WordPress · sirreal · Sep 11, 2024 · Sep 11, 2024 · Sep 11, 2024 · Sep 11, 2024
diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -422,6 +422,55 @@ function ( WP_HTML_Token $token ): void {
 		};
 	}
 
+	/**
+	 * Creates a fragment processor with the current node as its context element.
+	 *
+	 * @see https://html.spec.whatwg.org/multipage/parsing.html#html-fragment-parsing-algorithm
+	 *
+	 * @param string $html     Input HTML fragment to process.
+	 * @return static|null     The created processor if successful, otherwise null.
+	 */
+	private function spawn_fragment_parser( string $html ): ?self {
+		if ( $this->get_token_type() !== '#tag' ) {
+			return null;
+		}
+
+		/*
+		 * Prevent creating fragments at "self-contained" nodes.
+		 *
+		 * @see https://github.com/WordPress/wordpress-develop/pull/7141
+		 * @see https://github.com/WordPress/wordpress-develop/pull/7198
+		 */
+		if (
+			'html' === $this->get_namespace() &&
+			in_array( $this->get_tag(), array( 'IFRAME', 'NOEMBED', 'NOFRAMES', 'SCRIPT', 'STYLE', 'TEXTAREA', 'TITLE', 'XMP' ), true )
+		) {
+			return null;
+		}
+
+		$fragment_processor              = self::create_fragment( $html );
+		$fragment_processor->compat_mode = $this->compat_mode;
+
+		// @todo The context element probably needs a namespace{
+		$context_element = array( $this->get_tag(), array() );
+		foreach ( $this->get_attribute_names_with_prefix( '' ) as $name => $value ) {
+			$context_element[1][ $name ] = $value;
+		}
+		$fragment_processor->state->context_node = $context_element;
+
+		if ( 'TEMPLATE' === $context_element[0] ) {
+			$fragment_processor->state->stack_of_template_insertion_modes[] = WP_HTML_Processor_State::INSERTION_MODE_IN_TEMPLATE;
+		}
+
+		$fragment_processor->reset_insertion_mode_appropriately();
+
+		// @todo Set the parser's form element pointer.
+
+		$fragment_processor->state->encoding_confidence = 'irrelevant';
+
+		return $fragment_processor;
+	}
+
 	/**
 	 * Stops the parser and terminates its execution when encountering unsupported markup.
 	 *
@@ -5020,6 +5069,158 @@ public function get_comment_type(): ?string {
 		return $this->is_virtual() ? null : parent::get_comment_type();
 	}
 
