Merge "mediawiki.api.watch: Use formatversion=2 for API requests"

[lhc/web/wiklou.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>
 *
 * Nodes are stored in a recursive array data structure. A node store is an
 * array where each element may be either a scalar (representing a text node)
 * or a "descriptor", which is a two-element array where the first element is
 * the node name and the second element is the node store for the children.
 *
 * Attributes are represented as children that have a node name starting with
 * "@", and a single text node child.
 *
 * @todo: Consider replacing descriptor arrays with objects of a new class.
 * Benchmark and measure resulting memory impact.
 *
 * @ingroup Parser
 */
// @codingStandardsIgnoreStart Squiz.Classes.ValidClassName.NotCamelCaps
class Preprocessor_Hash extends Preprocessor {
        // @codingStandardsIgnoreEnd

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

        const CACHE_PREFIX = 'preprocess-hash';
        const CACHE_VERSION = 2;

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

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

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

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

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

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

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

        /**
         * Preprocess some wikitext and return the document tree.
         *
         * @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().
         *
         * @throws MWException
         * @return PPNode_Hash_Tree
         */
        public function preprocessToObj( $text, $flags = 0 ) {
                global $wgDisableLangConversion;

                $tree = $this->cacheGetTree( $text, $flags );
                if ( $tree !== false ) {
                        $store = json_decode( $tree );
                        if ( is_array( $store ) ) {
                                return new PPNode_Hash_Tree( $store, 0 );
                        }
                }

                $forInclusion = $flags & Parser::PTD_FOR_INCLUSION;

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

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

                $stack = new PPDStack_Hash;

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

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

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

                while ( true ) {
                        // $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[] = [ 'ignore', [ substr( $text, $i ) ] ];
                                        break;
                                }
                                $tagEndPos = $startPos + strlen( '<onlyinclude>' ); // past-the-end
                                $accum[] = [ 'ignore', [ substr( $text, $i, $tagEndPos - $i ) ] ];
                                $i = $tagEndPos;
                                $findOnlyinclude = false;
                        }

                        if ( $fakeLineStart ) {
                                $found = 'line-start';
                                $curChar = '';
                        } else {
                                # Find next opening brace, closing brace or pipe
                                $search = $searchBase;
                                if ( $stack->top === false ) {
                                        $currentClosing = '';
                                } else {
                                        $currentClosing = $stack->top->close;
                                        $search .= $currentClosing;
                                }
                                if ( $findPipe ) {
                                        $search .= '|';
                                }
                                if ( $findEquals ) {
                                        // First equals will be for the template
                                        $search .= '=';
                                }
                                $rule = null;
                                # Output literal section, advance input counter
                                $literalLength = strcspn( $text, $search, $i );
                                if ( $literalLength > 0 ) {
                                        self::addLiteral( $accum, substr( $text, $i, $literalLength ) );
                                        $i += $literalLength;
                                }
                                if ( $i >= $lengthText ) {
                                        if ( $currentClosing == "\n" ) {
                                                // Do a past-the-end run to finish off the heading
                                                $curChar = '';
                                                $found = 'line-end';
                                        } else {
                                                # All done
                                                break;
                                        }
                                } else {
                                        $curChar = $curTwoChar = $text[$i];
                                        if ( ( $i + 1 ) < $lengthText ) {
                                                $curTwoChar .= $text[$i + 1];
                                        }
                                        if ( $curChar == '|' ) {
                                                $found = 'pipe';
                                        } elseif ( $curChar == '=' ) {
                                                $found = 'equals';
                                        } elseif ( $curChar == '<' ) {
                                                $found = 'angle';
                                        } elseif ( $curChar == "\n" ) {
                                                if ( $inHeading ) {
                                                        $found = 'line-end';
                                                } else {
                                                        $found = 'line-start';
                                                }
                                        } elseif ( $curTwoChar == $currentClosing ) {
                                                $found = 'close';
                                                $curChar = $curTwoChar;
                                        } elseif ( $curChar == $currentClosing ) {
                                                $found = 'close';
                                        } elseif ( isset( $this->rules[$curTwoChar] ) ) {
                                                $curChar = $curTwoChar;
                                                $found = 'open';
                                                $rule = $this->rules[$curChar];
                                        } elseif ( isset( $this->rules[$curChar] ) ) {
                                                $found = 'open';
                                                $rule = $this->rules[$curChar];
                                        } elseif ( $curChar == '-' ) {
                                                $found = 'dash';
                                        } else {
                                                # Some versions of PHP have a strcspn which stops on null characters
                                                # Ignore and continue
                                                ++$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
                                        self::addLiteral( $accum, '<' );
                                        ++$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[] = [ '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 = [ [ $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[] = [ $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
                                                        $wsLength = $i - $wsStart;
                                                        $endIndex = count( $accum ) - 1;

