text is HTML, armour it against wikitext transformation
         *
         * @param string $id The magic word ID
         * @param callable $callback The callback function (and object) to use
         * @param int $flags A combination of the following flags:
         *     Parser::SFH_NO_HASH      No leading hash, i.e. {{plural:...}} instead of {{#if:...}}
         *
         *     Parser::SFH_OBJECT_ARGS  Pass the template arguments as PPNode objects instead of text.
         *     This allows for conditional expansion of the parse tree, allowing you to eliminate dead
         *     branches and thus speed up parsing. It is also possible to analyse the parse tree of
         *     the arguments, and to control the way they are expanded.
         *
         *     The $frame parameter is a PPFrame. This can be used to produce expanded text from the
         *     arguments, for instance:
         *         $text = isset( $args[0] ) ? $frame->expand( $args[0] ) : '';
         *
         *     For technical reasons, $args[0] is pre-expanded and will be a string. This may change in
         *     future versions. Please call $frame->expand() on it anyway so that your code keeps
         *     working if/when this is changed.
         *
         *     If you want whitespace to be trimmed from $args, you need to do it yourself, post-
         *     expansion.
         *
         *     Please read the documentation in includes/parser/Preprocessor.php for more information
         *     about the methods available in PPFrame and PPNode.
         *
         * @throws MWException
         * @return string|callable The old callback function for this name, if any
         */
        public function setFunctionHook( $id, $callback, $flags = 0 ) {
                global $wgContLang;

                $oldVal = isset( $this->mFunctionHooks[$id] ) ? $this->mFunctionHooks[$id][0] : null;
                $this->mFunctionHooks[$id] = [ $callback, $flags ];

                # Add to function cache
                $mw = MagicWord::get( $id );
                if ( !$mw ) {
                        throw new MWException( __METHOD__ . '() expecting a magic word identifier.' );
                }

                $synonyms = $mw->getSynonyms();
                $sensitive = intval( $mw->isCaseSensitive() );

                foreach ( $synonyms as $syn ) {
                        # Case
                        if ( !$sensitive ) {
                                $syn = $wgContLang->lc( $syn );
                        }
                        # Add leading hash
                        if ( !( $flags & self::SFH_NO_HASH ) ) {
                                $syn = '#' . $syn;
                        }
                        # Remove trailing colon
                        if ( substr( $syn, -1, 1 ) === ':' ) {
                                $syn = substr( $syn, 0, -1 );
                        }
                        $this->mFunctionSynonyms[$sensitive][$syn] = $id;
                }
                return $oldVal;
        }

        /**
         * Get all registered function hook identifiers
         *
         * @return array
         */
        public function getFunctionHooks() {
                return array_keys( $this->mFunctionHooks );
        }

        /**
         * Create a tag function, e.g. "<test>some stuff</test>".
         * Unlike tag hooks, tag functions are parsed at preprocessor level.
         * Unlike parser functions, their content is not preprocessed.
         * @param string $tag
         * @param callable $callback
         * @param int $flags
         * @throws MWException
         * @return null
         */
        public function setFunctionTagHook( $tag, $callback, $flags ) {
                $tag = strtolower( $tag );
                if ( preg_match( '/[<>\r\n]/', $tag, $m ) ) {
                        throw new MWException( "Invalid character {$m[0]} in setFunctionTagHook('$tag', ...) call" );
                }
                $old = isset( $this->mFunctionTagHooks[$tag] ) ?
                        $this->mFunctionTagHooks[$tag] : null;
                $this->mFunctionTagHooks[$tag] = [ $callback, $flags ];

                if ( !in_array( $tag, $this->mStripList ) ) {
                        $this->mStripList[] = $tag;
                }

                return $old;
        }

        /**
         * Replace "<!--LINK-->" link placeholders with actual links, in the buffer
         * Placeholders created in Linker::link()
         *
         * @param string $text
         * @param int $options
         */
        public function replaceLinkHolders( &$text, $options = 0 ) {
                $this->mLinkHolders->replace( $text );
        }

        /**
         * Replace "<!--LINK-->" link placeholders with plain text of links
         * (not HTML-formatted).
         *
         * @param string $text
         * @return string
         */
        public function replaceLinkHoldersText( $text ) {
                return $this->mLinkHolders->replaceText( $text );
        }

        /**
         * Renders an image gallery from a text with one line per image.
         * text labels may be given by using |-style alternative text. E.g.
         *   Image:one.jpg|The number "1"
         *   Image:tree.jpg|A tree
         * given as text will return the HTML of a gallery with two images,
         * labeled 'The number "1"' and
         * 'A tree'.
         *
         * @param string $text
         * @param array $params
         * @return string HTML
         */
        public function renderImageGallery( $text, $params ) {

                $mode = false;
                if ( isset( $params['mode'] ) ) {
                        $mode = $params['mode'];
                }

                try {
                        $ig = ImageGalleryBase::factory( $mode );
                } catch ( Exception $e ) {
                        // If invalid type set, fallback to default.
                        $ig = ImageGalleryBase::factory( false );
                }

                $ig->setContextTitle( $this->mTitle );
                $ig->setShowBytes( false );
                $ig->setShowFilename( false );
                $ig->setParser( $this );
                $ig->setHideBadImages();
                $ig->setAttributes( Sanitizer::validateTagAttributes( $params, 'table' ) );

                if ( isset( $params['showfilename'] ) ) {
                        $ig->setShowFilename( true );
                } else {
                        $ig->setShowFilename( false );
                }
                if ( isset( $params['caption'] ) ) {
                        $caption = $params['caption'];
                        $caption = htmlspecialchars( $caption );
                        $caption = $this->replaceInternalLinks( $caption );
                        $ig->setCaptionHtml( $caption );
                }
                if ( isset( $params['perrow'] ) ) {
                        $ig->setPerRow( $params['perrow'] );
                }
                if ( isset( $params['widths'] ) ) {
                        $ig->setWidths( $params['widths'] );
                }
                if ( isset( $params['heights'] ) ) {
                        $ig->setHeights( $params['heights'] );
                }
                $ig->setAdditionalOptions( $params );

