HTML API: Add get_full_comment_text() method.

Previously, there were a few cases where the modifiable text read from an HTML comment differs slightly from the parsed value of its inner text in a browser. This is due to the specific way that invalid HTML syntax tokens become "bogus comments."

This patch introduces a new method to the Tag Processor to allow differentiating these specific cases, such as when copying or serializing HTML from one source to another. Similar code has already been in use in the html5lib tests, and this patch simplifies the test runner, evidencing the fact that this method was already needed.

Developed in WordPress/wordpress-develop#7342
Discussed in https://core.trac.wordpress.org/ticket/62036

Props dmsnell, jonsurrell.
See #62036.

Built from https://develop.svn.wordpress.org/trunk@59075


git-svn-id: http://core.svn.wordpress.org/trunk@58471 1a063a9b-81f0-0310-95a4-ce76da25c4cd

Author: dmsnell

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

@@ -3385,6 +3385,58 @@ public function get_comment_type(): ?string {
 		return $this->comment_type;
 	}
 
+	/**
+	 * Returns the text of a matched comment or null if not on a comment type node.
+	 *
+	 * This method returns the entire text content of a comment node as it
+	 * would appear in the browser.
+	 *
+	 * This differs from {@see ::get_modifiable_text()} in that certain comment
+	 * types in the HTML API cannot allow their entire comment text content to
+	 * be modified. Namely, "bogus comments" of the form `<?not allowed in html>`
+	 * will create a comment whose text content starts with `?`. Note that if
+	 * that character were modified, it would be possible to change the node
+	 * type.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @return string|null The comment text as it would appear in the browser or null
+	 *                     if not on a comment type node.
+	 */
+	public function get_full_comment_text(): ?string {
+		if ( self::STATE_FUNKY_COMMENT === $this->parser_state ) {
+			return $this->get_modifiable_text();
+		}
+
+		if ( self::STATE_COMMENT !== $this->parser_state ) {
+			return null;
+		}
+
+		switch ( $this->get_comment_type() ) {
+			case self::COMMENT_AS_HTML_COMMENT:
+			case self::COMMENT_AS_ABRUPTLY_CLOSED_COMMENT:
+				return $this->get_modifiable_text();
+
+			case self::COMMENT_AS_CDATA_LOOKALIKE:
+				return "[CDATA[{$this->get_modifiable_text()}]]";
+
+			case self::COMMENT_AS_PI_NODE_LOOKALIKE:
+				return "?{$this->get_tag()}{$this->get_modifiable_text()}?";
+
+			/*
+			 * This represents "bogus comments state" from HTML tokenization.
+			 * This can be entered by `<?` or `<!`, where `?` is included in
+			 * the comment text but `!` is not.
+			 */
+			case self::COMMENT_AS_INVALID_HTML:
+				$preceding_character = $this->html[ $this->text_starts_at - 1 ];
+				$comment_start       = '?' === $preceding_character ? '?' : '';
+				return "{$comment_start}{$this->get_modifiable_text()}";
+		}
+
+		return null;
+	}
+
 	/**
 	 * Subdivides a matched text node, splitting NULL byte sequences and decoded whitespace as
 	 * distinct nodes prefixes.

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.7-alpha-59074';
+$wp_version = '6.7-alpha-59075';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.