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

<?php
/**
 * Preprocessor using PHP arrays
 *
 * 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
 */

namespace MediaWiki\Parser;

use Wikimedia\ObjectCache\WANObjectCache;

/**
 * Differences from DOM schema:
 *   * attribute nodes are children
 *   * "<h>" nodes that aren't at the top are replaced with <possible-h>
 *
 * Nodes are stored in a recursive array data structure. A node store is an
 * array where each element may be either a scalar (representing a text node)
 * or a "descriptor", which is a two-element array where the first element is
 * the node name and the second element is the node store for the children.
 *
 * Attributes are represented as children that have a node name starting with
 * "@", and a single text node child.
 *
 * @todo: Consider replacing descriptor arrays with objects of a new class.
 * Benchmark and measure resulting memory impact.
 *
 * @ingroup Parser
 */
// phpcs:ignore Squiz.Classes.ValidClassName.NotCamelCaps
class Preprocessor_Hash extends Preprocessor {
        /** Cache format version */
        protected const CACHE_VERSION = 4;

        /** @var int|false Min wikitext size for which to cache DOM tree */
        protected $cacheThreshold;

        /**
         * @see Preprocessor::__construct()
         * @param Parser $parser
         * @param WANObjectCache|null $wanCache
         * @param array $options Additional options include:
         *   - cacheThreshold: min text size for which to cache DOMs. [Default: false]
         */
        public function __construct(
                Parser $parser,
                ?WANObjectCache $wanCache = null,
                array $options = []
        ) {
                parent::__construct( $parser, $wanCache, $options );

                $this->cacheThreshold = $options['cacheThreshold'] ?? false;
        }

        /**
         * @return PPFrame_Hash
         */
        public function newFrame() {
                return new PPFrame_Hash( $this );
        }

        /**
         * @param array $args
         * @return PPCustomFrame_Hash
         */
        public function newCustomFrame( $args ) {
                return new PPCustomFrame_Hash( $this, $args );
        }

        /**
         * @param array $values
         * @return PPNode_Hash_Array
         */
        public function newPartNodeArray( $values ) {
                $list = [];

                foreach ( $values as $k => $val ) {
                        if ( is_int( $k ) ) {
                                $store = [ [ 'part', [
                                        [ 'name', [ [ '@index', [ $k ] ] ] ],
                                        [ 'value', [ strval( $val ) ] ],
                                ] ] ];
                        } else {
                                $store = [ [ 'part', [
                                        [ 'name', [ strval( $k ) ] ],
                                        '=',
                                        [ 'value', [ strval( $val ) ] ],
                                ] ] ];
                        }

                        $list[] = new PPNode_Hash_Tree( $store, 0 );
                }

                return new PPNode_Hash_Array( $list );
        }

        public function preprocessToObj( $text, $flags = 0 ) {
                if ( $this->disableLangConversion ) {
                        // Language conversions are globally disabled; implicitly set flag
                        $flags |= self::DOM_LANG_CONVERSION_DISABLED;
                }

                $domTreeArray = null;
                if (
                        $this->cacheThreshold !== false &&
                        strlen( $text ) >= $this->cacheThreshold &&
                        ( $flags & self::DOM_UNCACHED ) != self::DOM_UNCACHED
                ) {
                        $domTreeJson = $this->wanCache->getWithSetCallback(
                                $this->wanCache->makeKey( 'preprocess-hash', sha1( $text ), $flags ),
                                $this->wanCache::TTL_DAY,
                                function () use ( $text, $flags, &$domTreeArray ) {
                                        $domTreeArray = $this->buildDomTreeArrayFromText( $text, $flags );

                                        return json_encode(
                                                $domTreeArray,
                                                JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE
                                        );
                                },
                                [ 'version' => self::CACHE_VERSION, 'segmentable' => true ]
                        );
                        $domTreeArray ??= json_decode( $domTreeJson );
                }