                // Avoid PHP 7.1 warning from passing $this by reference
                $parser = $this;
                Hooks::run( 'BeforeParserrenderImageGallery', [ &$parser, &$ig ] );

                $lines = StringUtils::explode( "\n", $text );
                foreach ( $lines as $line ) {
                        # match lines like these:
                        # Image:someimage.jpg|This is some image
                        $matches = [];
                        preg_match( "/^([^|]+)(\\|(.*))?$/", $line, $matches );
                        # Skip empty lines
                        if ( count( $matches ) == 0 ) {
                                continue;
                        }

                        if ( strpos( $matches[0], '%' ) !== false ) {
                                $matches[1] = rawurldecode( $matches[1] );
                        }
                        $title = Title::newFromText( $matches[1], NS_FILE );
                        if ( is_null( $title ) ) {
                                # Bogus title. Ignore these so we don't bomb out later.
                                continue;
                        }

                        # We need to get what handler the file uses, to figure out parameters.
                        # Note, a hook can overide the file name, and chose an entirely different
                        # file (which potentially could be of a different type and have different handler).
                        $options = [];
                        $descQuery = false;
                        Hooks::run( 'BeforeParserFetchFileAndTitle',
                                [ $this, $title, &$options, &$descQuery ] );
                        # Don't register it now, as TraditionalImageGallery does that later.
                        $file = $this->fetchFileNoRegister( $title, $options );
                        $handler = $file ? $file->getHandler() : false;

                        $paramMap = [
                                'img_alt' => 'gallery-internal-alt',
                                'img_link' => 'gallery-internal-link',
                        ];
                        if ( $handler ) {
                                $paramMap = $paramMap + $handler->getParamMap();
                                // We don't want people to specify per-image widths.
                                // Additionally the width parameter would need special casing anyhow.
                                unset( $paramMap['img_width'] );
                        }

                        $mwArray = new MagicWordArray( array_keys( $paramMap ) );

                        $label = '';
                        $alt = '';
                        $link = '';
                        $handlerOptions = [];
                        if ( isset( $matches[3] ) ) {
                                // look for an |alt= definition while trying not to break existing
                                // captions with multiple pipes (|) in it, until a more sensible grammar
                                // is defined for images in galleries

                                // FIXME: Doing recursiveTagParse at this stage, and the trim before
                                // splitting on '|' is a bit odd, and different from makeImage.
                                $matches[3] = $this->recursiveTagParse( trim( $matches[3] ) );
                                // Protect LanguageConverter markup
                                $parameterMatches = StringUtils::delimiterExplode(
                                        '-{', '}-', '|', $matches[3], true /* nested */
                                );

                                foreach ( $parameterMatches as $parameterMatch ) {
                                        list( $magicName, $match ) = $mwArray->matchVariableStartToEnd( $parameterMatch );
                                        if ( $magicName ) {
                                                $paramName = $paramMap[$magicName];

                                                switch ( $paramName ) {
                                                case 'gallery-internal-alt':
                                                        $alt = $this->stripAltText( $match, false );
                                                        break;
                                                case 'gallery-internal-link':
                                                        $linkValue = strip_tags( $this->replaceLinkHoldersText( $match ) );
                                                        $chars = self::EXT_LINK_URL_CLASS;
                                                        $addr = self::EXT_LINK_ADDR;
                                                        $prots = $this->mUrlProtocols;
                                                        // check to see if link matches an absolute url, if not then it must be a wiki link.
                                                        if ( preg_match( '/^-{R|(.*)}-$/', $linkValue ) ) {
                                                                // Result of LanguageConverter::markNoConversion
                                                                // invoked on an external link.
                                                                $linkValue = substr( $linkValue, 4, -2 );
                                                        }
                                                        if ( preg_match( "/^($prots)$addr$chars*$/u", $linkValue ) ) {
                                                                $link = $linkValue;
                                                        } else {
                                                                $localLinkTitle = Title::newFromText( $linkValue );
                                                                if ( $localLinkTitle !== null ) {
                                                                        $link = $localLinkTitle->getLinkURL();
                                                                }
                                                        }
                                                        break;
                                                default:
                                                        // Must be a handler specific parameter.
                                                        if ( $handler->validateParam( $paramName, $match ) ) {
                                                                $handlerOptions[$paramName] = $match;
                                                        } else {
                                                                // Guess not, consider it as caption.
                                                                wfDebug( "$parameterMatch failed parameter validation\n" );
                                                                $label = '|' . $parameterMatch;
                                                        }
                                                }

                                        } else {
                                                // Last pipe wins.
                                                $label = '|' . $parameterMatch;
                                        }
                                }
                                // Remove the pipe.
                                $label = substr( $label, 1 );
                        }

                        $ig->add( $title, $label, $alt, $link, $handlerOptions );
                }
                $html = $ig->toHTML();
                Hooks::run( 'AfterParserFetchFileAndTitle', [ $this, $ig, &$html ] );
                return $html;
        }

