Preprocessor_DOM.php

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<?php
// phpcs:ignore Squiz.Classes.ValidClassName.NotCamelCaps
class Preprocessor_DOM extends Preprocessor {
 
    public $parser;
 
    public $memoryLimit;
 
    const CACHE_PREFIX = 'preprocess-xml';
 
    public function __construct( $parser ) {
        wfDeprecated( __METHOD__, '1.34' ); // T204945
        $this->parser = $parser;
        $mem = ini_get( 'memory_limit' );
        $this->memoryLimit = false;
        if ( strval( $mem ) !== '' && $mem != -1 ) {
            if ( preg_match( '/^\d+$/', $mem ) ) {
                $this->memoryLimit = $mem;
            } elseif ( preg_match( '/^(\d+)M$/i', $mem, $m ) ) {
                $this->memoryLimit = $m[1] * 1048576;
            }
        }
    }
 
    public function newFrame() {
        return new PPFrame_DOM( $this );
    }
 
    public function newCustomFrame( $args ) {
        return new PPCustomFrame_DOM( $this, $args );
    }
 
    public function newPartNodeArray( $values ) {
        // NOTE: DOM manipulation is slower than building & parsing XML! (or so Tim sais)
        $xml = "<list>";
 
        foreach ( $values as $k => $val ) {
            if ( is_int( $k ) ) {
                $xml .= "<part><name index=\"$k\"/><value>"
                    . htmlspecialchars( $val ) . "</value></part>";
            } else {
                $xml .= "<part><name>" . htmlspecialchars( $k )
                    . "</name>=<value>" . htmlspecialchars( $val ) . "</value></part>";
            }
        }
 
        $xml .= "</list>";
 
        $dom = new DOMDocument();
        Wikimedia\suppressWarnings();
        $result = $dom->loadXML( $xml );
        Wikimedia\restoreWarnings();
        if ( !$result ) {
            // Try running the XML through UtfNormal to get rid of invalid characters
            $xml = UtfNormal\Validator::cleanUp( $xml );
            // 1 << 19 == XML_PARSE_HUGE, needed so newer versions of libxml2
            // don't barf when the XML is >256 levels deep
            $result = $dom->loadXML( $xml, 1 << 19 );
        }
 
        if ( !$result ) {
            throw new MWException( 'Parameters passed to ' . __METHOD__ . ' result in invalid XML' );
        }
 
        $root = $dom->documentElement;
        $node = new PPNode_DOM( $root->childNodes );
        return $node;
    }
 
    public function memCheck() {
        if ( $this->memoryLimit === false ) {
            return true;
        }
        $usage = memory_get_usage();
        if ( $usage > $this->memoryLimit * 0.9 ) {
            $limit = intval( $this->memoryLimit * 0.9 / 1048576 + 0.5 );
            throw new MWException( "Preprocessor hit 90% memory limit ($limit MB)" );
        }
        return $usage <= $this->memoryLimit * 0.8;
    }
 
    public function preprocessToObj( $text, $flags = 0 ) {
        $xml = $this->cacheGetTree( $text, $flags );
        if ( $xml === false ) {
            $xml = $this->preprocessToXml( $text, $flags );
            $this->cacheSetTree( $text, $flags, $xml );
        }
 
        // Fail if the number of elements exceeds acceptable limits
        // Do not attempt to generate the DOM
        $this->parser->mGeneratedPPNodeCount += substr_count( $xml, '<' );
        $max = $this->parser->mOptions->getMaxGeneratedPPNodeCount();
        if ( $this->parser->mGeneratedPPNodeCount > $max ) {
            // if ( $cacheable ) { ... }
            throw new MWException( __METHOD__ . ': generated node count limit exceeded' );
        }
 
        $dom = new DOMDocument;
        Wikimedia\suppressWarnings();
        $result = $dom->loadXML( $xml );
        Wikimedia\restoreWarnings();
        if ( !$result ) {
            // Try running the XML through UtfNormal to get rid of invalid characters
            $xml = UtfNormal\Validator::cleanUp( $xml );
            // 1 << 19 == XML_PARSE_HUGE, needed so newer versions of libxml2
            // don't barf when the XML is >256 levels deep.
            $result = $dom->loadXML( $xml, 1 << 19 );
        }
        if ( $result ) {
            $obj = new PPNode_DOM( $dom->documentElement );
        }
 
