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<?php
/**
* HTML API: WP_HTML_Open_Elements class
*
* @package WordPress
* @subpackage HTML-API
* @since 6.4.0
*/
/**
* Core class used by the HTML processor during HTML parsing
* for managing the stack of open elements.
*
* This class is designed for internal use by the HTML processor.
*
* > 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|null
*/
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|null
*/
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 ): void {
$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 ): void {
$this->push_handler = $handler;
}
/**
* Returns the name of the node at the nth position on the stack
* of open elements, or `null` if no such position exists.
*
* Note that this uses a 1-based index, which represents the
* "nth item" on the stack, counting from the top, where the
* top-most element is the 1st, the second is the 2nd, etc...
*
* @since 6.7.0
*
* @param int $nth Retrieve the nth item on the stack, with 1 being
* the top element, 2 being the second, etc...
* @return WP_HTML_Token|null Name of the node on the stack at the given location,
* or `null` if the location isn't on the stack.
*/
public function at( int $nth ): ?WP_HTML_Token {
foreach ( $this->walk_down() as $item ) {
if ( 0 === --$nth ) {
return $item;
}
}
return null;
}
/**
* Reports if a node of a given name is in the stack of open elements.
*
* @since 6.7.0
*
* @param string $node_name Name of node for which to check.
* @return bool Whether a node of the given name is in the stack of open elements.
*/
public function contains( string $node_name ): bool {
foreach ( $this->walk_up() as $item ) {
if ( $node_name === $item->node_name ) {
return true;
}
}
return false;
}
/**
* 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( WP_HTML_Token $token ): bool {
foreach ( $this->walk_up() as $item ) {
if ( $token === $item ) {
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(): int {
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(): ?WP_HTML_Token {
$current_node = end( $this->stack );
return $current_node ? $current_node : null;
}
/**
* Indicates if the current node is of a given type or name.
*
* It's possible to pass either a node type or a node name to this function.
* In the case there is no current element it will always return `false`.
*
* Example:
*
* // Is the current node a text node?
* $stack->current_node_is( '#text' );
*
* // Is the current node a DIV element?
* $stack->current_node_is( 'DIV' );
*
* // Is the current node any element/tag?
* $stack->current_node_is( '#tag' );
*
* @see WP_HTML_Tag_Processor::get_token_type
* @see WP_HTML_Tag_Processor::get_token_name
*
* @since 6.7.0
*
* @access private
*
* @param string $identity Check if the current node has this name or type (depending on what is provided).
* @return bool Whether there is a current element that matches the given identity, whether a token name or type.
*/
public function current_node_is( string $identity ): bool {
$current_node = end( $this->stack );
if ( false === $current_node ) {
return false;
}
$current_node_name = $current_node->node_name;
return (
$current_node_name === $identity ||
( '#doctype' === $identity && 'html' === $current_node_name ) ||
( '#tag' === $identity && ctype_upper( $current_node_name ) )
);
}
/**
* Returns whether an element is in a specific scope.
*
* @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( string $tag_name, $termination_list ): bool {
foreach ( $this->walk_up() as $node ) {
$namespaced_name = 'html' === $node->namespace
? $node->node_name
: "{$node->namespace} {$node->node_name}";
if ( $namespaced_name === $tag_name ) {
return true;
}
if (
'(internal: H1 through H6 - do not use)' === $tag_name &&
in_array( $namespaced_name, array( 'H1', 'H2', 'H3', 'H4', 'H5', 'H6' ), true )
) {
return true;
}
if ( in_array( $namespaced_name, $termination_list, true ) ) {
return false;
}
}
return false;
}
/**
* Returns whether a particular element is in scope.
*
* > The stack of open elements is said to have a particular element in
* > scope when it has that element in the specific scope consisting of
* > the following element types:
* >
* > - applet
* > - caption
* > - html
* > - table
* > - td
* > - th
* > - marquee
* > - object
* > - template
* > - MathML mi
* > - MathML mo
* > - MathML mn
* > - MathML ms
* > - MathML mtext
* > - MathML annotation-xml
* > - SVG foreignObject
* > - SVG desc
* > - SVG title
*
* @since 6.4.0
* @since 6.7.0 Full support.
