Provide method for getting adjusted attribute names, and update testi…

…ng code.

src/wp-includes/html-api/class-wp-html-tag-processor.php

@@ -2898,6 +2898,245 @@ public function get_namespaced_tag_name(): ?string {
 		}
 	}
 
+	/**
+	 * Returns the adjusted attribute name for a given attribute, taking into
+	 * account the current parsing context, whether HTML, SVG, or MathML.
+	 *
+	 * @todo Find a better name.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @param string $attribute_name Which attribute to adjust.
+	 *
+	 * @return string|null
+	 */
+	public function get_namespaced_attribute_name( $attribute_name ): ?string {
+		if ( self::STATE_MATCHED_TAG !== $this->parser_state ) {
+			return null;
+		}
+
+		$lower_name = strtolower( $attribute_name );
+
+		if ( 'math' === $this->get_namespace() && 'definitionurl' === $lower_name ) {
+			return 'definitionURL';
+		}
+
+		if ( 'svg' === $this->get_namespace() ) {
+			switch ( $lower_name ) {
+				case 'attributename':
+					return 'attributeName';
+
+				case 'attributetype':
+					return 'attributeType';
+
+				case 'basefrequency':
+					return 'baseFrequency';
+
+				case 'baseprofile':
+					return 'baseProfile';
+
+				case 'calcmode':
+					return 'calcMode';
+
+				case 'clippathunits':
+					return 'clipPathUnits';
+
+				case 'diffuseconstant':
+					return 'diffuseConstant';
+
+				case 'edgemode':
+					return 'edgeMode';
+
+				case 'filterunits':
+					return 'filterUnits';
+
+				case 'glyphref':
+					return 'glyphRef';
+
+				case 'gradienttransform':
+					return 'gradientTransform';
+
+				case 'gradientunits':
+					return 'gradientUnits';
+
+				case 'kernelmatrix':
+					return 'kernelMatrix';
+
+				case 'kernelunitlength':
+					return 'kernelUnitLength';
+
+				case 'keypoints':
+					return 'keyPoints';
+
+				case 'keysplines':
+					return 'keySplines';
+
+				case 'keytimes':
+					return 'keyTimes';
+
+				case 'lengthadjust':
+					return 'lengthAdjust';
+
+				case 'limitingconeangle':
+					return 'limitingConeAngle';
+
+				case 'markerheight':
+					return 'markerHeight';
+
+				case 'markerunits':
+					return 'markerUnits';
+
+				case 'markerwidth':
+					return 'markerWidth';
+
+				case 'maskcontentunits':
+					return 'maskContentUnits';
+
+				case 'maskunits':
+					return 'maskUnits';
+
+				case 'numoctaves':
+					return 'numOctaves';
+
+				case 'pathlength':
+					return 'pathLength';
+
+				case 'patterncontentunits':
+					return 'patternContentUnits';
+
+				case 'patterntransform':
+					return 'patternTransform';
+
+				case 'patternunits':
+					return 'patternUnits';
+
+				case 'pointsatx':
+					return 'pointsAtX';
+
+				case 'pointsaty':
+					return 'pointsAtY';
+
+				case 'pointsatz':
+					return 'pointsAtZ';
+
+				case 'preservealpha':
+					return 'preserveAlpha';
+
+				case 'preserveaspectratio':
+					return 'preserveAspectRatio';
+
+				case 'primitiveunits':
+					return 'primitiveUnits';
+
+				case 'refx':
+					return 'refX';
+
+				case 'refy':
+					return 'refY';
+
+				case 'repeatcount':
+					return 'repeatCount';
+
+				case 'repeatdur':
+					return 'repeatDur';
+
+				case 'requiredextensions':
+					return 'requiredExtensions';
+
+				case 'requiredfeatures':
+					return 'requiredFeatures';
+
+				case 'specularconstant':
+					return 'specularConstant';
+
+				case 'specularexponent':
+					return 'specularExponent';
+
+				case 'spreadmethod':
+					return 'spreadMethod';
+
+				case 'startoffset':
+					return 'startOffset';
+
+				case 'stddeviation':
+					return 'stdDeviation';
+
+				case 'stitchtiles':
+					return 'stitchTiles';
+
+				case 'surfacescale':
+					return 'surfaceScale';
+
+				case 'systemlanguage':
+					return 'systemLanguage';
+
+				case 'tablevalues':
+					return 'tableValues';
+
+				case 'targetx':
+					return 'targetX';
+
+				case 'targety':
+					return 'targetY';
+
+				case 'textlength':
+					return 'textLength';
+
+				case 'viewbox':
+					return 'viewBox';
+
+				case 'viewtarget':
+					return 'viewTarget';
+
+				case 'xchannelselector':
+					return 'xChannelSelector';
+
+				case 'ychannelselector':
+					return 'yChannelSelector';
+
+				case 'zoomandpan':
+					return 'zoomAndPan';
+			}
+		}
+
+		switch ( $lower_name ) {
+			case 'xlink:actuate':
+				return 'xlink actuate';
+
+			case 'xlink:arcrole':
+				return 'xlink arcrole';
+
+			case 'xlink:href':
+				return 'xlink href';
+
+			case 'xlink:role':
+				return 'xlink role';
+
+			case 'xlink:show':
+				return 'xlink show';
+
+			case 'xlink:title':
+				return 'xlink title';
+
+			case 'xlink:type':
+				return 'xlink type';
+
+			case 'xml:lang':
+				return 'xml lang';
+
+			case 'xml:space':
+				return 'xml space';
+
+			case 'xmlns':
+				return 'xmlns';
+
+			case 'xmlns:xlink':
+				return 'xmlns xlink';
+		}
+
+		return $attribute_name;
+	}
+
 	/**
 	 * Indicates if the currently matched tag contains the self-closing flag.
 	 *

