Merge "tidy: Remove obsolete Depurate and Balancer drivers"
authorjenkins-bot <jenkins-bot@gerrit.wikimedia.org>
Tue, 8 May 2018 15:46:14 +0000 (15:46 +0000)
committerGerrit Code Review <gerrit@wikimedia.org>
Tue, 8 May 2018 15:46:14 +0000 (15:46 +0000)
RELEASE-NOTES-1.32
autoload.php
includes/DefaultSettings.php
includes/parser/MWTidy.php
includes/tidy/Balancer.php [deleted file]
includes/tidy/Html5Depurate.php [deleted file]
includes/tidy/Html5Internal.php [deleted file]
tests/phpunit/includes/tidy/BalancerTest.php [deleted file]

index b7500ae..9fd3161 100644 (file)
@@ -15,6 +15,8 @@ production.
   $wgJpegQuality (default 80). This aligns the quality to what ImageMagick uses.
 * $wgExperimentalHtmlIds, deprecated since 1.30, has been removed. The
   'html5-legacy' value for $wgFragmentMode is no longer accepted.
+* The experimental Html5Internal and Html5Depurate tidy drivers were removed.
+  RemexHtml, which is the default, should be used instead.
 
 === New features in 1.32 ===
 * (T112474) Generalized the ResourceLoader mechanism for overriding modules
@@ -76,6 +78,9 @@ because of Phabricator reports.
 * mw.util.updateTooltipAccessKeys(), deprecated in 1.24, was removed. Use
   jquery.accessKeyLabel instead.
 * The SqlDataUpdate class, deprecated in 1.28, has been removed.
+* The Html5Internal and Html5Depurate tidy driver classes were removed, along with the
+  Balancer tidy implementation. Both implementations were experimental, and were replaced
+  by RemexHtml.
 
 === Deprecations in 1.32 ===
 * Use of a StartProfiler.php file is deprecated in favour of placing
index e316bb5..f4ae8f6 100644 (file)
@@ -970,14 +970,6 @@ $wgAutoloadLocalClasses = [
        'MediaWiki\\Storage\\SlotRecord' => __DIR__ . '/includes/Storage/SlotRecord.php',
        'MediaWiki\\Storage\\SqlBlobStore' => __DIR__ . '/includes/Storage/SqlBlobStore.php',
        'MediaWiki\\Storage\\SuppressedDataException' => __DIR__ . '/includes/Storage/SuppressedDataException.php',
-       'MediaWiki\\Tidy\\BalanceActiveFormattingElements' => __DIR__ . '/includes/tidy/Balancer.php',
-       'MediaWiki\\Tidy\\BalanceElement' => __DIR__ . '/includes/tidy/Balancer.php',
-       'MediaWiki\\Tidy\\BalanceMarker' => __DIR__ . '/includes/tidy/Balancer.php',
-       'MediaWiki\\Tidy\\BalanceSets' => __DIR__ . '/includes/tidy/Balancer.php',
-       'MediaWiki\\Tidy\\BalanceStack' => __DIR__ . '/includes/tidy/Balancer.php',
-       'MediaWiki\\Tidy\\Balancer' => __DIR__ . '/includes/tidy/Balancer.php',
-       'MediaWiki\\Tidy\\Html5Depurate' => __DIR__ . '/includes/tidy/Html5Depurate.php',
-       'MediaWiki\\Tidy\\Html5Internal' => __DIR__ . '/includes/tidy/Html5Internal.php',
        'MediaWiki\\Tidy\\RaggettBase' => __DIR__ . '/includes/tidy/RaggettBase.php',
        'MediaWiki\\Tidy\\RaggettExternal' => __DIR__ . '/includes/tidy/RaggettExternal.php',
        'MediaWiki\\Tidy\\RaggettInternalHHVM' => __DIR__ . '/includes/tidy/RaggettInternalHHVM.php',
index 2dc43fe..ff8612b 100644 (file)
@@ -4273,8 +4273,6 @@ $wgAllowImageTag = false;
  *    - RaggettInternalHHVM: Use the limited-functionality HHVM extension
  *    - RaggettInternalPHP: Use the PECL extension
  *    - RaggettExternal: Shell out to an external binary (tidyBin)
- *    - Html5Depurate: Use external Depurate service
- *    - Html5Internal: Use the Balancer library in PHP
  *    - RemexHtml: Use the RemexHtml library in PHP
  *
  *  - tidyConfigFile: Path to configuration file for any of the Raggett drivers
index 19cf573..5788986 100644 (file)
@@ -111,12 +111,6 @@ class MWTidy {
                        case 'RaggettExternal':
                                $instance = new MediaWiki\Tidy\RaggettExternal( $config );
                                break;
-                       case 'Html5Depurate':
-                               $instance = new MediaWiki\Tidy\Html5Depurate( $config );
-                               break;
-                       case 'Html5Internal':
-                               $instance = new MediaWiki\Tidy\Html5Internal( $config );
-                               break;
                        case 'RemexHtml':
                                $instance = new MediaWiki\Tidy\RemexDriver( $config );
                                break;
diff --git a/includes/tidy/Balancer.php b/includes/tidy/Balancer.php
deleted file mode 100644 (file)
index 6671f49..0000000
+++ /dev/null
@@ -1,3584 +0,0 @@
-<?php
-/**
- * An implementation of the tree building portion of the HTML5 parsing
- * spec.
- *
- * 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
- * @since 1.27
- * @author C. Scott Ananian, 2016
- */
-
-namespace MediaWiki\Tidy;
-
-use ExplodeIterator;
-use IteratorAggregate;
-use ReverseArrayIterator;
-use Sanitizer;
-use Wikimedia\Assert\Assert;
-use Wikimedia\Assert\ParameterAssertionException;
-
-// A note for future librarization[1] -- this file is a good candidate
-// for splitting into an independent library, except that it is currently
-// highly optimized for MediaWiki use.  It only implements the portions
-// of the HTML5 tree builder used by tags supported by MediaWiki, and
-// does not contain a true tokenizer pass, instead relying on
-// comment stripping, attribute normalization, and escaping done by
-// the MediaWiki Sanitizer.  It also deliberately avoids building
-// a true DOM in memory, instead serializing elements to an output string
-// as soon as possible (usually as soon as the tag is closed) to reduce
-// its memory footprint.
-
-// We've been gradually lifting some of these restrictions to handle
-// non-sanitized output generated by extensions, but we shortcut the tokenizer
-// for speed (primarily by splitting on `<`) and so rely on syntactic
-// well-formedness.
-
-// On the other hand, I've been pretty careful to note with comments in the
-// code the places where this implementation omits features of the spec or
-// depends on the MediaWiki Sanitizer.  Perhaps in the future we'll want to
-// implement the missing pieces and make this a standalone PHP HTML5 parser.
-// In order to do so, some sort of MediaWiki-specific API will need
-// to be added to (a) allow the Balancer to bypass the tokenizer,
-// and (b) support on-the-fly flattening instead of DOM node creation.
-
-// [1]: https://www.mediawiki.org/wiki/Library_infrastructure_for_MediaWiki
-
-/**
- * Utility constants and sets for the HTML5 tree building algorithm.
- * Sets are associative arrays indexed first by namespace and then by
- * lower-cased tag name.
- *
- * @ingroup Parser
- * @since 1.27
- */
-class BalanceSets {
-       const HTML_NAMESPACE = 'http://www.w3.org/1999/xhtml';
-       const MATHML_NAMESPACE = 'http://www.w3.org/1998/Math/MathML';
-       const SVG_NAMESPACE = 'http://www.w3.org/2000/svg';
-
-       public static $unsupportedSet = [
-               self::HTML_NAMESPACE => [
-                       'html' => true, 'head' => true, 'body' => true, 'frameset' => true,
-                       'frame' => true,
-                       'plaintext' => true,
-                       'xmp' => true, 'iframe' => true, 'noembed' => true,
-                       'noscript' => true, 'script' => true,
-                       'title' => true
-               ]
-       ];
-
-       public static $emptyElementSet = [
-               self::HTML_NAMESPACE => [
-                       'area' => true, 'base' => true, 'basefont' => true,
-                       'bgsound' => true, 'br' => true, 'col' => true, 'command' => true,
-                       'embed' => true, 'frame' => true, 'hr' => true, 'img' => true,
-                       'input' => true, 'keygen' => true, 'link' => true, 'meta' => true,
-                       'param' => true, 'source' => true, 'track' => true, 'wbr' => true
-               ]
-       ];
-
-       public static $extraLinefeedSet = [
-               self::HTML_NAMESPACE => [
-                       'pre' => true, 'textarea' => true, 'listing' => true,
-               ]
-       ];
-
-       public static $headingSet = [
-               self::HTML_NAMESPACE => [
-                       'h1' => true, 'h2' => true, 'h3' => true,
-                       'h4' => true, 'h5' => true, 'h6' => true
-               ]
-       ];
-
-       public static $specialSet = [
-               self::HTML_NAMESPACE => [
-                       'address' => true, 'applet' => true, 'area' => true,
-                       'article' => true, 'aside' => true, 'base' => true,
-                       'basefont' => true, 'bgsound' => true, 'blockquote' => true,
-                       'body' => true, 'br' => true, 'button' => true, 'caption' => true,
-                       'center' => true, 'col' => true, 'colgroup' => true, 'dd' => true,
-                       'details' => true, 'dir' => true, 'div' => true, 'dl' => true,
-                       'dt' => true, 'embed' => true, 'fieldset' => true,
-                       'figcaption' => true, 'figure' => true, 'footer' => true,
-                       'form' => true, 'frame' => true, 'frameset' => true, 'h1' => true,
-                       'h2' => true, 'h3' => true, 'h4' => true, 'h5' => true,
-                       'h6' => true, 'head' => true, 'header' => true, 'hgroup' => true,
-                       'hr' => true, 'html' => true, 'iframe' => true, 'img' => true,
-                       'input' => true, 'li' => true, 'link' => true,
-                       'listing' => true, 'main' => true, 'marquee' => true,
-                       'menu' => true, 'meta' => true, 'nav' => true,
-                       'noembed' => true, 'noframes' => true, 'noscript' => true,
-                       'object' => true, 'ol' => true, 'p' => true, 'param' => true,
-                       'plaintext' => true, 'pre' => true, 'script' => true,
-                       'section' => true, 'select' => true, 'source' => true,
-                       'style' => true, 'summary' => true, 'table' => true,
-                       'tbody' => true, 'td' => true, 'template' => true,
-                       'textarea' => true, 'tfoot' => true, 'th' => true, 'thead' => true,
-                       'title' => true, 'tr' => true, 'track' => true, 'ul' => true,
-                       'wbr' => true, 'xmp' => true
-               ],
-               self::SVG_NAMESPACE => [
-                       'foreignobject' => true, 'desc' => true, 'title' => true
-               ],
-               self::MATHML_NAMESPACE => [
-                       'mi' => true, 'mo' => true, 'mn' => true, 'ms' => true,
-                       'mtext' => true, 'annotation-xml' => true
-               ]
-       ];
-
-       public static $addressDivPSet = [
-               self::HTML_NAMESPACE => [
-                       'address' => true, 'div' => true, 'p' => true
-               ]
-       ];
-
-       public static $tableSectionRowSet = [
-               self::HTML_NAMESPACE => [
-                       'table' => true, 'thead' => true, 'tbody' => true,
-                       'tfoot' => true, 'tr' => true
-               ]
-       ];
-
-       public static $impliedEndTagsSet = [
-               self::HTML_NAMESPACE => [
-                       'dd' => true, 'dt' => true, 'li' => true,
-                       'menuitem' => true, 'optgroup' => true,
-                       'option' => true, 'p' => true, 'rb' => true, 'rp' => true,
-                       'rt' => true, 'rtc' => true
-               ]
-       ];
-
-       public static $thoroughImpliedEndTagsSet = [
-               self::HTML_NAMESPACE => [
-                       'caption' => true, 'colgroup' => true, 'dd' => true, 'dt' => true,
-                       'li' => true, 'optgroup' => true, 'option' => true, 'p' => true,
-                       'rb' => true, 'rp' => true, 'rt' => true, 'rtc' => true,
-                       'tbody' => true, 'td' => true, 'tfoot' => true, 'th' => true,
-                       'thead' => true, 'tr' => true
-               ]
-       ];
-
-       public static $tableCellSet = [
-               self::HTML_NAMESPACE => [
-                       'td' => true, 'th' => true
-               ]
-       ];
-       public static $tableContextSet = [
-               self::HTML_NAMESPACE => [
-                       'table' => true, 'template' => true, 'html' => true
-               ]
-       ];
-
-       public static $tableBodyContextSet = [
-               self::HTML_NAMESPACE => [
-                       'tbody' => true, 'tfoot' => true, 'thead' => true,
-                       'template' => true, 'html' => true
-               ]
-       ];
-
-       public static $tableRowContextSet = [
-               self::HTML_NAMESPACE => [
-                       'tr' => true, 'template' => true, 'html' => true
-               ]
-       ];
-
-       // See https://html.spec.whatwg.org/multipage/forms.html#form-associated-element
-       public static $formAssociatedSet = [
-               self::HTML_NAMESPACE => [
-                       'button' => true, 'fieldset' => true, 'input' => true,
-                       'keygen' => true, 'object' => true, 'output' => true,
-                       'select' => true, 'textarea' => true, 'img' => true
-               ]
-       ];
-
-       public static $inScopeSet = [
-               self::HTML_NAMESPACE => [
-                       'applet' => true, 'caption' => true, 'html' => true,
-                       'marquee' => true, 'object' => true,
-                       'table' => true, 'td' => true, 'template' => true,
-                       'th' => true
-               ],
-               self::SVG_NAMESPACE => [
-                       'foreignobject' => true, 'desc' => true, 'title' => true
-               ],
-               self::MATHML_NAMESPACE => [
-                       'mi' => true, 'mo' => true, 'mn' => true, 'ms' => true,
-                       'mtext' => true, 'annotation-xml' => true
-               ]
-       ];
-
-       private static $inListItemScopeSet = null;
-       public static function inListItemScopeSet() {
-               if ( self::$inListItemScopeSet === null ) {
-                       self::$inListItemScopeSet = self::$inScopeSet;
-                       self::$inListItemScopeSet[self::HTML_NAMESPACE]['ol'] = true;
-                       self::$inListItemScopeSet[self::HTML_NAMESPACE]['ul'] = true;
-               }
-               return self::$inListItemScopeSet;
-       }
-
-       private static $inButtonScopeSet = null;
-       public static function inButtonScopeSet() {
-               if ( self::$inButtonScopeSet === null ) {
-                       self::$inButtonScopeSet = self::$inScopeSet;
-                       self::$inButtonScopeSet[self::HTML_NAMESPACE]['button'] = true;
-               }
-               return self::$inButtonScopeSet;
-       }
-
-       public static $inTableScopeSet = [
-               self::HTML_NAMESPACE => [
-                       'html' => true, 'table' => true, 'template' => true
-               ]
-       ];
-
-       public static $inInvertedSelectScopeSet = [
-               self::HTML_NAMESPACE => [
-                       'option' => true, 'optgroup' => true
-               ]
-       ];
-
-       public static $mathmlTextIntegrationPointSet = [
-               self::MATHML_NAMESPACE => [
-                       'mi' => true, 'mo' => true, 'mn' => true, 'ms' => true,
-                       'mtext' => true
-               ]
-       ];
-
-       public static $htmlIntegrationPointSet = [
-               self::SVG_NAMESPACE => [
-                       'foreignobject' => true,
-                       'desc' => true,
-                       'title' => true
-               ]
-       ];
-
-       // For tidy compatibility.
-       public static $tidyPWrapSet = [
-               self::HTML_NAMESPACE => [
-                       'body' => true, 'blockquote' => true,
-                       // We parse with <body> as the fragment context, but the top-level
-                       // element on the stack is actually <html>.  We could use the
-                       // "adjusted current node" everywhere to work around this, but it's
-                       // easier just to add <html> to the p-wrap set.
-                       'html' => true,
-               ],
-       ];
-       public static $tidyInlineSet = [
-               self::HTML_NAMESPACE => [
-                       'a' => true, 'abbr' => true, 'acronym' => true, 'applet' => true,
-                       'b' => true, 'basefont' => true, 'bdo' => true, 'big' => true,
-                       'br' => true, 'button' => true, 'cite' => true, 'code' => true,
-                       'dfn' => true, 'em' => true, 'font' => true, 'i' => true,
-                       'iframe' => true, 'img' => true, 'input' => true, 'kbd' => true,
-                       'label' => true, 'legend' => true, 'map' => true, 'object' => true,
-                       'param' => true, 'q' => true, 'rb' => true, 'rbc' => true,
-                       'rp' => true, 'rt' => true, 'rtc' => true, 'ruby' => true,
-                       's' => true, 'samp' => true, 'select' => true, 'small' => true,
-                       'span' => true, 'strike' => true, 'strong' => true, 'sub' => true,
-                       'sup' => true, 'textarea' => true, 'tt' => true, 'u' => true,
-                       'var' => true,
-                       // Those defined in tidy.conf
-                       'video' => true, 'audio' => true, 'bdi' => true, 'data' => true,
-                       'time' => true, 'mark' => true,
-               ],
-       ];
-}
-
-/**
- * A BalanceElement is a simplified version of a DOM Node.  The main
- * difference is that we only keep BalanceElements around for nodes
- * currently on the BalanceStack of open elements.  As soon as an
- * element is closed, with some minor exceptions relating to the
- * tree builder "adoption agency algorithm", the element and all its
- * children are serialized to a string using the flatten() method.
- * This keeps our memory usage low.