                $domTreeArray ??= $this->buildDomTreeArrayFromText( $text, $flags );

                return new PPNode_Hash_Tree( $domTreeArray, 0 );
        }

        /**
         * @param string $text Wikitext
         * @param int $flags Bit field of Preprocessor::DOM_* flags
         * @return array JSON-serializable document object model array
         */
        private function buildDomTreeArrayFromText( $text, $flags ) {
                $forInclusion = ( $flags & self::DOM_FOR_INCLUSION );
                $langConversionDisabled = ( $flags & self::DOM_LANG_CONVERSION_DISABLED );

                $xmlishElements = $this->parser->getStripList();
                $xmlishAllowMissingEndTag = [ 'includeonly', 'noinclude', 'onlyinclude' ];
                $enableOnlyinclude = false;
                if ( $forInclusion ) {
                        $ignoredTags = [ 'includeonly', '/includeonly' ];
                        $ignoredElements = [ 'noinclude' ];
                        $xmlishElements[] = 'noinclude';
                        if ( str_contains( $text, '<onlyinclude>' )
                                && str_contains( $text, '</onlyinclude>' )
                        ) {
                                $enableOnlyinclude = true;
                        }
                } else {
                        $ignoredTags = [ 'noinclude', '/noinclude', 'onlyinclude', '/onlyinclude' ];
                        $ignoredElements = [ 'includeonly' ];
                        $xmlishElements[] = 'includeonly';
                }
                $xmlishRegex = implode( '|', array_merge( $xmlishElements, $ignoredTags ) );

                // Use "A" modifier (anchored) instead of "^", because ^ doesn't work with an offset
                $elementsRegex = "~(?:$xmlishRegex)(?=\s|\/>|>)|!--~iA";

                $stack = new PPDStack_Hash;

                $searchBase = "[{<\n";
                if ( !$langConversionDisabled ) {
                        $searchBase .= '-';
                }

                // For fast reverse searches
                $revText = strrev( $text );
                $lengthText = strlen( $text );

                // Input pointer, starts out pointing to a pseudo-newline before the start
                $i = 0;
                // Current accumulator. See the doc comment for Preprocessor_Hash for the format.
                $accum =& $stack->getAccum();
                // True to find equals signs in arguments
                $findEquals = false;
                // True to take notice of pipe characters
                $findPipe = false;
                $headingIndex = 1;
                // True if $i is inside a possible heading
                $inHeading = false;
                // True if there are no more greater-than (>) signs right of $i
                $noMoreGT = false;
                // Map of tag name => true if there are no more closing tags of given type right of $i
                $noMoreClosingTag = [];
                // True to ignore all input up to the next <onlyinclude>
                $findOnlyinclude = $enableOnlyinclude;
                // Do a line-start run without outputting an LF character
                $fakeLineStart = true;

                while ( true ) {
                        if ( $findOnlyinclude ) {
                                // Ignore all input up to the next <onlyinclude>
                                $startPos = strpos( $text, '<onlyinclude>', $i );
                                if ( $startPos === false ) {
                                        // Ignored section runs to the end
                                        $accum[] = [ 'ignore', [ substr( $text, $i ) ] ];
                                        break;
                                }
                                $tagEndPos = $startPos + 13; // past-the-end of <onlyinclude>
                                $accum[] = [ 'ignore', [ substr( $text, $i, $tagEndPos - $i ) ] ];
                                $i = $tagEndPos;
                                $findOnlyinclude = false;
                        }