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

                                                        // Dump all but the last comment to the accumulator
                                                        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[] = [ '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[] = [ '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;
                                        self::addLiteral( $accum, '<' );
                                        ++$i;
                                        continue;
                                }

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

                                $tagStartPos = $i;
                                if ( $text[$tagEndPos - 1] == '/' ) {
                                        // Short end tag
                                        $attrEnd = $tagEndPos - 1;
                                        $inner = null;
                                        $i = $tagEndPos + 1;
                                        $close = null;
                                } else {
                                        $attrEnd = $tagEndPos;
                                        // Find closing tag
                                        if (
                                                !isset( $noMoreClosingTag[$name] ) &&
                                                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
                                                if ( in_array( $name, $xmlishAllowMissingEndTag ) ) {
                                                        // Let it run out to the end of the text.
                                                        $inner = substr( $text, $tagEndPos + 1 );
                                                        $i = $lengthText;
                                                        $close = null;
                                                } else {
                                                        // Don't match the tag, treat opening tag as literal and resume parsing.
                                                        $i = $tagEndPos + 1;
                                                        self::addLiteral( $accum,
                                                                substr( $text, $tagStartPos, $tagEndPos + 1 - $tagStartPos ) );
                                                        // Cache results, otherwise we have O(N^2) performance for input like <foo><foo><foo>...
                                                        $noMoreClosingTag[$name] = true;
                                                        continue;
                                                }
                                        }
                                }
                                // <includeonly> and <noinclude> just become <ignore> tags
                                if ( in_array( $lowerName, $ignoredElements ) ) {
                                        $accum[] = [ 'ignore', [ substr( $text, $tagStartPos, $i - $tagStartPos ) ] ];
                                        continue;
                                }

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

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

                                $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 = [
                                                'open' => "\n",
                                                'close' => "\n",
                                                'parts' => [ 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 = [ [ 'possible-h',
                                                        array_merge(
                                                                [
                                                                        [ '@level', [ $count ] ],
                                                                        [ '@i', [ $headingIndex++ ] ]
                                                                ],
                                                                $accum
                                                        )
                                                ] ];
                                        } else {
                                                // Single equals sign on its own line, count=0
                                                $element = $accum;
                                        }
                                } else {
                                        // No match, no <h>, just pass down the inner text
                                        $element = $accum;
                                }
                                // Unwind the stack
                                $stack->pop();
                                $accum =& $stack->getAccum();
                                extract( $stack->getFlags() );

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

                                // Note that we do NOT increment the input pointer.
                                // This is because the closing linebreak could be the opening linebreak of
                                // another heading. Infinite loops are avoided because the next iteration MUST
                                // hit the heading open case above, which unconditionally increments the
                                // input pointer.
                        } elseif ( $found == 'open' ) {
                                # count opening brace characters
                                $curLen = strlen( $curChar );
                                $count = ( $curLen > 1 ) ? 1 : 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 = [
                                                '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)
                                        self::addLiteral( $accum, str_repeat( $curChar, $count ) );
                                }
                                $i += $curLen * $count;
                        } elseif ( $found == 'close' ) {
                                $piece = $stack->top;
                                # lets check if there are enough characters for closing brace
                                $maxCount = $piece->count;
                                $curLen = strlen( $curChar );
                                $count = ( $curLen > 1 ) ? 1 : strspn( $text, $curChar, $i, $maxCount );

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

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

                                        $children = [];

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

                                # Advance input pointer
                                $i += $curLen * $matchingCount;

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

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

                                extract( $stack->getFlags() );

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

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

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

                $rootStore = [ [ 'root', $stack->rootAccum ] ];
                $rootNode = new PPNode_Hash_Tree( $rootStore, 0 );

