Merge "API: Add show=unread to ApiQueryWatchlist"

[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
 */

/**
 * Differences from DOM schema:
 *   * attribute nodes are children
 *   * "<h>" nodes that aren't at the top are replaced with <possible-h>
 * @ingroup Parser
 */
class Preprocessor_Hash implements Preprocessor {
        /**
         * @var Parser
         */
        var $parser;

        const CACHE_VERSION = 1;

        function __construct( $parser ) {
                $this->parser = $parser;
        }

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

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

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

                foreach ( $values as $k => $val ) {
                        $partNode = new PPNode_Hash_Tree( 'part' );
                        $nameNode = new PPNode_Hash_Tree( 'name' );

                        if ( is_int( $k ) ) {
                                $nameNode->addChild( new PPNode_Hash_Attr( 'index', $k ) );
                                $partNode->addChild( $nameNode );
                        } else {
                                $nameNode->addChild( new PPNode_Hash_Text( $k ) );
                                $partNode->addChild( $nameNode );
                                $partNode->addChild( new PPNode_Hash_Text( '=' ) );
                        }

                        $valueNode = new PPNode_Hash_Tree( 'value' );
                        $valueNode->addChild( new PPNode_Hash_Text( $val ) );
                        $partNode->addChild( $valueNode );

                        $list[] = $partNode;
                }

                $node = new PPNode_Hash_Array( $list );
                return $node;
        }

        /**
         * Preprocess some wikitext and return the document tree.
         * This is the ghost of Parser::replace_variables().
         *
         * @param string $text The text to parse
         * @param int $flags Bitwise combination of:
         *    Parser::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 bug 4899.
         *
         * 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.
         *
         * @throws MWException
         * @return PPNode_Hash_Tree
         */
        function preprocessToObj( $text, $flags = 0 ) {
                wfProfileIn( __METHOD__ );

                // Check cache.
                global $wgMemc, $wgPreprocessorCacheThreshold;

                $cacheable = $wgPreprocessorCacheThreshold !== false
                        && strlen( $text ) > $wgPreprocessorCacheThreshold;

                if ( $cacheable ) {
                        wfProfileIn( __METHOD__ . '-cacheable' );

                        $cacheKey = wfMemcKey( 'preprocess-hash', md5( $text ), $flags );
                        $cacheValue = $wgMemc->get( $cacheKey );
                        if ( $cacheValue ) {
                                $version = substr( $cacheValue, 0, 8 );
                                if ( intval( $version ) == self::CACHE_VERSION ) {
                                        $hash = unserialize( substr( $cacheValue, 8 ) );
                                        // From the cache
                                        wfDebugLog( "Preprocessor",
                                                "Loaded preprocessor hash from memcached (key $cacheKey)" );
                                        wfProfileOut( __METHOD__ . '-cacheable' );
                                        wfProfileOut( __METHOD__ );
                                        return $hash;
                                }
                        }
                        wfProfileIn( __METHOD__ . '-cache-miss' );
                }

                $rules = array(
                        '{' => array(
                                'end' => '}',
                                'names' => array(
                                        2 => 'template',
                                        3 => 'tplarg',
                                ),
                                'min' => 2,
                                'max' => 3,
                        ),
                        '[' => array(
                                'end' => ']',
                                'names' => array( 2 => null ),
                                'min' => 2,
                                'max' => 2,
                        )
                );

                $forInclusion = $flags & Parser::PTD_FOR_INCLUSION;

                $xmlishElements = $this->parser->getStripList();
                $enableOnlyinclude = false;
                if ( $forInclusion ) {
                        $ignoredTags = array( 'includeonly', '/includeonly' );
                        $ignoredElements = array( 'noinclude' );
                        $xmlishElements[] = 'noinclude';
                        if ( strpos( $text, '<onlyinclude>' ) !== false
                                && strpos( $text, '</onlyinclude>' ) !== false
                        ) {
                                $enableOnlyinclude = true;
                        }
                } else {
                        $ignoredTags = array( 'noinclude', '/noinclude', 'onlyinclude', '/onlyinclude' );
                        $ignoredElements = array( '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";
                // 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
                $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;
                // 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 ) {
                        //$this->memCheck();

                        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->addNodeWithText( 'ignore', substr( $text, $i ) );
                                        break;
                                }
                                $tagEndPos = $startPos + strlen( '<onlyinclude>' ); // past-the-end
                                $accum->addNodeWithText( '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 ) {
                                        $accum->addLiteral( 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 = $text[$i];
                                        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 ( $curChar == $currentClosing ) {
                                                $found = 'close';
                                        } elseif ( isset( $rules[$curChar] ) ) {
                                                $found = 'open';
                                                $rule = $rules[$curChar];
                                        } else {
                                                # Some versions of PHP have a strcspn which stops on null characters
                                                # Ignore and continue
                                                ++$i;
                                                continue;
                                        }
                                }
                        }

                        if ( $found == 'angle' ) {
                                $matches = false;
                                // Handle </onlyinclude>
                                if ( $enableOnlyinclude
                                        && substr( $text, $i, strlen( '</onlyinclude>' ) ) == '</onlyinclude>'
                                ) {
                                        $findOnlyinclude = true;
                                        continue;
                                }

                                // Determine element name
                                if ( !preg_match( $elementsRegex, $text, $matches, 0, $i + 1 ) ) {
                                        // Element name missing or not listed
                                        $accum->addLiteral( '<' );
                                        ++$i;
                                        continue;
                                }
                                // Handle comments
                                if ( isset( $matches[2] ) && $matches[2] == '!--' ) {

                                        // 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->addNodeWithText( 'comment', $inner );
                                                $i = $lengthText;
                                        } else {
                                                // Search backwards for leading whitespace
                                                $wsStart = $i ? ( $i - strspn( $revText, " \t", $lengthText - $i ) ) : 0;

                                                // Search forwards for trailing whitespace
                                                // $wsEnd will be the position of the last space (or the '>' if there's none)
                                                $wsEnd = $endPos + 2 + strspn( $text, " \t", $endPos + 3 );