        /**
         * @param MediaHandler $handler
         * @return array
         */
        public function getImageParams( $handler ) {
                if ( $handler ) {
                        $handlerClass = get_class( $handler );
                } else {
                        $handlerClass = '';
                }
                if ( !isset( $this->mImageParams[$handlerClass] ) ) {
                        # Initialise static lists
                        static $internalParamNames = [
                                'horizAlign' => [ 'left', 'right', 'center', 'none' ],
                                'vertAlign' => [ 'baseline', 'sub', 'super', 'top', 'text-top', 'middle',
                                        'bottom', 'text-bottom' ],
                                'frame' => [ 'thumbnail', 'manualthumb', 'framed', 'frameless',
                                        'upright', 'border', 'link', 'alt', 'class' ],
                        ];
                        static $internalParamMap;
                        if ( !$internalParamMap ) {
                                $internalParamMap = [];
                                foreach ( $internalParamNames as $type => $names ) {
                                        foreach ( $names as $name ) {
                                                $magicName = str_replace( '-', '_', "img_$name" );
                                                $internalParamMap[$magicName] = [ $type, $name ];
                                        }
                                }
                        }

                        # Add handler params
                        $paramMap = $internalParamMap;
                        if ( $handler ) {
                                $handlerParamMap = $handler->getParamMap();
                                foreach ( $handlerParamMap as $magic => $paramName ) {
                                        $paramMap[$magic] = [ 'handler', $paramName ];
                                }
                        }
                        $this->mImageParams[$handlerClass] = $paramMap;
                        $this->mImageParamsMagicArray[$handlerClass] = new MagicWordArray( array_keys( $paramMap ) );
                }
                return [ $this->mImageParams[$handlerClass], $this->mImageParamsMagicArray[$handlerClass] ];
        }

        /**
         * Parse image options text and use it to make an image
         *
         * @param Title $title
         * @param string $options
         * @param LinkHolderArray|bool $holders
         * @return string HTML
         */
        public function makeImage( $title, $options, $holders = false ) {
                # Check if the options text is of the form "options|alt text"
                # Options are:
                #  * thumbnail  make a thumbnail with enlarge-icon and caption, alignment depends on lang
                #  * left       no resizing, just left align. label is used for alt= only
                #  * right      same, but right aligned
                #  * none       same, but not aligned
                #  * ___px      scale to ___ pixels width, no aligning. e.g. use in taxobox
                #  * center     center the image
                #  * frame      Keep original image size, no magnify-button.
                #  * framed     Same as "frame"
                #  * frameless  like 'thumb' but without a frame. Keeps user preferences for width
                #  * upright    reduce width for upright images, rounded to full __0 px
                #  * border     draw a 1px border around the image
                #  * alt        Text for HTML alt attribute (defaults to empty)
                #  * class      Set a class for img node
                #  * link       Set the target of the image link. Can be external, interwiki, or local
                # vertical-align values (no % or length right now):
                #  * baseline
                #  * sub
                #  * super
                #  * top
                #  * text-top
                #  * middle
                #  * bottom
                #  * text-bottom

                # Protect LanguageConverter markup when splitting into parts
                $parts = StringUtils::delimiterExplode(
                        '-{', '}-', '|', $options, true /* allow nesting */
                );

                # Give extensions a chance to select the file revision for us
                $options = [];
                $descQuery = false;
                Hooks::run( 'BeforeParserFetchFileAndTitle',
                        [ $this, $title, &$options, &$descQuery ] );
                # Fetch and register the file (file title may be different via hooks)
                list( $file, $title ) = $this->fetchFileAndTitle( $title, $options );

                # Get parameter map
                $handler = $file ? $file->getHandler() : false;

                list( $paramMap, $mwArray ) = $this->getImageParams( $handler );

                if ( !$file ) {
                        $this->addTrackingCategory( 'broken-file-category' );
                }

                # Process the input parameters
                $caption = '';
                $params = [ 'frame' => [], 'handler' => [],
                        'horizAlign' => [], 'vertAlign' => [] ];
                $seenformat = false;
                foreach ( $parts as $part ) {
                        $part = trim( $part );
                        list( $magicName, $value ) = $mwArray->matchVariableStartToEnd( $part );
                        $validated = false;
                        if ( isset( $paramMap[$magicName] ) ) {
                                list( $type, $paramName ) = $paramMap[$magicName];