                        if ( $fakeLineStart ) {
                                $found = 'line-start';
                                $curChar = '';
                        } else {
                                # Find next opening brace, closing brace or pipe
                                $search = $searchBase;
                                if ( $stack->top === false ) {
                                        $currentClosing = '';
                                } else {
                                        $currentClosing = $stack->top->close;
                                        $search .= $currentClosing;
                                }
                                if ( $findPipe ) {
                                        $search .= '|';
                                }
                                if ( $findEquals ) {
                                        // First equals will be for the template
                                        $search .= '=';
                                }
                                $rule = null;
                                # Output literal section, advance input counter
                                $literalLength = strcspn( $text, $search, $i );
                                if ( $literalLength > 0 ) {
                                        self::addLiteral( $accum, substr( $text, $i, $literalLength ) );
                                        $i += $literalLength;
                                }
                                if ( $i >= $lengthText ) {
                                        if ( $currentClosing === "\n" ) {
                                                // Do a past-the-end run to finish off the heading
                                                $curChar = '';
                                                $found = 'line-end';
                                        } else {
                                                # All done
                                                break;
                                        }
                                } else {
                                        $curChar = $curTwoChar = $text[$i];
                                        if ( $i + 1 < $lengthText ) {
                                                $curTwoChar .= $text[$i + 1];
                                        }
                                        if ( $curChar === '|' ) {
                                                $found = 'pipe';
                                        } elseif ( $curChar === '=' ) {
                                                $found = 'equals';
                                        } elseif ( $curChar === '<' ) {
                                                $found = 'angle';
                                        } elseif ( $curChar === "\n" ) {
                                                if ( $inHeading ) {
                                                        $found = 'line-end';
                                                } else {
                                                        $found = 'line-start';
                                                }
                                        } elseif ( $curTwoChar === $currentClosing ) {
                                                $found = 'close';
                                                $curChar = $curTwoChar;
                                        } elseif ( $curChar === $currentClosing ) {
                                                $found = 'close';
                                        } elseif ( isset( $this->rules[$curTwoChar] ) ) {
                                                $curChar = $curTwoChar;
                                                $found = 'open';
                                                $rule = $this->rules[$curChar];
                                        } elseif ( isset( $this->rules[$curChar] ) ) {
                                                $found = 'open';
                                                $rule = $this->rules[$curChar];
                                        } else {
                                                # Some versions of PHP have a strcspn which stops on
                                                # null characters; ignore these and continue.
                                                # We also may get '-' and '}' characters here which
                                                # don't match -{ or $currentClosing.  Add these to
                                                # output and continue.
                                                if ( $curChar === '-' || $curChar === '}' ) {
                                                        self::addLiteral( $accum, $curChar );
                                                }
                                                ++$i;
                                                continue;
                                        }
                                }
                        }

                        if ( $found === 'angle' ) {
                                // Handle </onlyinclude>
                                if ( $enableOnlyinclude
                                        && substr_compare( $text, '</onlyinclude>', $i, 14 ) === 0
                                ) {
                                        $findOnlyinclude = true;
                                        continue;
                                }

                                // Determine element name
                                if ( !preg_match( $elementsRegex, $text, $matches, 0, $i + 1 ) ) {
                                        // Element name missing or not listed
                                        self::addLiteral( $accum, '<' );
                                        ++$i;
                                        continue;
                                }
                                $name = $matches[0];
                                // Handle comments
                                if ( $name === '!--' ) {
                                        // To avoid leaving blank lines, when a sequence of
                                        // space-separated comments is both preceded and followed by
                                        // a newline (ignoring spaces), then
                                        // trim leading and trailing spaces and the trailing newline.

                                        // Find the end
                                        $endPos = strpos( $text, '-->', $i + 4 );
                                        if ( $endPos === false ) {
                                                // Unclosed comment in input, runs to end
                                                $inner = substr( $text, $i );
                                                $accum[] = [ 'comment', [ $inner ] ];
                                                $i = $lengthText;
                                        } else {
                                                // Search backwards for leading whitespace
                                                // $wsStart is the first char of the comment (first of the leading space or '<')
                                                $wsStart = $i ? ( $i - strspn( $revText, " \t", $lengthText - $i ) ) : 0;

                                                // $wsEnd will be the char *after* the comment (after last space or the '>' if there's no space)
                                                $wsEnd = $endPos + 3; // add length of -->
                                                // Search forwards for trailing whitespace
                                                $wsEnd += strspn( $text, " \t", $wsEnd );