                                                // Keep looking forward as long as we're finding more
                                                // comments.
                                                $comments = array( array( $wsStart, $wsEnd ) );
                                                while ( substr( $text, $wsEnd + 1, 4 ) == '<!--' ) {
                                                        $c = strpos( $text, '-->', $wsEnd + 4 );
                                                        if ( $c === false ) {
                                                                break;
                                                        }
                                                        $c = $c + 2 + strspn( $text, " \t", $c + 3 );
                                                        $comments[] = array( $wsEnd + 1, $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( $text, $wsStart - 1, 1 ) == "\n"
                                                        && substr( $text, $wsEnd + 1, 1 ) == "\n"
                                                ) {
                                                        // Remove leading whitespace from the end of the accumulator
                                                        // Sanity check first though
                                                        $wsLength = $i - $wsStart;
                                                        if ( $wsLength > 0
                                                                && $accum->lastNode instanceof PPNode_Hash_Text
                                                                && strspn( $accum->lastNode->value, " \t", -$wsLength ) === $wsLength
                                                        ) {
                                                                $accum->lastNode->value = substr( $accum->lastNode->value, 0, -$wsLength );
                                                        }

                                                        // Dump all but the last comment to the accumulator
                                                        foreach ( $comments as $j => $com ) {
                                                                $startPos = $com[0];
                                                                $endPos = $com[1] + 1;
                                                                if ( $j == ( count( $comments ) - 1 ) ) {
                                                                        break;
                                                                }
                                                                $inner = substr( $text, $startPos, $endPos - $startPos );
                                                                $accum->addNodeWithText( '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 ( !( isset( $part->commentEnd ) && $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->addNodeWithText( 'comment', $inner );
                                        }
                                        continue;
                                }
                                $name = $matches[1];
                                $lowerName = strtolower( $name );
                                $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;
                                        $accum->addLiteral( '<' );
                                        ++$i;
                                        continue;
                                }

                                // Handle ignored tags
                                if ( in_array( $lowerName, $ignoredTags ) ) {
                                        $accum->addNodeWithText( '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 ( preg_match( "/<\/" . preg_quote( $name, '/' ) . "\s*>/i",
                                                        $text, $matches, PREG_OFFSET_CAPTURE, $tagEndPos + 1 )
                                        ) {
                                                $inner = substr( $text, $tagEndPos + 1, $matches[0][1] - $tagEndPos - 1 );
                                                $i = $matches[0][1] + strlen( $matches[0][0] );
                                                $close = $matches[0][0];
                                        } else {
                                                // No end tag -- let it run out to the end of the text.
                                                $inner = substr( $text, $tagEndPos + 1 );
                                                $i = $lengthText;
                                                $close = null;
                                        }
                                }
                                // <includeonly> and <noinclude> just become <ignore> tags
                                if ( in_array( $lowerName, $ignoredElements ) ) {
                                        $accum->addNodeWithText( '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 );
                                }

                                $extNode = new PPNode_Hash_Tree( 'ext' );
                                $extNode->addChild( PPNode_Hash_Tree::newWithText( 'name', $name ) );
                                $extNode->addChild( PPNode_Hash_Tree::newWithText( 'attr', $attr ) );
                                if ( $inner !== null ) {
                                        $extNode->addChild( PPNode_Hash_Tree::newWithText( 'inner', $inner ) );
                                }
                                if ( $close !== null ) {
                                        $extNode->addChild( PPNode_Hash_Tree::newWithText( 'close', $close ) );
                                }
                                $accum->addNode( $extNode );
                        } 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 {
                                        $accum->addLiteral( $curChar );
                                        $i++;
                                }

                                $count = strspn( $text, '=', $i, 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 = array(
                                                'open' => "\n",
                                                'close' => "\n",
                                                'parts' => array( new PPDPart_Hash( str_repeat( '=', $count ) ) ),
                                                'startPos' => $i,
                                                'count' => $count );
                                        $stack->push( $piece );
                                        $accum =& $stack->getAccum();
                                        extract( $stack->getFlags() );
                                        $i += $count;
                                }
                        } elseif ( $found == 'line-end' ) {
                                $piece = $stack->top;
                                // A heading must be open, otherwise \n wouldn't have been in the search list
                                assert( '$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 ( isset( $part->commentEnd ) && $searchStart - 1 == $part->commentEnd ) {
                                        // Comment found at line end
                                        // Search for equals signs before the comment
                                        $searchStart = $part->visualEnd;
                                        $searchStart -= strspn( $revText, " \t", $lengthText - $searchStart );
                                }
                                $count = $piece->count;
                                $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)
                                                $count = $equalsLength;
                                                if ( $count < 3 ) {
                                                        $count = 0;
                                                } else {
                                                        $count = min( 6, intval( ( $count - 1 ) / 2 ) );
                                                }
                                        } else {
                                                $count = min( $equalsLength, $count );
                                        }
                                        if ( $count > 0 ) {
                                                // Normal match, output <h>
                                                $element = new PPNode_Hash_Tree( 'possible-h' );
                                                $element->addChild( new PPNode_Hash_Attr( 'level', $count ) );
                                                $element->addChild( new PPNode_Hash_Attr( 'i', $headingIndex++ ) );
                                                $element->lastChild->nextSibling = $accum->firstNode;
                                                $element->lastChild = $accum->lastNode;
                                        } 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();
                                extract( $stack->getFlags() );

                                // Append the result to the enclosing accumulator
                                if ( $element instanceof PPNode ) {
                                        $accum->addNode( $element );
                                } else {
                                        $accum->addAccum( $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
                                $count = strspn( $text, $curChar, $i );

                                # 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 = array(
                                                'open' => $curChar,
                                                'close' => $rule['end'],
                                                'count' => $count,
                                                'lineStart' => ( $i > 0 && $text[$i - 1] == "\n" ),
                                        );

                                        $stack->push( $piece );
                                        $accum =& $stack->getAccum();
                                        extract( $stack->getFlags() );
                                } else {
                                        # Add literal brace(s)
                                        $accum->addLiteral( str_repeat( $curChar, $count ) );
                                }
                                $i += $count;
                        } elseif ( $found == 'close' ) {
                                $piece = $stack->top;
                                # lets check if there are enough characters for closing brace
                                $maxCount = $piece->count;
                                $count = 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 = $rules[$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
                                        $accum->addLiteral( str_repeat( $curChar, $count ) );
                                        $i += $count;
                                        continue;
                                }
                                $name = $rule['names'][$matchingCount];
                                if ( $name === null ) {
                                        // No element, just literal text
                                        $element = $piece->breakSyntax( $matchingCount );
                                        $element->addLiteral( str_repeat( $rule['end'], $matchingCount ) );
                                } else {
                                        # Create XML element
                                        # Note: $parts is already XML, does not need to be encoded further
                                        $parts = $piece->parts;
                                        $titleAccum = $parts[0]->out;
                                        unset( $parts[0] );

                                        $element = new PPNode_Hash_Tree( $name );