- *
- * @ingroup Parser
- * @since 1.27
- */
-class BalanceElement {
-       /**
-        * The namespace of the element.
-        * @var string $namespaceURI
-        */
-       public $namespaceURI;
-       /**
-        * The lower-cased name of the element.
-        * @var string $localName
-        */
-       public $localName;
-       /**
-        * Attributes for the element, in array form
-        * @var array $attribs
-        */
-       public $attribs;
-
-       /**
-        * Parent of this element, or the string "flat" if this element has
-        * already been flattened into its parent.
-        * @var BalanceElement|string|null $parent
-        */
-       public $parent;
-
-       /**
-        * An array of children of this element.  Typically only the last
-        * child will be an actual BalanceElement object; the rest will
-        * be strings, representing either text nodes or flattened
-        * BalanceElement objects.
-        * @var BalanceElement[]|string[] $children
-        */
-       public $children;
-
-       /**
-        * A unique string identifier for Noah's Ark purposes, lazy initialized
-        */
-       private $noahKey;
-
-       /**
-        * The next active formatting element in the list, or null if this is the
-        * end of the AFE list or if the element is not in the AFE list.
-        */
-       public $nextAFE;
-
-       /**
-        * The previous active formatting element in the list, or null if this is
-        * the start of the list or if the element is not in the AFE list.
-        */
-       public $prevAFE;
-
-       /**
-        * The next element in the Noah's Ark species bucket.
-        */
-       public $nextNoah;
-
-       /**
-        * Make a new BalanceElement corresponding to the HTML DOM Element
-        * with the given localname, namespace, and attributes.
-        *
-        * @param string $namespaceURI The namespace of the element.
-        * @param string $localName The lowercased name of the tag.
-        * @param array $attribs Attributes of the element
-        */
-       public function __construct( $namespaceURI, $localName, array $attribs ) {
-               $this->localName = $localName;
-               $this->namespaceURI = $namespaceURI;
-               $this->attribs = $attribs;
-               $this->contents = '';
-               $this->parent = null;
-               $this->children = [];
-       }
-
-       /**
-        * Remove the given child from this element.
-        * @param BalanceElement $elt
-        */
-       private function removeChild( BalanceElement $elt ) {
-               Assert::precondition(
-                       $this->parent !== 'flat', "Can't removeChild after flattening $this"
-               );
-               Assert::parameter(
-                       $elt->parent === $this, 'elt', 'must have $this as a parent'
-               );
-               $idx = array_search( $elt, $this->children, true );
-               Assert::parameter( $idx !== false, '$elt', 'must be a child of $this' );
-               $elt->parent = null;
-               array_splice( $this->children, $idx, 1 );
-       }
-
-       /**
-        * Find $a in the list of children and insert $b before it.
-        * @param BalanceElement $a
-        * @param BalanceElement|string $b
-        */
-       public function insertBefore( BalanceElement $a, $b ) {
-               Assert::precondition(
-                       $this->parent !== 'flat', "Can't insertBefore after flattening."
-               );
-               $idx = array_search( $a, $this->children, true );
-               Assert::parameter( $idx !== false, '$a', 'must be a child of $this' );
-               if ( is_string( $b ) ) {
-                       array_splice( $this->children, $idx, 0, [ $b ] );
-               } else {
-                       Assert::parameter( $b->parent !== 'flat', '$b', "Can't be flat" );
-                       if ( $b->parent !== null ) {
-                               $b->parent->removeChild( $b );
-                       }
-                       array_splice( $this->children, $idx, 0, [ $b ] );
-                       $b->parent = $this;
-               }
-       }
-
-       /**
-        * Append $elt to the end of the list of children.
-        * @param BalanceElement|string $elt
-        */
-       public function appendChild( $elt ) {
-               Assert::precondition(
-                       $this->parent !== 'flat', "Can't appendChild after flattening."
-               );
-               if ( is_string( $elt ) ) {
-                       array_push( $this->children, $elt );
-                       return;
-               }
-               // Remove $elt from parent, if it had one.
-               if ( $elt->parent !== null ) {
-                       $elt->parent->removeChild( $elt );
-               }
-               array_push( $this->children, $elt );
-               $elt->parent = $this;
-       }
-
-       /**
-        * Transfer all of the children of $elt to $this.
-        * @param BalanceElement $elt
-        */
-       public function adoptChildren( BalanceElement $elt ) {
-               Assert::precondition(
-                       $elt->parent !== 'flat', "Can't adoptChildren after flattening."
-               );
-               foreach ( $elt->children as $child ) {
-                       if ( !is_string( $child ) ) {
-                               // This is an optimization which avoids an O(n^2) set of
-                               // array_splice operations.
-                               $child->parent = null;
-                       }
-                       $this->appendChild( $child );
-               }
-               $elt->children = [];
-       }
-
-       /**
-        * Flatten this node and all of its children into a string, as specified
-        * by the HTML serialization specification, and replace this node
-        * in its parent by that string.
-        *
-        * @param array $config Balancer configuration; see Balancer::__construct().
-        * @return string
-        *
-        * @see __toString()
-        */
-       public function flatten( array $config ) {
-               Assert::parameter( $this->parent !== null, '$this', 'must be a child' );
-               Assert::parameter( $this->parent !== 'flat', '$this', 'already flat' );
-               $idx = array_search( $this, $this->parent->children, true );
-               Assert::parameter(
-                       $idx !== false, '$this', 'must be a child of its parent'
-               );
-               $tidyCompat = $config['tidyCompat'];
-               if ( $tidyCompat ) {
-                       $blank = true;
-                       foreach ( $this->children as $elt ) {
-                               if ( !is_string( $elt ) ) {
-                                       $elt = $elt->flatten( $config );
-                               }
-                               if ( $blank && preg_match( '/[^\t\n\f\r ]/', $elt ) ) {
-                                       $blank = false;
-                               }
-                       }
-                       if ( $this->isHtmlNamed( 'mw:p-wrap' ) ) {
-                               $this->localName = 'p';
-                       } elseif ( $blank ) {
-                               // Add 'mw-empty-elt' class so elements can be hidden via CSS
-                               // for compatibility with legacy tidy.
-                               if ( !count( $this->attribs ) &&
-                                       ( $this->localName === 'tr' || $this->localName === 'li' )
-                               ) {
-                                       $this->attribs = [ 'class' => "mw-empty-elt" ];
-                               }
-                               $blank = false;
-                       } elseif (
-                               $this->isA( BalanceSets::$extraLinefeedSet ) &&
-                               count( $this->children ) > 0 &&
-                               substr( $this->children[0], 0, 1 ) == "\n"
-                       ) {
-                               // Double the linefeed after pre/listing/textarea
-                               // according to the (old) HTML5 fragment serialization
-                               // algorithm (see https://github.com/whatwg/html/issues/944)
-                               // to ensure this will round-trip.
-                               array_unshift( $this->children, "\n" );
-                       }
-                       $flat = $blank ? '' : "{$this}";
-               } else {
-                       $flat = "{$this}";
-               }
-               $this->parent->children[$idx] = $flat;
-               $this->parent = 'flat'; // for assertion checking
-               return $flat;
-       }
-
-       /**
-        * Serialize this node and all of its children to a string, as specified
-        * by the HTML serialization specification.
-        *
-        * @return string The serialization of the BalanceElement
-        * @see https://html.spec.whatwg.org/multipage/syntax.html#serialising-html-fragments
-        */
-       public function __toString() {
-               $encAttribs = '';
-               foreach ( $this->attribs as $name => $value ) {
-                       $encValue = Sanitizer::encodeAttribute( $value );
-                       $encAttribs .= " $name=\"$encValue\"";
-               }
-               if ( !$this->isA( BalanceSets::$emptyElementSet ) ) {
-                       $out = "<{$this->localName}{$encAttribs}>";
-                       $len = strlen( $out );
-                       // flatten children
-                       foreach ( $this->children as $elt ) {
-                               $out .= "{$elt}";
-                       }
-                       $out .= "</{$this->localName}>";
-               } else {
-                       $out = "<{$this->localName}{$encAttribs} />";
-                       Assert::invariant(
-                               count( $this->children ) === 0,
-                               "Empty elements shouldn't have children."
-                       );
-               }
-               return $out;
-       }
-
-       // Utility functions on BalanceElements.
-
-       /**
-        * Determine if $this represents a specific HTML tag, is a member of
-        * a tag set, or is equal to another BalanceElement.
-        *
-        * @param BalanceElement|array|string $set The target BalanceElement,
-        *   set (from the BalanceSets class), or string (HTML tag name).
-        * @return bool
-        */
-       public function isA( $set ) {
-               if ( $set instanceof BalanceElement ) {
-                       return $this === $set;
-               } elseif ( is_array( $set ) ) {
-                       return isset( $set[$this->namespaceURI] ) &&
-                               isset( $set[$this->namespaceURI][$this->localName] );
-               } else {
-                       // assume this is an HTML element name.
-                       return $this->isHtml() && $this->localName === $set;
-               }
-       }
-
-       /**
-        * Determine if this element is an HTML element with the specified name
-        * @param string $tagName
-        * @return bool
-        */
-       public function isHtmlNamed( $tagName ) {
-               return $this->namespaceURI === BalanceSets::HTML_NAMESPACE
-                       && $this->localName === $tagName;
-       }
-
-       /**
-        * Determine if $this represents an element in the HTML namespace.
-        *
-        * @return bool
-        */
-       public function isHtml() {
-               return $this->namespaceURI === BalanceSets::HTML_NAMESPACE;
-       }
-
-       /**
-        * Determine if $this represents a MathML text integration point,
-        * as defined in the HTML5 specification.
-        *
-        * @return bool
-        * @see https://html.spec.whatwg.org/multipage/syntax.html#mathml-text-integration-point
-        */
-       public function isMathmlTextIntegrationPoint() {
-               return $this->isA( BalanceSets::$mathmlTextIntegrationPointSet );
-       }
-
-       /**
-        * Determine if $this represents an HTML integration point,
-        * as defined in the HTML5 specification.
-        *
-        * @return bool
-        * @see https://html.spec.whatwg.org/multipage/syntax.html#html-integration-point
-        */
-       public function isHtmlIntegrationPoint() {
-               if ( $this->isA( BalanceSets::$htmlIntegrationPointSet ) ) {
-                       return true;
-               }
-               if (
-                       $this->namespaceURI === BalanceSets::MATHML_NAMESPACE &&
-                       $this->localName === 'annotation-xml' &&
-                       isset( $this->attribs['encoding'] ) &&
-                       ( strcasecmp( $this->attribs['encoding'], 'text/html' ) == 0 ||
-                       strcasecmp( $this->attribs['encoding'], 'application/xhtml+xml' ) == 0 )
-               ) {
-                       return true;
-               }
-               return false;
-       }
-
-       /**
-        * Get a string key for the Noah's Ark algorithm
-        * @return string
-        */
-       public function getNoahKey() {
-               if ( $this->noahKey === null ) {
-                       $attribs = $this->attribs;
-                       ksort( $attribs );
-                       $this->noahKey = serialize( [ $this->namespaceURI, $this->localName, $attribs ] );
-               }
-               return $this->noahKey;
-       }
-}
-
-/**
- * The "stack of open elements" as defined in the HTML5 tree builder
- * spec.  This contains methods to ensure that content (start tags, text)
- * are inserted at the correct place in the output string, and to
- * flatten BalanceElements are they are closed to avoid holding onto
- * a complete DOM tree for the document in memory.
- *
- * The stack defines a PHP iterator to traverse it in "reverse order",
- * that is, the most-recently-added element is visited first in a
- * foreach loop.
- *
- * @ingroup Parser
- * @since 1.27
- * @see https://html.spec.whatwg.org/multipage/syntax.html#the-stack-of-open-elements
- */
-class BalanceStack implements IteratorAggregate {
-       /**
-        * Backing storage for the stack.
-        * @var BalanceElement[] $elements
-        */
-       private $elements = [];
-       /**
-        * Foster parent mode determines how nodes are inserted into the
-        * stack.
-        * @var bool $fosterParentMode
-        * @see https://html.spec.whatwg.org/multipage/syntax.html#foster-parent
-        */
-       public $fosterParentMode = false;
-       /**
-        * Configuration options governing flattening.
-        * @var array $config
-        * @see Balancer::__construct()
-        */
-       private $config;
-       /**
-        * Reference to the current element
-        */
-       public $currentNode;
-
-       /**
-        * Create a new BalanceStack with a single BalanceElement on it,
-        * representing the root &lt;html&gt; node.
-        * @param array $config Balancer configuration; see Balancer::_construct().
-        */
-       public function __construct( array $config ) {
-               // always a root <html> element on the stack
-               array_push(
-                       $this->elements,
-                       new BalanceElement( BalanceSets::HTML_NAMESPACE, 'html', [] )
-               );
-               $this->currentNode = $this->elements[0];
-               $this->config = $config;
-       }
-
-       /**
-        * Return a string representing the output of the tree builder:
-        * all the children of the root &lt;html&gt; node.
-        * @return string
-        */
-       public function getOutput() {
-               // Don't include the outer '<html>....</html>'
-               $out = '';
-               foreach ( $this->elements[0]->children as $elt ) {
-                       $out .= is_string( $elt ) ? $elt :
-                               $elt->flatten( $this->config );
-               }
-               return $out;
-       }
-
-       /**
-        * Insert a comment at the appropriate place for inserting a node.
-        * @param string $value Content of the comment.
-        * @return string
-        * @see https://html.spec.whatwg.org/multipage/syntax.html#insert-a-comment
-        */
-       public function insertComment( $value ) {
-               // Just another type of text node, except for tidy p-wrapping.
-               return $this->insertText( '<!--' . $value . '-->', true );
-       }
-
-       /**
-        * Insert text at the appropriate place for inserting a node.
-        * @param string $value
-        * @param bool $isComment
-        * @return string
-        * @see https://html.spec.whatwg.org/multipage/syntax.html#appropriate-place-for-inserting-a-node
-        */
-       public function insertText( $value, $isComment = false ) {
-               if (
-                       $this->fosterParentMode &&
-                       $this->currentNode->isA( BalanceSets::$tableSectionRowSet )
-               ) {
-                       $this->fosterParent( $value );
-               } elseif (
-                       $this->config['tidyCompat'] && !$isComment &&
-                       $this->currentNode->isA( BalanceSets::$tidyPWrapSet )
-               ) {
-                       $this->insertHTMLElement( 'mw:p-wrap', [] );
-                       return $this->insertText( $value );
-               } else {
-                       $this->currentNode->appendChild( $value );
-               }
-       }
-
-       /**
-        * Insert a BalanceElement at the appropriate place, pushing it
-        * on to the open elements stack.
-        * @param string $namespaceURI The element namespace
-        * @param string $tag The tag name
-        * @param string $attribs Normalized attributes, as a string.
-        * @return BalanceElement
-        * @see https://html.spec.whatwg.org/multipage/syntax.html#insert-a-foreign-element
-        */
-       public function insertForeignElement( $namespaceURI, $tag, $attribs ) {
-               return $this->insertElement(
-                       new BalanceElement( $namespaceURI, $tag, $attribs )
-               );
-       }
-
-       /**
-        * Insert an HTML element at the appropriate place, pushing it on to
-        * the open elements stack.
-        * @param string $tag The tag name
-        * @param string $attribs Normalized attributes, as a string.
-        * @return BalanceElement
-        * @see https://html.spec.whatwg.org/multipage/syntax.html#insert-an-html-element
-        */
-       public function insertHTMLElement( $tag, $attribs ) {
-               return $this->insertForeignElement(
-                       BalanceSets::HTML_NAMESPACE, $tag, $attribs
-               );
-       }
-
-       /**
-        * Insert an element at the appropriate place and push it on to the
-        * open elements stack.
-        * @param BalanceElement $elt
-        * @return BalanceElement
-        * @see https://html.spec.whatwg.org/multipage/syntax.html#appropriate-place-for-inserting-a-node
-        */
-       public function insertElement( BalanceElement $elt ) {
-               if (
-                       $this->currentNode->isHtmlNamed( 'mw:p-wrap' ) &&
-                       !$elt->isA( BalanceSets::$tidyInlineSet )
-               ) {
-                       // Tidy compatibility.
-                       $this->pop();
-               }
-               if (
-                       $this->fosterParentMode &&
-                       $this->currentNode->isA( BalanceSets::$tableSectionRowSet )
-               ) {
-                       $elt = $this->fosterParent( $elt );
-               } else {
-                       $this->currentNode->appendChild( $elt );
-               }
-               Assert::invariant( $elt->parent !== null, "$elt must be in tree" );
-               Assert::invariant( $elt->parent !== 'flat', "$elt must not have been previous flattened" );
-               array_push( $this->elements, $elt );
-               $this->currentNode = $elt;
-               return $elt;
-       }
-
-       /**
-        * Determine if the stack has $tag in scope.
-        * @param BalanceElement|array|string $tag
-        * @return bool
-        * @see https://html.spec.whatwg.org/multipage/syntax.html#has-an-element-in-scope
-        */
-       public function inScope( $tag ) {
-               return $this->inSpecificScope( $tag, BalanceSets::$inScopeSet );
-       }
-
-       /**
-        * Determine if the stack has $tag in button scope.
-        * @param BalanceElement|array|string $tag
-        * @return bool
-        * @see https://html.spec.whatwg.org/multipage/syntax.html#has-an-element-in-button-scope
-        */
-       public function inButtonScope( $tag ) {
-               return $this->inSpecificScope( $tag, BalanceSets::inButtonScopeSet() );
-       }
-
-       /**
-        * Determine if the stack has $tag in list item scope.