                                                // Keep looking forward as long as we're finding more comments on the line
                                                $comments = [ [ $wsStart, $wsEnd ] ];
                                                while ( substr_compare( $text, '<!--', $wsEnd, 4 ) === 0 ) {
                                                        $c = strpos( $text, '-->', $wsEnd + 4 );
                                                        if ( $c === false ) {
                                                                break;
                                                        }
                                                        $c += 3; // add length of -->
                                                        // Search forwards for trailing whitespace
                                                        $c += strspn( $text, " \t", $c );
                                                        $comments[] = [ $wsEnd, $c ];
                                                        $wsEnd = $c;
                                                }

                                                // Eat the line if possible
                                                // TODO: This could theoretically be done if $wsStart === 0, i.e. for comments at
                                                // the overall start. That's not how Sanitizer::removeHTMLcomments() did it, but
                                                // it's a possible beneficial b/c break.
                                                if ( $wsStart > 0 && substr_compare( $text, "\n", $wsStart - 1, 1 ) === 0
                                                        && substr_compare( $text, "\n", $wsEnd, 1 ) === 0
                                                ) {
                                                        // Remove leading whitespace from the end of the accumulator
                                                        $wsLength = $i - $wsStart;
                                                        $endIndex = count( $accum ) - 1;

                                                        if ( $wsLength > 0
                                                                && $endIndex >= 0
                                                                && is_string( $accum[$endIndex] )
                                                                && strspn( $accum[$endIndex], " \t", -$wsLength ) === $wsLength
                                                        ) {
                                                                $accum[$endIndex] = substr( $accum[$endIndex], 0, -$wsLength );
                                                        }

                                                        // Dump all but the last comment to the accumulator
                                                        // $endPos includes the newline from the if above, want also eat that
                                                        [ $startPos, $endPos ] = array_pop( $comments );
                                                        foreach ( $comments as [ $cStartPos, $cEndPos ] ) {
                                                                // $cEndPos is the next char, no +1 needed to get correct length between start/end
                                                                $inner = substr( $text, $cStartPos, $cEndPos - $cStartPos );
                                                                $accum[] = [ 'comment', [ $inner ] ];
                                                        }

                                                        // Do a line-start run next time to look for headings after the comment
                                                        $fakeLineStart = true;
                                                } else {
                                                        // No line to eat, just take the comment itself
                                                        $startPos = $i;
                                                        $endPos += 2;
                                                }

                                                if ( $stack->top ) {
                                                        $part = $stack->top->getCurrentPart();
                                                        if ( $part->commentEnd !== $wsStart - 1 ) {
                                                                $part->visualEnd = $wsStart;
                                                        }
                                                        // Else comments abutting, no change in visual end
                                                        $part->commentEnd = $endPos;
                                                }
                                                $i = $endPos + 1;
                                                $inner = substr( $text, $startPos, $endPos - $startPos + 1 );
                                                $accum[] = [ 'comment', [ $inner ] ];
                                        }
                                        continue;
                                }
                                $attrStart = $i + strlen( $name ) + 1;

                                // Find end of tag
                                $tagEndPos = $noMoreGT ? false : strpos( $text, '>', $attrStart );
                                if ( $tagEndPos === false ) {
                                        // Infinite backtrack
                                        // Disable tag search to prevent worst-case O(N^2) performance
                                        $noMoreGT = true;
                                        self::addLiteral( $accum, '<' );
                                        ++$i;
                                        continue;
                                }

                                $lowerName = strtolower( $name );
                                // Handle ignored tags
                                if ( in_array( $lowerName, $ignoredTags ) ) {
                                        $accum[] = [ 'ignore', [ substr( $text, $i, $tagEndPos - $i + 1 ) ] ];
                                        $i = $tagEndPos + 1;
                                        continue;
                                }