                                        # 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 && !empty( $piece->lineStart ) ) {
                                                $element->addChild( new PPNode_Hash_Attr( 'lineStart', 1 ) );
                                        }
                                        $titleNode = new PPNode_Hash_Tree( 'title' );
                                        $titleNode->firstChild = $titleAccum->firstNode;
                                        $titleNode->lastChild = $titleAccum->lastNode;
                                        $element->addChild( $titleNode );
                                        $argIndex = 1;
                                        foreach ( $parts as $part ) {
                                                if ( isset( $part->eqpos ) ) {
                                                        // Find equals
                                                        $lastNode = false;
                                                        for ( $node = $part->out->firstNode; $node; $node = $node->nextSibling ) {
                                                                if ( $node === $part->eqpos ) {
                                                                        break;
                                                                }
                                                                $lastNode = $node;
                                                        }
                                                        if ( !$node ) {
                                                                if ( $cacheable ) {
                                                                        wfProfileOut( __METHOD__ . '-cache-miss' );
                                                                        wfProfileOut( __METHOD__ . '-cacheable' );
                                                                }
                                                                wfProfileOut( __METHOD__ );
                                                                throw new MWException( __METHOD__ . ': eqpos not found' );
                                                        }
                                                        if ( $node->name !== 'equals' ) {
                                                                if ( $cacheable ) {
                                                                        wfProfileOut( __METHOD__ . '-cache-miss' );
                                                                        wfProfileOut( __METHOD__ . '-cacheable' );
                                                                }
                                                                wfProfileOut( __METHOD__ );
                                                                throw new MWException( __METHOD__ . ': eqpos is not equals' );
                                                        }
                                                        $equalsNode = $node;

                                                        // Construct name node
                                                        $nameNode = new PPNode_Hash_Tree( 'name' );
                                                        if ( $lastNode !== false ) {
                                                                $lastNode->nextSibling = false;
                                                                $nameNode->firstChild = $part->out->firstNode;
                                                                $nameNode->lastChild = $lastNode;
                                                        }

                                                        // Construct value node
                                                        $valueNode = new PPNode_Hash_Tree( 'value' );
                                                        if ( $equalsNode->nextSibling !== false ) {
                                                                $valueNode->firstChild = $equalsNode->nextSibling;
                                                                $valueNode->lastChild = $part->out->lastNode;
                                                        }
                                                        $partNode = new PPNode_Hash_Tree( 'part' );
                                                        $partNode->addChild( $nameNode );
                                                        $partNode->addChild( $equalsNode->firstChild );
                                                        $partNode->addChild( $valueNode );
                                                        $element->addChild( $partNode );
                                                } else {
                                                        $partNode = new PPNode_Hash_Tree( 'part' );
                                                        $nameNode = new PPNode_Hash_Tree( 'name' );
                                                        $nameNode->addChild( new PPNode_Hash_Attr( 'index', $argIndex++ ) );
                                                        $valueNode = new PPNode_Hash_Tree( 'value' );
                                                        $valueNode->firstChild = $part->out->firstNode;
                                                        $valueNode->lastChild = $part->out->lastNode;
                                                        $partNode->addChild( $nameNode );
                                                        $partNode->addChild( $valueNode );
                                                        $element->addChild( $partNode );
                                                }
                                        }
                                }

                                # 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 = array( new PPDPart_Hash );
                                        $piece->count -= $matchingCount;
                                        # do we still qualify for any callback with remaining count?
                                        $min = $rules[$piece->open]['min'];
                                        if ( $piece->count >= $min ) {
                                                $stack->push( $piece );
                                                $accum =& $stack->getAccum();
                                        } else {
                                                $accum->addLiteral( str_repeat( $piece->open, $piece->count ) );
                                        }
                                }

                                extract( $stack->getFlags() );

                                # Add XML element to the enclosing accumulator
                                if ( $element instanceof PPNode ) {
                                        $accum->addNode( $element );
                                } else {
                                        $accum->addAccum( $element );
                                }
                        } elseif ( $found == 'pipe' ) {
                                $findEquals = true; // shortcut for getFlags()
                                $stack->addPart();
                                $accum =& $stack->getAccum();
                                ++$i;
                        } elseif ( $found == 'equals' ) {
                                $findEquals = false; // shortcut for getFlags()
                                $accum->addNodeWithText( 'equals', '=' );
                                $stack->getCurrentPart()->eqpos = $accum->lastNode;
                                ++$i;
                        }
                }

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

                # Enable top-level headings
                for ( $node = $stack->rootAccum->firstNode; $node; $node = $node->nextSibling ) {
                        if ( isset( $node->name ) && $node->name === 'possible-h' ) {
                                $node->name = 'h';
                        }
                }

                $rootNode = new PPNode_Hash_Tree( 'root' );
                $rootNode->firstChild = $stack->rootAccum->firstNode;
                $rootNode->lastChild = $stack->rootAccum->lastNode;

                // Cache
                if ( $cacheable ) {
                        $cacheValue = sprintf( "%08d", self::CACHE_VERSION ) . serialize( $rootNode );
                        $wgMemc->set( $cacheKey, $cacheValue, 86400 );
                        wfProfileOut( __METHOD__ . '-cache-miss' );
                        wfProfileOut( __METHOD__ . '-cacheable' );
                        wfDebugLog( "Preprocessor", "Saved preprocessor Hash to memcached (key $cacheKey)" );
                }

                wfProfileOut( __METHOD__ );
                return $rootNode;
        }
}

/**
 * Stack class to help Preprocessor::preprocessToObj()
 * @ingroup Parser
 */
class PPDStack_Hash extends PPDStack {
        function __construct() {
                $this->elementClass = 'PPDStackElement_Hash';
                parent::__construct();
                $this->rootAccum = new PPDAccum_Hash;
        }
}

/**
 * @ingroup Parser
 */
class PPDStackElement_Hash extends PPDStackElement {
        function __construct( $data = array() ) {
                $this->partClass = 'PPDPart_Hash';
                parent::__construct( $data );
        }

        /**
         * Get the accumulator that would result if the close is not found.
         *
         * @param int|bool $openingCount
         * @return PPDAccum_Hash
         */
        function breakSyntax( $openingCount = false ) {
                if ( $this->open == "\n" ) {
                        $accum = $this->parts[0]->out;
                } else {
                        if ( $openingCount === false ) {
                                $openingCount = $this->count;
                        }
                        $accum = new PPDAccum_Hash;
                        $accum->addLiteral( str_repeat( $this->open, $openingCount ) );
                        $first = true;
                        foreach ( $this->parts as $part ) {
                                if ( $first ) {
                                        $first = false;
                                } else {
                                        $accum->addLiteral( '|' );
                                }
                                $accum->addAccum( $part->out );
                        }
                }
                return $accum;
        }
}