                                # Special case; width and height come in one variable together
                                if ( $type === 'handler' && $paramName === 'width' ) {
                                        $parsedWidthParam = $this->parseWidthParam( $value );
                                        if ( isset( $parsedWidthParam['width'] ) ) {
                                                $width = $parsedWidthParam['width'];
                                                if ( $handler->validateParam( 'width', $width ) ) {
                                                        $params[$type]['width'] = $width;
                                                        $validated = true;
                                                }
                                        }
                                        if ( isset( $parsedWidthParam['height'] ) ) {
                                                $height = $parsedWidthParam['height'];
                                                if ( $handler->validateParam( 'height', $height ) ) {
                                                        $params[$type]['height'] = $height;
                                                        $validated = true;
                                                }
                                        }
                                        # else no validation -- T15436
                                } else {
                                        if ( $type === 'handler' ) {
                                                # Validate handler parameter
                                                $validated = $handler->validateParam( $paramName, $value );
                                        } else {
                                                # Validate internal parameters
                                                switch ( $paramName ) {
                                                case 'manualthumb':
                                                case 'alt':
                                                case 'class':
                                                        # @todo FIXME: Possibly check validity here for
                                                        # manualthumb? downstream behavior seems odd with
                                                        # missing manual thumbs.
                                                        $validated = true;
                                                        $value = $this->stripAltText( $value, $holders );
                                                        break;
                                                case 'link':
                                                        $chars = self::EXT_LINK_URL_CLASS;
                                                        $addr = self::EXT_LINK_ADDR;
                                                        $prots = $this->mUrlProtocols;
                                                        if ( $value === '' ) {
                                                                $paramName = 'no-link';
                                                                $value = true;
                                                                $validated = true;
                                                        } elseif ( preg_match( "/^((?i)$prots)/", $value ) ) {
                                                                if ( preg_match( "/^((?i)$prots)$addr$chars*$/u", $value, $m ) ) {
                                                                        $paramName = 'link-url';
                                                                        $this->mOutput->addExternalLink( $value );
                                                                        if ( $this->mOptions->getExternalLinkTarget() ) {
                                                                                $params[$type]['link-target'] = $this->mOptions->getExternalLinkTarget();
                                                                        }
                                                                        $validated = true;
                                                                }
                                                        } else {
                                                                $linkTitle = Title::newFromText( $value );
                                                                if ( $linkTitle ) {
                                                                        $paramName = 'link-title';
                                                                        $value = $linkTitle;
                                                                        $this->mOutput->addLink( $linkTitle );
                                                                        $validated = true;
                                                                }
                                                        }
                                                        break;
                                                case 'frameless':
                                                case 'framed':
                                                case 'thumbnail':
                                                        // use first appearing option, discard others.
                                                        $validated = !$seenformat;
                                                        $seenformat = true;
                                                        break;
                                                default:
                                                        # Most other things appear to be empty or numeric...
                                                        $validated = ( $value === false || is_numeric( trim( $value ) ) );
                                                }
                                        }

                                        if ( $validated ) {
                                                $params[$type][$paramName] = $value;
                                        }
                                }
                        }
                        if ( !$validated ) {
                                $caption = $part;
                        }
                }

                # Process alignment parameters
                if ( $params['horizAlign'] ) {
                        $params['frame']['align'] = key( $params['horizAlign'] );
                }
                if ( $params['vertAlign'] ) {
                        $params['frame']['valign'] = key( $params['vertAlign'] );
                }

                $params['frame']['caption'] = $caption;

                # Will the image be presented in a frame, with the caption below?
                $imageIsFramed = isset( $params['frame']['frame'] )
                        || isset( $params['frame']['framed'] )
                        || isset( $params['frame']['thumbnail'] )
                        || isset( $params['frame']['manualthumb'] );

                # In the old days, [[Image:Foo|text...]] would set alt text.  Later it
                # came to also set the caption, ordinary text after the image -- which
                # makes no sense, because that just repeats the text multiple times in
                # screen readers.  It *also* came to set the title attribute.
                # Now that we have an alt attribute, we should not set the alt text to
                # equal the caption: that's worse than useless, it just repeats the
                # text.  This is the framed/thumbnail case.  If there's no caption, we
                # use the unnamed parameter for alt text as well, just for the time be-
                # ing, if the unnamed param is set and the alt param is not.
                # For the future, we need to figure out if we want to tweak this more,
                # e.g., introducing a title= parameter for the title; ignoring the un-
                # named parameter entirely for images without a caption; adding an ex-
                # plicit caption= parameter and preserving the old magic unnamed para-
                # meter for BC; ...
                if ( $imageIsFramed ) { # Framed image
                        if ( $caption === '' && !isset( $params['frame']['alt'] ) ) {
                                # No caption or alt text, add the filename as the alt text so
                                # that screen readers at least get some description of the image
                                $params['frame']['alt'] = $title->getText();
                        }
                        # Do not set $params['frame']['title'] because tooltips don't make sense
                        # for framed images
                } else { # Inline image
                        if ( !isset( $params['frame']['alt'] ) ) {
                                # No alt text, use the "caption" for the alt text
                                if ( $caption !== '' ) {
                                        $params['frame']['alt'] = $this->stripAltText( $caption, $holders );
                                } else {
                                        # No caption, fall back to using the filename for the
                                        # alt text
                                        $params['frame']['alt'] = $title->getText();
                                }
                        }
                        # Use the "caption" for the tooltip text
                        $params['frame']['title'] = $this->stripAltText( $caption, $holders );
                }

                Hooks::run( 'ParserMakeImageParams', [ $title, $file, &$params, $this ] );

                # Linker does the rest
                $time = isset( $options['time'] ) ? $options['time'] : false;
                $ret = Linker::makeImageLink( $this, $title, $file, $params['frame'], $params['handler'],
                        $time, $descQuery, $this->mOptions->getThumbSize() );

                # Give the handler a chance to modify the parser object
                if ( $handler ) {
                        $handler->parserTransformHook( $this, $file );
                }

                return $ret;
        }

        /**
         * @param string $caption
         * @param LinkHolderArray|bool $holders
         * @return mixed|string
         */
        protected function stripAltText( $caption, $holders ) {
                # Strip bad stuff out of the title (tooltip).  We can't just use
                # replaceLinkHoldersText() here, because if this function is called
                # from replaceInternalLinks2(), mLinkHolders won't be up-to-date.
                if ( $holders ) {
                        $tooltip = $holders->replaceText( $caption );
                } else {
                        $tooltip = $this->replaceLinkHoldersText( $caption );
                }

                # make sure there are no placeholders in thumbnail attributes
                # that are later expanded to html- so expand them now and
                # remove the tags
                $tooltip = $this->mStripState->unstripBoth( $tooltip );
                $tooltip = Sanitizer::stripAllTags( $tooltip );

                return $tooltip;
        }

        /**
         * Set a flag in the output object indicating that the content is dynamic and
         * shouldn't be cached.
         * @deprecated since 1.28; use getOutput()->updateCacheExpiry()
         */
        public function disableCache() {
                wfDebug( "Parser output marked as uncacheable.\n" );
                if ( !$this->mOutput ) {
                        throw new MWException( __METHOD__ .
                                " can only be called when actually parsing something" );
                }
                $this->mOutput->updateCacheExpiry( 0 ); // new style, for consistency
        }