                                $tagStartPos = $i;
                                if ( $text[$tagEndPos - 1] === '/' ) {
                                        // Short end tag
                                        $attrEnd = $tagEndPos - 1;
                                        $inner = null;
                                        $i = $tagEndPos + 1;
                                        $close = null;
                                } else {
                                        $attrEnd = $tagEndPos;
                                        // Find closing tag
                                        if (
                                                !isset( $noMoreClosingTag[$lowerName] ) &&
                                                preg_match( "/<\/" . preg_quote( $name, '/' ) . "\s*>/i",
                                                        $text, $matches, PREG_OFFSET_CAPTURE, $tagEndPos + 1 )
                                        ) {
                                                [ $close, $closeTagStartPos ] = $matches[0];
                                                $inner = substr( $text, $tagEndPos + 1, $closeTagStartPos - $tagEndPos - 1 );
                                                $i = $closeTagStartPos + strlen( $close );
                                        } else {
                                                // No end tag
                                                if ( in_array( $name, $xmlishAllowMissingEndTag ) ) {
                                                        // Let it run out to the end of the text.
                                                        $inner = substr( $text, $tagEndPos + 1 );
                                                        $i = $lengthText;
                                                        $close = null;
                                                } else {
                                                        // Don't match the tag, treat opening tag as literal and resume parsing.
                                                        $i = $tagEndPos + 1;
                                                        self::addLiteral( $accum, substr( $text, $tagStartPos, $tagEndPos + 1 - $tagStartPos ) );
                                                        // Cache results, otherwise we have O(N^2) performance for input like <foo><foo><foo>...
                                                        $noMoreClosingTag[$lowerName] = true;
                                                        continue;
                                                }
                                        }
                                }
                                // <includeonly> and <noinclude> just become <ignore> tags
                                if ( in_array( $lowerName, $ignoredElements ) ) {
                                        $accum[] = [ 'ignore', [ substr( $text, $tagStartPos, $i - $tagStartPos ) ] ];
                                        continue;
                                }

                                if ( $attrEnd <= $attrStart ) {
                                        $attr = '';
                                } else {
                                        // Note that the attr element contains the whitespace between name and attribute,
                                        // this is necessary for precise reconstruction during pre-save transform.
                                        $attr = substr( $text, $attrStart, $attrEnd - $attrStart );
                                }

                                $children = [
                                        [ 'name', [ $name ] ],
                                        [ 'attr', [ $attr ] ],
                                ];
                                if ( $inner !== null ) {
                                        $children[] = [ 'inner', [ $inner ] ];
                                }
                                if ( $close !== null ) {
                                        $children[] = [ 'close', [ $close ] ];
                                }
                                $accum[] = [ 'ext', $children ];
                        } elseif ( $found === 'line-start' ) {
                                // Is this the start of a heading?
                                // Line break belongs before the heading element in any case
                                if ( $fakeLineStart ) {
                                        $fakeLineStart = false;
                                } else {
                                        self::addLiteral( $accum, $curChar );
                                        $i++;
                                }