/**
 * @ingroup Parser
 */
class PPDPart_Hash extends PPDPart {
        function __construct( $out = '' ) {
                $accum = new PPDAccum_Hash;
                if ( $out !== '' ) {
                        $accum->addLiteral( $out );
                }
                parent::__construct( $accum );
        }
}

/**
 * @ingroup Parser
 */
class PPDAccum_Hash {
        var $firstNode, $lastNode;

        function __construct() {
                $this->firstNode = $this->lastNode = false;
        }

        /**
         * Append a string literal
         * @param string $s
         */
        function addLiteral( $s ) {
                if ( $this->lastNode === false ) {
                        $this->firstNode = $this->lastNode = new PPNode_Hash_Text( $s );
                } elseif ( $this->lastNode instanceof PPNode_Hash_Text ) {
                        $this->lastNode->value .= $s;
                } else {
                        $this->lastNode->nextSibling = new PPNode_Hash_Text( $s );
                        $this->lastNode = $this->lastNode->nextSibling;
                }
        }

        /**
         * Append a PPNode
         * @param PPNode $node
         */
        function addNode( PPNode $node ) {
                if ( $this->lastNode === false ) {
                        $this->firstNode = $this->lastNode = $node;
                } else {
                        $this->lastNode->nextSibling = $node;
                        $this->lastNode = $node;
                }
        }

        /**
         * Append a tree node with text contents
         * @param string $name
         * @param string $value
         */
        function addNodeWithText( $name, $value ) {
                $node = PPNode_Hash_Tree::newWithText( $name, $value );
                $this->addNode( $node );
        }

        /**
         * Append a PPDAccum_Hash
         * Takes over ownership of the nodes in the source argument. These nodes may
         * subsequently be modified, especially nextSibling.
         * @param PPDAccum_Hash $accum
         */
        function addAccum( $accum ) {
                if ( $accum->lastNode === false ) {
                        // nothing to add
                } elseif ( $this->lastNode === false ) {
                        $this->firstNode = $accum->firstNode;
                        $this->lastNode = $accum->lastNode;
                } else {
                        $this->lastNode->nextSibling = $accum->firstNode;
                        $this->lastNode = $accum->lastNode;
                }
        }
}

/**
 * An expansion frame, used as a context to expand the result of preprocessToObj()
 * @ingroup Parser
 */
class PPFrame_Hash implements PPFrame {

        /**
         * @var Parser
         */
        var $parser;

        /**
         * @var Preprocessor
         */
        var $preprocessor;

        /**
         * @var Title
         */
        var $title;
        var $titleCache;

        /**
         * Hashtable listing templates which are disallowed for expansion in this frame,
         * having been encountered previously in parent frames.
         */
        var $loopCheckHash;

        /**
         * Recursion depth of this frame, top = 0
         * Note that this is NOT the same as expansion depth in expand()
         */
        var $depth;

        private $volatile = false;

        /**
         * @var array
         */
        protected $childExpansionCache;

        /**
         * Construct a new preprocessor frame.
         * @param Preprocessor $preprocessor The parent preprocessor
         */
        function __construct( $preprocessor ) {
                $this->preprocessor = $preprocessor;
                $this->parser = $preprocessor->parser;
                $this->title = $this->parser->mTitle;
                $this->titleCache = array( $this->title ? $this->title->getPrefixedDBkey() : false );
                $this->loopCheckHash = array();
                $this->depth = 0;
                $this->childExpansionCache = array();
        }

        /**
         * Create a new child frame
         * $args is optionally a multi-root PPNode or array containing the template arguments
         *
         * @param array|bool|PPNode_Hash_Array $args
         * @param Title|bool $title
         * @param int $indexOffset
         * @throws MWException
         * @return PPTemplateFrame_Hash
         */
        function newChild( $args = false, $title = false, $indexOffset = 0 ) {
                $namedArgs = array();
                $numberedArgs = array();
                if ( $title === false ) {
                        $title = $this->title;
                }
                if ( $args !== false ) {
                        if ( $args instanceof PPNode_Hash_Array ) {
                                $args = $args->value;
                        } elseif ( !is_array( $args ) ) {
                                throw new MWException( __METHOD__ . ': $args must be array or PPNode_Hash_Array' );
                        }
                        foreach ( $args as $arg ) {
                                $bits = $arg->splitArg();
                                if ( $bits['index'] !== '' ) {
                                        // Numbered parameter
                                        $index = $bits['index'] - $indexOffset;
                                        $numberedArgs[$index] = $bits['value'];
                                        unset( $namedArgs[$index] );
                                } else {
                                        // Named parameter
                                        $name = trim( $this->expand( $bits['name'], PPFrame::STRIP_COMMENTS ) );
                                        $namedArgs[$name] = $bits['value'];
                                        unset( $numberedArgs[$name] );
                                }
                        }
                }
                return new PPTemplateFrame_Hash( $this->preprocessor, $this, $numberedArgs, $namedArgs, $title );
        }

        /**
         * @throws MWException
         * @param string|int $key
         * @param string|PPNode_Hash|DOMDocument $root
         * @param int $flags
         * @return string
         */
        function cachedExpand( $key, $root, $flags = 0 ) {
                // we don't have a parent, so we don't have a cache
                return $this->expand( $root, $flags );
        }

        /**
         * @throws MWException
         * @param string|PPNode$root
         * @param int $flags
         * @return string
         */
        function expand( $root, $flags = 0 ) {
                static $expansionDepth = 0;
                if ( is_string( $root ) ) {
                        return $root;
                }

                if ( ++$this->parser->mPPNodeCount > $this->parser->mOptions->getMaxPPNodeCount() ) {
                        $this->parser->limitationWarn( 'node-count-exceeded',
                                        $this->parser->mPPNodeCount,
                                        $this->parser->mOptions->getMaxPPNodeCount()
                        );
                        return '<span class="error">Node-count limit exceeded</span>';
                }
                if ( $expansionDepth > $this->parser->mOptions->getMaxPPExpandDepth() ) {
                        $this->parser->limitationWarn( 'expansion-depth-exceeded',
                                        $expansionDepth,
                                        $this->parser->mOptions->getMaxPPExpandDepth()
                        );
                        return '<span class="error">Expansion depth limit exceeded</span>';
                }
                ++$expansionDepth;
                if ( $expansionDepth > $this->parser->mHighestExpansionDepth ) {
                        $this->parser->mHighestExpansionDepth = $expansionDepth;
                }

