Implement SELECT and related tags handling

src/wp-includes/html-api/class-wp-html-open-elements.php

@@ -219,19 +219,34 @@ public function has_element_in_table_scope( $tag_name ) {
 	/**
 	 * Returns whether a particular element is in select scope.
 	 *
-	 * @since 6.4.0
+	 * @since 6.4.0 - Stub, always throws.
+	 * @since 6.5.0 - Implemented.
 	 *
 	 * @see https://html.spec.whatwg.org/#has-an-element-in-select-scope
 	 *
-	 * @throws WP_HTML_Unsupported_Exception Always until this function is implemented.
+	 * > The stack of open elements is said to have a particular element in select scope when it has
+	 * > that element in the specific scope consisting of all element types except the following:
+	 * > - optgroup in the HTML namespace
+	 * > - option in the HTML namespace
 	 *
 	 * @param string $tag_name Name of tag to check.
 	 * @return bool Whether given element is in scope.
 	 */
 	public function has_element_in_select_scope( $tag_name ) {
-		throw new WP_HTML_Unsupported_Exception( 'Cannot process elements depending on select scope.' );
+		foreach ( $this->walk_up() as $node ) {
+			if ( $node->node_name === $tag_name ) {
+				return true;
+			}
 
-		return false; // The linter requires this unreachable code until the function is implemented and can return.
+			if (
+				'OPTION' !== $node->node_name &&
+				'OPTGROUP' !== $node->node_name
+			) {
+				return false;
+			}
+		}
+
+		return false;
 	}
 
 	/**

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

@@ -59,6 +59,114 @@ class WP_HTML_Processor_State {
 	 */
 	const INSERTION_MODE_IN_BODY = 'insertion-mode-in-body';
 
+	/**
+	 * In select insertion mode for full HTML parser.
+	 *
+	 * @since 6.5.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-inselect
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_SELECT = 'insertion-mode-in-select';
+
+	/**
+	 * In select in table insertion mode for full HTML parser.
+	 *
+	 * @since 6.5.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-inselectintable
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_SELECT_IN_TABLE = 'insertion-mode-in-select-in-table';
+
+	/**
+	 * In table insertion mode for full HTML parser.
+	 *
+	 * @since 6.5.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-intable
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_TABLE = 'insertion-mode-in-table';
+
+	/**
+	 * In caption insertion mode for full HTML parser.
+	 *
+	 * @since 6.5.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-incaption
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_CAPTION = 'insertion-mode-in-caption';
+
+	/**
+	 * In table body insertion mode for full HTML parser.
+	 *
+	 * @since 6.5.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-intablebody
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_TABLE_BODY = 'insertion-mode-in-table-body';
+
+	/**
+	 * In row insertion mode for full HTML parser.
+	 *
+	 * @since 6.5.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-inrow
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_ROW = 'insertion-mode-in-row';
+
+	/**
+	 * In cell insertion mode for full HTML parser.
+	 *
+	 * @since 6.5.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-incell
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_CELL = 'insertion-mode-in-cell';
+
+	/**
+	 * In column group insertion mode for full HTML parser.
+	 *
+	 * @since 6.5.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-incolumngroup
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_COLUMN_GROUP = 'insertion-mode-in-column-group';
+
+	/**
+	 * In frameset insertion mode for full HTML parser.
+	 *
+	 * @since 6.5.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-inframeset
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_FRAMESET = 'insertion-mode-in-frameset';
+
 	/**
 	 * Tracks open elements while scanning HTML.
 	 *