        // if ( $cacheable ) { ... }
 
        if ( !$result ) {
            throw new MWException( __METHOD__ . ' generated invalid XML' );
        }
        return $obj;
    }
 
    public function preprocessToXml( $text, $flags = 0 ) {
        global $wgDisableLangConversion;
 
        $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;
 
        $searchBase = "[{<\n"; # }
        if ( !$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
        $accum =& $stack->getAccum();
        $accum = '<root>';
        // 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>' . htmlspecialchars( substr( $text, $i ) ) . '</ignore>';
                    break;
                }
                $tagEndPos = $startPos + strlen( '<onlyinclude>' ); // past-the-end
                $accum .= '<ignore>' . htmlspecialchars( substr( $text, $i, $tagEndPos - $i ) ) . '</ignore>';
                $i = $tagEndPos;
                $findOnlyinclude = false;
            }
 
            if ( $fakeLineStart ) {
                $found = 'line-start';
                $curChar = '';
            } else {
                # Find next opening brace, closing brace or pipe
                $search = $searchBase;
                if ( $stack->top === false ) {
                    $currentClosing = '';
                } else {
                    $currentClosing = $stack->top->close;
                    $search .= $currentClosing;
                }
                if ( $findPipe ) {
                    $search .= '|';
                }
                if ( $findEquals ) {
                    // First equals will be for the template
                    $search .= '=';
                }
                $rule = null;
                # Output literal section, advance input counter
                $literalLength = strcspn( $text, $search, $i );
                if ( $literalLength > 0 ) {
                    $accum .= htmlspecialchars( substr( $text, $i, $literalLength ) );
                    $i += $literalLength;
                }
                if ( $i >= $lengthText ) {
                    if ( $currentClosing == "\n" ) {
                        // Do a past-the-end run to finish off the heading
                        $curChar = '';
                        $found = 'line-end';
                    } else {
                        # All done
                        break;
                    }
                } else {
                    $curChar = $curTwoChar = $text[$i];
                    if ( ( $i + 1 ) < $lengthText ) {
                        $curTwoChar .= $text[$i + 1];
                    }
                    if ( $curChar == '|' ) {
                        $found = 'pipe';
                    } elseif ( $curChar == '=' ) {
                        $found = 'equals';
                    } elseif ( $curChar == '<' ) {
                        $found = 'angle';
                    } elseif ( $curChar == "\n" ) {
                        if ( $inHeading ) {
                            $found = 'line-end';
                        } else {
                            $found = 'line-start';
                        }
                    } elseif ( $curTwoChar == $currentClosing ) {
                        $found = 'close';
                        $curChar = $curTwoChar;
                    } elseif ( $curChar == $currentClosing ) {
                        $found = 'close';
                    } elseif ( isset( $this->rules[$curTwoChar] ) ) {
                        $curChar = $curTwoChar;
                        $found = 'open';
                        $rule = $this->rules[$curChar];
                    } elseif ( isset( $this->rules[$curChar] ) ) {
                        $found = 'open';
                        $rule = $this->rules[$curChar];
                    } else {
                        # Some versions of PHP have a strcspn which stops on
                        # null characters; ignore these and continue.
                        # We also may get '-' and '}' characters here which
                        # don't match -{ or $currentClosing.  Add these to
                        # output and continue.
                        if ( $curChar == '-' || $curChar == '}' ) {
                            $accum .= $curChar;
                        }
                        ++$i;
                        continue;
                    }
                }
            }
 
            if ( $found == 'angle' ) {
                $matches = false;
                // Handle </onlyinclude>
                if ( $enableOnlyinclude
                    && substr( $text, $i, strlen( '</onlyinclude>' ) ) == '</onlyinclude>'
                ) {
                    $findOnlyinclude = true;
                    continue;
                }
 