                $outStack = array( '', '' );
                $iteratorStack = array( false, $root );
                $indexStack = array( 0, 0 );

                while ( count( $iteratorStack ) > 1 ) {
                        $level = count( $outStack ) - 1;
                        $iteratorNode =& $iteratorStack[$level];
                        $out =& $outStack[$level];
                        $index =& $indexStack[$level];

                        if ( is_array( $iteratorNode ) ) {
                                if ( $index >= count( $iteratorNode ) ) {
                                        // All done with this iterator
                                        $iteratorStack[$level] = false;
                                        $contextNode = false;
                                } else {
                                        $contextNode = $iteratorNode[$index];
                                        $index++;
                                }
                        } elseif ( $iteratorNode instanceof PPNode_Hash_Array ) {
                                if ( $index >= $iteratorNode->getLength() ) {
                                        // All done with this iterator
                                        $iteratorStack[$level] = false;
                                        $contextNode = false;
                                } else {
                                        $contextNode = $iteratorNode->item( $index );
                                        $index++;
                                }
                        } else {
                                // Copy to $contextNode and then delete from iterator stack,
                                // because this is not an iterator but we do have to execute it once
                                $contextNode = $iteratorStack[$level];
                                $iteratorStack[$level] = false;
                        }

                        $newIterator = false;

                        if ( $contextNode === false ) {
                                // nothing to do
                        } elseif ( is_string( $contextNode ) ) {
                                $out .= $contextNode;
                        } elseif ( is_array( $contextNode ) || $contextNode instanceof PPNode_Hash_Array ) {
                                $newIterator = $contextNode;
                        } elseif ( $contextNode instanceof PPNode_Hash_Attr ) {
                                // No output
                        } elseif ( $contextNode instanceof PPNode_Hash_Text ) {
                                $out .= $contextNode->value;
                        } elseif ( $contextNode instanceof PPNode_Hash_Tree ) {
                                if ( $contextNode->name == 'template' ) {
                                        # Double-brace expansion
                                        $bits = $contextNode->splitTemplate();
                                        if ( $flags & PPFrame::NO_TEMPLATES ) {
                                                $newIterator = $this->virtualBracketedImplode(
                                                        '{{', '|', '}}',
                                                        $bits['title'],
                                                        $bits['parts']
                                                );
                                        } else {
                                                $ret = $this->parser->braceSubstitution( $bits, $this );
                                                if ( isset( $ret['object'] ) ) {
                                                        $newIterator = $ret['object'];
                                                } else {
                                                        $out .= $ret['text'];
                                                }
                                        }
                                } elseif ( $contextNode->name == 'tplarg' ) {
                                        # Triple-brace expansion
                                        $bits = $contextNode->splitTemplate();
                                        if ( $flags & PPFrame::NO_ARGS ) {
                                                $newIterator = $this->virtualBracketedImplode(
                                                        '{{{', '|', '}}}',
                                                        $bits['title'],
                                                        $bits['parts']
                                                );
                                        } else {
                                                $ret = $this->parser->argSubstitution( $bits, $this );
                                                if ( isset( $ret['object'] ) ) {
                                                        $newIterator = $ret['object'];
                                                } else {
                                                        $out .= $ret['text'];
                                                }
                                        }
                                } elseif ( $contextNode->name == 'comment' ) {
                                        # HTML-style comment
                                        # Remove it in HTML, pre+remove and STRIP_COMMENTS modes
                                        if ( $this->parser->ot['html']
                                                || ( $this->parser->ot['pre'] && $this->parser->mOptions->getRemoveComments() )
                                                || ( $flags & PPFrame::STRIP_COMMENTS )
                                        ) {
                                                $out .= '';
                                        } elseif ( $this->parser->ot['wiki'] && !( $flags & PPFrame::RECOVER_COMMENTS ) ) {
                                                # Add a strip marker in PST mode so that pstPass2() can
                                                # run some old-fashioned regexes on the result.
                                                # Not in RECOVER_COMMENTS mode (extractSections) though.
                                                $out .= $this->parser->insertStripItem( $contextNode->firstChild->value );
                                        } else {
                                                # Recover the literal comment in RECOVER_COMMENTS and pre+no-remove
                                                $out .= $contextNode->firstChild->value;
                                        }
                                } elseif ( $contextNode->name == 'ignore' ) {
                                        # Output suppression used by <includeonly> etc.
                                        # OT_WIKI will only respect <ignore> in substed templates.
                                        # The other output types respect it unless NO_IGNORE is set.
                                        # extractSections() sets NO_IGNORE and so never respects it.
                                        if ( ( !isset( $this->parent ) && $this->parser->ot['wiki'] )
                                                || ( $flags & PPFrame::NO_IGNORE )
                                        ) {
                                                $out .= $contextNode->firstChild->value;
                                        } else {
                                                //$out .= '';
                                        }
                                } elseif ( $contextNode->name == 'ext' ) {
                                        # Extension tag
                                        $bits = $contextNode->splitExt() + array( 'attr' => null, 'inner' => null, 'close' => null );
                                        $out .= $this->parser->extensionSubstitution( $bits, $this );
                                } elseif ( $contextNode->name == 'h' ) {
                                        # Heading
                                        if ( $this->parser->ot['html'] ) {
                                                # Expand immediately and insert heading index marker
                                                $s = '';
                                                for ( $node = $contextNode->firstChild; $node; $node = $node->nextSibling ) {
                                                        $s .= $this->expand( $node, $flags );
                                                }

                                                $bits = $contextNode->splitHeading();
                                                $titleText = $this->title->getPrefixedDBkey();
                                                $this->parser->mHeadings[] = array( $titleText, $bits['i'] );
                                                $serial = count( $this->parser->mHeadings ) - 1;
                                                $marker = "{$this->parser->mUniqPrefix}-h-$serial-" . Parser::MARKER_SUFFIX;
                                                $s = substr( $s, 0, $bits['level'] ) . $marker . substr( $s, $bits['level'] );
                                                $this->parser->mStripState->addGeneral( $marker, '' );
                                                $out .= $s;
                                        } else {
                                                # Expand in virtual stack
                                                $newIterator = $contextNode->getChildren();
                                        }
                                } else {
                                        # Generic recursive expansion
                                        $newIterator = $contextNode->getChildren();
                                }
                        } else {
                                throw new MWException( __METHOD__ . ': Invalid parameter type' );
                        }