                // Cache
                $tree = json_encode( $rootStore, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE );
                if ( $tree !== false ) {
                        $this->cacheSetTree( $text, $flags, $tree );
                }

                return $rootNode;
        }

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

/**
 * Stack class to help Preprocessor::preprocessToObj()
 * @ingroup Parser
 */
// @codingStandardsIgnoreStart Squiz.Classes.ValidClassName.NotCamelCaps
class PPDStack_Hash extends PPDStack {
        // @codingStandardsIgnoreEnd

        public function __construct() {
                $this->elementClass = 'PPDStackElement_Hash';
                parent::__construct();
                $this->rootAccum = [];
        }
}

/**
 * @ingroup Parser
 */
// @codingStandardsIgnoreStart Squiz.Classes.ValidClassName.NotCamelCaps
class PPDStackElement_Hash extends PPDStackElement {
        // @codingStandardsIgnoreEnd

        public function __construct( $data = [] ) {
                $this->partClass = 'PPDPart_Hash';
                parent::__construct( $data );
        }

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

/**
 * @ingroup Parser
 */
// @codingStandardsIgnoreStart Squiz.Classes.ValidClassName.NotCamelCaps
class PPDPart_Hash extends PPDPart {
        // @codingStandardsIgnoreEnd

        public function __construct( $out = '' ) {
                if ( $out !== '' ) {
                        $accum = [ $out ];
                } else {
                        $accum = [];
                }
                parent::__construct( $accum );
        }
}

/**
 * An expansion frame, used as a context to expand the result of preprocessToObj()
 * @ingroup Parser
 */
// @codingStandardsIgnoreStart Squiz.Classes.ValidClassName.NotCamelCaps
class PPFrame_Hash implements PPFrame {
        // @codingStandardsIgnoreEnd

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

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

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

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

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

        private $volatile = false;
        private $ttl = null;

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

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

        /**
         * 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
         */
        public function newChild( $args = false, $title = false, $indexOffset = 0 ) {
                $namedArgs = [];
                $numberedArgs = [];
                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;
                                        if ( isset( $namedArgs[$index] ) || isset( $numberedArgs[$index] ) ) {
                                                $this->parser->getOutput()->addWarning( wfMessage( 'duplicate-args-warning',
                                                        wfEscapeWikiText( $this->title ),
                                                        wfEscapeWikiText( $title ),
                                                        wfEscapeWikiText( $index ) )->text() );
                                                $this->parser->addTrackingCategory( 'duplicate-args-category' );
                                        }
                                        $numberedArgs[$index] = $bits['value'];
                                        unset( $namedArgs[$index] );
                                } else {
                                        // Named parameter
                                        $name = trim( $this->expand( $bits['name'], PPFrame::STRIP_COMMENTS ) );
                                        if ( isset( $namedArgs[$name] ) || isset( $numberedArgs[$name] ) ) {
                                                $this->parser->getOutput()->addWarning( wfMessage( 'duplicate-args-warning',
                                                        wfEscapeWikiText( $this->title ),
                                                        wfEscapeWikiText( $title ),
                                                        wfEscapeWikiText( $name ) )->text() );
                                                $this->parser->addTrackingCategory( 'duplicate-args-category' );
                                        }
                                        $namedArgs[$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 $root
         * @param int $flags
         * @return string
         */
        public 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
         */
        public 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 = [ '', '' ];
                $iteratorStack = [ false, $root ];
                $indexStack = [ 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;
                        $contextName = false;
                        $contextChildren = false;

                        if ( $contextNode === false ) {
                                // nothing to do
                        } elseif ( is_string( $contextNode ) ) {
                                $out .= $contextNode;
                        } elseif ( $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 ) {
                                $contextName = $contextNode->name;
                                $contextChildren = $contextNode->getRawChildren();
                        } elseif ( is_array( $contextNode ) ) {
                                // Node descriptor array
                                if ( count( $contextNode ) !== 2 ) {
                                        throw new MWException( __METHOD__.
                                                ': found an array where a node descriptor should be' );
                                }
                                list( $contextName, $contextChildren ) = $contextNode;
                        } else {
                                throw new MWException( __METHOD__ . ': Invalid parameter type' );
                        }