                // Determine element name
                if ( !preg_match( $elementsRegex, $text, $matches, 0, $i + 1 ) ) {
                    // Element name missing or not listed
                    $accum .= '&lt;';
                    ++$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>' . htmlspecialchars( $inner ) . '</comment>';
                        $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
                            // Sanity check first though
                            $wsLength = $i - $wsStart;
                            if ( $wsLength > 0
                                && strspn( $accum, " \t", -$wsLength ) === $wsLength
                            ) {
                                $accum = substr( $accum, 0, -$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>' . htmlspecialchars( $inner ) . '</comment>';
                            }
 
                            // 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>' . htmlspecialchars( $inner ) . '</comment>';
                    }
                    continue;
                }
                $name = $matches[1];
                $lowerName = strtolower( $name );
                $attrStart = $i + strlen( $name ) + 1;
 
                // Find end of tag
                $tagEndPos = $noMoreGT ? false : strpos( $text, '>', $attrStart );
                if ( $tagEndPos === false ) {
                    // Infinite backtrack
                    // Disable tag search to prevent worst-case O(N^2) performance
                    $noMoreGT = true;
                    $accum .= '&lt;';
                    ++$i;
                    continue;
                }
 
                // Handle ignored tags
                if ( in_array( $lowerName, $ignoredTags ) ) {
                    $accum .= '<ignore>'
                        . htmlspecialchars( substr( $text, $i, $tagEndPos - $i + 1 ) )
                        . '</ignore>';
                    $i = $tagEndPos + 1;
                    continue;
                }
 
                $tagStartPos = $i;
                if ( $text[$tagEndPos - 1] == '/' ) {
                    $attrEnd = $tagEndPos - 1;
                    $inner = null;
                    $i = $tagEndPos + 1;
                    $close = '';
                } 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 = '<close>' . htmlspecialchars( $matches[0][0] ) . '</close>';
                    } else {
                        // No end tag
                        if ( in_array( $name, $xmlishAllowMissingEndTag ) ) {
                            // Let it run out to the end of the text.
                            $inner = substr( $text, $tagEndPos + 1 );
                            $i = $lengthText;
                            $close = '';
                        } else {
                            // Don't match the tag, treat opening tag as literal and resume parsing.
                            $i = $tagEndPos + 1;
                            $accum .= htmlspecialchars( 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>' . htmlspecialchars( substr( $text, $tagStartPos, $i - $tagStartPos ) )
                        . '</ignore>';
                    continue;
                }
 
                $accum .= '<ext>';
                if ( $attrEnd <= $attrStart ) {
                    $attr = '';
                } else {
                    $attr = substr( $text, $attrStart, $attrEnd - $attrStart );
                }
                $accum .= '<name>' . htmlspecialchars( $name ) . '</name>' .
                    // Note that the attr element contains the whitespace between name and attribute,
                    // this is necessary for precise reconstruction during pre-save transform.
                    '<attr>' . htmlspecialchars( $attr ) . '</attr>';
                if ( $inner !== null ) {
                    $accum .= '<inner>' . htmlspecialchars( $inner ) . '</inner>';
                }
                $accum .= $close . '</ext>';
            } elseif ( $found == 'line-start' ) {
                // Is this the start of a heading?
                // Line break belongs before the heading element in any case
                if ( $fakeLineStart ) {
                    $fakeLineStart = false;
                } else {
                    $accum .= $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( str_repeat( '=', $count ) ) ],
                        'startPos' => $i,
                        'count' => $count ];
                    $stack->push( $piece );
                    $accum =& $stack->getAccum();
                    $stackFlags = $stack->getFlags();
                    if ( isset( $stackFlags['findEquals'] ) ) {
                        $findEquals = $stackFlags['findEquals'];
                    }
                    if ( isset( $stackFlags['findPipe'] ) ) {
                        $findPipe = $stackFlags['findPipe'];
                    }
                    if ( isset( $stackFlags['inHeading'] ) ) {
                        $inHeading = $stackFlags['inHeading'];
                    }
                    $i += $count;
                }
            } elseif ( $found == 'line-end' ) {
                $piece = $stack->top;
                // A heading must be open, otherwise \n wouldn't have been in the search list
                // FIXME: Don't use assert()
                // phpcs:ignore MediaWiki.Usage.ForbiddenFunctions.assert
                assert( $piece->open === "\n" );
                $part = $piece->getCurrentPart();
                // Search back through the input to see if it has a proper close.
                // Do this using the reversed string since the other solutions
                // (end anchor, etc.) are inefficient.
                $wsLength = strspn( $revText, " \t", $lengthText - $i );
                $searchStart = $i - $wsLength;
                if ( 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>
                        $element = "<h level=\"$count\" i=\"$headingIndex\">$accum</h>";
                        $headingIndex++;
                    } else {
                        // Single equals sign on its own line, count=0
                        $element = $accum;
                    }
                } else {
                    // No match, no <h>, just pass down the inner text
                    $element = $accum;
                }
                // Unwind the stack
                $stack->pop();
                $accum =& $stack->getAccum();
                $stackFlags = $stack->getFlags();
                if ( isset( $stackFlags['findEquals'] ) ) {
                    $findEquals = $stackFlags['findEquals'];
                }
                if ( isset( $stackFlags['findPipe'] ) ) {
                    $findPipe = $stackFlags['findPipe'];
                }
                if ( isset( $stackFlags['inHeading'] ) ) {
                    $inHeading = $stackFlags['inHeading'];
                }
 