                        if ( $newIterator !== false ) {
                                $outStack[] = '';
                                $iteratorStack[] = $newIterator;
                                $indexStack[] = 0;
                        } elseif ( $iteratorStack[$level] === false ) {
                                // Return accumulated value to parent
                                // With tail recursion
                                while ( $iteratorStack[$level] === false && $level > 0 ) {
                                        $outStack[$level - 1] .= $out;
                                        array_pop( $outStack );
                                        array_pop( $iteratorStack );
                                        array_pop( $indexStack );
                                        $level--;
                                }
                        }
                }
                --$expansionDepth;
                return $outStack[0];
        }

        /**
         * @param string $sep
         * @param int $flags
         * @return string
         */
        function implodeWithFlags( $sep, $flags /*, ... */ ) {
                $args = array_slice( func_get_args(), 2 );

                $first = true;
                $s = '';
                foreach ( $args as $root ) {
                        if ( $root instanceof PPNode_Hash_Array ) {
                                $root = $root->value;
                        }
                        if ( !is_array( $root ) ) {
                                $root = array( $root );
                        }
                        foreach ( $root as $node ) {
                                if ( $first ) {
                                        $first = false;
                                } else {
                                        $s .= $sep;
                                }
                                $s .= $this->expand( $node, $flags );
                        }
                }
                return $s;
        }

        /**
         * Implode with no flags specified
         * This previously called implodeWithFlags but has now been inlined to reduce stack depth
         * @param string $sep
         * @return string
         */
        function implode( $sep /*, ... */ ) {
                $args = array_slice( func_get_args(), 1 );

                $first = true;
                $s = '';
                foreach ( $args as $root ) {
                        if ( $root instanceof PPNode_Hash_Array ) {
                                $root = $root->value;
                        }
                        if ( !is_array( $root ) ) {
                                $root = array( $root );
                        }
                        foreach ( $root as $node ) {
                                if ( $first ) {
                                        $first = false;
                                } else {
                                        $s .= $sep;
                                }
                                $s .= $this->expand( $node );
                        }
                }
                return $s;
        }

        /**
         * Makes an object that, when expand()ed, will be the same as one obtained
         * with implode()
         *
         * @param string $sep
         * @return PPNode_Hash_Array
         */
        function virtualImplode( $sep /*, ... */ ) {
                $args = array_slice( func_get_args(), 1 );
                $out = array();
                $first = true;

                foreach ( $args as $root ) {
                        if ( $root instanceof PPNode_Hash_Array ) {
                                $root = $root->value;
                        }
                        if ( !is_array( $root ) ) {
                                $root = array( $root );
                        }
                        foreach ( $root as $node ) {
                                if ( $first ) {
                                        $first = false;
                                } else {
                                        $out[] = $sep;
                                }
                                $out[] = $node;
                        }
                }
                return new PPNode_Hash_Array( $out );
        }

        /**
         * Virtual implode with brackets
         *
         * @param string $start
         * @param string $sep
         * @param string $end
         * @return PPNode_Hash_Array
         */
        function virtualBracketedImplode( $start, $sep, $end /*, ... */ ) {
                $args = array_slice( func_get_args(), 3 );
                $out = array( $start );
                $first = true;

                foreach ( $args as $root ) {
                        if ( $root instanceof PPNode_Hash_Array ) {
                                $root = $root->value;
                        }
                        if ( !is_array( $root ) ) {
                                $root = array( $root );
                        }
                        foreach ( $root as $node ) {
                                if ( $first ) {
                                        $first = false;
                                } else {
                                        $out[] = $sep;
                                }
                                $out[] = $node;
                        }
                }
                $out[] = $end;
                return new PPNode_Hash_Array( $out );
        }

        function __toString() {
                return 'frame{}';
        }

        /**
         * @param bool $level
         * @return array|bool|string
         */
        function getPDBK( $level = false ) {
                if ( $level === false ) {
                        return $this->title->getPrefixedDBkey();
                } else {
                        return isset( $this->titleCache[$level] ) ? $this->titleCache[$level] : false;
                }
        }

        /**
         * @return array
         */
        function getArguments() {
                return array();
        }

        /**
         * @return array
         */
        function getNumberedArguments() {
                return array();
        }

        /**
         * @return array
         */
        function getNamedArguments() {
                return array();
        }

        /**
         * Returns true if there are no arguments in this frame
         *
         * @return bool
         */
        function isEmpty() {
                return true;
        }

        /**
         * @param string $name
         * @return bool
         */
        function getArgument( $name ) {
                return false;
        }

        /**
         * Returns true if the infinite loop check is OK, false if a loop is detected
         *
         * @param Title $title
         *
         * @return bool
         */
        function loopCheck( $title ) {
                return !isset( $this->loopCheckHash[$title->getPrefixedDBkey()] );
        }

        /**
         * Return true if the frame is a template frame
         *
         * @return bool
         */
        function isTemplate() {
                return false;
        }

        /**
         * Get a title of frame
         *
         * @return Title
         */
        function getTitle() {
                return $this->title;
        }

        /**
         * Set the volatile flag
         *
         * @param bool $flag
         */
        function setVolatile( $flag = true ) {
                $this->volatile = $flag;
        }

        /**
         * Get the volatile flag
         *
         * @return bool
         */
        function isVolatile() {
                return $this->volatile;
        }
}

/**
 * Expansion frame with template arguments
 * @ingroup Parser
 */
class PPTemplateFrame_Hash extends PPFrame_Hash {
        var $numberedArgs, $namedArgs, $parent;
        var $numberedExpansionCache, $namedExpansionCache;

        /**
         * @param Preprocessor $preprocessor
         * @param bool|PPFrame $parent
         * @param array $numberedArgs
         * @param array $namedArgs
         * @param bool|Title $title
         */
        function __construct( $preprocessor, $parent = false, $numberedArgs = array(),
                $namedArgs = array(), $title = false
        ) {
                parent::__construct( $preprocessor );

                $this->parent = $parent;
                $this->numberedArgs = $numberedArgs;
                $this->namedArgs = $namedArgs;
                $this->title = $title;
                $pdbk = $title ? $title->getPrefixedDBkey() : false;
                $this->titleCache = $parent->titleCache;
                $this->titleCache[] = $pdbk;
                $this->loopCheckHash = /*clone*/ $parent->loopCheckHash;
                if ( $pdbk !== false ) {
                        $this->loopCheckHash[$pdbk] = true;
                }
                $this->depth = $parent->depth + 1;
                $this->numberedExpansionCache = $this->namedExpansionCache = array();
        }

        function __toString() {
                $s = 'tplframe{';
                $first = true;
                $args = $this->numberedArgs + $this->namedArgs;
                foreach ( $args as $name => $value ) {
                        if ( $first ) {
                                $first = false;
                        } else {
                                $s .= ', ';
                        }
                        $s .= "\"$name\":\"" .
                                str_replace( '"', '\\"', $value->__toString() ) . '"';
                }
                $s .= '}';
                return $s;
        }