                        // Handle node descriptor array or tree object
                        if ( $contextName === false ) {
                                // Not a node, already handled above
                        } elseif ( $contextName[0] === '@' ) {
                                // Attribute: no output
                        } elseif ( $contextName === 'template' ) {
                                # Double-brace expansion
                                $bits = PPNode_Hash_Tree::splitRawTemplate( $contextChildren );
                                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 ( $contextName === 'tplarg' ) {
                                # Triple-brace expansion
                                $bits = PPNode_Hash_Tree::splitRawTemplate( $contextChildren );
                                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 ( $contextName === 'comment' ) {
                                # HTML-style comment
                                # Remove it in HTML, pre+remove and STRIP_COMMENTS modes
                                # Not in RECOVER_COMMENTS mode (msgnw) though.
                                if ( ( $this->parser->ot['html']
                                        || ( $this->parser->ot['pre'] && $this->parser->mOptions->getRemoveComments() )
                                        || ( $flags & PPFrame::STRIP_COMMENTS )
                                        ) && !( $flags & PPFrame::RECOVER_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( $contextChildren[0] );
                                } else {
                                        # Recover the literal comment in RECOVER_COMMENTS and pre+no-remove
                                        $out .= $contextChildren[0];
                                }
                        } elseif ( $contextName === '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 .= $contextChildren[0];
                                } else {
                                        // $out .= '';
                                }
                        } elseif ( $contextName === 'ext' ) {
                                # Extension tag
                                $bits = PPNode_Hash_Tree::splitRawExt( $contextChildren ) +
                                        [ 'attr' => null, 'inner' => null, 'close' => null ];
                                if ( $flags & PPFrame::NO_TAGS ) {
                                        $s = '<' . $bits['name']->getFirstChild()->value;
                                        if ( $bits['attr'] ) {
                                                $s .= $bits['attr']->getFirstChild()->value;
                                        }
                                        if ( $bits['inner'] ) {
                                                $s .= '>' . $bits['inner']->getFirstChild()->value;
                                                if ( $bits['close'] ) {
                                                        $s .= $bits['close']->getFirstChild()->value;
                                                }
                                        } else {
                                                $s .= '/>';
                                        }
                                        $out .= $s;
                                } else {
                                        $out .= $this->parser->extensionSubstitution( $bits, $this );
                                }
                        } elseif ( $contextName === 'h' ) {
                                # Heading
                                if ( $this->parser->ot['html'] ) {
                                        # Expand immediately and insert heading index marker
                                        $s = $this->expand( $contextChildren, $flags );
                                        $bits = PPNode_Hash_Tree::splitRawHeading( $contextChildren );
                                        $titleText = $this->title->getPrefixedDBkey();
                                        $this->parser->mHeadings[] = [ $titleText, $bits['i'] ];
                                        $serial = count( $this->parser->mHeadings ) - 1;
                                        $marker = Parser::MARKER_PREFIX . "-h-$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 = $contextChildren;
                                }
                        } else {
                                # Generic recursive expansion
                                $newIterator = $contextChildren;
                        }

                        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
         * @param string|PPNode $args,...
         * @return string
         */
        public 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 = [ $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
         * @param string|PPNode $args,...
         * @return string
         */
        public 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 = [ $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
         * @param string|PPNode $args,...
         * @return PPNode_Hash_Array
         */
        public function virtualImplode( $sep /*, ... */ ) {
                $args = array_slice( func_get_args(), 1 );
                $out = [];
                $first = true;

                foreach ( $args as $root ) {
                        if ( $root instanceof PPNode_Hash_Array ) {
                                $root = $root->value;
                        }
                        if ( !is_array( $root ) ) {
                                $root = [ $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
         * @param string|PPNode $args,...
         * @return PPNode_Hash_Array
         */
        public function virtualBracketedImplode( $start, $sep, $end /*, ... */ ) {
                $args = array_slice( func_get_args(), 3 );
                $out = [ $start ];
                $first = true;

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

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

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

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

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

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

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

        /**
         * @param int|string $name
         * @return bool Always false in this implementation.
         */
        public 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
         */
        public function loopCheck( $title ) {
                return !isset( $this->loopCheckHash[$title->getPrefixedDBkey()] );
        }