                // Append the result to the enclosing accumulator
                $accum .= $element;
                // Note that we do NOT increment the input pointer.
                // This is because the closing linebreak could be the opening linebreak of
                // another heading. Infinite loops are avoided because the next iteration MUST
                // hit the heading open case above, which unconditionally increments the
                // input pointer.
            } elseif ( $found == 'open' ) {
                # count opening brace characters
                $curLen = strlen( $curChar );
                $count = ( $curLen > 1 ) ?
                    # allow the final character to repeat
                    strspn( $text, $curChar[$curLen - 1], $i + 1 ) + 1 :
                    strspn( $text, $curChar, $i );
 
                $savedPrefix = '';
                $lineStart = ( $i > 0 && $text[$i - 1] == "\n" );
 
                if ( $curChar === "-{" && $count > $curLen ) {
                    // -{ => {{ transition because rightmost wins
                    $savedPrefix = '-';
                    $i++;
                    $curChar = '{';
                    $count--;
                    $rule = $this->rules[$curChar];
                }
 
                # we need to add to stack only if opening brace count is enough for one of the rules
                if ( $count >= $rule['min'] ) {
                    # Add it to the stack
                    $piece = [
                        'open' => $curChar,
                        'close' => $rule['end'],
                        'savedPrefix' => $savedPrefix,
                        'count' => $count,
                        'lineStart' => $lineStart,
                    ];
 
                    $stack->push( $piece );
                    $accum =& $stack->getAccum();
                    $stackFlags = $stack->getFlags();
                    if ( isset( $stackFlags['findEquals'] ) ) {
                        $findEquals = $stackFlags['findEquals'];
                    }
                    if ( isset( $stackFlags['findPipe'] ) ) {
                        $findPipe = $stackFlags['findPipe'];
                    }
                    if ( isset( $stackFlags['inHeading'] ) ) {
                        $inHeading = $stackFlags['inHeading'];
                    }
                } else {
                    # Add literal brace(s)
                    $accum .= htmlspecialchars( $savedPrefix . str_repeat( $curChar, $count ) );
                }
                $i += $count;
            } elseif ( $found == 'close' ) {
                $piece = $stack->top;
                # lets check if there are enough characters for closing brace
                $maxCount = $piece->count;
                if ( $piece->close === '}-' && $curChar === '}' ) {
                    $maxCount--; # don't try to match closing '-' as a '}'
                }
                $curLen = strlen( $curChar );
                $count = ( $curLen > 1 ) ? $curLen :
                    strspn( $text, $curChar, $i, $maxCount );
 