        /**
         * @throws MWException
         * @param string|int $key
         * @param string|PPNode_Hash|DOMDocument $root
         * @param int $flags
         * @return string
         */
        function cachedExpand( $key, $root, $flags = 0 ) {
                if ( isset( $this->parent->childExpansionCache[$key] ) ) {
                        return $this->parent->childExpansionCache[$key];
                }
                $retval = $this->expand( $root, $flags );
                if ( !$this->isVolatile() ) {
                        $this->parent->childExpansionCache[$key] = $retval;
                }
                return $retval;
        }

        /**
         * Returns true if there are no arguments in this frame
         *
         * @return bool
         */
        function isEmpty() {
                return !count( $this->numberedArgs ) && !count( $this->namedArgs );
        }

        /**
         * @return array
         */
        function getArguments() {
                $arguments = array();
                foreach ( array_merge(
                                array_keys( $this->numberedArgs ),
                                array_keys( $this->namedArgs ) ) as $key ) {
                        $arguments[$key] = $this->getArgument( $key );
                }
                return $arguments;
        }

        /**
         * @return array
         */
        function getNumberedArguments() {
                $arguments = array();
                foreach ( array_keys( $this->numberedArgs ) as $key ) {
                        $arguments[$key] = $this->getArgument( $key );
                }
                return $arguments;
        }

        /**
         * @return array
         */
        function getNamedArguments() {
                $arguments = array();
                foreach ( array_keys( $this->namedArgs ) as $key ) {
                        $arguments[$key] = $this->getArgument( $key );
                }
                return $arguments;
        }

        /**
         * @param int $index
         * @return array|bool
         */
        function getNumberedArgument( $index ) {
                if ( !isset( $this->numberedArgs[$index] ) ) {
                        return false;
                }
                if ( !isset( $this->numberedExpansionCache[$index] ) ) {
                        # No trimming for unnamed arguments
                        $this->numberedExpansionCache[$index] = $this->parent->expand(
                                $this->numberedArgs[$index],
                                PPFrame::STRIP_COMMENTS
                        );
                }
                return $this->numberedExpansionCache[$index];
        }

        /**
         * @param string $name
         * @return bool
         */
        function getNamedArgument( $name ) {
                if ( !isset( $this->namedArgs[$name] ) ) {
                        return false;
                }
                if ( !isset( $this->namedExpansionCache[$name] ) ) {
                        # Trim named arguments post-expand, for backwards compatibility
                        $this->namedExpansionCache[$name] = trim(
                                $this->parent->expand( $this->namedArgs[$name], PPFrame::STRIP_COMMENTS ) );
                }
                return $this->namedExpansionCache[$name];
        }

        /**
         * @param string $name
         * @return array|bool
         */
        function getArgument( $name ) {
                $text = $this->getNumberedArgument( $name );
                if ( $text === false ) {
                        $text = $this->getNamedArgument( $name );
                }
                return $text;
        }

        /**
         * Return true if the frame is a template frame
         *
         * @return bool
         */
        function isTemplate() {
                return true;
        }

        function setVolatile( $flag = true ) {
                parent::setVolatile( $flag );
                $this->parent->setVolatile( $flag );
        }
}

/**
 * Expansion frame with custom arguments
 * @ingroup Parser
 */
class PPCustomFrame_Hash extends PPFrame_Hash {
        var $args;

        function __construct( $preprocessor, $args ) {
                parent::__construct( $preprocessor );
                $this->args = $args;
        }

        function __toString() {
                $s = 'cstmframe{';
                $first = true;
                foreach ( $this->args as $name => $value ) {
                        if ( $first ) {
                                $first = false;
                        } else {
                                $s .= ', ';
                        }
                        $s .= "\"$name\":\"" .
                                str_replace( '"', '\\"', $value->__toString() ) . '"';
                }
                $s .= '}';
                return $s;
        }

        /**
         * @return bool
         */
        function isEmpty() {
                return !count( $this->args );
        }

        /**
         * @param int $index
         * @return bool
         */
        function getArgument( $index ) {
                if ( !isset( $this->args[$index] ) ) {
                        return false;
                }
                return $this->args[$index];
        }

        function getArguments() {
                return $this->args;
        }
}

/**
 * @ingroup Parser
 */
class PPNode_Hash_Tree implements PPNode {
        var $name, $firstChild, $lastChild, $nextSibling;

        function __construct( $name ) {
                $this->name = $name;
                $this->firstChild = $this->lastChild = $this->nextSibling = false;
        }

        function __toString() {
                $inner = '';
                $attribs = '';
                for ( $node = $this->firstChild; $node; $node = $node->nextSibling ) {
                        if ( $node instanceof PPNode_Hash_Attr ) {
                                $attribs .= ' ' . $node->name . '="' . htmlspecialchars( $node->value ) . '"';
                        } else {
                                $inner .= $node->__toString();
                        }
                }
                if ( $inner === '' ) {
                        return "<{$this->name}$attribs/>";
                } else {
                        return "<{$this->name}$attribs>$inner</{$this->name}>";
                }
        }

        /**
         * @param string $name
         * @param string $text
         * @return PPNode_Hash_Tree
         */
        static function newWithText( $name, $text ) {
                $obj = new self( $name );
                $obj->addChild( new PPNode_Hash_Text( $text ) );
                return $obj;
        }

        function addChild( $node ) {
                if ( $this->lastChild === false ) {
                        $this->firstChild = $this->lastChild = $node;
                } else {
                        $this->lastChild->nextSibling = $node;
                        $this->lastChild = $node;
                }
        }

        /**
         * @return PPNode_Hash_Array
         */
        function getChildren() {
                $children = array();
                for ( $child = $this->firstChild; $child; $child = $child->nextSibling ) {
                        $children[] = $child;
                }
                return new PPNode_Hash_Array( $children );
        }

        function getFirstChild() {
                return $this->firstChild;
        }

        function getNextSibling() {
                return $this->nextSibling;
        }

        function getChildrenOfType( $name ) {
                $children = array();
                for ( $child = $this->firstChild; $child; $child = $child->nextSibling ) {
                        if ( isset( $child->name ) && $child->name === $name ) {
                                $children[] = $child;
                        }
                }
                return $children;
        }

        /**
         * @return bool
         */
        function getLength() {
                return false;
        }

        /**
         * @param int $i
         * @return bool
         */
        function item( $i ) {
                return false;
        }