+	/**
+	 * Normalize an HTML string by serializing it.
+	 *
+	 * This removes any partial syntax at the end of the string.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @param string $html Input HTML to normalize.
+	 *
+	 * @return string|null Normalized output, or `null` if unable to normalize.
+	 */
+	public static function normalize( string $html ): ?string {
+		return static::create_fragment( $html )->serialize();
+	}
+
+	/**
+	 * Generate normalized markup for the HTML in the provided processor.
+	 *
+	 * This removes any partial syntax at the end of the string.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @return string|null Normalized HTML markup represented by processor,
+	 *                     or `null` if unable to generate serialization.
+	 */
+	public function serialize(): ?string {
+		if ( WP_HTML_Tag_Processor::STATE_READY !== $this->parser_state ) {
+			return null;
+		}
+
+		$html = '';
+		while ( $this->next_token() ) {
+			$token_type = $this->get_token_type();
+
+			switch ( $token_type ) {
+				case '#text':
+					$html .= htmlspecialchars( $this->get_modifiable_text(), ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML5, 'UTF-8' );
+					break;
+
+				case '#funky-comment':
+				case '#comment':
+					$html .= "<!--{$this->get_modifiable_text()}-->";
+					break;
+
+				case '#cdata-section':
+					$html .= "<![CDATA[{$this->get_modifiable_text()}]]>";
+					break;
+
+				case 'html':
+					$html .= '<!DOCTYPE html>';
+					break;
+			}
+
+			if ( '#tag' !== $token_type ) {
+				continue;
+			}
+
+			if ( $this->is_tag_closer() ) {
+				$html .= "</{$this->get_qualified_tag_name()}>";
+				continue;
+			}
+
+			$attribute_names = $this->get_attribute_names_with_prefix( '' );
+			if ( ! isset( $attribute_names ) ) {
+				$html .= "<{$this->get_qualified_tag_name()}>";
+				continue;
+			}
+
+			$html .= "<{$this->get_qualified_tag_name()}";
+			foreach ( $attribute_names as $attribute_name ) {
+				$html .= " {$this->get_qualified_attribute_name( $attribute_name )}";
+				$value = $this->get_attribute( $attribute_name );
+
+				if ( is_string( $value ) ) {
+					$html .= '="' . htmlspecialchars( $value, ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML5 ) . '"';
+				}
+			}
+
+			if ( 'html' !== $this->get_namespace() && $this->has_self_closing_flag() ) {
+				$html .= '/';
+			}
+
+			$html .= '>';
+		}
+
+		if ( null !== $this->get_last_error() ) {
+			return null;
+		}
+
+		return $html;
+	}
+
+	/**
+	 * Replaces the inner markup of the currently-matched tag with provided HTML.
+	 *
+	 * This function will normalize the given input and enforce the boundaries
+	 * within the existing HTML where it's called.
+	 *
+	 * @since 6.8.0
+	 *
+	 * @param string $new_inner_html New HTML to inject as inner HTML for the currently-matched tag.
+	 * @return bool Whether the inner markup was modified for the currently-matched tag, or `NULL`
+	 *              if called on a node which doesn't allow changing the inner HTML.
+	 */
+	public function set_inner_html( string $new_inner_html ): ?bool {
+		$tag_name = $this->get_tag();
+
+		if (
+			WP_HTML_Tag_Processor::STATE_MATCHED_TAG !== $this->parser_state ||
+			$this->is_tag_closer() ||
+			( 'html' === $this->get_namespace() &&
+				(
+					self::is_void( $tag_name ) ||
+					in_array( $tag_name, array( 'IFRAME', 'NOEMBED', 'NOFRAMES', 'SCRIPT', 'STYLE', 'TEXTAREA', 'TITLE', 'XMP' ), true )
+				)
+			)
+		) {
+			// @todo Support setting inner HTML for SCRIPT, STYLE, TEXTAREA, and TITLE.
+			return null;
+		}
+
+		$fragment   = $this->spawn_fragment_parser( $new_inner_html );
+		$new_markup = $fragment->serialize();
+
+		$this->set_bookmark( 'start' );
+		$depth = $this->get_current_depth();
+		while ( $this->get_current_depth() >= $depth && $this->next_token() ) {
+			continue;
+		}
+
+		if (
+			$this->paused_at_incomplete_token() ||
+			null !== $this->get_last_error()
+		) {
+			return false;
+		}
+
+		$this->set_bookmark( 'end' );
+		$start = $this->bookmarks['_start'];
+		$end   = $this->bookmarks['_end'];
+
+		$this->lexical_updates[] = new WP_HTML_Text_Replacement(
+			$start->start + $start->length,
+			$end->start - ( $start->start + $start->length ),
+			$new_markup
+		);
+
+		$this->get_updated_html();
+		$this->seek( 'start' );
+		return true;
+	}
+
 	/**
 	 * Removes a bookmark that is no longer needed.
 	 *

diff --git a/src/wp-includes/html-api/class-wp-html-tag-processor.php b/src/wp-includes/html-api/class-wp-html-tag-processor.php
@@ -2840,7 +2840,7 @@ public function get_qualified_tag_name(): ?string {
 		}
 
 		if ( 'html' === $this->get_namespace() ) {
-			return $tag_name;
+			return strtolower( $tag_name );
 		}
 
 		$lower_tag_name = strtolower( $tag_name );