diff -r 7b1b88e27a20 -r 48c4eec2b7e6 wp/wp-includes/html-api/class-wp-html-open-elements.php --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/wp/wp-includes/html-api/class-wp-html-open-elements.php Fri Sep 05 18:40:08 2025 +0200 @@ -0,0 +1,541 @@ + Initially, the stack of open elements is empty. The stack grows + * > downwards; the topmost node on the stack is the first one added + * > to the stack, and the bottommost node of the stack is the most + * > recently added node in the stack (notwithstanding when the stack + * > is manipulated in a random access fashion as part of the handling + * > for misnested tags). + * + * @since 6.4.0 + * + * @access private + * + * @see https://html.spec.whatwg.org/#stack-of-open-elements + * @see WP_HTML_Processor + */ +class WP_HTML_Open_Elements { + /** + * Holds the stack of open element references. + * + * @since 6.4.0 + * + * @var WP_HTML_Token[] + */ + public $stack = array(); + + /** + * Whether a P element is in button scope currently. + * + * This class optimizes scope lookup by pre-calculating + * this value when elements are added and removed to the + * stack of open elements which might change its value. + * This avoids frequent iteration over the stack. + * + * @since 6.4.0 + * + * @var bool + */ + private $has_p_in_button_scope = false; + + /** + * A function that will be called when an item is popped off the stack of open elements. + * + * The function will be called with the popped item as its argument. + * + * @since 6.6.0 + * + * @var Closure + */ + private $pop_handler = null; + + /** + * A function that will be called when an item is pushed onto the stack of open elements. + * + * The function will be called with the pushed item as its argument. + * + * @since 6.6.0 + * + * @var Closure + */ + private $push_handler = null; + + /** + * Sets a pop handler that will be called when an item is popped off the stack of + * open elements. + * + * The function will be called with the pushed item as its argument. + * + * @since 6.6.0 + * + * @param Closure $handler The handler function. + */ + public function set_pop_handler( Closure $handler ) { + $this->pop_handler = $handler; + } + + /** + * Sets a push handler that will be called when an item is pushed onto the stack of + * open elements. + * + * The function will be called with the pushed item as its argument. + * + * @since 6.6.0 + * + * @param Closure $handler The handler function. + */ + public function set_push_handler( Closure $handler ) { + $this->push_handler = $handler; + } + + /** + * Reports if a specific node is in the stack of open elements. + * + * @since 6.4.0 + * + * @param WP_HTML_Token $token Look for this node in the stack. + * @return bool Whether the referenced node is in the stack of open elements. + */ + public function contains_node( $token ) { + foreach ( $this->walk_up() as $item ) { + if ( $token->bookmark_name === $item->bookmark_name ) { + return true; + } + } + + return false; + } + + /** + * Returns how many nodes are currently in the stack of open elements. + * + * @since 6.4.0 + * + * @return int How many node are in the stack of open elements. + */ + public function count() { + return count( $this->stack ); + } + + /** + * Returns the node at the end of the stack of open elements, + * if one exists. If the stack is empty, returns null. + * + * @since 6.4.0 + * + * @return WP_HTML_Token|null Last node in the stack of open elements, if one exists, otherwise null. + */ + public function current_node() { + $current_node = end( $this->stack ); + + return $current_node ? $current_node : null; + } + + /** + * Returns whether an element is in a specific scope. + * + * ## HTML Support + * + * This function skips checking for the termination list because there + * are no supported elements which appear in the termination list. + * + * @since 6.4.0 + * + * @see https://html.spec.whatwg.org/#has-an-element-in-the-specific-scope + * + * @param string $tag_name Name of tag check. + * @param string[] $termination_list List of elements that terminate the search. + * @return bool Whether the element was found in a specific scope. + */ + public function has_element_in_specific_scope( $tag_name, $termination_list ) { + foreach ( $this->walk_up() as $node ) { + if ( $node->node_name === $tag_name ) { + return true; + } + + if ( + '(internal: H1 through H6 - do not use)' === $tag_name && + in_array( $node->node_name, array( 'H1', 'H2', 'H3', 'H4', 'H5', 'H6' ), true ) + ) { + return true; + } + + switch ( $node->node_name ) { + case 'HTML': + return false; + } + + if ( in_array( $node->node_name, $termination_list, true ) ) { + return false; + } + } + + return false; + } + + /** + * Returns whether