-        * @param BalanceElement|array|string $tag
-        * @return bool
-        * @see https://html.spec.whatwg.org/multipage/syntax.html#has-an-element-in-list-item-scope
-        */
-       public function inListItemScope( $tag ) {
-               return $this->inSpecificScope( $tag, BalanceSets::inListItemScopeSet() );
-       }
-
-       /**
-        * Determine if the stack has $tag in table scope.
-        * @param BalanceElement|array|string $tag
-        * @return bool
-        * @see https://html.spec.whatwg.org/multipage/syntax.html#has-an-element-in-table-scope
-        */
-       public function inTableScope( $tag ) {
-               return $this->inSpecificScope( $tag, BalanceSets::$inTableScopeSet );
-       }
-
-       /**
-        * Determine if the stack has $tag in select scope.
-        * @param BalanceElement|array|string $tag
-        * @return bool
-        * @see https://html.spec.whatwg.org/multipage/syntax.html#has-an-element-in-select-scope
-        */
-       public function inSelectScope( $tag ) {
-               // Can't use inSpecificScope to implement this, since it involves
-               // *inverting* a set of tags.  Implement manually.
-               foreach ( $this as $elt ) {
-                       if ( $elt->isA( $tag ) ) {
-                               return true;
-                       }
-                       if ( !$elt->isA( BalanceSets::$inInvertedSelectScopeSet ) ) {
-                               return false;
-                       }
-               }
-               return false;
-       }
-
-       /**
-        * Determine if the stack has $tag in a specific scope, $set.
-        * @param BalanceElement|array|string $tag
-        * @param BalanceElement|array|string $set
-        * @return bool
-        * @see https://html.spec.whatwg.org/multipage/syntax.html#has-an-element-in-the-specific-scope
-        */
-       public function inSpecificScope( $tag, $set ) {
-               foreach ( $this as $elt ) {
-                       if ( $elt->isA( $tag ) ) {
-                               return true;
-                       }
-                       if ( $elt->isA( $set ) ) {
-                               return false;
-                       }
-               }
-               return false;
-       }
-
-       /**
-        * Generate implied end tags.
-        * @param string $butnot
-        * @param bool $thorough True if we should generate end tags thoroughly.
-        * @see https://html.spec.whatwg.org/multipage/syntax.html#generate-implied-end-tags
-        */
-       public function generateImpliedEndTags( $butnot = null, $thorough = false ) {
-               $endTagSet = $thorough ?
-                       BalanceSets::$thoroughImpliedEndTagsSet :
-                       BalanceSets::$impliedEndTagsSet;
-               while ( $this->currentNode ) {
-                       if ( $butnot !== null && $this->currentNode->isHtmlNamed( $butnot ) ) {
-                               break;
-                       }
-                       if ( !$this->currentNode->isA( $endTagSet ) ) {
-                               break;
-                       }
-                       $this->pop();
-               }
-       }
-
-       /**
-        * Return the adjusted current node.
-        * @param string $fragmentContext
-        * @return string
-        */
-       public function adjustedCurrentNode( $fragmentContext ) {
-               return ( $fragmentContext && count( $this->elements ) === 1 ) ?
-                       $fragmentContext : $this->currentNode;
-       }
-
-       /**
-        * Return an iterator over this stack which visits the current node
-        * first, and the root node last.
-        * @return \Iterator
-        */
-       public function getIterator() {
-               return new ReverseArrayIterator( $this->elements );
-       }
-
-       /**
-        * Return the BalanceElement at the given position $idx, where
-        * position 0 represents the root element.
-        * @param int $idx
-        * @return BalanceElement
-        */
-       public function node( $idx ) {
-               return $this->elements[ $idx ];
-       }
-
-       /**
-        * Replace the element at position $idx in the BalanceStack with $elt.
-        * @param int $idx
-        * @param BalanceElement $elt
-        */
-       public function replaceAt( $idx, BalanceElement $elt ) {
-               Assert::precondition(
-                       $this->elements[$idx]->parent !== 'flat',
-                       'Replaced element should not have already been flattened.'
-               );
-               Assert::precondition(
-                       $elt->parent !== 'flat',
-                       'New element should not have already been flattened.'
-               );
-               $this->elements[$idx] = $elt;
-               if ( $idx === count( $this->elements ) - 1 ) {
-                       $this->currentNode = $elt;
-               }
-       }
-
-       /**
-        * Return the position of the given BalanceElement, set, or
-        * HTML tag name string in the BalanceStack.
-        * @param BalanceElement|array|string $tag
-        * @return int
-        */
-       public function indexOf( $tag ) {
-               for ( $i = count( $this->elements ) - 1; $i >= 0; $i-- ) {
-                       if ( $this->elements[$i]->isA( $tag ) ) {
-                               return $i;
-                       }
-               }
-               return -1;
-       }
-
-       /**
-        * Return the number of elements currently in the BalanceStack.
-        * @return int
-        */
-       public function length() {
-               return count( $this->elements );
-       }
-
-       /**
-        * Remove the current node from the BalanceStack, flattening it
-        * in the process.
-        */
-       public function pop() {
-               $elt = array_pop( $this->elements );
-               if ( count( $this->elements ) ) {
-                       $this->currentNode = $this->elements[ count( $this->elements ) - 1 ];
-               } else {
-                       $this->currentNode = null;
-               }
-               if ( !$elt->isHtmlNamed( 'mw:p-wrap' ) ) {
-                       $elt->flatten( $this->config );
-               }
-       }
-
-       /**
-        * Remove all nodes up to and including position $idx from the
-        * BalanceStack, flattening them in the process.
-        * @param int $idx
-        */
-       public function popTo( $idx ) {
-               for ( $length = count( $this->elements ); $length > $idx; $length-- ) {
-                       $this->pop();
-               }
-       }
-
-       /**
-        * Pop elements off the stack up to and including the first
-        * element with the specified HTML tagname (or matching the given
-        * set).
-        * @param BalanceElement|array|string $tag
-        */
-       public function popTag( $tag ) {
-               while ( $this->currentNode ) {
-                       if ( $this->currentNode->isA( $tag ) ) {
-                               $this->pop();
-                               break;
-                       }
-                       $this->pop();
-               }
-       }
-
-       /**
-        * Pop elements off the stack *not including* the first element
-        * in the specified set.
-        * @param BalanceElement|array|string $set
-        */
-       public function clearToContext( $set ) {
-               // Note that we don't loop to 0. Never pop the <html> elt off.
-               for ( $length = count( $this->elements ); $length > 1; $length-- ) {
-                       if ( $this->currentNode->isA( $set ) ) {
-                               break;
-                       }
-                       $this->pop();
-               }
-       }
-
-       /**
-        * Remove the given $elt from the BalanceStack, optionally
-        * flattening it in the process.
-        * @param BalanceElement $elt The element to remove.
-        * @param bool $flatten Whether to flatten the removed element.
-        */
-       public function removeElement( BalanceElement $elt, $flatten = true ) {
-               Assert::parameter(
-                       $elt->parent !== 'flat',
-                       '$elt',
-                       '$elt should not already have been flattened.'
-               );
-               Assert::parameter(
-                       $elt->parent->parent !== 'flat',
-                       '$elt',
-                       'The parent of $elt should not already have been flattened.'
-               );
-               $idx = array_search( $elt, $this->elements, true );
-               Assert::parameter( $idx !== false, '$elt', 'must be in stack' );
-               array_splice( $this->elements, $idx, 1 );
-               if ( $idx === count( $this->elements ) ) {
-                       $this->currentNode = $this->elements[$idx - 1];
-               }
-               if ( $flatten ) {
-                       // serialize $elt into its parent
-                       // otherwise, it will eventually serialize when the parent
-                       // is serialized, we just hold onto the memory for its
-                       // tree of objects a little longer.
-                       $elt->flatten( $this->config );
-               }
-               Assert::postcondition(
-                       array_search( $elt, $this->elements, true ) === false,
-                       '$elt should no longer be in open elements stack'
-               );
-       }
-
-       /**
-        * Find $a in the BalanceStack and insert $b after it.
-        * @param BalanceElement $a
-        * @param BalanceElement $b
-        */
-       public function insertAfter( BalanceElement $a, BalanceElement $b ) {
-               $idx = $this->indexOf( $a );
-               Assert::parameter( $idx !== false, '$a', 'must be in stack' );
-               if ( $idx === count( $this->elements ) - 1 ) {
-                       array_push( $this->elements, $b );
-                       $this->currentNode = $b;
-               } else {
-                       array_splice( $this->elements, $idx + 1, 0, [ $b ] );
-               }
-       }
-
-       // Fostering and adoption.
-
-       /**
-        * Foster parent the given $elt in the stack of open elements.
-        * @param BalanceElement|string $elt
-        * @return BalanceElement|string
-        *
-        * @see https://html.spec.whatwg.org/multipage/syntax.html#foster-parent
-        */
-       private function fosterParent( $elt ) {
-               $lastTable = $this->indexOf( 'table' );
-               $lastTemplate = $this->indexOf( 'template' );
-               $parent = null;
-               $before = null;
-
-               if ( $lastTemplate >= 0 && ( $lastTable < 0 || $lastTemplate > $lastTable ) ) {
-                       $parent = $this->elements[$lastTemplate];
-               } elseif ( $lastTable >= 0 ) {
-                       $parent = $this->elements[$lastTable]->parent;
-                       // Assume all tables have parents, since we're not running scripts!
-                       Assert::invariant(
-                               $parent !== null, "All tables should have parents"
-                       );
-                       $before = $this->elements[$lastTable];
-               } else {
-                       $parent = $this->elements[0]; // the `html` element.
-               }
-
-               if ( $this->config['tidyCompat'] ) {
-                       if ( is_string( $elt ) ) {
-                               // We're fostering text: do we need a p-wrapper?
-                               if ( $parent->isA( BalanceSets::$tidyPWrapSet ) ) {
-                                       $this->insertHTMLElement( 'mw:p-wrap', [] );
-                                       $this->insertText( $elt );
-                                       return $elt;
-                               }
-                       } else {
-                               // We're fostering an element; do we need to merge p-wrappers?
-                               if ( $elt->isHtmlNamed( 'mw:p-wrap' ) ) {
-                                       $idx = $before ?
-                                               array_search( $before, $parent->children, true ) :
-                                               count( $parent->children );
-                                       $after = $idx > 0 ? $parent->children[$idx - 1] : '';
-                                       if (
-                                               $after instanceof BalanceElement &&
-                                               $after->isHtmlNamed( 'mw:p-wrap' )
-                                       ) {
-                                               return $after; // Re-use existing p-wrapper.
-                                       }
-                               }
-                       }
-               }
-
-               if ( $before ) {
-                       $parent->insertBefore( $before, $elt );
-               } else {
-                       $parent->appendChild( $elt );
-               }
-               return $elt;
-       }
-
-       /**
-        * Run the "adoption agency algoritm" (AAA) for the given subject
-        * tag name.
-        * @param string $tag The subject tag name.
-        * @param BalanceActiveFormattingElements $afe The current
-        *   active formatting elements list.
-        * @return true if the adoption agency algorithm "did something", false
-        *   if more processing is required by the caller.
-        * @see https://html.spec.whatwg.org/multipage/syntax.html#adoption-agency-algorithm
-        */
-       public function adoptionAgency( $tag, $afe ) {
-               // If the current node is an HTML element whose tag name is subject,
-               // and the current node is not in the list of active formatting
-               // elements, then pop the current node off the stack of open
-               // elements and abort these steps.
-               if (
-                       $this->currentNode->isHtmlNamed( $tag ) &&
-                       !$afe->isInList( $this->currentNode )
-               ) {
-                       $this->pop();
-                       return true; // no more handling required
-               }
-
-               // Outer loop: If outer loop counter is greater than or
-               // equal to eight, then abort these steps.
-               for ( $outer = 0; $outer < 8; $outer++ ) {
-                       // Let the formatting element be the last element in the list
-                       // of active formatting elements that: is between the end of
-                       // the list and the last scope marker in the list, if any, or
-                       // the start of the list otherwise, and has the same tag name
-                       // as the token.
-                       $fmtElt = $afe->findElementByTag( $tag );
-
-                       // If there is no such node, then abort these steps and instead
-                       // act as described in the "any other end tag" entry below.
-                       if ( !$fmtElt ) {
-                               return false; // false means handle by the default case
-                       }
-
-                       // Otherwise, if there is such a node, but that node is not in
-                       // the stack of open elements, then this is a parse error;
-                       // remove the element from the list, and abort these steps.
-                       $index = $this->indexOf( $fmtElt );
-                       if ( $index < 0 ) {
-                               $afe->remove( $fmtElt );
-                               return true;   // true means no more handling required
-                       }
-
-                       // Otherwise, if there is such a node, and that node is also in
-                       // the stack of open elements, but the element is not in scope,
-                       // then this is a parse error; ignore the token, and abort
-                       // these steps.
-                       if ( !$this->inScope( $fmtElt ) ) {
-                               return true;
-                       }
-
-                       // Let the furthest block be the topmost node in the stack of
-                       // open elements that is lower in the stack than the formatting
-                       // element, and is an element in the special category. There
-                       // might not be one.
-                       $furthestBlock = null;
-                       $furthestBlockIndex = -1;
-                       $stackLength = $this->length();
-                       for ( $i = $index + 1; $i < $stackLength; $i++ ) {
-                               if ( $this->node( $i )->isA( BalanceSets::$specialSet ) ) {
-                                       $furthestBlock = $this->node( $i );
-                                       $furthestBlockIndex = $i;
-                                       break;
-                               }
-                       }
-
-                       // If there is no furthest block, then the UA must skip the
-                       // subsequent steps and instead just pop all the nodes from the
-                       // bottom of the stack of open elements, from the current node
-                       // up to and including the formatting element, and remove the
-                       // formatting element from the list of active formatting
-                       // elements.
-                       if ( !$furthestBlock ) {
-                               $this->popTag( $fmtElt );
-                               $afe->remove( $fmtElt );
-                               return true;
-                       }
-
-                       // Let the common ancestor be the element immediately above
-                       // the formatting element in the stack of open elements.
-                       $ancestor = $this->node( $index - 1 );
-
-                       // Let a bookmark note the position of the formatting
-                       // element in the list of active formatting elements
-                       // relative to the elements on either side of it in the
-                       // list.
-                       $BOOKMARK = new BalanceElement( '[bookmark]', '[bookmark]', [] );
-                       $afe->insertAfter( $fmtElt, $BOOKMARK );
-
-                       // Let node and last node be the furthest block.
-                       $node = $furthestBlock;
-                       $lastNode = $furthestBlock;
-                       $nodeIndex = $furthestBlockIndex;
-                       $isAFE = false;
-
-                       // Inner loop
-                       for ( $inner = 1; true; $inner++ ) {
-                               // Let node be the element immediately above node in
-                               // the stack of open elements, or if node is no longer
-                               // in the stack of open elements (e.g. because it got
-                               // removed by this algorithm), the element that was
-                               // immediately above node in the stack of open elements
-                               // before node was removed.
-                               $node = $this->node( --$nodeIndex );
-
-                               // If node is the formatting element, then go
-                               // to the next step in the overall algorithm.
-                               if ( $node === $fmtElt ) break;
-
-                               // If the inner loop counter is greater than three and node
-                               // is in the list of active formatting elements, then remove
-                               // node from the list of active formatting elements.
-                               $isAFE = $afe->isInList( $node );
-                               if ( $inner > 3 && $isAFE ) {
-                                       $afe->remove( $node );
-                                       $isAFE = false;
-                               }
-
-                               // If node is not in the list of active formatting
-                               // elements, then remove node from the stack of open
-                               // elements and then go back to the step labeled inner
-                               // loop.
-                               if ( !$isAFE ) {
-                                       // Don't flatten here, since we're about to relocate
-                                       // parts of this $node.
-                                       $this->removeElement( $node, false );
-                                       continue;
-                               }
-
-                               // Create an element for the token for which the
-                               // element node was created with common ancestor as
-                               // the intended parent, replace the entry for node
-                               // in the list of active formatting elements with an
-                               // entry for the new element, replace the entry for
-                               // node in the stack of open elements with an entry for
-                               // the new element, and let node be the new element.
-                               $newElt = new BalanceElement(
-                                       $node->namespaceURI, $node->localName, $node->attribs );
-                               $afe->replace( $node, $newElt );
-                               $this->replaceAt( $nodeIndex, $newElt );
-                               $node = $newElt;
-
-                               // If last node is the furthest block, then move the
-                               // aforementioned bookmark to be immediately after the
-                               // new node in the list of active formatting elements.
-                               if ( $lastNode === $furthestBlock ) {
-                                       $afe->remove( $BOOKMARK );
-                                       $afe->insertAfter( $newElt, $BOOKMARK );
-                               }
-
-                               // Insert last node into node, first removing it from
-                               // its previous parent node if any.
-                               $node->appendChild( $lastNode );
-
-                               // Let last node be node.
-                               $lastNode = $node;
-                       }
-
-                       // If the common ancestor node is a table, tbody, tfoot,
-                       // thead, or tr element, then, foster parent whatever last
-                       // node ended up being in the previous step, first removing
-                       // it from its previous parent node if any.
-                       if (
-                               $this->fosterParentMode &&
-                               $ancestor->isA( BalanceSets::$tableSectionRowSet )
-                       ) {
-                               $this->fosterParent( $lastNode );
-                       } else {
-                               // Otherwise, append whatever last node ended up being in
-                               // the previous step to the common ancestor node, first
-                               // removing it from its previous parent node if any.
-                               $ancestor->appendChild( $lastNode );
-                       }
-
-                       // Create an element for the token for which the
-                       // formatting element was created, with furthest block
-                       // as the intended parent.