        /**
         * Callback from the Sanitizer for expanding items found in HTML attribute
         * values, so they can be safely tested and escaped.
         *
         * @param string $text
         * @param bool|PPFrame $frame
         * @return string
         */
        public function attributeStripCallback( &$text, $frame = false ) {
                $text = $this->replaceVariables( $text, $frame );
                $text = $this->mStripState->unstripBoth( $text );
                return $text;
        }

        /**
         * Accessor
         *
         * @return array
         */
        public function getTags() {
                return array_merge(
                        array_keys( $this->mTransparentTagHooks ),
                        array_keys( $this->mTagHooks ),
                        array_keys( $this->mFunctionTagHooks )
                );
        }

        /**
         * Replace transparent tags in $text with the values given by the callbacks.
         *
         * Transparent tag hooks are like regular XML-style tag hooks, except they
         * operate late in the transformation sequence, on HTML instead of wikitext.
         *
         * @param string $text
         *
         * @return string
         */
        public function replaceTransparentTags( $text ) {
                $matches = [];
                $elements = array_keys( $this->mTransparentTagHooks );
                $text = self::extractTagsAndParams( $elements, $text, $matches );
                $replacements = [];

                foreach ( $matches as $marker => $data ) {
                        list( $element, $content, $params, $tag ) = $data;
                        $tagName = strtolower( $element );
                        if ( isset( $this->mTransparentTagHooks[$tagName] ) ) {
                                $output = call_user_func_array(
                                        $this->mTransparentTagHooks[$tagName],
                                        [ $content, $params, $this ]
                                );
                        } else {
                                $output = $tag;
                        }
                        $replacements[$marker] = $output;
                }
                return strtr( $text, $replacements );
        }

        /**
         * Break wikitext input into sections, and either pull or replace
         * some particular section's text.
         *
         * External callers should use the getSection and replaceSection methods.
         *
         * @param string $text Page wikitext
         * @param string|int $sectionId A section identifier string of the form:
         *   "<flag1> - <flag2> - ... - <section number>"
         *
         * Currently the only recognised flag is "T", which means the target section number
         * was derived during a template inclusion parse, in other words this is a template
         * section edit link. If no flags are given, it was an ordinary section edit link.
         * This flag is required to avoid a section numbering mismatch when a section is
         * enclosed by "<includeonly>" (T8563).
         *
         * The section number 0 pulls the text before the first heading; other numbers will
         * pull the given section along with its lower-level subsections. If the section is
         * not found, $mode=get will return $newtext, and $mode=replace will return $text.
         *
         * Section 0 is always considered to exist, even if it only contains the empty
         * string. If $text is the empty string and section 0 is replaced, $newText is
         * returned.
         *
         * @param string $mode One of "get" or "replace"
         * @param string $newText Replacement text for section data.
         * @return string For "get", the extracted section text.
         *   for "replace", the whole page with the section replaced.
         */
        private function extractSections( $text, $sectionId, $mode, $newText = '' ) {
                global $wgTitle; # not generally used but removes an ugly failure mode

                $magicScopeVariable = $this->lock();
                $this->startParse( $wgTitle, new ParserOptions, self::OT_PLAIN, true );
                $outText = '';
                $frame = $this->getPreprocessor()->newFrame();

                # Process section extraction flags
                $flags = 0;
                $sectionParts = explode( '-', $sectionId );
                $sectionIndex = array_pop( $sectionParts );
                foreach ( $sectionParts as $part ) {
                        if ( $part === 'T' ) {
                                $flags |= self::PTD_FOR_INCLUSION;
                        }
                }

                # Check for empty input
                if ( strval( $text ) === '' ) {
                        # Only sections 0 and T-0 exist in an empty document
                        if ( $sectionIndex == 0 ) {
                                if ( $mode === 'get' ) {
                                        return '';
                                } else {
                                        return $newText;
                                }
                        } else {
                                if ( $mode === 'get' ) {
                                        return $newText;
                                } else {
                                        return $text;
                                }
                        }
                }

                # Preprocess the text
                $root = $this->preprocessToDom( $text, $flags );

                # <h> nodes indicate section breaks
                # They can only occur at the top level, so we can find them by iterating the root's children
                $node = $root->getFirstChild();

                # Find the target section
                if ( $sectionIndex == 0 ) {
                        # Section zero doesn't nest, level=big
                        $targetLevel = 1000;
                } else {
                        while ( $node ) {
                                if ( $node->getName() === 'h' ) {
                                        $bits = $node->splitHeading();
                                        if ( $bits['i'] == $sectionIndex ) {
                                                $targetLevel = $bits['level'];
                                                break;
                                        }
                                }
                                if ( $mode === 'replace' ) {
                                        $outText .= $frame->expand( $node, PPFrame::RECOVER_ORIG );
                                }
                                $node = $node->getNextSibling();
                        }
                }

                if ( !$node ) {
                        # Not found
                        if ( $mode === 'get' ) {
                                return $newText;
                        } else {
                                return $text;
                        }
                }