a particular element is in scope. + * + * @since 6.4.0 + * + * @see https://html.spec.whatwg.org/#has-an-element-in-scope + * + * @param string $tag_name Name of tag to check. + * @return bool Whether given element is in scope. + */ + public function has_element_in_scope( $tag_name ) { + return $this->has_element_in_specific_scope( + $tag_name, + array( + + /* + * Because it's not currently possible to encounter + * one of the termination elements, they don't need + * to be listed here. If they were, they would be + * unreachable and only waste CPU cycles while + * scanning through HTML. + */ + ) + ); + } + + /** + * Returns whether a particular element is in list item scope. + * + * @since 6.4.0 + * @since 6.5.0 Implemented: no longer throws on every invocation. + * + * @see https://html.spec.whatwg.org/#has-an-element-in-list-item-scope + * + * @param string $tag_name Name of tag to check. + * @return bool Whether given element is in scope. + */ + public function has_element_in_list_item_scope( $tag_name ) { + return $this->has_element_in_specific_scope( + $tag_name, + array( + // There are more elements that belong here which aren't currently supported. + 'OL', + 'UL', + ) + ); + } + + /** + * Returns whether a particular element is in button scope. + * + * @since 6.4.0 + * + * @see https://html.spec.whatwg.org/#has-an-element-in-button-scope + * + * @param string $tag_name Name of tag to check. + * @return bool Whether given element is in scope. + */ + public function has_element_in_button_scope( $tag_name ) { + return $this->has_element_in_specific_scope( $tag_name, array( 'BUTTON' ) ); + } + + /** + * Returns whether a particular element is in table scope. + * + * @since 6.4.0 + * + * @see https://html.spec.whatwg.org/#has-an-element-in-table-scope + * + * @throws WP_HTML_Unsupported_Exception Always until this function is implemented. + * + * @param string $tag_name Name of tag to check. + * @return bool Whether given element is in scope. + */ + public function has_element_in_table_scope( $tag_name ) { + throw new WP_HTML_Unsupported_Exception( 'Cannot process elements depending on table scope.' ); + + return false; // The linter requires this unreachable code until the function is implemented and can return. + } + + /** + * Returns whether a particular element is in select scope. + * + * @since 6.4.0 + * + * @see https://html.spec.whatwg.org/#has-an-element-in-select-scope + * + * @throws WP_HTML_Unsupported_Exception Always until this function is implemented. + * + * @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.' ); + + return false; // The linter requires this unreachable code until the function is implemented and can return. + } + + /** + * Returns whether a P is in BUTTON scope. + * + * @since 6.4.0 + * + * @see https://html.spec.whatwg.org/#has-an-element-in-button-scope + * + * @return bool Whether a P is in BUTTON scope. + */ + public function has_p_in_button_scope() { + return $this->has_p_in_button_scope; + } + + /** + * Pops a node off of the stack of open elements. + * + * @since 6.4.0 + * + * @see https://html.spec.whatwg.org/#stack-of-open-elements + * + * @return bool Whether a node was popped off of the stack. + */ + public function pop() { + $item = array_pop( $this->stack ); + if ( null === $item ) { + return false; + } + + if ( 'context-node' === $item->bookmark_name ) { + $this->stack[] = $item; + return false; + } + + $this->after_element_pop( $item ); + return true; + } + + /** + * Pops nodes off of the stack of open elements until one with the given tag name has been popped. + * + * @since 6.4.0 + * + * @see WP_HTML_Open_Elements::pop + * + * @param string $tag_name Name of tag that needs to be popped off of the stack of open elements. + * @return bool Whether a tag of the given name was found and popped off of the stack of open elements. + */ + public function pop_until( $tag_name ) { + foreach ( $this->walk_up() as $item ) { + if ( 'context-node' === $item->bookmark_name ) { + return true; + } + + $this->pop(); + + if ( + '(internal: H1 through H6 - do not use)' === $tag_name && + in_array( $item->node_name, array( 'H1', 'H2', 'H3', 'H4', 'H5', 'H6' ), true ) + ) { + return true; + } + + if ( $tag_name === $item->node_name ) { + return true; + } + } + + return false; + } + + /** + * Pushes a node onto the stack of open elements. + * + * @since 6.4.0 + * + * @see https://html.spec.whatwg.org/#stack-of-open-elements + * + * @param WP_HTML_Token $stack_item Item to add onto stack. + */ + public function push( $stack_item ) { + $this->stack[] = $stack_item; + $this->after_element_push( $stack_item ); + } + + /** + * Removes a specific node from the stack of open elements. + * + * @since 6.4.0 + * + * @param WP_HTML_Token $token The node to remove from the stack of open elements. + * @return bool Whether the node was found and removed from the stack of open elements. + */ + public function remove_node( $token ) { + if ( 'context-node' === $token->bookmark_name ) { + return false; + } + + foreach ( $this->walk_up() as $position_from_end => $item ) { + if ( $token->bookmark_name !