-                       $newElt2 = new BalanceElement(
-                               $fmtElt->namespaceURI, $fmtElt->localName, $fmtElt->attribs );
-
-                       // Take all of the child nodes of the furthest block and
-                       // append them to the element created in the last step.
-                       $newElt2->adoptChildren( $furthestBlock );
-
-                       // Append that new element to the furthest block.
-                       $furthestBlock->appendChild( $newElt2 );
-
-                       // Remove the formatting element from the list of active
-                       // formatting elements, and insert the new element into the
-                       // list of active formatting elements at the position of
-                       // the aforementioned bookmark.
-                       $afe->remove( $fmtElt );
-                       $afe->replace( $BOOKMARK, $newElt2 );
-
-                       // Remove the formatting element from the stack of open
-                       // elements, and insert the new element into the stack of
-                       // open elements immediately below the position of the
-                       // furthest block in that stack.
-                       $this->removeElement( $fmtElt );
-                       $this->insertAfter( $furthestBlock, $newElt2 );
-               }
-
-               return true;
-       }
-
-       /**
-        * Return the contents of the open elements stack as a string for
-        * debugging.
-        * @return string
-        */
-       public function __toString() {
-               $r = [];
-               foreach ( $this->elements as $elt ) {
-                       array_push( $r, $elt->localName );
-               }
-               return implode( ' ', $r );
-       }
-}
-
-/**
- * A pseudo-element used as a marker in the list of active formatting elements
- *
- * @ingroup Parser
- * @since 1.27
- */
-class BalanceMarker {
-       public $nextAFE;
-       public $prevAFE;
-}
-
-/**
- * The list of active formatting elements, which is used to handle
- * mis-nested formatting element tags in the HTML5 tree builder
- * specification.
- *
- * @ingroup Parser
- * @since 1.27
- * @see https://html.spec.whatwg.org/multipage/syntax.html#list-of-active-formatting-elements
- */
-class BalanceActiveFormattingElements {
-       /** The last (most recent) element in the list */
-       private $tail;
-
-       /** The first (least recent) element in the list */
-       private $head;
-
-       /**
-        * An array of arrays representing the population of elements in each bucket
-        * according to the Noah's Ark clause. The outer array is stack-like, with each
-        * integer-indexed element representing a segment of the list, bounded by
-        * markers. The first element represents the segment of the list before the
-        * first marker.
-        *
-        * The inner arrays are indexed by "Noah key", which is a string which uniquely
-        * identifies each bucket according to the rules in the spec. The value in
-        * the inner array is the first (least recently inserted) element in the bucket,
-        * and subsequent members of the bucket can be found by iterating through the
-        * singly-linked list via $node->nextNoah.
-        *
-        * This is optimised for the most common case of inserting into a bucket
-        * with zero members, and deleting a bucket containing one member. In the
-        * worst case, iteration through the list is still O(1) in the document
-        * size, since each bucket can have at most 3 members.
-        */
-       private $noahTableStack = [ [] ];
-
-       public function __destruct() {
-               $next = null;
-               for ( $node = $this->head; $node; $node = $next ) {
-                       $next = $node->nextAFE;
-                       $node->prevAFE = $node->nextAFE = $node->nextNoah = null;
-               }
-               $this->head = $this->tail = $this->noahTableStack = null;
-       }
-
-       public function insertMarker() {
-               $elt = new BalanceMarker;
-               if ( $this->tail ) {
-                       $this->tail->nextAFE = $elt;
-                       $elt->prevAFE = $this->tail;
-               } else {
-                       $this->head = $elt;
-               }
-               $this->tail = $elt;
-               $this->noahTableStack[] = [];
-       }
-
-       /**
-        * Follow the steps required when the spec requires us to "push onto the
-        * list of active formatting elements".
-        * @param BalanceElement $elt
-        */
-       public function push( BalanceElement $elt ) {
-               // Must not be in the list already
-               if ( $elt->prevAFE !== null || $this->head === $elt ) {
-                       throw new ParameterAssertionException( '$elt',
-                               'Cannot insert a node into the AFE list twice' );
-               }
-
-               // "Noah's Ark clause" -- if there are already three copies of
-               // this element before we encounter a marker, then drop the last
-               // one.
-               $noahKey = $elt->getNoahKey();
-               $table =& $this->noahTableStack[ count( $this->noahTableStack ) - 1 ];
-               if ( !isset( $table[$noahKey] ) ) {
-                       $table[$noahKey] = $elt;
-               } else {
-                       $count = 1;
-                       $head = $tail = $table[$noahKey];
-                       while ( $tail->nextNoah ) {
-                               $tail = $tail->nextNoah;
-                               $count++;
-                       }
-                       if ( $count >= 3 ) {
-                               $this->remove( $head );
-                       }
-                       $tail->nextNoah = $elt;
-               }
-               // Add to the main AFE list
-               if ( $this->tail ) {
-                       $this->tail->nextAFE = $elt;
-                       $elt->prevAFE = $this->tail;
-               } else {
-                       $this->head = $elt;
-               }
-               $this->tail = $elt;
-       }
-
-       /**
-        * Follow the steps required when the spec asks us to "clear the list of
-        * active formatting elements up to the last marker".
-        */
-       public function clearToMarker() {
-               // Iterate back through the list starting from the tail
-               $tail = $this->tail;
-               while ( $tail && !( $tail instanceof BalanceMarker ) ) {
-                       // Unlink the element
-                       $prev = $tail->prevAFE;
-                       $tail->prevAFE = null;
-                       if ( $prev ) {
-                               $prev->nextAFE = null;
-                       }
-                       $tail->nextNoah = null;
-                       $tail = $prev;
-               }
-               // If we finished on a marker, unlink it and pop it off the Noah table stack
-               if ( $tail ) {
-                       $prev = $tail->prevAFE;
-                       if ( $prev ) {
-                               $prev->nextAFE = null;
-                       }
-                       $tail = $prev;
-                       array_pop( $this->noahTableStack );
-               } else {
-                       // No marker: wipe the top-level Noah table (which is the only one)
-                       $this->noahTableStack[0] = [];
-               }
-               // If we removed all the elements, clear the head pointer
-               if ( !$tail ) {
-                       $this->head = null;
-               }
-               $this->tail = $tail;
-       }
-
-       /**
-        * Find and return the last element with the specified tag between the
-        * end of the list and the last marker on the list.
-        * Used when parsing &lt;a&gt; "in body mode".
-        * @param string $tag
-        * @return null|Node
-        */
-       public function findElementByTag( $tag ) {
-               $elt = $this->tail;
-               while ( $elt && !( $elt instanceof BalanceMarker ) ) {
-                       if ( $elt->localName === $tag ) {
-                               return $elt;
-                       }
-                       $elt = $elt->prevAFE;
-               }
-               return null;
-       }
-
-       /**
-        * Determine whether an element is in the list of formatting elements.
-        * @param BalanceElement $elt
-        * @return bool
-        */
-       public function isInList( BalanceElement $elt ) {
-               return $this->head === $elt || $elt->prevAFE;
-       }
-
-       /**
-        * Find the element $elt in the list and remove it.
-        * Used when parsing &lt;a&gt; in body mode.
-        *
-        * @param BalanceElement $elt
-        */
-       public function remove( BalanceElement $elt ) {
-               if ( $this->head !== $elt && !$elt->prevAFE ) {
-                       throw new ParameterAssertionException( '$elt',
-                               "Attempted to remove an element which is not in the AFE list" );
-               }
-               // Update head and tail pointers
-               if ( $this->head === $elt ) {
-                       $this->head = $elt->nextAFE;
-               }
-               if ( $this->tail === $elt ) {
-                       $this->tail = $elt->prevAFE;
-               }
-               // Update previous element
-               if ( $elt->prevAFE ) {
-                       $elt->prevAFE->nextAFE = $elt->nextAFE;
-               }
-               // Update next element
-               if ( $elt->nextAFE ) {
-                       $elt->nextAFE->prevAFE = $elt->prevAFE;
-               }
-               // Clear pointers so that isInList() etc. will work
-               $elt->prevAFE = $elt->nextAFE = null;
-               // Update Noah list
-               $this->removeFromNoahList( $elt );
-       }
-
-       private function addToNoahList( BalanceElement $elt ) {
-               $noahKey = $elt->getNoahKey();
-               $table =& $this->noahTableStack[ count( $this->noahTableStack ) - 1 ];
-               if ( !isset( $table[$noahKey] ) ) {
-                       $table[$noahKey] = $elt;
-               } else {
-                       $tail = $table[$noahKey];
-                       while ( $tail->nextNoah ) {
-                               $tail = $tail->nextNoah;
-                       }
-                       $tail->nextNoah = $elt;
-               }
-       }
-
-       private function removeFromNoahList( BalanceElement $elt ) {
-               $table =& $this->noahTableStack[ count( $this->noahTableStack ) - 1 ];
-               $key = $elt->getNoahKey();
-               $noahElt = $table[$key];
-               if ( $noahElt === $elt ) {
-                       if ( $noahElt->nextNoah ) {
-                               $table[$key] = $noahElt->nextNoah;
-                               $noahElt->nextNoah = null;
-                       } else {
-                               unset( $table[$key] );
-                       }
-               } else {
-                       do {
-                               $prevNoahElt = $noahElt;
-                               $noahElt = $prevNoahElt->nextNoah;
-                               if ( $noahElt === $elt ) {
-                                       // Found it, unlink
-                                       $prevNoahElt->nextNoah = $elt->nextNoah;
-                                       $elt->nextNoah = null;
-                                       break;
-                               }
-                       } while ( $noahElt );
-               }
-       }
-
-       /**
-        * Find element $a in the list and replace it with element $b
-        *
-        * @param BalanceElement $a
-        * @param BalanceElement $b
-        */
-       public function replace( BalanceElement $a, BalanceElement $b ) {
-               if ( $this->head !== $a && !$a->prevAFE ) {
-                       throw new ParameterAssertionException( '$a',
-                               "Attempted to replace an element which is not in the AFE list" );
-               }
-               // Update head and tail pointers
-               if ( $this->head === $a ) {
-                       $this->head = $b;
-               }
-               if ( $this->tail === $a ) {
-                       $this->tail = $b;
-               }
-               // Update previous element
-               if ( $a->prevAFE ) {
-                       $a->prevAFE->nextAFE = $b;
-               }
-               // Update next element
-               if ( $a->nextAFE ) {
-                       $a->nextAFE->prevAFE = $b;
-               }
-               $b->prevAFE = $a->prevAFE;
-               $b->nextAFE = $a->nextAFE;
-               $a->nextAFE = $a->prevAFE = null;
-               // Update Noah list
-               $this->removeFromNoahList( $a );
-               $this->addToNoahList( $b );
-       }
-
-       /**
-        * Find $a in the list and insert $b after it.
-
-        * @param BalanceElement $a
-        * @param BalanceElement $b
-        */
-       public function insertAfter( BalanceElement $a, BalanceElement $b ) {
-               if ( $this->head !== $a && !$a->prevAFE ) {
-                       throw new ParameterAssertionException( '$a',
-                               "Attempted to insert after an element which is not in the AFE list" );
-               }
-               if ( $this->tail === $a ) {
-                       $this->tail = $b;
-               }
-               if ( $a->nextAFE ) {
-                       $a->nextAFE->prevAFE = $b;
-               }
-               $b->nextAFE = $a->nextAFE;
-               $b->prevAFE = $a;
-               $a->nextAFE = $b;
-               $this->addToNoahList( $b );
-       }
-
-       /**
-        * Reconstruct the active formatting elements.
-        * @param BalanceStack $stack The open elements stack
-        * @see https://html.spec.whatwg.org/multipage/syntax.html#reconstruct-the-active-formatting-elements
-        */
-       public function reconstruct( $stack ) {
-               $entry = $this->tail;
-               // If there are no entries in the list of active formatting elements,
-               // then there is nothing to reconstruct
-               if ( !$entry ) {
-                       return;
-               }
-               // If the last is a marker, do nothing.
-               if ( $entry instanceof BalanceMarker ) {
-                       return;
-               }
-               // Or if it is an open element, do nothing.
-               if ( $stack->indexOf( $entry ) >= 0 ) {
-                       return;
-               }
-
-               // Loop backward through the list until we find a marker or an
-               // open element
-               $foundIt = false;
-               while ( $entry->prevAFE ) {
-                       $entry = $entry->prevAFE;
-                       if ( $entry instanceof BalanceMarker || $stack->indexOf( $entry ) >= 0 ) {
-                               $foundIt = true;
-                               break;
-                       }
-               }
-
-               // Now loop forward, starting from the element after the current one (or
-               // the first element if we didn't find a marker or open element),
-               // recreating formatting elements and pushing them back onto the list
-               // of open elements.
-               if ( $foundIt ) {
-                       $entry = $entry->nextAFE;
-               }
-               do {
-                       $newElement = $stack->insertHTMLElement(
-                               $entry->localName,
-                               $entry->attribs );
-                       $this->replace( $entry, $newElement );
-                       $entry = $newElement->nextAFE;
-               } while ( $entry );
-       }
-
-       /**
-        * Get a string representation of the AFE list, for debugging
-        */
-       public function __toString() {
-               $prev = null;
-               $s = '';
-               for ( $node = $this->head; $node; $prev = $node, $node = $node->nextAFE ) {
-                       if ( $node instanceof BalanceMarker ) {
-                               $s .= "MARKER\n";
-                               continue;
-                       }
-                       $s .= $node->localName . '#' . substr( md5( spl_object_hash( $node ) ), 0, 8 );
-                       if ( $node->nextNoah ) {
-                               $s .= " (noah sibling: {$node->nextNoah->localName}#" .
-                                       substr( md5( spl_object_hash( $node->nextNoah ) ), 0, 8 ) .
-                                       ')';
-                       }
-                       if ( $node->nextAFE && $node->nextAFE->prevAFE !== $node ) {
-                               $s .= " (reverse link is wrong!)";
-                       }
-                       $s .= "\n";
-               }
-               if ( $prev !== $this->tail ) {
-                       $s .= "(tail pointer is wrong!)\n";
-               }
-               return $s;
-       }
-}
-
-/**
- * An implementation of the tree building portion of the HTML5 parsing
- * spec.
- *
- * This is used to balance and tidy output so that the result can
- * always be cleanly serialized/deserialized by an HTML5 parser.  It
- * does *not* guarantee "conforming" output -- the HTML5 spec contains
- * a number of constraints which are not enforced by the HTML5 parsing
- * process.  But the result will be free of gross errors: misnested or
- * unclosed tags, for example, and will be unchanged by spec-complient
- * parsing followed by serialization.
- *
- * The tree building stage is structured as a state machine.
- * When comparing the implementation to
- * https://www.w3.org/TR/html5/syntax.html#tree-construction
- * note that each state is implemented as a function with a
- * name ending in `Mode` (because the HTML spec refers to them
- * as insertion modes).  The current insertion mode is held by
- * the $parseMode property.
- *
- * The following simplifications have been made:
- * - We handle body content only (ie, we start `in body`.)
- * - The document is never in "quirks mode".
- * - All occurrences of < and > have been entity escaped, so we
- *   can parse tags by simply splitting on those two characters.
- *   (This also simplifies the handling of < inside <textarea>.)
- *   The character < must not appear inside comments.
- *   Similarly, all attributes have been "cleaned" and are double-quoted
- *   and escaped.
- * - All null characters are assumed to have been removed.
- * - The following elements are disallowed: <html>, <head>, <body>, <frameset>,
- *   <frame>, <plaintext>, <xmp>, <iframe>,
- *   <noembed>, <noscript>, <script>, <title>.  As a result,
- *   further simplifications can be made:
- *   - `frameset-ok` is not tracked.
- *   - `head element pointer` is not tracked (but presumed non-null)
- *   - Tokenizer has only a single mode. (<textarea> wants RCDATA and
- *     <style>/<noframes> want RAWTEXT modes which we only loosely emulate.)
- *
- *   We generally mark places where we omit cases from the spec due to
- *   disallowed elements with a comment: `// OMITTED: <element-name>`.
- *
- *   The HTML spec keeps a flag during the parsing process to track
- *   whether or not a "parse error" has been encountered.  We don't
- *   bother to track that flag, we just implement the error-handling
- *   process as specified.
- *
- * @ingroup Parser
- * @since 1.27
- * @see https://html.spec.whatwg.org/multipage/syntax.html#tree-construction
- */
-class Balancer {
-       private $parseMode;
-       /** @var \Iterator */
-       private $bitsIterator;
-       private $allowedHtmlElements;
-       /** @var BalanceActiveFormattingElements */
-       private $afe;
-       /** @var BalanceStack */
-       private $stack;
-       private $strict;
-       private $allowComments;
-       private $config;
-
-       private $textIntegrationMode;
-       private $pendingTableText;
-       private $originalInsertionMode;
-       private $fragmentContext;
-       private $formElementPointer;
-       private $ignoreLinefeed;
-       private $inRCDATA;
-       private $inRAWTEXT;
-
-       /** @var callable|null */
-       private $processingCallback;
-       /** @var array */
-       private $processingArgs;
-
-       /**
-        * Valid HTML5 comments.
-        * Regex borrowed from Tim Starling's "remex-html" project.
-        */
-       const VALID_COMMENT_REGEX = "~ !--
-               (                           # 1. Comment match detector
-                       > | -> | # Invalid short close
-                       (                         # 2. Comment contents
-                               (?:
-                                       (?! --> )
-                                       (?! --!> )
-                                       (?! --! \z )
-                                       (?! -- \z )
-                                       (?! - \z )
-                                       .