                                // Examine upto 6 characters
                                $count = strspn( $text, '=', $i, min( $lengthText, 6 ) );
                                if ( $count === 1 && $findEquals ) {
                                        // DWIM: This looks kind of like a name/value separator.
                                        // Let's let the equals handler have it and break the potential
                                        // heading. This is heuristic, but AFAICT the methods for
                                        // completely correct disambiguation are very complex.
                                } elseif ( $count > 0 ) {
                                        $piece = [
                                                'open' => "\n",
                                                'close' => "\n",
                                                'parts' => [ new PPDPart_Hash( str_repeat( '=', $count ) ) ],
                                                'startPos' => $i,
                                                'count' => $count,
                                        ];
                                        $stack->push( $piece );
                                        $accum =& $stack->getAccum();
                                        $stackFlags = $stack->getFlags();
                                        if ( isset( $stackFlags['findEquals'] ) ) {
                                                $findEquals = $stackFlags['findEquals'];
                                        }
                                        if ( isset( $stackFlags['findPipe'] ) ) {
                                                $findPipe = $stackFlags['findPipe'];
                                        }
                                        if ( isset( $stackFlags['inHeading'] ) ) {
                                                $inHeading = $stackFlags['inHeading'];
                                        }
                                        $i += $count;
                                }
                        } elseif ( $found === 'line-end' ) {
                                $piece = $stack->top;
                                // A heading must be open, otherwise \n wouldn't have been in the search list
                                // FIXME: Don't use assert()
                                // phpcs:ignore MediaWiki.Usage.ForbiddenFunctions.assert
                                assert( $piece->open === "\n" );
                                $part = $piece->getCurrentPart();
                                // Search back through the input to see if it has a proper close.
                                // Do this using the reversed string since the other solutions
                                // (end anchor, etc.) are inefficient.
                                $wsLength = strspn( $revText, " \t", $lengthText - $i );
                                $searchStart = $i - $wsLength;
                                if ( $part->commentEnd === $searchStart - 1 ) {
                                        // Comment found at line end
                                        // Search for equals signs before the comment
                                        $searchStart = $part->visualEnd;
                                        $searchStart -= strspn( $revText, " \t", $lengthText - $searchStart );
                                }
                                $equalsLength = strspn( $revText, '=', $lengthText - $searchStart );
                                if ( $equalsLength > 0 ) {
                                        if ( $searchStart - $equalsLength === $piece->startPos ) {
                                                // This is just a single string of equals signs on its own line
                                                // Replicate the doHeadings behavior /={count}(.+)={count}/
                                                // First find out how many equals signs there really are (don't stop at 6)
                                                if ( $equalsLength < 3 ) {
                                                        $count = 0;
                                                } else {
                                                        $count = min( 6, intval( ( $equalsLength - 1 ) / 2 ) );
                                                }
                                        } else {
                                                $count = min( $equalsLength, $piece->count );
                                        }
                                        if ( $count > 0 ) {
                                                // Normal match, output <h>
                                                $element = [ [ 'possible-h',
                                                        array_merge(
                                                                [
                                                                        [ '@level', [ $count ] ],
                                                                        [ '@i', [ $headingIndex++ ] ]
                                                                ],
                                                                $accum
                                                        )
                                                ] ];
                                        } else {
                                                // Single equals sign on its own line, count=0
                                                $element = $accum;
                                        }
                                } else {
                                        // No match, no <h>, just pass down the inner text
                                        $element = $accum;
                                }
                                // Unwind the stack
                                $stack->pop();
                                $accum =& $stack->getAccum();
                                $stackFlags = $stack->getFlags();
                                if ( isset( $stackFlags['findEquals'] ) ) {
                                        $findEquals = $stackFlags['findEquals'];
                                }
                                if ( isset( $stackFlags['findPipe'] ) ) {
                                        $findPipe = $stackFlags['findPipe'];
                                }
                                if ( isset( $stackFlags['inHeading'] ) ) {
                                        $inHeading = $stackFlags['inHeading'];
                                }

                                // Append the result to the enclosing accumulator
                                array_splice( $accum, count( $accum ), 0, $element );

                                // Note that we do NOT increment the input pointer.
                                // This is because the closing linebreak could be the opening linebreak of
                                // another heading. Infinite loops are avoided because the next iteration MUST
                                // hit the heading open case above, which unconditionally increments the
                                // input pointer.
                        } elseif ( $found === 'open' ) {
                                # count opening brace characters
                                $curLen = strlen( $curChar );
                                $count = $curLen > 1
                                        # allow the final character to repeat
                                        ? strspn( $text, $curChar[$curLen - 1], $i + 1 ) + 1
                                        : strspn( $text, $curChar, $i );

                                $savedPrefix = '';
                                $lineStart = $i > 0 && $text[$i - 1] === "\n";

                                if ( $curChar === "-{" && $count > $curLen ) {
                                        // -{ => {{ transition because rightmost wins
                                        $savedPrefix = '-';
                                        $i++;
                                        $curChar = '{';
                                        $count--;
                                        $rule = $this->rules[$curChar];
                                }