== $item->bookmark_name ) { + continue; + } + + $position_from_start = $this->count() - $position_from_end - 1; + array_splice( $this->stack, $position_from_start, 1 ); + $this->after_element_pop( $item ); + return true; + } + + return false; + } + + + /** + * Steps through the stack of open elements, starting with the top element + * (added first) and walking downwards to the one added last. + * + * This generator function is designed to be used inside a "foreach" loop. + * + * Example: + * + * $html = 'We are here'; + * foreach ( $stack->walk_down() as $node ) { + * echo "{$node->node_name} -> "; + * } + * > EM -> STRONG -> A -> + * + * To start with the most-recently added element and walk towards the top, + * see WP_HTML_Open_Elements::walk_up(). + * + * @since 6.4.0 + */ + public function walk_down() { + $count = count( $this->stack ); + + for ( $i = 0; $i < $count; $i++ ) { + yield $this->stack[ $i ]; + } + } + + /** + * Steps through the stack of open elements, starting with the bottom element + * (added last) and walking upwards to the one added first. + * + * This generator function is designed to be used inside a "foreach" loop. + * + * Example: + * + * $html = 'We are here'; + * foreach ( $stack->walk_up() as $node ) { + * echo "{$node->node_name} -> "; + * } + * > A -> STRONG -> EM -> + * + * To start with the first added element and walk towards the bottom, + * see WP_HTML_Open_Elements::walk_down(). + * + * @since 6.4.0 + * @since 6.5.0 Accepts $above_this_node to start traversal above a given node, if it exists. + * + * @param ?WP_HTML_Token $above_this_node Start traversing above this node, if provided and if the node exists. + */ + public function walk_up( $above_this_node = null ) { + $has_found_node = null === $above_this_node; + + for ( $i = count( $this->stack ) - 1; $i >= 0; $i-- ) { + $node = $this->stack[ $i ]; + + if ( ! $has_found_node ) { + $has_found_node = $node === $above_this_node; + continue; + } + + yield $node; + } + } + + /* + * Internal helpers. + */ + + /** + * Updates internal flags after adding an element. + * + * Certain conditions (such as "has_p_in_button_scope") are maintained here as + * flags that are only modified when adding and removing elements. This allows + * the HTML Processor to quickly check for these conditions instead of iterating + * over the open stack elements upon each new tag it encounters. These flags, + * however, need to be maintained as items are added and removed from the stack. + * + * @since 6.4.0 + * + * @param WP_HTML_Token $item Element that was added to the stack of open elements. + */ + public function after_element_push( $item ) { + /* + * When adding support for new elements, expand this switch to trap + * cases where the precalculated value needs to change. + */ + switch ( $item->node_name ) { + case 'BUTTON': + $this->has_p_in_button_scope = false; + break; + + case 'P': + $this->has_p_in_button_scope = true; + break; + } + + if ( null !== $this->push_handler ) { + ( $this->push_handler )( $item ); + } + } + + /** + * Updates internal flags after removing an element. + * + * Certain conditions (such as "has_p_in_button_scope") are maintained here as + * flags that are only modified when adding and removing elements. This allows + * the HTML Processor to quickly check for these conditions instead of iterating + * over the open stack elements upon each new tag it encounters. These flags, + * however, need to be maintained as items are added and removed from the stack. + * + * @since 6.4.0 + * + * @param WP_HTML_Token $item Element that was removed from the stack of open elements. + */ + public function after_element_pop( $item ) { + /* + * When adding support for new elements, expand this switch to trap + * cases where the precalculated value needs to change. + */ + switch ( $item->node_name ) { + case 'BUTTON': + $this->has_p_in_button_scope = $this->has_element_in_button_scope( 'P' ); + break; + + case 'P': + $this->has_p_in_button_scope = $this->has_element_in_button_scope( 'P' ); + break; + } + + if ( null !== $this->pop_handler ) { + ( $this->pop_handler )( $item ); + } + } + + /** + * Wakeup magic method. + * + * @since 6.6.0 + */ + public function __wakeup() { + throw new \LogicException( __CLASS__ . ' should never be unserialized' ); + } +}