-                               )*+
-                       )
-                       (                         # 3. Comment close
-                               --> |   # Normal close
-                               --!> |  # Comment end bang
-                               (                       # 4. Indicate matches requiring EOF
-                                       --! |                   # EOF in comment end bang state
-                                       -- |                    # EOF in comment end state
-                                       -  |                    # EOF in comment end dash state
-                                       (?#nothing)             # EOF in comment state
-                               )
-                       )
-               )
-               ([^<]*) \z                  # 5. Non-tag text after the comment
-               ~xs";
-
-       /**
-        * Create a new Balancer.
-        * @param array $config Balancer configuration.  Includes:
-        *     'strict' : boolean, defaults to false.
-        *         When true, enforces syntactic constraints on input:
-        *         all non-tag '<' must be escaped, all attributes must be
-        *         separated by a single space and double-quoted.  This is
-        *         consistent with the output of the Sanitizer.
-        *     'allowedHtmlElements' : array, defaults to null.
-        *         When present, the keys of this associative array give
-        *         the acceptable HTML tag names.  When not present, no
-        *         tag sanitization is done.
-        *     'tidyCompat' : boolean, defaults to false.
-        *         When true, the serialization algorithm is tweaked to
-        *         provide historical compatibility with the old "tidy"
-        *         program: <p>-wrapping is done to the children of
-        *         <body> and <blockquote> elements, and empty elements
-        *         are removed.  The <pre>/<listing>/<textarea> serialization
-        *         is also tweaked to allow lossless round trips.
-        *         (See: https://github.com/whatwg/html/issues/944)
-        *     'allowComments': boolean, defaults to true.
-        *         When true, allows HTML comments in the input.
-        *         The Sanitizer generally strips all comments, so if you
-        *         are running on sanitized output you can set this to
-        *         false to get a bit more performance.
-        */
-       public function __construct( array $config = [] ) {
-               $this->config = $config = $config + [
-                       'strict' => false,
-                       'allowedHtmlElements' => null,
-                       'tidyCompat' => false,
-                       'allowComments' => true,
-               ];
-               $this->allowedHtmlElements = $config['allowedHtmlElements'];
-               $this->strict = $config['strict'];
-               $this->allowComments = $config['allowComments'];
-               if ( $this->allowedHtmlElements !== null ) {
-                       // Sanity check!
-                       $bad = array_uintersect_assoc(
-                               $this->allowedHtmlElements,
-                               BalanceSets::$unsupportedSet[BalanceSets::HTML_NAMESPACE],
-                               function ( $a, $b ) {
-                                       // Ignore the values (just intersect the keys) by saying
-                                       // all values are equal to each other.
-                                       return 0;
-                               }
-                       );
-                       if ( count( $bad ) > 0 ) {
-                               $badstr = implode( ',', array_keys( $bad ) );
-                               throw new ParameterAssertionException(
-                                       '$config',
-                                       'Balance attempted with sanitization including ' .
-                                       "unsupported elements: {$badstr}"
-                               );
-                       }
-               }
-       }
-
-       /**
-        * Return a balanced HTML string for the HTML fragment given by $text,
-        * subject to the caveats listed in the class description.  The result
-        * will typically be idempotent -- that is, rebalancing the output
-        * would result in no change.
-        *
-        * @param string $text The markup to be balanced
-        * @param callable $processingCallback Callback to do any variable or
-        *   parameter replacements in HTML attributes values
-        * @param array|bool $processingArgs Arguments for the processing callback
-        * @return string The balanced markup
-        */
-       public function balance( $text, $processingCallback = null, $processingArgs = [] ) {
-               $this->parseMode = 'inBodyMode';
-               $this->bitsIterator = new ExplodeIterator( '<', $text );
-               $this->afe = new BalanceActiveFormattingElements();
-               $this->stack = new BalanceStack( $this->config );
-               $this->processingCallback = $processingCallback;
-               $this->processingArgs = $processingArgs;
-
-               $this->textIntegrationMode =
-                       $this->ignoreLinefeed =
-                       $this->inRCDATA =
-                       $this->inRAWTEXT = false;
-
-               // The stack is constructed with an <html> element already on it.
-               // Set this up as a fragment parsed with <body> as the context.
-               $this->fragmentContext =
-                       new BalanceElement( BalanceSets::HTML_NAMESPACE, 'body', [] );
-               $this->resetInsertionMode();
-               $this->formElementPointer = null;
-               for ( $e = $this->fragmentContext; $e != null; $e = $e->parent ) {
-                       if ( $e->isHtmlNamed( 'form' ) ) {
-                               $this->formElementPointer = $e;
-                               break;
-                       }
-               }
-
-               // First element is text not tag
-               $x = $this->bitsIterator->current();
-               $this->bitsIterator->next();
-               $this->insertToken( 'text', str_replace( '>', '&gt;', $x ) );
-               // Now process each tag.
-               while ( $this->bitsIterator->valid() ) {
-                       $this->advance();
-               }
-               $this->insertToken( 'eof', null );
-               $result = $this->stack->getOutput();
-               // Free memory before returning.
-               $this->bitsIterator = null;
-               $this->afe = null;
-               $this->stack = null;
-               $this->fragmentContext = null;
-               $this->formElementPointer = null;
-               return $result;
-       }
-
-       /**
-        * Pass a token to the tree builder.  The $token will be one of the
-        * strings "tag", "endtag", or "text".
-        */
-       private function insertToken( $token, $value, $attribs = null, $selfClose = false ) {
-               // validate tags against $unsupportedSet
-               if ( $token === 'tag' || $token === 'endtag' ) {
-                       if ( isset( BalanceSets::$unsupportedSet[BalanceSets::HTML_NAMESPACE][$value] ) ) {
-                               // As described in "simplifications" above, these tags are
-                               // not supported in the balancer.
-                               Assert::invariant(
-                                       !$this->strict,
-                                       "Unsupported $token <$value> found."
-                               );
-                               return false;
-                       }
-               } elseif ( $token === 'text' && $value === '' ) {
-                       // Don't actually inject the empty string as a text token.
-                       return true;
-               }
-               // Support pre/listing/textarea by suppressing initial linefeed
-               if ( $this->ignoreLinefeed ) {
-                       $this->ignoreLinefeed = false;
-                       if ( $token === 'text' ) {
-                               if ( $value[0] === "\n" ) {
-                                       if ( $value === "\n" ) {
-                                               // Nothing would be left, don't inject the empty string.
-                                               return true;
-                                       }
-                                       $value = substr( $value, 1 );
-                               }
-                       }
-               }
-               // Some hoops we have to jump through
-               $adjusted = $this->stack->adjustedCurrentNode( $this->fragmentContext );
-
-               // The spec calls this the "tree construction dispatcher".
-               $isForeign = true;
-               if (
-                       $this->stack->length() === 0 ||
-                       $adjusted->isHtml() ||
-                       $token === 'eof'
-               ) {
-                       $isForeign = false;
-               } elseif ( $adjusted->isMathmlTextIntegrationPoint() ) {
-                       if ( $token === 'text' ) {
-                               $isForeign = false;
-                       } elseif (
-                               $token === 'tag' &&
-                               $value !== 'mglyph' && $value !== 'malignmark'
-                       ) {
-                               $isForeign = false;
-                       }
-               } elseif (
-                       $adjusted->namespaceURI === BalanceSets::MATHML_NAMESPACE &&
-                       $adjusted->localName === 'annotation-xml' &&
-                       $token === 'tag' && $value === 'svg'
-               ) {
-                       $isForeign = false;
-               } elseif (
-                       $adjusted->isHtmlIntegrationPoint() &&
-                       ( $token === 'tag' || $token === 'text' )
-               ) {
-                       $isForeign = false;
-               }
-               if ( $isForeign ) {
-                       return $this->insertForeignToken( $token, $value, $attribs, $selfClose );
-               } else {
-                       $func = $this->parseMode;
-                       return $this->$func( $token, $value, $attribs, $selfClose );
-               }
-       }
-
-       private function insertForeignToken( $token, $value, $attribs = null, $selfClose = false ) {
-               if ( $token === 'text' ) {
-                       $this->stack->insertText( $value );
-                       return true;
-               } elseif ( $token === 'comment' ) {
-                       $this->stack->insertComment( $value );
-                       return true;
-               } elseif ( $token === 'tag' ) {
-                       switch ( $value ) {
-                               case 'font':
-                                       if ( isset( $attribs['color'] )
-                                               || isset( $attribs['face'] )
-                                               || isset( $attribs['size'] )
-                                       ) {
-                                               break;
-                                       }
-                                       // otherwise, fall through
-                               case 'b':
-                               case 'big':
-                               case 'blockquote':
-                               case 'body':
-                               case 'br':
-                               case 'center':
-                               case 'code':
-                               case 'dd':
-                               case 'div':
-                               case 'dl':
-                               case 'dt':
-                               case 'em':
-                               case 'embed':
-                               case 'h1':
-                               case 'h2':
-                               case 'h3':
-                               case 'h4':
-                               case 'h5':
-                               case 'h6':
-                               case 'head':
-                               case 'hr':
-                               case 'i':
-                               case 'img':
-                               case 'li':
-                               case 'listing':
-                               case 'menu':
-                               case 'meta':
-                               case 'nobr':
-                               case 'ol':
-                               case 'p':
-                               case 'pre':
-                               case 'ruby':
-                               case 's':
-                               case 'small':
-                               case 'span':
-                               case 'strong':
-                               case 'strike':
-                               case 'sub':
-                               case 'sup':
-                               case 'table':
-                               case 'tt':
-                               case 'u':
-                               case 'ul':
-                               case 'var':
-                                       if ( $this->fragmentContext ) {
-                                               break;
-                                       }
-                                       while ( true ) {
-                                               $this->stack->pop();
-                                               $node = $this->stack->currentNode;
-                                               if (
-                                                       $node->isMathmlTextIntegrationPoint() ||
-                                                       $node->isHtmlIntegrationPoint() ||
-                                                       $node->isHtml()
-                                               ) {
-                                                       break;
-                                               }
-                                       }
-                                       return $this->insertToken( $token, $value, $attribs, $selfClose );
-                       }
-                       // "Any other start tag"
-                       $adjusted = ( $this->fragmentContext && $this->stack->length() === 1 ) ?
-                               $this->fragmentContext : $this->stack->currentNode;
-                       $this->stack->insertForeignElement(
-                               $adjusted->namespaceURI, $value, $attribs
-                       );
-                       if ( $selfClose ) {
-                               $this->stack->pop();
-                       }
-                       return true;
-               } elseif ( $token === 'endtag' ) {
-                       $first = true;
-                       foreach ( $this->stack as $i => $node ) {
-                               if ( $node->isHtml() && !$first ) {
-                                       // process the end tag as HTML
-                                       $func = $this->parseMode;
-                                       return $this->$func( $token, $value, $attribs, $selfClose );
-                               } elseif ( $i === 0 ) {
-                                       return true;
-                               } elseif ( $node->localName === $value ) {
-                                       $this->stack->popTag( $node );
-                                       return true;
-                               }
-                               $first = false;
-                       }
-               }
-       }
-
-       /**
-        * Grab the next "token" from $bitsIterator.  This is either a open/close
-        * tag or text or a comment, depending on whether the Sanitizer approves.
-        */
-       private function advance() {
-               $x = $this->bitsIterator->current();
-               $this->bitsIterator->next();
-               $regs = [];
-               // Handle comments.  These won't be generated by mediawiki (they
-               // are stripped in the Sanitizer) but may be generated by extensions.
-               if (
-                       $this->allowComments &&
-                       !( $this->inRCDATA || $this->inRAWTEXT ) &&
-                       preg_match( self::VALID_COMMENT_REGEX, $x, $regs, PREG_OFFSET_CAPTURE ) &&
-                       // verify EOF condition where necessary
-                       ( $regs[4][1] < 0 || !$this->bitsIterator->valid() )
-               ) {
-                       $contents = $regs[2][0];
-                       $rest = $regs[5][0];
-                       $this->insertToken( 'comment', $contents );
-                       $this->insertToken( 'text', str_replace( '>', '&gt;', $rest ) );
-                       return;
-               }
-               // $slash: Does the current element start with a '/'?
-               // $t: Current element name
-               // $attribStr: String between element name and >
-               // $brace: Ending '>' or '/>'
-               // $rest: Everything until the next element from the $bitsIterator
-               if ( preg_match( Sanitizer::ELEMENT_BITS_REGEX, $x, $regs ) ) {
-                       list( /* $qbar */, $slash, $t, $attribStr, $brace, $rest ) = $regs;
-                       $t = strtolower( $t );
-                       if ( $this->strict ) {
-                               // Verify that attributes are all properly double-quoted
-                               Assert::invariant(
-                                       preg_match(
-                                               '/^( [:_A-Z0-9][-.:_A-Z0-9]*="[^"]*")*[ ]*$/i', $attribStr
-                                       ),
-                                       "Bad attribute string found"
-                               );
-                       }
-               } else {
-                       Assert::invariant(
-                               !$this->strict, "< found which does not start a valid tag"
-                       );
-                       $slash = $t = $attribStr = $brace = $rest = null;
-               }
-               $goodTag = $t;
-               if ( $this->inRCDATA ) {
-                       if ( $slash && $t === $this->inRCDATA ) {
-                               $this->inRCDATA = false;
-                       } else {
-                               // No tags allowed; this emulates the "rcdata" tokenizer mode.
-                               $goodTag = false;
-                       }
-               }
-               if ( $this->inRAWTEXT ) {
-                       if ( $slash && $t === $this->inRAWTEXT ) {
-                               $this->inRAWTEXT = false;
-                       } else {
-                               // No tags allowed, no entity-escaping done.
-                               $goodTag = false;
-                       }
-               }
-               $sanitize = $this->allowedHtmlElements !== null;
-               if ( $sanitize ) {
-                       $goodTag = $t && isset( $this->allowedHtmlElements[$t] );
-               }
-               if ( $goodTag ) {
-                       if ( is_callable( $this->processingCallback ) ) {
-                               call_user_func_array( $this->processingCallback, [ &$attribStr, $this->processingArgs ] );
-                       }
-                       if ( $sanitize ) {
-                               $goodTag = Sanitizer::validateTag( $attribStr, $t );
-                       }
-               }
-               if ( $goodTag ) {
-                       if ( $sanitize ) {
-                               $attribs = Sanitizer::decodeTagAttributes( $attribStr );
-                               $attribs = Sanitizer::validateTagAttributes( $attribs, $t );
-                       } else {
-                               $attribs = Sanitizer::decodeTagAttributes( $attribStr );
-                       }
-                       $goodTag = $this->insertToken(
-                               $slash ? 'endtag' : 'tag', $t, $attribs, $brace === '/>'
-                       );
-               }
-               if ( $goodTag ) {
-                       $rest = str_replace( '>', '&gt;', $rest );
-                       $this->insertToken( 'text', str_replace( '>', '&gt;', $rest ) );
-               } elseif ( $this->inRAWTEXT ) {
-                       $this->insertToken( 'text', "<$x" );
-               } else {
-                       // bad tag; serialize entire thing as text.
-                       $this->insertToken( 'text', '&lt;' . str_replace( '>', '&gt;', $x ) );
-               }
-       }
-
-       private function switchMode( $mode ) {
-               Assert::parameter(
-                       substr( $mode, -4 ) === 'Mode', '$mode', 'should end in Mode'
-               );
-               $oldMode = $this->parseMode;
-               $this->parseMode = $mode;
-               return $oldMode;
-       }
-
-       private function switchModeAndReprocess( $mode, $token, $value, $attribs, $selfClose ) {
-               $this->switchMode( $mode );
-               return $this->insertToken( $token, $value, $attribs, $selfClose );
-       }
-
-       private function resetInsertionMode() {
-               $last = false;
-               foreach ( $this->stack as $i => $node ) {
-                       if ( $i === 0 ) {
-                               $last = true;
-                               if ( $this->fragmentContext ) {
-                                       $node = $this->fragmentContext;
-                               }
-                       }
-                       if ( $node->isHtml() ) {
-                               switch ( $node->localName ) {
-                                       case 'select':
-                                               $stackLength = $this->stack->length();
-                                               for ( $j = $i + 1; $j < $stackLength - 1; $j++ ) {
-                                                       $ancestor = $this->stack->node( $stackLength - $j - 1 );
-                                                       if ( $ancestor->isHtmlNamed( 'template' ) ) {
-                                                               break;
-                                                       }
-                                                       if ( $ancestor->isHtmlNamed( 'table' ) ) {
-                                                               $this->switchMode( 'inSelectInTableMode' );
-                                                               return;
-                                                       }
-                                               }
-                                               $this->switchMode( 'inSelectMode' );
-                                               return;
-                                       case 'tr':
-                                               $this->switchMode( 'inRowMode' );
-                                               return;
-                                       case 'tbody':
-                                       case 'tfoot':
-                                       case 'thead':
-                                               $this->switchMode( 'inTableBodyMode' );
-                                               return;
-                                       case 'caption':
-                                               $this->switchMode( 'inCaptionMode' );
-                                               return;
-                                       case 'colgroup':
-                                               $this->switchMode( 'inColumnGroupMode' );
-                                               return;
-                                       case 'table':
-                                               $this->switchMode( 'inTableMode' );
-                                               return;
-                                       case 'template':
-                                               $this->switchMode(
-                                                       array_slice( $this->templateInsertionModes, -1 )[0]
-                                               );
-                                               return;
-                                       case 'body':
-                                               $this->switchMode( 'inBodyMode' );
-                                               return;
-                                       // OMITTED: <frameset>
-                                       // OMITTED: <html>
-                                       // OMITTED: <head>
-                                       default:
-                                               if ( !$last ) {
-                                                       // OMITTED: <head>
-                                                       if ( $node->isA( BalanceSets::$tableCellSet ) ) {
-                                                               $this->switchMode( 'inCellMode' );
-                                                               return;
-                                                       }
-                                               }
-                               }
-                       }
-                       if ( $last ) {
-                               $this->switchMode( 'inBodyMode' );
-                               return;
-                       }
-               }
-       }
-
-       private function stopParsing() {
-               // Most of the spec methods are inapplicable, other than step 2:
-               // "pop all the nodes off the stack of open elements".