                # Find the end of the section, including nested sections
                do {
                        if ( $node->getName() === 'h' ) {
                                $bits = $node->splitHeading();
                                $curLevel = $bits['level'];
                                if ( $bits['i'] != $sectionIndex && $curLevel <= $targetLevel ) {
                                        break;
                                }
                        }
                        if ( $mode === 'get' ) {
                                $outText .= $frame->expand( $node, PPFrame::RECOVER_ORIG );
                        }
                        $node = $node->getNextSibling();
                } while ( $node );

                # Write out the remainder (in replace mode only)
                if ( $mode === 'replace' ) {
                        # Output the replacement text
                        # Add two newlines on -- trailing whitespace in $newText is conventionally
                        # stripped by the editor, so we need both newlines to restore the paragraph gap
                        # Only add trailing whitespace if there is newText
                        if ( $newText != "" ) {
                                $outText .= $newText . "\n\n";
                        }

                        while ( $node ) {
                                $outText .= $frame->expand( $node, PPFrame::RECOVER_ORIG );
                                $node = $node->getNextSibling();
                        }
                }

                if ( is_string( $outText ) ) {
                        # Re-insert stripped tags
                        $outText = rtrim( $this->mStripState->unstripBoth( $outText ) );
                }

                return $outText;
        }

        /**
         * This function returns the text of a section, specified by a number ($section).
         * A section is text under a heading like == Heading == or \<h1\>Heading\</h1\>, or
         * the first section before any such heading (section 0).
         *
         * If a section contains subsections, these are also returned.
         *
         * @param string $text Text to look in
         * @param string|int $sectionId Section identifier as a number or string
         * (e.g. 0, 1 or 'T-1').
         * @param string $defaultText Default to return if section is not found
         *
         * @return string Text of the requested section
         */
        public function getSection( $text, $sectionId, $defaultText = '' ) {
                return $this->extractSections( $text, $sectionId, 'get', $defaultText );
        }

        /**
         * This function returns $oldtext after the content of the section
         * specified by $section has been replaced with $text. If the target
         * section does not exist, $oldtext is returned unchanged.
         *
         * @param string $oldText Former text of the article
         * @param string|int $sectionId Section identifier as a number or string
         * (e.g. 0, 1 or 'T-1').
         * @param string $newText Replacing text
         *
         * @return string Modified text
         */
        public function replaceSection( $oldText, $sectionId, $newText ) {
                return $this->extractSections( $oldText, $sectionId, 'replace', $newText );
        }

        /**
         * Get the ID of the revision we are parsing
         *
         * @return int|null
         */
        public function getRevisionId() {
                return $this->mRevisionId;
        }

        /**
         * Get the revision object for $this->mRevisionId
         *
         * @return Revision|null Either a Revision object or null
         * @since 1.23 (public since 1.23)
         */
        public function getRevisionObject() {
                if ( !is_null( $this->mRevisionObject ) ) {
                        return $this->mRevisionObject;
                }
                if ( is_null( $this->mRevisionId ) ) {
                        return null;
                }

                $rev = call_user_func(
                        $this->mOptions->getCurrentRevisionCallback(), $this->getTitle(), $this
                );

                # If the parse is for a new revision, then the callback should have
                # already been set to force the object and should match mRevisionId.
                # If not, try to fetch by mRevisionId for sanity.
                if ( $rev && $rev->getId() != $this->mRevisionId ) {
                        $rev = Revision::newFromId( $this->mRevisionId );
                }

                $this->mRevisionObject = $rev;

                return $this->mRevisionObject;
        }

        /**
         * Get the timestamp associated with the current revision, adjusted for
         * the default server-local timestamp
         * @return string
         */
        public function getRevisionTimestamp() {
                if ( is_null( $this->mRevisionTimestamp ) ) {
                        global $wgContLang;

                        $revObject = $this->getRevisionObject();
                        $timestamp = $revObject ? $revObject->getTimestamp() : wfTimestampNow();

                        # The cryptic '' timezone parameter tells to use the site-default
                        # timezone offset instead of the user settings.
                        # Since this value will be saved into the parser cache, served
                        # to other users, and potentially even used inside links and such,
                        # it needs to be consistent for all visitors.
                        $this->mRevisionTimestamp = $wgContLang->userAdjust( $timestamp, '' );

                }
                return $this->mRevisionTimestamp;
        }

        /**
         * Get the name of the user that edited the last revision
         *
         * @return string User name
         */
        public function getRevisionUser() {
                if ( is_null( $this->mRevisionUser ) ) {
                        $revObject = $this->getRevisionObject();

                        # if this template is subst: the revision id will be blank,
                        # so just use the current user's name
                        if ( $revObject ) {
                                $this->mRevisionUser = $revObject->getUserText();
                        } elseif ( $this->ot['wiki'] || $this->mOptions->getIsPreview() ) {
                                $this->mRevisionUser = $this->getUser()->getName();
                        }
                }
                return $this->mRevisionUser;
        }

        /**
         * Get the size of the revision
         *
         * @return int|null Revision size
         */
        public function getRevisionSize() {
                if ( is_null( $this->mRevisionSize ) ) {
                        $revObject = $this->getRevisionObject();

                        # if this variable is subst: the revision id will be blank,
                        # so just use the parser input size, because the own substituation
                        # will change the size.
                        if ( $revObject ) {
                                $this->mRevisionSize = $revObject->getSize();
                        } else {
                                $this->mRevisionSize = $this->mInputSize;
                        }
                }
                return $this->mRevisionSize;
        }

        /**
         * Mutator for $mDefaultSort
         *
         * @param string $sort New value
         */
        public function setDefaultSort( $sort ) {
                $this->mDefaultSort = $sort;
                $this->mOutput->setProperty( 'defaultsort', $sort );
        }