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

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

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

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

        /**
         * Set the TTL
         *
         * @param int $ttl
         */
        public function setTTL( $ttl ) {
                if ( $ttl !== null && ( $this->ttl === null || $ttl < $this->ttl ) ) {
                        $this->ttl = $ttl;
                }
        }

        /**
         * Get the TTL
         *
         * @return int|null
         */
        public function getTTL() {
                return $this->ttl;
        }
}

/**
 * Expansion frame with template arguments
 * @ingroup Parser
 */
// @codingStandardsIgnoreStart Squiz.Classes.ValidClassName.NotCamelCaps
class PPTemplateFrame_Hash extends PPFrame_Hash {
        // @codingStandardsIgnoreEnd

        public $numberedArgs, $namedArgs, $parent;
        public $numberedExpansionCache, $namedExpansionCache;

        /**
         * @param Preprocessor $preprocessor
         * @param bool|PPFrame $parent
         * @param array $numberedArgs
         * @param array $namedArgs
         * @param bool|Title $title
         */
        public function __construct( $preprocessor, $parent = false, $numberedArgs = [],
                $namedArgs = [], $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 = [];
        }

        public 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 $root
         * @param int $flags
         * @return string
         */
        public 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
         */
        public function isEmpty() {
                return !count( $this->numberedArgs ) && !count( $this->namedArgs );
        }

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

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

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

        /**
         * @param int $index
         * @return string|bool
         */
        public 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 string|bool
         */
        public 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 int|string $name
         * @return string|bool
         */
        public 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
         */
        public function isTemplate() {
                return true;
        }

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

        public function setTTL( $ttl ) {
                parent::setTTL( $ttl );
                $this->parent->setTTL( $ttl );
        }
}

/**
 * Expansion frame with custom arguments
 * @ingroup Parser
 */
// @codingStandardsIgnoreStart Squiz.Classes.ValidClassName.NotCamelCaps
class PPCustomFrame_Hash extends PPFrame_Hash {
        // @codingStandardsIgnoreEnd

        public $args;

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

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

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

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

/**
 * @ingroup Parser
 */
// @codingStandardsIgnoreStart Squiz.Classes.ValidClassName.NotCamelCaps
class PPNode_Hash_Tree implements PPNode {
        // @codingStandardsIgnoreEnd

        public $name;

        /**
         * The store array for children of this node. It is "raw" in the sense that
         * nodes are two-element arrays ("descriptors") rather than PPNode_Hash_*
         * objects.
         */
        private $rawChildren;

        /**
         * The store array for the siblings of this node, including this node itself.
         */
        private $store;

        /**
         * The index into $this->store which contains the descriptor of this node.
         */
        private $index;

        /**
         * The offset of the name within descriptors, used in some places for
         * readability.
         */
        const NAME = 0;

        /**
         * The offset of the child list within descriptors, used in some places for
         * readability.
         */
        const CHILDREN = 1;

        /**
         * Construct an object using the data from $store[$index]. The rest of the
         * store array can be accessed via getNextSibling().
         *
         * @param array $store
         * @param integer $index
         */
        public function __construct( array $store, $index ) {
                $this->store = $store;
                $this->index = $index;
                list( $this->name, $this->rawChildren ) = $this->store[$index];
        }

        /**
         * Construct an appropriate PPNode_Hash_* object with a class that depends
         * on what is at the relevant store index.
         *
         * @param array $store
         * @param integer $index
         * @return PPNode_Hash_Tree|PPNode_Hash_Attr|PPNode_Hash_Text
         */
        public static function factory( array $store, $index ) {
                if ( !isset( $store[$index] ) ) {
                        return false;
                }

                $descriptor = $store[$index];
                if ( is_string( $descriptor ) ) {
                        $class = 'PPNode_Hash_Text';
                } elseif ( is_array( $descriptor ) ) {
                        if ( $descriptor[self::NAME][0] === '@' ) {
                                $class = 'PPNode_Hash_Attr';
                        } else {
                                $class = 'PPNode_Hash_Tree';
                        }
                } else {
                        throw new MWException( __METHOD__.': invalid node descriptor' );
                }
                return new $class( $store, $index );
        }

        /**
         * Convert a node to XML, for debugging
         */
        public function __toString() {
                $inner = '';
                $attribs = '';
                for ( $node = $this->getFirstChild(); $node; $node = $node->getNextSibling() ) {
                        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}>";
                }
        }