-               // We're going to keep the top-most <html> element on the stack, though.
-
-               // Clear the AFE list first, otherwise the element objects will stay live
-               // during serialization, potentially using O(N^2) memory. Note that
-               // popping the stack will never result in reconstructing the active
-               // formatting elements.
-               $this->afe = null;
-               $this->stack->popTo( 1 );
-       }
-
-       private function parseRawText( $value, $attribs = null ) {
-               $this->stack->insertHTMLElement( $value, $attribs );
-               $this->inRAWTEXT = $value;
-               $this->originalInsertionMode = $this->switchMode( 'inTextMode' );
-               return true;
-       }
-
-       private function inTextMode( $token, $value, $attribs = null, $selfClose = false ) {
-               if ( $token === 'text' ) {
-                       $this->stack->insertText( $value );
-                       return true;
-               } elseif ( $token === 'eof' ) {
-                       $this->stack->pop();
-                       return $this->switchModeAndReprocess(
-                               $this->originalInsertionMode, $token, $value, $attribs, $selfClose
-                       );
-               } elseif ( $token === 'endtag' ) {
-                       $this->stack->pop();
-                       $this->switchMode( $this->originalInsertionMode );
-                       return true;
-               }
-               return true;
-       }
-
-       private function inHeadMode( $token, $value, $attribs = null, $selfClose = false ) {
-               if ( $token === 'text' ) {
-                       if ( preg_match( '/^[\x09\x0A\x0C\x0D\x20]+/', $value, $matches ) ) {
-                               $this->stack->insertText( $matches[0] );
-                               $value = substr( $value, strlen( $matches[0] ) );
-                       }
-                       if ( strlen( $value ) === 0 ) {
-                               return true; // All text handled.
-                       }
-                       // Fall through to handle non-whitespace below.
-               } elseif ( $token === 'tag' ) {
-                       switch ( $value ) {
-                               case 'meta':
-                                       // OMITTED: in a full HTML parser, this might change the encoding.
-                                       // falls through
-                               // OMITTED: <html>
-                               case 'base':
-                               case 'basefont':
-                               case 'bgsound':
-                               case 'link':
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       $this->stack->pop();
-                                       return true;
-                               // OMITTED: <title>
-                               // OMITTED: <noscript>
-                               case 'noframes':
-                               case 'style':
-                                       return $this->parseRawText( $value, $attribs );
-                               // OMITTED: <script>
-                               case 'template':
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       $this->afe->insertMarker();
-                                       // OMITTED: frameset_ok
-                                       $this->switchMode( 'inTemplateMode' );
-                                       $this->templateInsertionModes[] = $this->parseMode;
-                                       return true;
-                               // OMITTED: <head>
-                       }
-               } elseif ( $token === 'endtag' ) {
-                       switch ( $value ) {
-                               // OMITTED: <head>
-                               // OMITTED: <body>
-                               // OMITTED: <html>
-                               case 'br':
-                                       break; // handle at the bottom of the function
-                               case 'template':
-                                       if ( $this->stack->indexOf( $value ) < 0 ) {
-                                               return true; // Ignore the token.
-                                       }
-                                       $this->stack->generateImpliedEndTags( null, true /* thorough */ );
-                                       $this->stack->popTag( $value );
-                                       $this->afe->clearToMarker();
-                                       array_pop( $this->templateInsertionModes );
-                                       $this->resetInsertionMode();
-                                       return true;
-                               default:
-                                       // ignore any other end tag
-                                       return true;
-                       }
-               } elseif ( $token === 'comment' ) {
-                       $this->stack->insertComment( $value );
-                       return true;
-               }
-
-               // If not handled above
-               $this->inHeadMode( 'endtag', 'head' ); // synthetic </head>
-               // Then redo this one
-               return $this->insertToken( $token, $value, $attribs, $selfClose );
-       }
-
-       private function inBodyMode( $token, $value, $attribs = null, $selfClose = false ) {
-               if ( $token === 'text' ) {
-                       $this->afe->reconstruct( $this->stack );
-                       $this->stack->insertText( $value );
-                       return true;
-               } elseif ( $token === 'eof' ) {
-                       if ( !empty( $this->templateInsertionModes ) ) {
-                               return $this->inTemplateMode( $token, $value, $attribs, $selfClose );
-                       }
-                       $this->stopParsing();
-                       return true;
-               } elseif ( $token === 'tag' ) {
-                       switch ( $value ) {
-                               // OMITTED: <html>
-                               case 'base':
-                               case 'basefont':
-                               case 'bgsound':
-                               case 'link':
-                               case 'meta':
-                               case 'noframes':
-                               // OMITTED: <script>
-                               case 'style':
-                               case 'template':
-                               // OMITTED: <title>
-                                       return $this->inHeadMode( $token, $value, $attribs, $selfClose );
-                               // OMITTED: <body>
-                               // OMITTED: <frameset>
-
-                               case 'address':
-                               case 'article':
-                               case 'aside':
-                               case 'blockquote':
-                               case 'center':
-                               case 'details':
-                               case 'dialog':
-                               case 'dir':
-                               case 'div':
-                               case 'dl':
-                               case 'fieldset':
-                               case 'figcaption':
-                               case 'figure':
-                               case 'footer':
-                               case 'header':
-                               case 'hgroup':
-                               case 'main':
-                               case 'nav':
-                               case 'ol':
-                               case 'p':
-                               case 'section':
-                               case 'summary':
-                               case 'ul':
-                                       if ( $this->stack->inButtonScope( 'p' ) ) {
-                                               $this->inBodyMode( 'endtag', 'p' );
-                                       }
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       return true;
-
-                               case 'menu':
-                                       if ( $this->stack->inButtonScope( "p" ) ) {
-                                               $this->inBodyMode( 'endtag', 'p' );
-                                       }
-                                       if ( $this->stack->currentNode->isHtmlNamed( 'menuitem' ) ) {
-                                               $this->stack->pop();
-                                       }
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       return true;
-
-                               case 'h1':
-                               case 'h2':
-                               case 'h3':
-                               case 'h4':
-                               case 'h5':
-                               case 'h6':
-                                       if ( $this->stack->inButtonScope( 'p' ) ) {
-                                               $this->inBodyMode( 'endtag', 'p' );
-                                       }
-                                       if ( $this->stack->currentNode->isA( BalanceSets::$headingSet ) ) {
-                                               $this->stack->pop();
-                                       }
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       return true;
-
-                               case 'pre':
-                               case 'listing':
-                                       if ( $this->stack->inButtonScope( 'p' ) ) {
-                                               $this->inBodyMode( 'endtag', 'p' );
-                                       }
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       $this->ignoreLinefeed = true;
-                                       // OMITTED: frameset_ok
-                                       return true;
-
-                               case 'form':
-                                       if (
-                                               $this->formElementPointer &&
-                                               $this->stack->indexOf( 'template' ) < 0
-                                       ) {
-                                               return true; // in a form, not in a template.
-                                       }
-                                       if ( $this->stack->inButtonScope( "p" ) ) {
-                                               $this->inBodyMode( 'endtag', 'p' );
-                                       }
-                                       $elt = $this->stack->insertHTMLElement( $value, $attribs );
-                                       if ( $this->stack->indexOf( 'template' ) < 0 ) {
-                                               $this->formElementPointer = $elt;
-                                       }
-                                       return true;
-
-                               case 'li':
-                                       // OMITTED: frameset_ok
-                                       foreach ( $this->stack as $node ) {
-                                               if ( $node->isHtmlNamed( 'li' ) ) {
-                                                       $this->inBodyMode( 'endtag', 'li' );
-                                                       break;
-                                               }
-                                               if (
-                                                       $node->isA( BalanceSets::$specialSet ) &&
-                                                       !$node->isA( BalanceSets::$addressDivPSet )
-                                               ) {
-                                                       break;
-                                               }
-                                       }
-                                       if ( $this->stack->inButtonScope( 'p' ) ) {
-                                               $this->inBodyMode( 'endtag', 'p' );
-                                       }
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       return true;
-
-                               case 'dd':
-                               case 'dt':
-                                       // OMITTED: frameset_ok
-                                       foreach ( $this->stack as $node ) {
-                                               if ( $node->isHtmlNamed( 'dd' ) ) {
-                                                       $this->inBodyMode( 'endtag', 'dd' );
-                                                       break;
-                                               }
-                                               if ( $node->isHtmlNamed( 'dt' ) ) {
-                                                       $this->inBodyMode( 'endtag', 'dt' );
-                                                       break;
-                                               }
-                                               if (
-                                                       $node->isA( BalanceSets::$specialSet ) &&
-                                                       !$node->isA( BalanceSets::$addressDivPSet )
-                                               ) {
-                                                       break;
-                                               }
-                                       }
-                                       if ( $this->stack->inButtonScope( 'p' ) ) {
-                                               $this->inBodyMode( 'endtag', 'p' );
-                                       }
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       return true;
-
-                               // OMITTED: <plaintext>
-
-                               case 'button':
-                                       if ( $this->stack->inScope( 'button' ) ) {
-                                               $this->inBodyMode( 'endtag', 'button' );
-                                               return $this->insertToken( $token, $value, $attribs, $selfClose );
-                                       }
-                                       $this->afe->reconstruct( $this->stack );
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       return true;
-
-                               case 'a':
-                                       $activeElement = $this->afe->findElementByTag( 'a' );
-                                       if ( $activeElement ) {
-                                               $this->inBodyMode( 'endtag', 'a' );
-                                               if ( $this->afe->isInList( $activeElement ) ) {
-                                                       $this->afe->remove( $activeElement );
-                                                       // Don't flatten here, since when we fall
-                                                       // through below we might foster parent
-                                                       // the new <a> tag inside this one.
-                                                       $this->stack->removeElement( $activeElement, false );
-                                               }
-                                       }
-                                       // Falls through
-                               case 'b':
-                               case 'big':
-                               case 'code':
-                               case 'em':
-                               case 'font':
-                               case 'i':
-                               case 's':
-                               case 'small':
-                               case 'strike':
-                               case 'strong':
-                               case 'tt':
-                               case 'u':
-                                       $this->afe->reconstruct( $this->stack );
-                                       $this->afe->push( $this->stack->insertHTMLElement( $value, $attribs ) );
-                                       return true;
-
-                               case 'nobr':
-                                       $this->afe->reconstruct( $this->stack );
-                                       if ( $this->stack->inScope( 'nobr' ) ) {
-                                               $this->inBodyMode( 'endtag', 'nobr' );
-                                               $this->afe->reconstruct( $this->stack );
-                                       }
-                                       $this->afe->push( $this->stack->insertHTMLElement( $value, $attribs ) );
-                                       return true;
-
-                               case 'applet':
-                               case 'marquee':
-                               case 'object':
-                                       $this->afe->reconstruct( $this->stack );
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       $this->afe->insertMarker();
-                                       // OMITTED: frameset_ok
-                                       return true;
-
-                               case 'table':
-                                       // The document is never in "quirks mode"; see simplifications
-                                       // above.
-                                       if ( $this->stack->inButtonScope( 'p' ) ) {
-                                               $this->inBodyMode( 'endtag', 'p' );
-                                       }
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       // OMITTED: frameset_ok
-                                       $this->switchMode( 'inTableMode' );
-                                       return true;
-
-                               case 'area':
-                               case 'br':
-                               case 'embed':
-                               case 'img':
-                               case 'keygen':
-                               case 'wbr':
-                                       $this->afe->reconstruct( $this->stack );
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       $this->stack->pop();
-                                       // OMITTED: frameset_ok
-                                       return true;
-
-                               case 'input':
-                                       $this->afe->reconstruct( $this->stack );
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       $this->stack->pop();
-                                       // OMITTED: frameset_ok
-                                       // (hence we don't need to examine the tag's "type" attribute)
-                                       return true;
-
-                               case 'param':
-                               case 'source':
-                               case 'track':
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       $this->stack->pop();
-                                       return true;
-
-                               case 'hr':
-                                       if ( $this->stack->inButtonScope( 'p' ) ) {
-                                               $this->inBodyMode( 'endtag', 'p' );
-                                       }
-                                       if ( $this->stack->currentNode->isHtmlNamed( 'menuitem' ) ) {
-                                               $this->stack->pop();
-                                       }
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       $this->stack->pop();
-                                       return true;
-
-                               case 'image':
-                                       // warts!
-                                       return $this->inBodyMode( $token, 'img', $attribs, $selfClose );
-
-                               case 'textarea':
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       $this->ignoreLinefeed = true;
-                                       $this->inRCDATA = $value; // emulate rcdata tokenizer mode
-                                       // OMITTED: frameset_ok
-                                       return true;
-
-                               // OMITTED: <xmp>
-                               // OMITTED: <iframe>
-                               // OMITTED: <noembed>
-                               // OMITTED: <noscript>
-
-                               case 'select':
-                                       $this->afe->reconstruct( $this->stack );
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       switch ( $this->parseMode ) {
-                                               case 'inTableMode':
-                                               case 'inCaptionMode':
-                                               case 'inTableBodyMode':
-                                               case 'inRowMode':
-                                               case 'inCellMode':
-                                                       $this->switchMode( 'inSelectInTableMode' );
-                                                       return true;
-                                               default:
-                                                       $this->switchMode( 'inSelectMode' );
-                                                       return true;
-                                       }
-
-                               case 'optgroup':
-                               case 'option':
-                                       if ( $this->stack->currentNode->isHtmlNamed( 'option' ) ) {
-                                               $this->inBodyMode( 'endtag', 'option' );
-                                       }
-                                       $this->afe->reconstruct( $this->stack );
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       return true;
-
-                               case 'menuitem':
-                                       if ( $this->stack->currentNode->isHtmlNamed( 'menuitem' ) ) {
-                                               $this->stack->pop();
-                                       }
-                                       $this->afe->reconstruct( $this->stack );
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       return true;
-
-                               case 'rb':
-                               case 'rtc':
-                                       if ( $this->stack->inScope( 'ruby' ) ) {
-                                               $this->stack->generateImpliedEndTags();
-                                       }
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       return true;
-
-                               case 'rp':
-                               case 'rt':
-                                       if ( $this->stack->inScope( 'ruby' ) ) {
-                                               $this->stack->generateImpliedEndTags( 'rtc' );
-                                       }
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       return true;
-
-                               case 'math':
-                                       $this->afe->reconstruct( $this->stack );
-                                       // We skip the spec's "adjust MathML attributes" and
-                                       // "adjust foreign attributes" steps, since the browser will
-                                       // do this later when it parses the output and it doesn't affect
-                                       // balancing.
-                                       $this->stack->insertForeignElement(
-                                               BalanceSets::MATHML_NAMESPACE, $value, $attribs
-                                       );
-                                       if ( $selfClose ) {
-                                               // emit explicit </math> tag.
-                                               $this->stack->pop();
-                                       }
-                                       return true;
-
-                               case 'svg':
-                                       $this->afe->reconstruct( $this->stack );
-                                       // We skip the spec's "adjust SVG attributes" and
-                                       // "adjust foreign attributes" steps, since the browser will
-                                       // do this later when it parses the output and it doesn't affect
-                                       // balancing.
-                                       $this->stack->insertForeignElement(
-                                               BalanceSets::SVG_NAMESPACE, $value, $attribs
-                                       );
-                                       if ( $selfClose ) {
-                                               // emit explicit </svg> tag.
-                                               $this->stack->pop();
-                                       }
-                                       return true;
-
-                               case 'caption':
-                               case 'col':
-                               case 'colgroup':
-                               // OMITTED: <frame>
-                               case 'head':
-                               case 'tbody':
-                               case 'td':
-                               case 'tfoot':
-                               case 'th':
-                               case 'thead':
-                               case 'tr':
-                                       // Ignore table tags if we're not inTableMode
-                                       return true;
-                       }
-
-                       // Handle any other start tag here
-                       $this->afe->reconstruct( $this->stack );
-                       $this->stack->insertHTMLElement( $value, $attribs );
-                       return true;
-               } elseif ( $token === 'endtag' ) {
-                       switch ( $value ) {
-                               // </body>,</html> are unsupported.