        /**
         * Accessor for $mDefaultSort
         * Will use the empty string if none is set.
         *
         * This value is treated as a prefix, so the
         * empty string is equivalent to sorting by
         * page name.
         *
         * @return string
         */
        public function getDefaultSort() {
                if ( $this->mDefaultSort !== false ) {
                        return $this->mDefaultSort;
                } else {
                        return '';
                }
        }

        /**
         * Accessor for $mDefaultSort
         * Unlike getDefaultSort(), will return false if none is set
         *
         * @return string|bool
         */
        public function getCustomDefaultSort() {
                return $this->mDefaultSort;
        }

        /**
         * Try to guess the section anchor name based on a wikitext fragment
         * presumably extracted from a heading, for example "Header" from
         * "== Header ==".
         *
         * @param string $text
         *
         * @return string
         */
        public function guessSectionNameFromWikiText( $text ) {
                # Strip out wikitext links(they break the anchor)
                $text = $this->stripSectionName( $text );
                $text = Sanitizer::normalizeSectionNameWhitespace( $text );
                return '#' . Sanitizer::escapeId( $text, 'noninitial' );
        }

        /**
         * Same as guessSectionNameFromWikiText(), but produces legacy anchors
         * instead.  For use in redirects, since IE6 interprets Redirect: headers
         * as something other than UTF-8 (apparently?), resulting in breakage.
         *
         * @param string $text The section name
         * @return string An anchor
         */
        public function guessLegacySectionNameFromWikiText( $text ) {
                # Strip out wikitext links(they break the anchor)
                $text = $this->stripSectionName( $text );
                $text = Sanitizer::normalizeSectionNameWhitespace( $text );
                return '#' . Sanitizer::escapeId( $text, [ 'noninitial', 'legacy' ] );
        }

        /**
         * Strips a text string of wikitext for use in a section anchor
         *
         * Accepts a text string and then removes all wikitext from the
         * string and leaves only the resultant text (i.e. the result of
         * [[User:WikiSysop|Sysop]] would be "Sysop" and the result of
         * [[User:WikiSysop]] would be "User:WikiSysop") - this is intended
         * to create valid section anchors by mimicing the output of the
         * parser when headings are parsed.
         *
         * @param string $text Text string to be stripped of wikitext
         * for use in a Section anchor
         * @return string Filtered text string
         */
        public function stripSectionName( $text ) {
                # Strip internal link markup
                $text = preg_replace( '/\[\[:?([^[|]+)\|([^[]+)\]\]/', '$2', $text );
                $text = preg_replace( '/\[\[:?([^[]+)\|?\]\]/', '$1', $text );

                # Strip external link markup
                # @todo FIXME: Not tolerant to blank link text
                # I.E. [https://www.mediawiki.org] will render as [1] or something depending
                # on how many empty links there are on the page - need to figure that out.
                $text = preg_replace( '/\[(?i:' . $this->mUrlProtocols . ')([^ ]+?) ([^[]+)\]/', '$2', $text );

                # Parse wikitext quotes (italics & bold)
                $text = $this->doQuotes( $text );

                # Strip HTML tags
                $text = StringUtils::delimiterReplace( '<', '>', '', $text );
                return $text;
        }

        /**
         * strip/replaceVariables/unstrip for preprocessor regression testing
         *
         * @param string $text
         * @param Title $title
         * @param ParserOptions $options
         * @param int $outputType
         *
         * @return string
         */
        public function testSrvus( $text, Title $title, ParserOptions $options,
                $outputType = self::OT_HTML
        ) {
                $magicScopeVariable = $this->lock();
                $this->startParse( $title, $options, $outputType, true );

                $text = $this->replaceVariables( $text );
                $text = $this->mStripState->unstripBoth( $text );
                $text = Sanitizer::removeHTMLtags( $text );
                return $text;
        }

        /**
         * @param string $text
         * @param Title $title
         * @param ParserOptions $options
         * @return string
         */
        public function testPst( $text, Title $title, ParserOptions $options ) {
                return $this->preSaveTransform( $text, $title, $options->getUser(), $options );
        }

        /**
         * @param string $text
         * @param Title $title
         * @param ParserOptions $options
         * @return string
         */
        public function testPreprocess( $text, Title $title, ParserOptions $options ) {
                return $this->testSrvus( $text, $title, $options, self::OT_PREPROCESS );
        }

        /**
         * Call a callback function on all regions of the given text that are not
         * inside strip markers, and replace those regions with the return value
         * of the callback. For example, with input:
         *
         *  aaa<MARKER>bbb
         *
         * This will call the callback function twice, with 'aaa' and 'bbb'. Those
         * two strings will be replaced with the value returned by the callback in
         * each case.
         *
         * @param string $s
         * @param callable $callback
         *
         * @return string
         */
        public function markerSkipCallback( $s, $callback ) {
                $i = 0;
                $out = '';
                while ( $i < strlen( $s ) ) {
                        $markerStart = strpos( $s, self::MARKER_PREFIX, $i );
                        if ( $markerStart === false ) {
                                $out .= call_user_func( $callback, substr( $s, $i ) );
                                break;
                        } else {
                                $out .= call_user_func( $callback, substr( $s, $i, $markerStart - $i ) );
                                $markerEnd = strpos( $s, self::MARKER_SUFFIX, $markerStart );
                                if ( $markerEnd === false ) {
                                        $out .= substr( $s, $markerStart );
                                        break;
                                } else {
                                        $markerEnd += strlen( self::MARKER_SUFFIX );
                                        $out .= substr( $s, $markerStart, $markerEnd - $markerStart );
                                        $i = $markerEnd;
                                }
                        }
                }
                return $out;
        }