        /**
         * @return PPNode_Hash_Array
         */
        public function getChildren() {
                $children = [];
                foreach ( $this->rawChildren as $i => $child ) {
                        $children[] = self::factory( $this->rawChildren, $i );
                }
                return new PPNode_Hash_Array( $children );
        }

        /**
         * Get the first child, or false if there is none. Note that this will
         * return a temporary proxy object: different instances will be returned
         * if this is called more than once on the same node.
         *
         * @return PPNode_Hash_Tree|PPNode_Hash_Attr|PPNode_Hash_Text|boolean
         */
        public function getFirstChild() {
                if ( !isset( $this->rawChildren[0] ) ) {
                        return false;
                } else {
                        return self::factory( $this->rawChildren, 0 );
                }
        }

        /**
         * Get the next sibling, or false if there is none. Note that this will
         * return a temporary proxy object: different instances will be returned
         * if this is called more than once on the same node.
         *
         * @return PPNode_Hash_Tree|PPNode_Hash_Attr|PPNode_Hash_Text|boolean
         */
        public function getNextSibling() {
                return self::factory( $this->store, $this->index + 1 );
        }

        /**
         * Get an array of the children with a given node name
         *
         * @param string $name
         * @return PPNode_Hash_Array
         */
        public function getChildrenOfType( $name ) {
                $children = [];
                foreach ( $this->rawChildren as $i => $child ) {
                        if ( is_array( $child ) && $child[self::NAME] === $name ) {
                                $children[] = self::factory( $this->rawChildren, $i );
                        }
                }
                return new PPNode_Hash_Array( $children );
        }

        /**
         * Get the raw child array. For internal use.
         * @return array
         */
        public function getRawChildren() {
                return $this->rawChildren;
        }

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

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

        /**
         * @return string
         */
        public 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
         */
        public function splitArg() {
                return self::splitRawArg( $this->rawChildren );
        }

        /**
         * Like splitArg() but for a raw child array. For internal use only.
         */
        public static function splitRawArg( array $children ) {
                $bits = [];
                foreach ( $children as $i => $child ) {
                        if ( !is_array( $child ) ) {
                                continue;
                        }
                        if ( $child[self::NAME] === 'name' ) {
                                $bits['name'] = new self( $children, $i );
                                if ( isset( $child[self::CHILDREN][0][self::NAME] )
                                        && $child[self::CHILDREN][0][self::NAME] === '@index'
                                ) {
                                        $bits['index'] = $child[self::CHILDREN][0][self::CHILDREN][0];
                                }
                        } elseif ( $child[self::NAME] === 'value' ) {
                                $bits['value'] = new self( $children, $i );
                        }
                }

                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
         */
        public function splitExt() {
                return self::splitRawExt( $this->rawChildren );
        }

        /**
         * Like splitExt() but for a raw child array. For internal use only.
         */
        public static function splitRawExt( array $children ) {
                $bits = [];
                foreach ( $children as $i => $child ) {
                        if ( !is_array( $child ) ) {
                                continue;
                        }
                        switch ( $child[self::NAME] ) {
                        case 'name':
                                $bits['name'] = new self( $children, $i );
                                break;
                        case 'attr':
                                $bits['attr'] = new self( $children, $i );
                                break;
                        case 'inner':
                                $bits['inner'] = new self( $children, $i );
                                break;
                        case 'close':
                                $bits['close'] = new self( $children, $i );
                                break;
                        }
                }
                if ( !isset( $bits['name'] ) ) {
                        throw new MWException( 'Invalid ext node passed to ' . __METHOD__ );
                }
                return $bits;
        }

        /**
         * Split an "<h>" node
         *
         * @throws MWException
         * @return array
         */
        public function splitHeading() {
                if ( $this->name !== 'h' ) {
                        throw new MWException( 'Invalid h node passed to ' . __METHOD__ );
                }
                return self::splitRawHeading( $this->rawChildren );
        }