                                # we need to add to stack only if opening brace count is enough for one of the rules
                                if ( $count >= $rule['min'] ) {
                                        # Add it to the stack
                                        $piece = [
                                                'open' => $curChar,
                                                'close' => $rule['end'],
                                                'savedPrefix' => $savedPrefix,
                                                'count' => $count,
                                                'lineStart' => $lineStart,
                                        ];

                                        $stack->push( $piece );
                                        $accum =& $stack->getAccum();
                                        $stackFlags = $stack->getFlags();
                                        if ( isset( $stackFlags['findEquals'] ) ) {
                                                $findEquals = $stackFlags['findEquals'];
                                        }
                                        if ( isset( $stackFlags['findPipe'] ) ) {
                                                $findPipe = $stackFlags['findPipe'];
                                        }
                                        if ( isset( $stackFlags['inHeading'] ) ) {
                                                $inHeading = $stackFlags['inHeading'];
                                        }
                                } else {
                                        # Add literal brace(s)
                                        self::addLiteral( $accum, $savedPrefix . str_repeat( $curChar, $count ) );
                                }
                                $i += $count;
                        } elseif ( $found === 'close' ) {
                                /** @var PPDStackElement_Hash $piece */
                                $piece = $stack->top;
                                '@phan-var PPDStackElement_Hash $piece';
                                # lets check if there are enough characters for closing brace
                                $maxCount = $piece->count;
                                if ( $piece->close === '}-' && $curChar === '}' ) {
                                        $maxCount--; # don't try to match closing '-' as a '}'
                                }
                                $curLen = strlen( $curChar );
                                $count = $curLen > 1
                                        ? $curLen
                                        : strspn( $text, $curChar, $i, $maxCount );

                                # check for maximum matching characters (if there are 5 closing
                                # characters, we will probably need only 3 - depending on the rules)
                                $rule = $this->rules[$piece->open];
                                if ( $count > $rule['max'] ) {
                                        # The specified maximum exists in the callback array, unless the caller
                                        # has made an error
                                        $matchingCount = $rule['max'];
                                } else {
                                        # Count is less than the maximum
                                        # Skip any gaps in the callback array to find the true largest match
                                        # Need to use array_key_exists not isset because the callback can be null
                                        $matchingCount = $count;
                                        while ( $matchingCount > 0 && !array_key_exists( $matchingCount, $rule['names'] ) ) {
                                                --$matchingCount;
                                        }
                                }

                                if ( $matchingCount <= 0 ) {
                                        # No matching element found in callback array
                                        # Output a literal closing brace and continue
                                        $endText = substr( $text, $i, $count );
                                        self::addLiteral( $accum, $endText );
                                        $i += $count;
                                        continue;
                                }
                                // @phan-suppress-next-line PhanTypeArraySuspiciousNullable
                                $name = $rule['names'][$matchingCount];
                                if ( $name === null ) {
                                        // No element, just literal text
                                        $endText = substr( $text, $i, $matchingCount );
                                        $element = $piece->breakSyntax( $matchingCount );
                                        self::addLiteral( $element, $endText );
                                } else {
                                        # Create XML element
                                        $parts = $piece->parts;
                                        $titleAccum = $parts[0]->out;
                                        unset( $parts[0] );

                                        $children = [];

                                        # The invocation is at the start of the line if lineStart is set in
                                        # the stack, and all opening brackets are used up.
                                        if ( $maxCount === $matchingCount &&
                                                $piece->lineStart &&
                                                $piece->savedPrefix === ''
                                        ) {
                                                $children[] = [ '@lineStart', [ 1 ] ];
                                        }
                                        $titleNode = [ 'title', $titleAccum ];
                                        $children[] = $titleNode;
                                        $argIndex = 1;
                                        foreach ( $parts as $part ) {
                                                if ( $part->eqpos !== null ) {
                                                        $equalsNode = $part->out[$part->eqpos];
                                                        $nameNode = [ 'name', array_slice( $part->out, 0, $part->eqpos ) ];
                                                        $valueNode = [ 'value', array_slice( $part->out, $part->eqpos + 1 ) ];
                                                        $partNode = [ 'part', [ $nameNode, $equalsNode, $valueNode ] ];
                                                        $children[] = $partNode;
                                                } else {
                                                        $nameNode = [ 'name', [ [ '@index', [ $argIndex++ ] ] ] ];
                                                        $valueNode = [ 'value', $part->out ];
                                                        $partNode = [ 'part', [ $nameNode, $valueNode ] ];
                                                        $children[] = $partNode;
                                                }
                                        }
                                        $element = [ [ $name, $children ] ];
                                }