*
* @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( string $tag_name ): bool {
return $this->has_element_in_specific_scope(
$tag_name,
array(
'APPLET',
'CAPTION',
'HTML',
'TABLE',
'TD',
'TH',
'MARQUEE',
'OBJECT',
'TEMPLATE',
'math MI',
'math MO',
'math MN',
'math MS',
'math MTEXT',
'math ANNOTATION-XML',
'svg FOREIGNOBJECT',
'svg DESC',
'svg TITLE',
)
);
}
/**
* Returns whether a particular element is in list item scope.
*
* > The stack of open elements is said to have a particular element
* > in list item scope when it has that element in the specific scope
* > consisting of the following element types:
* >
* > - All the element types listed above for the has an element in scope algorithm.
* > - ol in the HTML namespace
* > - ul in the HTML namespace
*
* @since 6.4.0
* @since 6.5.0 Implemented: no longer throws on every invocation.
* @since 6.7.0 Supports all required HTML elements.
*
* @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( string $tag_name ): bool {
return $this->has_element_in_specific_scope(
$tag_name,
array(
'APPLET',
'BUTTON',
'CAPTION',
'HTML',
'TABLE',
'TD',
'TH',
'MARQUEE',
'OBJECT',
'OL',
'TEMPLATE',
'UL',
'math MI',
'math MO',
'math MN',
'math MS',
'math MTEXT',
'math ANNOTATION-XML',
'svg FOREIGNOBJECT',
'svg DESC',
'svg TITLE',
)
);
}
/**
* Returns whether a particular element is in button scope.
*
* > The stack of open elements is said to have a particular element
* > in button scope when it has that element in the specific scope
* > consisting of the following element types:
* >
* > - All the element types listed above for the has an element in scope algorithm.
* > - button in the HTML namespace
*
* @since 6.4.0
* @since 6.7.0 Supports all required HTML elements.
*
* @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( string $tag_name ): bool {
return $this->has_element_in_specific_scope(
$tag_name,
array(
'APPLET',
'BUTTON',
'CAPTION',
'HTML',
'TABLE',
'TD',
'TH',
'MARQUEE',
'OBJECT',
'TEMPLATE',
'math MI',
'math MO',
'math MN',
'math MS',
'math MTEXT',
'math ANNOTATION-XML',
'svg FOREIGNOBJECT',
'svg DESC',
'svg TITLE',
)
);
}
/**
* Returns whether a particular element is in table scope.
*
* > The stack of open elements is said to have a particular element
* > in table scope when it has that element in the specific scope
* > consisting of the following element types:
* >
* > - html in the HTML namespace
* > - table in the HTML namespace
* > - template in the HTML namespace
*
* @since 6.4.0
* @since 6.7.0 Full implementation.
*
* @see https://html.spec.whatwg.org/#has-an-element-in-table-scope
*
* @param string $tag_name Name of tag to check.
* @return bool Whether given element is in scope.
*/
public function has_element_in_table_scope( string $tag_name ): bool {
return $this->has_element_in_specific_scope(
$tag_name,
array(
'HTML',
'TABLE',
'TEMPLATE',
)
);
}
/**
* Returns whether a particular element is in select scope.
*
* This test differs from the others like it, in that its rules are inverted.
* Instead of arriving at a match when one of any tag in a termination group
* is reached, this one terminates if any other tag is reached.
*
* > 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
*
* @since 6.4.0 Stub implementation (throws).
* @since 6.7.0 Full implementation.
*
* @see https://html.spec.whatwg.org/#has-an-element-in-select-scope
*
* @param string $tag_name Name of tag to check.
* @return bool Whether the given element is in SELECT scope.
*/
public function has_element_in_select_scope( string $tag_name ): bool {
foreach ( $this->walk_up() as $node ) {
if ( $node->node_name === $tag_name ) {
return true;
}
if (
'OPTION' !== $node->node_name &&
'OPTGROUP' !== $node->node_name
) {
return false;
}
}
return false;
}
/**
* 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(): bool {
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(): bool {
$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 an HTML tag with the given name has been popped.
*
* @since 6.4.0
*
* @see WP_HTML_Open_Elements::pop
*
* @param string $html_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( string $html_tag_name ): bool {
foreach ( $this->walk_up() as $item ) {
$this->pop();
if ( 'html' !== $item->namespace ) {
continue;
}
if (
'(internal: H1 through H6 - do not use)' === $html_tag_name &&
in_array( $item->node_name, array( 'H1', 'H2', 'H3', 'H4', 'H5', 'H6' ), true )
) {
return true;
}
if ( $html_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( WP_HTML_Token $stack_item ): void {
$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( WP_HTML_Token $token ): bool {
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 = '<em><strong><a>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 = '<em><strong><a>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|null $above_this_node Optional. Start traversing above this node,
* if provided and if the node exists.