                # check for maximum matching characters (if there are 5 closing
                # characters, we will probably need only 3 - depending on the rules)
                $rule = $this->rules[$piece->open];
                if ( $count > $rule['max'] ) {
                    # The specified maximum exists in the callback array, unless the caller
                    # has made an error
                    $matchingCount = $rule['max'];
                } else {
                    # Count is less than the maximum
                    # Skip any gaps in the callback array to find the true largest match
                    # Need to use array_key_exists not isset because the callback can be null
                    $matchingCount = $count;
                    while ( $matchingCount > 0 && !array_key_exists( $matchingCount, $rule['names'] ) ) {
                        --$matchingCount;
                    }
                }
 
                if ( $matchingCount <= 0 ) {
                    # No matching element found in callback array
                    # Output a literal closing brace and continue
                    $endText = substr( $text, $i, $count );
                    $accum .= htmlspecialchars( $endText );
                    $i += $count;
                    continue;
                }
                $name = $rule['names'][$matchingCount];
                if ( $name === null ) {
                    // No element, just literal text
                    $endText = substr( $text, $i, $matchingCount );
                    $element = $piece->breakSyntax( $matchingCount ) . $endText;
                } else {
                    # Create XML element
                    # Note: $parts is already XML, does not need to be encoded further
                    $parts = $piece->parts;
                    $title = $parts[0]->out;
                    unset( $parts[0] );
 
                    # 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 ) &&
                            strlen( $piece->savedPrefix ) == 0 ) {
                        $attr = ' lineStart="1"';
                    } else {
                        $attr = '';
                    }
 
                    $element = "<$name$attr>";
                    $element .= "<title>$title</title>";
                    $argIndex = 1;
                    foreach ( $parts as $part ) {
                        if ( isset( $part->eqpos ) ) {
                            $argName = substr( $part->out, 0, $part->eqpos );
                            $argValue = substr( $part->out, $part->eqpos + 1 );
                            $element .= "<part><name>$argName</name>=<value>$argValue</value></part>";
                        } else {
                            $element .= "<part><name index=\"$argIndex\" /><value>{$part->out}</value></part>";
                            $argIndex++;
                        }
                    }
                    $element .= "</$name>";
                }
 
                # Advance input pointer
                $i += $matchingCount;
 
                # Unwind the stack
                $stack->pop();
                $accum =& $stack->getAccum();
 
                # Re-add the old stack element if it still has unmatched opening characters remaining
                if ( $matchingCount < $piece->count ) {
                    $piece->parts = [ new PPDPart ];
                    $piece->count -= $matchingCount;
                    # do we still qualify for any callback with remaining count?
                    $min = $this->rules[$piece->open]['min'];
                    if ( $piece->count >= $min ) {
                        $stack->push( $piece );
                        $accum =& $stack->getAccum();
                    } elseif ( $piece->count == 1 && $piece->open === '{' && $piece->savedPrefix === '-' ) {
                        $piece->savedPrefix = '';
                        $piece->open = '-{';
                        $piece->count = 2;
                        $piece->close = $this->rules[$piece->open]['end'];
                        $stack->push( $piece );
                        $accum =& $stack->getAccum();
                    } else {
                        $s = substr( $piece->open, 0, -1 );
                        $s .= str_repeat(
                            substr( $piece->open, -1 ),
                            $piece->count - strlen( $s )
                        );
                        $accum .= $piece->savedPrefix . $s;
                    }
                } elseif ( $piece->savedPrefix !== '' ) {
                    $accum .= $piece->savedPrefix;
                }
 
                $stackFlags = $stack->getFlags();
                if ( isset( $stackFlags['findEquals'] ) ) {
                    $findEquals = $stackFlags['findEquals'];
                }
                if ( isset( $stackFlags['findPipe'] ) ) {
                    $findPipe = $stackFlags['findPipe'];
                }
                if ( isset( $stackFlags['inHeading'] ) ) {
                    $inHeading = $stackFlags['inHeading'];
                }
 
                # Add XML element to the enclosing accumulator
                $accum .= $element;
            } elseif ( $found == 'pipe' ) {
                $findEquals = true; // shortcut for getFlags()
                $stack->addPart();
                $accum =& $stack->getAccum();
                ++$i;
            } elseif ( $found == 'equals' ) {
                $findEquals = false; // shortcut for getFlags()
                $stack->getCurrentPart()->eqpos = strlen( $accum );
                $accum .= '=';
                ++$i;
            }
        }
 
        # Output any remaining unclosed brackets
        foreach ( $stack->stack as $piece ) {
            $stack->rootAccum .= $piece->breakSyntax();
        }
        $stack->rootAccum .= '</root>';
        $xml = $stack->rootAccum;
 
        return $xml;
    }
}