-
-                               case 'template':
-                                       return $this->inHeadMode( $token, $value, $attribs, $selfClose );
-
-                               case 'address':
-                               case 'article':
-                               case 'aside':
-                               case 'blockquote':
-                               case 'button':
-                               case 'center':
-                               case 'details':
-                               case 'dialog':
-                               case 'dir':
-                               case 'div':
-                               case 'dl':
-                               case 'fieldset':
-                               case 'figcaption':
-                               case 'figure':
-                               case 'footer':
-                               case 'header':
-                               case 'hgroup':
-                               case 'listing':
-                               case 'main':
-                               case 'menu':
-                               case 'nav':
-                               case 'ol':
-                               case 'pre':
-                               case 'section':
-                               case 'summary':
-                               case 'ul':
-                                       // Ignore if there is not a matching open tag
-                                       if ( !$this->stack->inScope( $value ) ) {
-                                               return true;
-                                       }
-                                       $this->stack->generateImpliedEndTags();
-                                       $this->stack->popTag( $value );
-                                       return true;
-
-                               case 'form':
-                                       if ( $this->stack->indexOf( 'template' ) < 0 ) {
-                                               $openform = $this->formElementPointer;
-                                               $this->formElementPointer = null;
-                                               if ( !$openform || !$this->stack->inScope( $openform ) ) {
-                                                       return true;
-                                               }
-                                               $this->stack->generateImpliedEndTags();
-                                               // Don't flatten yet if we're removing a <form> element
-                                               // out-of-order. (eg. `<form><div></form>`)
-                                               $flatten = ( $this->stack->currentNode === $openform );
-                                               $this->stack->removeElement( $openform, $flatten );
-                                       } else {
-                                               if ( !$this->stack->inScope( 'form' ) ) {
-                                                       return true;
-                                               }
-                                               $this->stack->generateImpliedEndTags();
-                                               $this->stack->popTag( 'form' );
-                                       }
-                                       return true;
-
-                               case 'p':
-                                       if ( !$this->stack->inButtonScope( 'p' ) ) {
-                                               $this->inBodyMode( 'tag', 'p', [] );
-                                               return $this->insertToken( $token, $value, $attribs, $selfClose );
-                                       }
-                                       $this->stack->generateImpliedEndTags( $value );
-                                       $this->stack->popTag( $value );
-                                       return true;
-
-                               case 'li':
-                                       if ( !$this->stack->inListItemScope( $value ) ) {
-                                               return true; // ignore
-                                       }
-                                       $this->stack->generateImpliedEndTags( $value );
-                                       $this->stack->popTag( $value );
-                                       return true;
-
-                               case 'dd':
-                               case 'dt':
-                                       if ( !$this->stack->inScope( $value ) ) {
-                                               return true; // ignore
-                                       }
-                                       $this->stack->generateImpliedEndTags( $value );
-                                       $this->stack->popTag( $value );
-                                       return true;
-
-                               case 'h1':
-                               case 'h2':
-                               case 'h3':
-                               case 'h4':
-                               case 'h5':
-                               case 'h6':
-                                       if ( !$this->stack->inScope( BalanceSets::$headingSet ) ) {
-                                               return true; // ignore
-                                       }
-                                       $this->stack->generateImpliedEndTags();
-                                       $this->stack->popTag( BalanceSets::$headingSet );
-                                       return true;
-
-                               case 'sarcasm':
-                                       // Take a deep breath, then:
-                                       break;
-
-                               case 'a':
-                               case 'b':
-                               case 'big':
-                               case 'code':
-                               case 'em':
-                               case 'font':
-                               case 'i':
-                               case 'nobr':
-                               case 's':
-                               case 'small':
-                               case 'strike':
-                               case 'strong':
-                               case 'tt':
-                               case 'u':
-                                       if ( $this->stack->adoptionAgency( $value, $this->afe ) ) {
-                                               return true; // If we did something, we're done.
-                                       }
-                                       break; // Go to the "any other end tag" case.
-
-                               case 'applet':
-                               case 'marquee':
-                               case 'object':
-                                       if ( !$this->stack->inScope( $value ) ) {
-                                               return true; // ignore
-                                       }
-                                       $this->stack->generateImpliedEndTags();
-                                       $this->stack->popTag( $value );
-                                       $this->afe->clearToMarker();
-                                       return true;
-
-                               case 'br':
-                                       // Turn </br> into <br>
-                                       return $this->inBodyMode( 'tag', $value, [] );
-                       }
-
-                       // Any other end tag goes here
-                       foreach ( $this->stack as $i => $node ) {
-                               if ( $node->isHtmlNamed( $value ) ) {
-                                       $this->stack->generateImpliedEndTags( $value );
-                                       $this->stack->popTo( $i ); // including $i
-                                       break;
-                               } elseif ( $node->isA( BalanceSets::$specialSet ) ) {
-                                       return true; // ignore this close token.
-                               }
-                       }
-                       return true;
-               } elseif ( $token === 'comment' ) {
-                       $this->stack->insertComment( $value );
-                       return true;
-               } else {
-                       Assert::invariant( false, "Bad token type: $token" );
-               }
-       }
-
-       private function inTableMode( $token, $value, $attribs = null, $selfClose = false ) {
-               if ( $token === 'text' ) {
-                       if ( $this->textIntegrationMode ) {
-                               return $this->inBodyMode( $token, $value, $attribs, $selfClose );
-                       } elseif ( $this->stack->currentNode->isA( BalanceSets::$tableSectionRowSet ) ) {
-                               $this->pendingTableText = '';
-                               $this->originalInsertionMode = $this->parseMode;
-                               return $this->switchModeAndReprocess( 'inTableTextMode',
-                                       $token, $value, $attribs, $selfClose );
-                       }
-                       // fall through to default case.
-               } elseif ( $token === 'eof' ) {
-                       $this->stopParsing();
-                       return true;
-               } elseif ( $token === 'tag' ) {
-                       switch ( $value ) {
-                               case 'caption':
-                                       $this->afe->insertMarker();
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       $this->switchMode( 'inCaptionMode' );
-                                       return true;
-                               case 'colgroup':
-                                       $this->stack->clearToContext( BalanceSets::$tableContextSet );
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       $this->switchMode( 'inColumnGroupMode' );
-                                       return true;
-                               case 'col':
-                                       $this->inTableMode( 'tag', 'colgroup', [] );
-                                       return $this->insertToken( $token, $value, $attribs, $selfClose );
-                               case 'tbody':
-                               case 'tfoot':
-                               case 'thead':
-                                       $this->stack->clearToContext( BalanceSets::$tableContextSet );
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       $this->switchMode( 'inTableBodyMode' );
-                                       return true;
-                               case 'td':
-                               case 'th':
-                               case 'tr':
-                                       $this->inTableMode( 'tag', 'tbody', [] );
-                                       return $this->insertToken( $token, $value, $attribs, $selfClose );
-                               case 'table':
-                                       if ( !$this->stack->inTableScope( $value ) ) {
-                                               return true; // Ignore this tag.
-                                       }
-                                       $this->inTableMode( 'endtag', $value );
-                                       return $this->insertToken( $token, $value, $attribs, $selfClose );
-
-                               case 'style':
-                               // OMITTED: <script>
-                               case 'template':
-                                       return $this->inHeadMode( $token, $value, $attribs, $selfClose );
-
-                               case 'input':
-                                       if ( !isset( $attribs['type'] ) || strcasecmp( $attribs['type'], 'hidden' ) !== 0 ) {
-                                               break; // Handle this as "everything else"
-                                       }
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       $this->stack->pop();
-                                       return true;
-
-                               case 'form':
-                                       if (
-                                               $this->formElementPointer ||
-                                               $this->stack->indexOf( 'template' ) >= 0
-                                       ) {
-                                               return true; // ignore this token
-                                       }
-                                       $this->formElementPointer =
-                                               $this->stack->insertHTMLElement( $value, $attribs );
-                                       $this->stack->popTag( $this->formElementPointer );
-                                       return true;
-                       }
-                       // Fall through for "anything else" clause.
-               } elseif ( $token === 'endtag' ) {
-                       switch ( $value ) {
-                               case 'table':
-                                       if ( !$this->stack->inTableScope( $value ) ) {
-                                               return true; // Ignore.
-                                       }
-                                       $this->stack->popTag( $value );
-                                       $this->resetInsertionMode();
-                                       return true;
-                               // OMITTED: <body>
-                               case 'caption':
-                               case 'col':
-                               case 'colgroup':
-                               // OMITTED: <html>
-                               case 'tbody':
-                               case 'td':
-                               case 'tfoot':
-                               case 'th':
-                               case 'thead':
-                               case 'tr':
-                                       return true; // Ignore the token.
-                               case 'template':
-                                       return $this->inHeadMode( $token, $value, $attribs, $selfClose );
-                       }
-                       // Fall through for "anything else" clause.
-               } elseif ( $token === 'comment' ) {
-                       $this->stack->insertComment( $value );
-                       return true;
-               }
-               // This is the "anything else" case:
-               $this->stack->fosterParentMode = true;
-               $this->inBodyMode( $token, $value, $attribs, $selfClose );
-               $this->stack->fosterParentMode = false;
-               return true;
-       }
-
-       private function inTableTextMode( $token, $value, $attribs = null, $selfClose = false ) {
-               if ( $token === 'text' ) {
-                       $this->pendingTableText .= $value;
-                       return true;
-               }
-               // Non-text token:
-               $text = $this->pendingTableText;
-               $this->pendingTableText = '';
-               if ( preg_match( '/[^\x09\x0A\x0C\x0D\x20]/', $text ) ) {
-                       // This should match the "anything else" case inTableMode
-                       $this->stack->fosterParentMode = true;
-                       $this->inBodyMode( 'text', $text );
-                       $this->stack->fosterParentMode = false;
-               } else {
-                       // Pending text is just whitespace.
-                       $this->stack->insertText( $text );
-               }
-               return $this->switchModeAndReprocess(
-                       $this->originalInsertionMode, $token, $value, $attribs, $selfClose
-               );
-       }
-
-       // helper for inCaptionMode
-       private function endCaption() {
-               if ( !$this->stack->inTableScope( 'caption' ) ) {
-                       return false;
-               }
-               $this->stack->generateImpliedEndTags();
-               $this->stack->popTag( 'caption' );
-               $this->afe->clearToMarker();
-               $this->switchMode( 'inTableMode' );
-               return true;
-       }
-
-       private function inCaptionMode( $token, $value, $attribs = null, $selfClose = false ) {
-               if ( $token === 'tag' ) {
-                       switch ( $value ) {
-                               case 'caption':
-                               case 'col':
-                               case 'colgroup':
-                               case 'tbody':
-                               case 'td':
-                               case 'tfoot':
-                               case 'th':
-                               case 'thead':
-                               case 'tr':
-                                       if ( $this->endCaption() ) {
-                                               $this->insertToken( $token, $value, $attribs, $selfClose );
-                                       }
-                                       return true;
-                       }
-                       // Fall through to "anything else" case.
-               } elseif ( $token === 'endtag' ) {
-                       switch ( $value ) {
-                               case 'caption':
-                                       $this->endCaption();
-                                       return true;
-                               case 'table':
-                                       if ( $this->endCaption() ) {
-                                               $this->insertToken( $token, $value, $attribs, $selfClose );
-                                       }
-                                       return true;
-                               case 'body':
-                               case 'col':
-                               case 'colgroup':
-                               // OMITTED: <html>
-                               case 'tbody':
-                               case 'td':
-                               case 'tfoot':
-                               case 'th':
-                               case 'thead':
-                               case 'tr':
-                                       // Ignore the token
-                                       return true;
-                       }
-                       // Fall through to "anything else" case.
-               }
-               // The Anything Else case
-               return $this->inBodyMode( $token, $value, $attribs, $selfClose );
-       }
-
-       private function inColumnGroupMode( $token, $value, $attribs = null, $selfClose = false ) {
-               if ( $token === 'text' ) {
-                       if ( preg_match( '/^[\x09\x0A\x0C\x0D\x20]+/', $value, $matches ) ) {
-                               $this->stack->insertText( $matches[0] );
-                               $value = substr( $value, strlen( $matches[0] ) );
-                       }
-                       if ( strlen( $value ) === 0 ) {
-                               return true; // All text handled.
-                       }
-                       // Fall through to handle non-whitespace below.
-               } elseif ( $token === 'tag' ) {
-                       switch ( $value ) {
-                               // OMITTED: <html>
-                               case 'col':
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       $this->stack->pop();
-                                       return true;
-                               case 'template':
-                                       return $this->inHeadMode( $token, $value, $attribs, $selfClose );
-                       }
-                       // Fall through for "anything else".
-               } elseif ( $token === 'endtag' ) {
-                       switch ( $value ) {
-                               case 'colgroup':
-                                       if ( !$this->stack->currentNode->isHtmlNamed( 'colgroup' ) ) {
-                                               return true; // Ignore the token.
-                                       }
-                                       $this->stack->pop();
-                                       $this->switchMode( 'inTableMode' );
-                                       return true;
-                               case 'col':
-                                       return true; // Ignore the token.
-                               case 'template':
-                                       return $this->inHeadMode( $token, $value, $attribs, $selfClose );
-                       }
-                       // Fall through for "anything else".
-               } elseif ( $token === 'eof' ) {
-                       return $this->inBodyMode( $token, $value, $attribs, $selfClose );
-               } elseif ( $token === 'comment' ) {
-                       $this->stack->insertComment( $value );
-                       return true;
-               }
-
-               // Anything else
-               if ( !$this->stack->currentNode->isHtmlNamed( 'colgroup' ) ) {
-                       return true; // Ignore the token.
-               }
-               $this->inColumnGroupMode( 'endtag', 'colgroup' );
-               return $this->insertToken( $token, $value, $attribs, $selfClose );
-       }
-
-       // Helper function for inTableBodyMode
-       private function endSection() {
-               if ( !(
-                       $this->stack->inTableScope( 'tbody' ) ||
-                       $this->stack->inTableScope( 'thead' ) ||
-                       $this->stack->inTableScope( 'tfoot' )
-               ) ) {
-                       return false;
-               }
-               $this->stack->clearToContext( BalanceSets::$tableBodyContextSet );
-               $this->stack->pop();
-               $this->switchMode( 'inTableMode' );
-               return true;
-       }
-       private function inTableBodyMode( $token, $value, $attribs = null, $selfClose = false ) {
-               if ( $token === 'tag' ) {
-                       switch ( $value ) {
-                               case 'tr':
-                                       $this->stack->clearToContext( BalanceSets::$tableBodyContextSet );
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       $this->switchMode( 'inRowMode' );
-                                       return true;
-                               case 'th':
-                               case 'td':
-                                       $this->inTableBodyMode( 'tag', 'tr', [] );
-                                       $this->insertToken( $token, $value, $attribs, $selfClose );
-                                       return true;
-                               case 'caption':
-                               case 'col':
-                               case 'colgroup':
-                               case 'tbody':
-                               case 'tfoot':
-                               case 'thead':
-                                       if ( $this->endSection() ) {
-                                               $this->insertToken( $token, $value, $attribs, $selfClose );
-                                       }
-                                       return true;
-                       }
-               } elseif ( $token === 'endtag' ) {
-                       switch ( $value ) {
-                               case 'table':
-                                       if ( $this->endSection() ) {
-                                               $this->insertToken( $token, $value, $attribs, $selfClose );
-                                       }
-                                       return true;
-                               case 'tbody':
-                               case 'tfoot':
-                               case 'thead':
-                                       if ( $this->stack->inTableScope( $value ) ) {
-                                               $this->endSection();
-                                       }
-                                       return true;
-                               // OMITTED: <body>
-                               case 'caption':
-                               case 'col':
-                               case 'colgroup':
-                               // OMITTED: <html>
-                               case 'td':
-                               case 'th':
-                               case 'tr':
-                                       return true; // Ignore the token.
-                       }
-               }
-               // Anything else:
-               return $this->inTableMode( $token, $value, $attribs, $selfClose );
-       }
-
-       // Helper function for inRowMode
-       private function endRow() {
-               if ( !$this->stack->inTableScope( 'tr' ) ) {
-                       return false;
-               }
-               $this->stack->clearToContext( BalanceSets::$tableRowContextSet );
-               $this->stack->pop();
-               $this->switchMode( 'inTableBodyMode' );
-               return true;
-       }
-       private function inRowMode( $token, $value, $attribs = null, $selfClose = false ) {
-               if ( $token === 'tag' ) {
-                       switch ( $value ) {
-                               case 'th':
-                               case 'td':
-                                       $this->stack->clearToContext( BalanceSets::$tableRowContextSet );
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       $this->switchMode( 'inCellMode' );
-                                       $this->afe->insertMarker();
-                                       return true;
-                               case 'caption':
-                               case 'col':
-                               case 'colgroup':
-                               case 'tbody':
-                               case 'tfoot':
-                               case 'thead':
-                               case 'tr':
-                                       if ( $this->endRow() ) {
-                                               $this->insertToken( $token, $value, $attribs, $selfClose );
-                                       }
-                                       return true;
-                       }
-               } elseif ( $token === 'endtag' ) {
-                       switch ( $value ) {
-                               case 'tr':
-                                       $this->endRow();
-                                       return true;
-                               case 'table':
-                                       if ( $this->endRow() ) {
-                                               $this->insertToken( $token, $value, $attribs, $selfClose );
-                                       }
-                                       return true;
-                               case 'tbody':
-                               case 'tfoot':
-                               case 'thead':
-                                       if (
-                                               $this->stack->inTableScope( $value ) &&
-                                               $this->endRow()
-                                       ) {
-                                               $this->insertToken( $token, $value, $attribs, $selfClose );
-                                       }
-                                       return true;
-                               // OMITTED: <body>
-                               case 'caption':
-                               case 'col':
-                               case 'colgroup':
-                               // OMITTED: <html>
-                               case 'td':
-                               case 'th':
-                                       return true; // Ignore the token.