tests/phpunit/tests/html-api/wpHtmlProcessorHtml5lib.php

@@ -200,9 +200,47 @@ private static function build_tree_representation( ?string $fragment_context, st
 
 					$attribute_names = $processor->get_attribute_names_with_prefix( '' );
 					if ( $attribute_names ) {
-						sort( $attribute_names, SORT_STRING );
-
+						$sorted_attributes = array();
 						foreach ( $attribute_names as $attribute_name ) {
+							$sorted_attributes[ $attribute_name ] = $processor->get_namespaced_attribute_name( $attribute_name );
+						}
+
+						/*
+						 * Sorts attributes to match html5lib sort order.
+						 *
+						 *  - First comes normal HTML attributes.
+						 *  - Then come adjusted foreign attributes; these have spaces in their names.
+						 *  - Finally come non-adjusted foreign attributes; these have a colon in their names.
+						 *
+						 * Example:
+						 *
+						 *       From: <math xlink:author definitionurl xlink:title xlink:show>
+						 *     Sorted: 'definitionURL', 'xlink show', 'xlink title', 'xlink:author'
+						 */
+						uasort(
+							$sorted_attributes,
+							static function ( $a, $b ) {
+								$a_has_ns = str_contains( $a, ':' );
+								$b_has_ns = str_contains( $b, ':' );
+
+								// Attributes with `:` should follow all other attributes.
+								if ( $a_has_ns !== $b_has_ns ) {
+									return $a_has_ns ? 1 : -1;
+								}
+
+								$a_has_sp = str_contains( $a, ' ' );
+								$b_has_sp = str_contains( $b, ' ' );
+
+								// Attributes with a namespace ' ' should come after those without.
+								if ( $a_has_sp !== $b_has_sp ) {
+									return $a_has_sp ? 1 : -1;
+								}
+
+								return $a <=> $b;
+							}
+						);
+
+						foreach ( $sorted_attributes as $attribute_name => $display_name ) {
 							$val = $processor->get_attribute( $attribute_name );
 							/*
 							 * Attributes with no value are `true` with the HTML API,
@@ -211,7 +249,7 @@ private static function build_tree_representation( ?string $fragment_context, st
 							if ( true === $val ) {
 								$val = '';
 							}
-							$output .= str_repeat( $indent, $tag_indent + 1 ) . "{$attribute_name}=\"{$val}\"\n";
+							$output .= str_repeat( $indent, $tag_indent + 1 ) . "{$display_name}=\"{$val}\"\n";
 						}
 					}