                                # Advance input pointer
                                $i += $matchingCount;

                                # Unwind the stack
                                $stack->pop();
                                $accum =& $stack->getAccum();

                                # Re-add the old stack element if it still has unmatched opening characters remaining
                                if ( $matchingCount < $piece->count ) {
                                        $piece->parts = [ new PPDPart_Hash ];
                                        $piece->count -= $matchingCount;
                                        # do we still qualify for any callback with remaining count?
                                        $min = $this->rules[$piece->open]['min'];
                                        if ( $piece->count >= $min ) {
                                                $stack->push( $piece );
                                                $accum =& $stack->getAccum();
                                        } elseif ( $piece->count === 1 && $piece->open === '{' && $piece->savedPrefix === '-' ) {
                                                $piece->savedPrefix = '';
                                                $piece->open = '-{';
                                                $piece->count = 2;
                                                $piece->close = $this->rules[$piece->open]['end'];
                                                $stack->push( $piece );
                                                $accum =& $stack->getAccum();
                                        } else {
                                                $s = substr( $piece->open, 0, -1 );
                                                $s .= str_repeat(
                                                        substr( $piece->open, -1 ),
                                                        $piece->count - strlen( $s )
                                                );
                                                self::addLiteral( $accum, $piece->savedPrefix . $s );
                                        }
                                } elseif ( $piece->savedPrefix !== '' ) {
                                        self::addLiteral( $accum, $piece->savedPrefix );
                                }

                                $stackFlags = $stack->getFlags();
                                if ( isset( $stackFlags['findEquals'] ) ) {
                                        $findEquals = $stackFlags['findEquals'];
                                }
                                if ( isset( $stackFlags['findPipe'] ) ) {
                                        $findPipe = $stackFlags['findPipe'];
                                }
                                if ( isset( $stackFlags['inHeading'] ) ) {
                                        $inHeading = $stackFlags['inHeading'];
                                }

                                # Add XML element to the enclosing accumulator
                                array_splice( $accum, count( $accum ), 0, $element );
                        } elseif ( $found === 'pipe' ) {
                                $findEquals = true; // shortcut for getFlags()
                                $stack->addPart();
                                $accum =& $stack->getAccum();
                                ++$i;
                        } elseif ( $found === 'equals' ) {
                                $findEquals = false; // shortcut for getFlags()
                                $accum[] = [ 'equals', [ '=' ] ];
                                $stack->getCurrentPart()->eqpos = count( $accum ) - 1;
                                ++$i;
                        }
                }

                # Output any remaining unclosed brackets
                foreach ( $stack->stack as $piece ) {
                        array_splice( $stack->rootAccum, count( $stack->rootAccum ), 0, $piece->breakSyntax() );
                }

                # Enable top-level headings
                foreach ( $stack->rootAccum as &$node ) {
                        if ( is_array( $node ) && $node[PPNode_Hash_Tree::NAME] === 'possible-h' ) {
                                $node[PPNode_Hash_Tree::NAME] = 'h';
                        }
                }

                return [ [ 'root', $stack->rootAccum ] ];
        }

        private static function addLiteral( array &$accum, $text ) {
                $n = count( $accum );
                if ( $n && is_string( $accum[$n - 1] ) ) {
                        $accum[$n - 1] .= $text;
                } else {
                        $accum[] = $text;
                }
        }
}

/** @deprecated class alias since 1.43 */
class_alias( Preprocessor_Hash::class, 'Preprocessor_Hash' );