        /**
         * Remove any strip markers found in the given text.
         *
         * @param string $text Input string
         * @return string
         */
        public function killMarkers( $text ) {
                return $this->mStripState->killMarkers( $text );
        }

        /**
         * Save the parser state required to convert the given half-parsed text to
         * HTML. "Half-parsed" in this context means the output of
         * recursiveTagParse() or internalParse(). This output has strip markers
         * from replaceVariables (extensionSubstitution() etc.), and link
         * placeholders from replaceLinkHolders().
         *
         * Returns an array which can be serialized and stored persistently. This
         * array can later be loaded into another parser instance with
         * unserializeHalfParsedText(). The text can then be safely incorporated into
         * the return value of a parser hook.
         *
         * @param string $text
         *
         * @return array
         */
        public function serializeHalfParsedText( $text ) {
                $data = [
                        'text' => $text,
                        'version' => self::HALF_PARSED_VERSION,
                        'stripState' => $this->mStripState->getSubState( $text ),
                        'linkHolders' => $this->mLinkHolders->getSubArray( $text )
                ];
                return $data;
        }

        /**
         * Load the parser state given in the $data array, which is assumed to
         * have been generated by serializeHalfParsedText(). The text contents is
         * extracted from the array, and its markers are transformed into markers
         * appropriate for the current Parser instance. This transformed text is
         * returned, and can be safely included in the return value of a parser
         * hook.
         *
         * If the $data array has been stored persistently, the caller should first
         * check whether it is still valid, by calling isValidHalfParsedText().
         *
         * @param array $data Serialized data
         * @throws MWException
         * @return string
         */
        public function unserializeHalfParsedText( $data ) {
                if ( !isset( $data['version'] ) || $data['version'] != self::HALF_PARSED_VERSION ) {
                        throw new MWException( __METHOD__ . ': invalid version' );
                }

                # First, extract the strip state.
                $texts = [ $data['text'] ];
                $texts = $this->mStripState->merge( $data['stripState'], $texts );

                # Now renumber links
                $texts = $this->mLinkHolders->mergeForeign( $data['linkHolders'], $texts );

                # Should be good to go.
                return $texts[0];
        }

        /**
         * Returns true if the given array, presumed to be generated by
         * serializeHalfParsedText(), is compatible with the current version of the
         * parser.
         *
         * @param array $data
         *
         * @return bool
         */
        public function isValidHalfParsedText( $data ) {
                return isset( $data['version'] ) && $data['version'] == self::HALF_PARSED_VERSION;
        }

        /**
         * Parsed a width param of imagelink like 300px or 200x300px
         *
         * @param string $value
         *
         * @return array
         * @since 1.20
         */
        public function parseWidthParam( $value ) {
                $parsedWidthParam = [];
                if ( $value === '' ) {
                        return $parsedWidthParam;
                }
                $m = [];
                # (T15500) In both cases (width/height and width only),
                # permit trailing "px" for backward compatibility.
                if ( preg_match( '/^([0-9]*)x([0-9]*)\s*(?:px)?\s*$/', $value, $m ) ) {
                        $width = intval( $m[1] );
                        $height = intval( $m[2] );
                        $parsedWidthParam['width'] = $width;
                        $parsedWidthParam['height'] = $height;
                } elseif ( preg_match( '/^[0-9]*\s*(?:px)?\s*$/', $value ) ) {
                        $width = intval( $value );
                        $parsedWidthParam['width'] = $width;
                }
                return $parsedWidthParam;
        }

        /**
         * Lock the current instance of the parser.
         *
         * This is meant to stop someone from calling the parser
         * recursively and messing up all the strip state.
         *
         * @throws MWException If parser is in a parse
         * @return ScopedCallback The lock will be released once the return value goes out of scope.
         */
        protected function lock() {
                if ( $this->mInParse ) {
                        throw new MWException( "Parser state cleared while parsing. "
                                . "Did you call Parser::parse recursively?" );
                }
                $this->mInParse = true;

                $recursiveCheck = new ScopedCallback( function() {
                        $this->mInParse = false;
                } );

                return $recursiveCheck;
        }

        /**
         * Strip outer <p></p> tag from the HTML source of a single paragraph.
         *
         * Returns original HTML if the <p/> tag has any attributes, if there's no wrapping <p/> tag,
         * or if there is more than one <p/> tag in the input HTML.
         *
         * @param string $html
         * @return string
         * @since 1.24
         */
        public static function stripOuterParagraph( $html ) {
                $m = [];
                if ( preg_match( '/^<p>(.*)\n?<\/p>\n?$/sU', $html, $m ) ) {
                        if ( strpos( $m[1], '</p>' ) === false ) {
                                $html = $m[1];
                        }
                }

                return $html;
        }

        /**
         * Return this parser if it is not doing anything, otherwise
         * get a fresh parser. You can use this method by doing
         * $myParser = $wgParser->getFreshParser(), or more simply
         * $wgParser->getFreshParser()->parse( ... );
         * if you're unsure if $wgParser is safe to use.
         *
         * @since 1.24
         * @return Parser A parser object that is not parsing anything
         */
        public function getFreshParser() {
                global $wgParserConf;
                if ( $this->mInParse ) {
                        return new $wgParserConf['class']( $wgParserConf );
                } else {
                        return $this;
                }
        }

        /**
         * Set's up the PHP implementation of OOUI for use in this request
         * and instructs OutputPage to enable OOUI for itself.
         *
         * @since 1.26
         */
        public function enableOOUI() {
                OutputPage::setupOOUI();
                $this->mOutput->setEnableOOUI( true );
        }
}