        /**
         * @return string
         */
        function getName() {
                return $this->name;
        }

        /**
         * Split a "<part>" node into an associative array containing:
         *  - name          PPNode name
         *  - index         String index
         *  - value         PPNode value
         *
         * @throws MWException
         * @return array
         */
        function splitArg() {
                $bits = array();
                for ( $child = $this->firstChild; $child; $child = $child->nextSibling ) {
                        if ( !isset( $child->name ) ) {
                                continue;
                        }
                        if ( $child->name === 'name' ) {
                                $bits['name'] = $child;
                                if ( $child->firstChild instanceof PPNode_Hash_Attr
                                        && $child->firstChild->name === 'index'
                                ) {
                                        $bits['index'] = $child->firstChild->value;
                                }
                        } elseif ( $child->name === 'value' ) {
                                $bits['value'] = $child;
                        }
                }

                if ( !isset( $bits['name'] ) ) {
                        throw new MWException( 'Invalid brace node passed to ' . __METHOD__ );
                }
                if ( !isset( $bits['index'] ) ) {
                        $bits['index'] = '';
                }
                return $bits;
        }

        /**
         * Split an "<ext>" node into an associative array containing name, attr, inner and close
         * All values in the resulting array are PPNodes. Inner and close are optional.
         *
         * @throws MWException
         * @return array
         */
        function splitExt() {
                $bits = array();
                for ( $child = $this->firstChild; $child; $child = $child->nextSibling ) {
                        if ( !isset( $child->name ) ) {
                                continue;
                        }
                        if ( $child->name == 'name' ) {
                                $bits['name'] = $child;
                        } elseif ( $child->name == 'attr' ) {
                                $bits['attr'] = $child;
                        } elseif ( $child->name == 'inner' ) {
                                $bits['inner'] = $child;
                        } elseif ( $child->name == 'close' ) {
                                $bits['close'] = $child;
                        }
                }
                if ( !isset( $bits['name'] ) ) {
                        throw new MWException( 'Invalid ext node passed to ' . __METHOD__ );
                }
                return $bits;
        }

        /**
         * Split an "<h>" node
         *
         * @throws MWException
         * @return array
         */
        function splitHeading() {
                if ( $this->name !== 'h' ) {
                        throw new MWException( 'Invalid h node passed to ' . __METHOD__ );
                }
                $bits = array();
                for ( $child = $this->firstChild; $child; $child = $child->nextSibling ) {
                        if ( !isset( $child->name ) ) {
                                continue;
                        }
                        if ( $child->name == 'i' ) {
                                $bits['i'] = $child->value;
                        } elseif ( $child->name == 'level' ) {
                                $bits['level'] = $child->value;
                        }
                }
                if ( !isset( $bits['i'] ) ) {
                        throw new MWException( 'Invalid h node passed to ' . __METHOD__ );
                }
                return $bits;
        }

        /**
         * Split a "<template>" or "<tplarg>" node
         *
         * @throws MWException
         * @return array
         */
        function splitTemplate() {
                $parts = array();
                $bits = array( 'lineStart' => '' );
                for ( $child = $this->firstChild; $child; $child = $child->nextSibling ) {
                        if ( !isset( $child->name ) ) {
                                continue;
                        }
                        if ( $child->name == 'title' ) {
                                $bits['title'] = $child;
                        }
                        if ( $child->name == 'part' ) {
                                $parts[] = $child;
                        }
                        if ( $child->name == 'lineStart' ) {
                                $bits['lineStart'] = '1';
                        }
                }
                if ( !isset( $bits['title'] ) ) {
                        throw new MWException( 'Invalid node passed to ' . __METHOD__ );
                }
                $bits['parts'] = new PPNode_Hash_Array( $parts );
                return $bits;
        }
}

/**
 * @ingroup Parser
 */
class PPNode_Hash_Text implements PPNode {
        var $value, $nextSibling;

        function __construct( $value ) {
                if ( is_object( $value ) ) {
                        throw new MWException( __CLASS__ . ' given object instead of string' );
                }
                $this->value = $value;
        }

        function __toString() {
                return htmlspecialchars( $this->value );
        }

        function getNextSibling() {
                return $this->nextSibling;
        }

        function getChildren() {
                return false;
        }

        function getFirstChild() {
                return false;
        }

        function getChildrenOfType( $name ) {
                return false;
        }

        function getLength() {
                return false;
        }

        function item( $i ) {
                return false;
        }

        function getName() {
                return '#text';
        }

        function splitArg() {
                throw new MWException( __METHOD__ . ': not supported' );
        }

        function splitExt() {
                throw new MWException( __METHOD__ . ': not supported' );
        }

        function splitHeading() {
                throw new MWException( __METHOD__ . ': not supported' );
        }
}

/**
 * @ingroup Parser
 */
class PPNode_Hash_Array implements PPNode {
        var $value, $nextSibling;

        function __construct( $value ) {
                $this->value = $value;
        }

        function __toString() {
                return var_export( $this, true );
        }

        function getLength() {
                return count( $this->value );
        }

        function item( $i ) {
                return $this->value[$i];
        }

        function getName() {
                return '#nodelist';
        }

        function getNextSibling() {
                return $this->nextSibling;
        }

        function getChildren() {
                return false;
        }

        function getFirstChild() {
                return false;
        }

        function getChildrenOfType( $name ) {
                return false;
        }

        function splitArg() {
                throw new MWException( __METHOD__ . ': not supported' );
        }

        function splitExt() {
                throw new MWException( __METHOD__ . ': not supported' );
        }

        function splitHeading() {
                throw new MWException( __METHOD__ . ': not supported' );
        }
}

/**
 * @ingroup Parser
 */
class PPNode_Hash_Attr implements PPNode {
        var $name, $value, $nextSibling;

        function __construct( $name, $value ) {
                $this->name = $name;
                $this->value = $value;
        }

        function __toString() {
                return "<@{$this->name}>" . htmlspecialchars( $this->value ) . "</@{$this->name}>";
        }

        function getName() {
                return $this->name;
        }

        function getNextSibling() {
                return $this->nextSibling;
        }

        function getChildren() {
                return false;
        }

        function getFirstChild() {
                return false;
        }

        function getChildrenOfType( $name ) {
                return false;
        }

        function getLength() {
                return false;
        }

        function item( $i ) {
                return false;
        }

        function splitArg() {
                throw new MWException( __METHOD__ . ': not supported' );
        }

        function splitExt() {
                throw new MWException( __METHOD__ . ': not supported' );
        }

        function splitHeading() {
                throw new MWException( __METHOD__ . ': not supported' );
        }
}