*/
public function walk_up( ?WP_HTML_Token $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( WP_HTML_Token $item ): void {
$namespaced_name = 'html' === $item->namespace
? $item->node_name
: "{$item->namespace} {$item->node_name}";
/*
* When adding support for new elements, expand this switch to trap
* cases where the precalculated value needs to change.
*/
switch ( $namespaced_name ) {
case 'APPLET':
case 'BUTTON':
case 'CAPTION':
case 'HTML':
case 'TABLE':
case 'TD':
case 'TH':
case 'MARQUEE':
case 'OBJECT':
case 'TEMPLATE':
case 'math MI':
case 'math MO':
case 'math MN':
case 'math MS':
case 'math MTEXT':
case 'math ANNOTATION-XML':
case 'svg FOREIGNOBJECT':
case 'svg DESC':
case 'svg TITLE':
$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( WP_HTML_Token $item ): void {
/*
* When adding support for new elements, expand this switch to trap
* cases where the precalculated value needs to change.
*/
switch ( $item->node_name ) {
case 'APPLET':
case 'BUTTON':
case 'CAPTION':
case 'HTML':
case 'P':
case 'TABLE':
case 'TD':
case 'TH':
case 'MARQUEE':
case 'OBJECT':
case 'TEMPLATE':
case 'math MI':
case 'math MO':
case 'math MN':
case 'math MS':
case 'math MTEXT':
case 'math ANNOTATION-XML':
case 'svg FOREIGNOBJECT':
case 'svg DESC':
case 'svg TITLE':
$this->has_p_in_button_scope = $this->has_element_in_button_scope( 'P' );
break;
}
if ( null !== $this->pop_handler ) {
( $this->pop_handler )( $item );
}
}
/**
* Clear the stack back to a table context.
*
* > When the steps above require the UA to clear the stack back to a table context, it means
* > that the UA must, while the current node is not a table, template, or html element, pop
* > elements from the stack of open elements.
*
* @see https://html.spec.whatwg.org/multipage/parsing.html#clear-the-stack-back-to-a-table-context
*
* @since 6.7.0
*/
public function clear_to_table_context(): void {
foreach ( $this->walk_up() as $item ) {
if (
'TABLE' === $item->node_name ||
'TEMPLATE' === $item->node_name ||
'HTML' === $item->node_name
) {
break;
}
$this->pop();
}
}
/**
* Clear the stack back to a table body context.
*
* > When the steps above require the UA to clear the stack back to a table body context, it
* > means that the UA must, while the current node is not a tbody, tfoot, thead, template, or
* > html element, pop elements from the stack of open elements.
*
* @see https://html.spec.whatwg.org/multipage/parsing.html#clear-the-stack-back-to-a-table-body-context
*
* @since 6.7.0
*/
public function clear_to_table_body_context(): void {
foreach ( $this->walk_up() as $item ) {
if (
'TBODY' === $item->node_name ||
'TFOOT' === $item->node_name ||
'THEAD' === $item->node_name ||
'TEMPLATE' === $item->node_name ||
'HTML' === $item->node_name
) {
break;
}
$this->pop();
}
}
/**
* Clear the stack back to a table row context.
*
* > When the steps above require the UA to clear the stack back to a table row context, it
* > means that the UA must, while the current node is not a tr, template, or html element, pop
* > elements from the stack of open elements.
*
* @see https://html.spec.whatwg.org/multipage/parsing.html#clear-the-stack-back-to-a-table-row-context
*
* @since 6.7.0
*/
public function clear_to_table_row_context(): void {
foreach ( $this->walk_up() as $item ) {
if (
'TR' === $item->node_name ||
'TEMPLATE' === $item->node_name ||
'HTML' === $item->node_name
) {
break;
}
$this->pop();
}
}
/**
* Wakeup magic method.
*
* @since 6.6.0
*/
public function __wakeup() {
throw new \LogicException( __CLASS__ . ' should never be unserialized' );
}
}
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