        /**
         * Like splitHeading() but for a raw child array. For internal use only.
         */
        public static function splitRawHeading( array $children ) {
                $bits = [];
                foreach ( $children as $i => $child ) {
                        if ( !is_array( $child ) ) {
                                continue;
                        }
                        if ( $child[self::NAME] === '@i' ) {
                                $bits['i'] = $child[self::CHILDREN][0];
                        } elseif ( $child[self::NAME] === '@level' ) {
                                $bits['level'] = $child[self::CHILDREN][0];
                        }
                }
                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
         */
        public function splitTemplate() {
                return self::splitRawTemplate( $this->rawChildren );
        }

        /**
         * Like splitTemplate() but for a raw child array. For internal use only.
         */
        public static function splitRawTemplate( array $children ) {
                $parts = [];
                $bits = [ 'lineStart' => '' ];
                foreach ( $children as $i => $child ) {
                        if ( !is_array( $child ) ) {
                                continue;
                        }
                        switch ( $child[self::NAME] ) {
                        case 'title':
                                $bits['title'] = new self( $children, $i );
                                break;
                        case 'part':
                                $parts[] = new self( $children, $i );
                                break;
                        case '@lineStart':
                                $bits['lineStart'] = '1';
                                break;
                        }
                }
                if ( !isset( $bits['title'] ) ) {
                        throw new MWException( 'Invalid node passed to ' . __METHOD__ );
                }
                $bits['parts'] = new PPNode_Hash_Array( $parts );
                return $bits;
        }
}

/**
 * @ingroup Parser
 */
// @codingStandardsIgnoreStart Squiz.Classes.ValidClassName.NotCamelCaps
class PPNode_Hash_Text implements PPNode {
        // @codingStandardsIgnoreEnd

        public $value;
        private $store, $index;

        /**
         * Construct an object using the data from $store[$index]. The rest of the
         * store array can be accessed via getNextSibling().
         *
         * @param array $store
         * @param integer $index
         */
        public function __construct( array $store, $index ) {
                $this->value = $store[$index];
                if ( !is_scalar( $this->value ) ) {
                        throw new MWException( __CLASS__ . ' given object instead of string' );
                }
                $this->store = $store;
                $this->index = $index;
        }

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

        public function getNextSibling() {
                return PPNode_Hash_Tree::factory( $this->store, $this->index + 1 );
        }

        public function getChildren() {
                return false;
        }

        public function getFirstChild() {
                return false;
        }

        public function getChildrenOfType( $name ) {
                return false;
        }

        public function getLength() {
                return false;
        }

        public function item( $i ) {
                return false;
        }

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

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

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

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

/**
 * @ingroup Parser
 */
// @codingStandardsIgnoreStart Squiz.Classes.ValidClassName.NotCamelCaps
class PPNode_Hash_Array implements PPNode {
        // @codingStandardsIgnoreEnd

        public $value;

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

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

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

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

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

        public function getNextSibling() {
                return false;
        }

        public function getChildren() {
                return false;
        }

        public function getFirstChild() {
                return false;
        }

        public function getChildrenOfType( $name ) {
                return false;
        }

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

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

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

/**
 * @ingroup Parser
 */
// @codingStandardsIgnoreStart Squiz.Classes.ValidClassName.NotCamelCaps
class PPNode_Hash_Attr implements PPNode {
        // @codingStandardsIgnoreEnd

        public $name, $value;
        private $store, $index;

        /**
         * Construct an object using the data from $store[$index]. The rest of the
         * store array can be accessed via getNextSibling().
         *
         * @param array $store
         * @param integer $index
         */
        public function __construct( array $store, $index ) {
                $descriptor = $store[$index];
                if ( $descriptor[PPNode_Hash_Tree::NAME][0] !== '@' ) {
                        throw new MWException( __METHOD__.': invalid name in attribute descriptor' );
                }
                $this->name = substr( $descriptor[PPNode_Hash_Tree::NAME], 1 );
                $this->value = $descriptor[PPNode_Hash_Tree::CHILDREN][0];
                $this->store = $store;
                $this->index = $index;
        }

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

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

        public function getNextSibling() {
                return PPNode_Hash_Tree::factory( $this->store, $this->index + 1 );
        }

        public function getChildren() {
                return false;
        }

        public function getFirstChild() {
                return false;
        }

        public function getChildrenOfType( $name ) {
                return false;
        }

        public function getLength() {
                return false;
        }

        public function item( $i ) {
                return false;
        }

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

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

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