-                       }
-               }
-               // Anything else:
-               return $this->inTableMode( $token, $value, $attribs, $selfClose );
-       }
-
-       // Helper for inCellMode
-       private function endCell() {
-               if ( $this->stack->inTableScope( 'td' ) ) {
-                       $this->inCellMode( 'endtag', 'td' );
-                       return true;
-               } elseif ( $this->stack->inTableScope( 'th' ) ) {
-                       $this->inCellMode( 'endtag', 'th' );
-                       return true;
-               } else {
-                       return false;
-               }
-       }
-       private function inCellMode( $token, $value, $attribs = null, $selfClose = false ) {
-               if ( $token === 'tag' ) {
-                       switch ( $value ) {
-                               case 'caption':
-                               case 'col':
-                               case 'colgroup':
-                               case 'tbody':
-                               case 'td':
-                               case 'tfoot':
-                               case 'th':
-                               case 'thead':
-                               case 'tr':
-                                       if ( $this->endCell() ) {
-                                               $this->insertToken( $token, $value, $attribs, $selfClose );
-                                       }
-                                       return true;
-                       }
-               } elseif ( $token === 'endtag' ) {
-                       switch ( $value ) {
-                               case 'td':
-                               case 'th':
-                                       if ( $this->stack->inTableScope( $value ) ) {
-                                               $this->stack->generateImpliedEndTags();
-                                               $this->stack->popTag( $value );
-                                               $this->afe->clearToMarker();
-                                               $this->switchMode( 'inRowMode' );
-                                       }
-                                       return true;
-                               // OMITTED: <body>
-                               case 'caption':
-                               case 'col':
-                               case 'colgroup':
-                               // OMITTED: <html>
-                                       return true;
-
-                               case 'table':
-                               case 'tbody':
-                               case 'tfoot':
-                               case 'thead':
-                               case 'tr':
-                                       if ( $this->stack->inTableScope( $value ) ) {
-                                               $this->stack->generateImpliedEndTags();
-                                               $this->stack->popTag( BalanceSets::$tableCellSet );
-                                               $this->afe->clearToMarker();
-                                               $this->switchMode( 'inRowMode' );
-                                               $this->insertToken( $token, $value, $attribs, $selfClose );
-                                       }
-                                       return true;
-                       }
-               }
-               // Anything else:
-               return $this->inBodyMode( $token, $value, $attribs, $selfClose );
-       }
-
-       private function inSelectMode( $token, $value, $attribs = null, $selfClose = false ) {
-               if ( $token === 'text' ) {
-                       $this->stack->insertText( $value );
-                       return true;
-               } elseif ( $token === 'eof' ) {
-                       return $this->inBodyMode( $token, $value, $attribs, $selfClose );
-               } elseif ( $token === 'tag' ) {
-                       switch ( $value ) {
-                               // OMITTED: <html>
-                               case 'option':
-                                       if ( $this->stack->currentNode->isHtmlNamed( 'option' ) ) {
-                                               $this->stack->pop();
-                                       }
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       return true;
-                               case 'optgroup':
-                                       if ( $this->stack->currentNode->isHtmlNamed( 'option' ) ) {
-                                               $this->stack->pop();
-                                       }
-                                       if ( $this->stack->currentNode->isHtmlNamed( 'optgroup' ) ) {
-                                               $this->stack->pop();
-                                       }
-                                       $this->stack->insertHTMLElement( $value, $attribs );
-                                       return true;
-                               case 'select':
-                                       $this->inSelectMode( 'endtag', $value ); // treat it like endtag
-                                       return true;
-                               case 'input':
-                               case 'keygen':
-                               case 'textarea':
-                                       if ( !$this->stack->inSelectScope( 'select' ) ) {
-                                               return true; // ignore token (fragment case)
-                                       }
-                                       $this->inSelectMode( 'endtag', 'select' );
-                                       return $this->insertToken( $token, $value, $attribs, $selfClose );
-                               case 'script':
-                               case 'template':
-                                       return $this->inHeadMode( $token, $value, $attribs, $selfClose );
-                       }
-               } elseif ( $token === 'endtag' ) {
-                       switch ( $value ) {
-                               case 'optgroup':
-                                       if (
-                                               $this->stack->currentNode->isHtmlNamed( 'option' ) &&
-                                               $this->stack->length() >= 2 &&
-                                               $this->stack->node( $this->stack->length() - 2 )->isHtmlNamed( 'optgroup' )
-                                       ) {
-                                               $this->stack->pop();
-                                       }
-                                       if ( $this->stack->currentNode->isHtmlNamed( 'optgroup' ) ) {
-                                               $this->stack->pop();
-                                       }
-                                       return true;
-                               case 'option':
-                                       if ( $this->stack->currentNode->isHtmlNamed( 'option' ) ) {
-                                               $this->stack->pop();
-                                       }
-                                       return true;
-                               case 'select':
-                                       if ( !$this->stack->inSelectScope( $value ) ) {
-                                               return true; // fragment case
-                                       }
-                                       $this->stack->popTag( $value );
-                                       $this->resetInsertionMode();
-                                       return true;
-                               case 'template':
-                                       return $this->inHeadMode( $token, $value, $attribs, $selfClose );
-                       }
-               } elseif ( $token === 'comment' ) {
-                       $this->stack->insertComment( $value );
-                       return true;
-               }
-               // anything else: just ignore the token
-               return true;
-       }
-
-       private function inSelectInTableMode( $token, $value, $attribs = null, $selfClose = false ) {
-               switch ( $value ) {
-                       case 'caption':
-                       case 'table':
-                       case 'tbody':
-                       case 'tfoot':
-                       case 'thead':
-                       case 'tr':
-                       case 'td':
-                       case 'th':
-                               if ( $token === 'tag' ) {
-                                       $this->inSelectInTableMode( 'endtag', 'select' );
-                                       return $this->insertToken( $token, $value, $attribs, $selfClose );
-                               } elseif ( $token === 'endtag' ) {
-                                       if ( $this->stack->inTableScope( $value ) ) {
-                                               $this->inSelectInTableMode( 'endtag', 'select' );
-                                               return $this->insertToken( $token, $value, $attribs, $selfClose );
-                                       }
-                                       return true;
-                               }
-               }
-               // anything else
-               return $this->inSelectMode( $token, $value, $attribs, $selfClose );
-       }
-
-       private function inTemplateMode( $token, $value, $attribs = null, $selfClose = false ) {
-               if ( $token === 'text' || $token === 'comment' ) {
-                       return $this->inBodyMode( $token, $value, $attribs, $selfClose );
-               } elseif ( $token === 'eof' ) {
-                       if ( $this->stack->indexOf( 'template' ) < 0 ) {
-                               $this->stopParsing();
-                       } else {
-                               $this->stack->popTag( 'template' );
-                               $this->afe->clearToMarker();
-                               array_pop( $this->templateInsertionModes );
-                               $this->resetInsertionMode();
-                               $this->insertToken( $token, $value, $attribs, $selfClose );
-                       }
-                       return true;
-               } elseif ( $token === 'tag' ) {
-                       switch ( $value ) {
-                               case 'base':
-                               case 'basefont':
-                               case 'bgsound':
-                               case 'link':
-                               case 'meta':
-                               case 'noframes':
-                               // OMITTED: <script>
-                               case 'style':
-                               case 'template':
-                               // OMITTED: <title>
-                                       return $this->inHeadMode( $token, $value, $attribs, $selfClose );
-
-                               case 'caption':
-                               case 'colgroup':
-                               case 'tbody':
-                               case 'tfoot':
-                               case 'thead':
-                                       return $this->switchModeAndReprocess(
-                                               'inTableMode', $token, $value, $attribs, $selfClose
-                                       );
-
-                               case 'col':
-                                       return $this->switchModeAndReprocess(
-                                               'inColumnGroupMode', $token, $value, $attribs, $selfClose
-                                       );
-
-                               case 'tr':
-                                       return $this->switchModeAndReprocess(
-                                               'inTableBodyMode', $token, $value, $attribs, $selfClose
-                                       );
-
-                               case 'td':
-                               case 'th':
-                                       return $this->switchModeAndReprocess(
-                                               'inRowMode', $token, $value, $attribs, $selfClose
-                                       );
-                       }
-                       return $this->switchModeAndReprocess(
-                               'inBodyMode', $token, $value, $attribs, $selfClose
-                       );
-               } elseif ( $token === 'endtag' ) {
-                       switch ( $value ) {
-                               case 'template':
-                                       return $this->inHeadMode( $token, $value, $attribs, $selfClose );
-                       }
-                       return true;
-               } else {
-                       Assert::invariant( false, "Bad token type: $token" );
-               }
-       }
-}
diff --git a/includes/tidy/Html5Depurate.php b/includes/tidy/Html5Depurate.php
deleted file mode 100644 (file)
index c6acd66..0000000
+++ /dev/null
@@ -1,47 +0,0 @@
-<?php
-
-namespace MediaWiki\Tidy;
-
-use MWHttpRequest;
-use Exception;
-
-class Html5Depurate extends TidyDriverBase {
-       public function __construct( array $config ) {
-               parent::__construct( $config + [
-                       'url' => 'http://localhost:4339/document',
-                       'timeout' => 10,
-                       'connectTimeout' => 0.5,
-               ] );
-       }
-
-       public function tidy( $text ) {
-               $wrappedtext = '<!DOCTYPE html><html>' .
-                       '<body>' . $text . '</body></html>';
-
-               $req = MWHttpRequest::factory( $this->config['url'],
-                       [
-                               'method' => 'POST',
-                               'timeout' => $this->config['timeout'],
-                               'connectTimeout' => $this->config['connectTimeout'],
-                               'postData' => [
-                                       'text' => $wrappedtext
-                               ]
-                       ] );
-               $status = $req->execute();
-               if ( !$status->isOK() ) {
-                       throw new Exception( "Error contacting depurate service: "
-                               . $status->getWikiText( false, false, 'en' ) );
-               } elseif ( $req->getStatus() !== 200 ) {
-                       throw new Exception( "Depurate returned error: " . $status->getWikiText( false, false, 'en' ) );
-               }
-               $result = $req->getContent();
-               $startBody = strpos( $result, "<body>" );
-               $endBody = strrpos( $result, "</body>" );
-               if ( $startBody !== false && $endBody !== false && $endBody > $startBody ) {
-                       $startBody += strlen( "<body>" );
-                       return substr( $result, $startBody, $endBody - $startBody );
-               } else {
-                       return $text . "\n<!-- Html5Depurate returned an invalid result -->";
-               }
-       }
-}
diff --git a/includes/tidy/Html5Internal.php b/includes/tidy/Html5Internal.php
deleted file mode 100644 (file)
index 4ad8200..0000000
+++ /dev/null
@@ -1,18 +0,0 @@
-<?php
-
-namespace MediaWiki\Tidy;
-
-class Html5Internal extends TidyDriverBase {
-       private $balancer;
-       public function __construct( array $config ) {
-               parent::__construct( $config + [
-                       'strict' => true,
-                       'tidyCompat' => true,
-               ] );
-               $this->balancer = new Balancer( $this->config );
-       }
-
-       public function tidy( $text ) {
-               return $this->balancer->balance( $text );
-       }
-}
diff --git a/tests/phpunit/includes/tidy/BalancerTest.php b/tests/phpunit/includes/tidy/BalancerTest.php
deleted file mode 100644 (file)
index 8a4f662..0000000
+++ /dev/null
@@ -1,169 +0,0 @@
-<?php
-
-class BalancerTest extends MediaWikiTestCase {
-
-       /**
-        * Anything that needs to happen before your tests should go here.
-        */
-       protected function setUp() {
-               // Be sure to do call the parent setup and teardown functions.
-               // This makes sure that all the various cleanup and restorations
-               // happen as they should (including the restoration for setMwGlobals).
-               parent::setUp();
-       }
-
-       /**
-        * @covers MediaWiki\Tidy\Balancer
-        * @covers MediaWiki\Tidy\BalanceSets
-        * @covers MediaWiki\Tidy\BalanceElement
-        * @covers MediaWiki\Tidy\BalanceStack
-        * @covers MediaWiki\Tidy\BalanceMarker
-        * @covers MediaWiki\Tidy\BalanceActiveFormattingElements
-        * @dataProvider provideBalancerTests
-        */
-       public function testBalancer( $description, $input, $expected, $useTidy ) {
-               $balancer = new MediaWiki\Tidy\Balancer( [
-                       'strict' => false, /* not strict */
-                       'allowedHtmlElements' => null, /* no sanitization */
-                       'tidyCompat' => $useTidy, /* standard parser */
-                       'allowComments' => true, /* comment parsing */
-               ] );
-               $output = $balancer->balance( $input );
-
-               // Ignore self-closing tags
-               $output = preg_replace( '/\s*\/>/', '>', $output );
-
-               $this->assertEquals( $expected, $output, $description );
-       }
-
-       public static function provideBalancerTests() {
-               // Get the tests from html5lib-tests.json
-               $json = json_decode( file_get_contents(
-                       __DIR__ . '/html5lib-tests.json'
-               ), true );
-               // Munge this slightly into the format phpunit expects
-               // for providers, and filter out HTML constructs which
-               // the balancer doesn't support.
-               $tests = [];
-               $okre = "~ \A
-                       (?i:<!DOCTYPE\ html>)?
-                       <html><head></head><body>
-                       .*
-                       </body></html>
-               \z ~xs";
-               foreach ( $json as $filename => $cases ) {
-                       foreach ( $cases as $case ) {
-                               $html = $case['document']['html'];
-                               if ( !preg_match( $okre, $html ) ) {
-                                       // Skip tests which involve stuff in the <head> or
-                                       // weird doctypes.
-                                       continue;
-                               }
-                               // We used to do this:
-                               //   $html = substr( $html, strlen( $start ), -strlen( $end ) );
-                               // But now we use a different field in the test case,
-                               // which reports how domino would parse this case in a
-                               // no-quirks <body> context.  (The original test case may
-                               // have had a different context, or relied on quirks mode.)
-                               $html = $case['document']['noQuirksBodyHtml'];
-                               // Normalize case of SVG attributes.
-                               $html = str_replace( 'foreignObject', 'foreignobject', $html );
-                               // Normalize case of MathML attributes.
-                               $html = str_replace( 'definitionURL', 'definitionurl', $html );
-
-                               if (
-                                       isset( $case['document']['props']['comment'] ) &&
-                                       preg_match( ',<!--[^>]*<,', $html )
-                               ) {
-                                       // Skip tests which include HTML comments containing
-                                       // the < character, which we don't support.
-                                       continue;
-                               }
-                               if ( strpos( $case['data'], '<![CDATA[' ) !== false ) {
-                                       // Skip tests involving <![CDATA[ ]]> quoting.
-                                       continue;
-                               }
-                               if (
-                                       stripos( $case['data'], '<!DOCTYPE' ) !== false &&
-                                       stripos( $case['data'], '<!DOCTYPE html>' ) === false
-                               ) {
-                                       // Skip tests involving unusual doctypes.
-                                       continue;
-                               }
-                               $literalre = "~ <rdar: | < /? (
-                                       html | head | body | frame | frameset | plaintext
-                               ) > ~xi";
-                               if ( preg_match( $literalre, $case['data'] ) ) {
-                                       // Skip tests involving some literal tags, which are
-                                       // unsupported but don't show up in the expected output.
-                                       continue;
-                               }
-                               if (
-                                       isset( $case['document']['props']['tags']['iframe'] ) ||
-                                       isset( $case['document']['props']['tags']['noembed'] ) ||
-                                       isset( $case['document']['props']['tags']['noscript'] ) ||
-                                       isset( $case['document']['props']['tags']['script'] ) ||
-                                       isset( $case['document']['props']['tags']['svg script'] ) ||
-                                       isset( $case['document']['props']['tags']['svg title'] ) ||
-                                       isset( $case['document']['props']['tags']['title'] ) ||
-                                       isset( $case['document']['props']['tags']['xmp'] )
-                               ) {
-                                       // Skip tests with unsupported tags which *do* show
-                                       // up in the expected output.
-                                       continue;
-                               }
-                               if (
-                                       $filename === 'entities01.dat' ||
-                                       $filename === 'entities02.dat' ||
-                                       preg_match( '/&([a-z]+|#x[0-9A-F]+);/i', $case['data'] ) ||
-                                       preg_match( '/^(&|&#|&#X|&#x|&#45|&x-test|&AMP)$/', $case['data'] )
-                               ) {
-                                       // Skip tests involving entity encoding.
-                                       continue;
-                               }
-                               if (
-                                       isset( $case['document']['props']['tagWithLt'] ) ||
-                                       isset( $case['document']['props']['attrWithFunnyChar'] ) ||
-                                       preg_match( ':^(</b test|<di|<foo bar=qux/>)$:', $case['data'] ) ||
-                                       preg_match( ':</p<p>:', $case['data'] ) ||
-                                       preg_match( ':<b &=&amp>|<p/x/y/z>:', $case['data'] )
-                               ) {
-                                       // Skip tests with funny tag or attribute names,
-                                       // which are really tests of the HTML tokenizer, not
-                                       // the tree builder.
-                                       continue;
-                               }
-                               if (
-                                       preg_match( ':encoding=" text/html "|type=" hidden":', $case['data'] )
-                               ) {
-                                       // The Sanitizer normalizes whitespace in attribute
-                                       // values, which makes this test case invalid.
-                                       continue;
-                               }
-                               if ( $filename === 'plain-text-unsafe.dat' ) {
-                                       // Skip tests with ASCII null, etc.
-                                       continue;
-                               }
-                               $data = preg_replace(
-                                       '~<!DOCTYPE html>~i', '', $case['data']
-                               );
-                               $tests[] = [
-                                       $filename, # use better description?
-                                       $data,
-                                       $html,
-                                       false # strict HTML5 compat mode, no tidy
-                               ];
-                       }
-               }
-
-               # Some additional tests for mediawiki-specific features
-               $tests[] = [
-                       'Round-trip serialization for <pre>/<listing>/<textarea>',
-                       "<pre>\n\na</pre><listing>\n\nb</listing><textarea>\n\nc</textarea>",
-                       "<pre>\n\na</pre><listing>\n\nb</listing><textarea>\n\nc</textarea>",
-                       true # use the tidy-compatible mode
-               ];
-
-               return $tests;
-       }
-}