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This patch adds support to process the BUTTON element. This requires adding some additional semantic rules to handle situations where a BUTTON element is already in scope. Also included is a fixup to enforce that `WP_HTML_Processor::next_tag()` never returns for a tag closer. This is useful with the Tag Processor, but not for the HTML Processor. There were tests relying on this behavior to assert that internal processes were working as they should, but those tests have been updated to use the semi-private `step()` function, which does stop on tag closers. This patch is one in a series of changes to expand support within the HTML API, moving gradually to allow for more focused changes that are easier to review and test. The HTML Processor is a work in progress with a certain set of features slated to be ready and tested by 6.4.0, but it will only contain partial support of the HTML5 specification even after that. Whenever it cannot positively recognize and process its input it bails, and certain function stubs and logical stubs exist to structure future expansions of support. Props dmsnell. Fixes #58961. Built from https://develop.svn.wordpress.org/trunk@56380 git-svn-id: http://core.svn.wordpress.org/trunk@55892 1a063a9b-81f0-0310-95a4-ce76da25c4cd
433 lines
12 KiB
PHP
433 lines
12 KiB
PHP
<?php
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/**
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* HTML API: WP_HTML_Open_Elements class
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*
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* @package WordPress
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* @subpackage HTML-API
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* @since 6.4.0
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*/
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/**
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* Core class used by the HTML processor during HTML parsing
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* for managing the stack of open elements.
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*
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* This class is designed for internal use by the HTML processor.
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*
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* > Initially, the stack of open elements is empty. The stack grows
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* > downwards; the topmost node on the stack is the first one added
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* > to the stack, and the bottommost node of the stack is the most
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* > recently added node in the stack (notwithstanding when the stack
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* > is manipulated in a random access fashion as part of the handling
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* > for misnested tags).
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*
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* @since 6.4.0
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*
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* @access private
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*
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* @see https://html.spec.whatwg.org/#stack-of-open-elements
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* @see WP_HTML_Processor
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*/
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class WP_HTML_Open_Elements {
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/**
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* Holds the stack of open element references.
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*
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* @since 6.4.0
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*
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* @var WP_HTML_Token[]
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*/
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public $stack = array();
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/**
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* Whether a P element is in button scope currently.
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*
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* This class optimizes scope lookup by pre-calculating
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* this value when elements are added and removed to the
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* stack of open elements which might change its value.
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* This avoids frequent iteration over the stack.
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*
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* @since 6.4.0
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*
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* @var bool
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*/
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private $has_p_in_button_scope = false;
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/**
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* Reports if a specific node is in the stack of open elements.
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*
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* @since 6.4.0
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*
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* @param WP_HTML_Token $token Look for this node in the stack.
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* @return bool Whether the referenced node is in the stack of open elements.
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*/
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public function contains_node( $token ) {
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foreach ( $this->walk_up() as $item ) {
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if ( $token->bookmark_name === $item->bookmark_name ) {
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return true;
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}
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}
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return false;
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}
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/**
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* Returns how many nodes are currently in the stack of open elements.
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*
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* @since 6.4.0
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*
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* @return int How many node are in the stack of open elements.
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*/
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public function count() {
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return count( $this->stack );
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}
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/**
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* Returns the node at the end of the stack of open elements,
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* if one exists. If the stack is empty, returns null.
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*
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* @since 6.4.0
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*
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* @return WP_HTML_Token|null Last node in the stack of open elements, if one exists, otherwise null.
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*/
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public function current_node() {
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$current_node = end( $this->stack );
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return $current_node ? $current_node : null;
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}
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/**
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* Returns whether an element is in a specific scope.
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*
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* ## HTML Support
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*
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* This function skips checking for the termination list because there
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* are no supported elements which appear in the termination list.
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*
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* @since 6.4.0
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*
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* @see https://html.spec.whatwg.org/#has-an-element-in-the-specific-scope
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*
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* @param string $tag_name Name of tag check.
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* @param string[] $termination_list List of elements that terminate the search.
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* @return bool Whether the element was found in a specific scope.
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*/
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public function has_element_in_specific_scope( $tag_name, $termination_list ) { // phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable
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foreach ( $this->walk_up() as $node ) {
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if ( $node->node_name === $tag_name ) {
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return true;
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}
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switch ( $node->node_name ) {
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case 'HTML':
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return false;
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}
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if ( in_array( $node->node_name, $termination_list, true ) ) {
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return true;
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}
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}
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return false;
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}
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/**
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* Returns whether a particular element is in scope.
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*
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* @since 6.4.0
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*
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* @see https://html.spec.whatwg.org/#has-an-element-in-scope
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*
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* @param string $tag_name Name of tag to check.
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* @return bool Whether given element is in scope.
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*/
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public function has_element_in_scope( $tag_name ) {
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return $this->has_element_in_specific_scope(
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$tag_name,
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array(
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/*
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* Because it's not currently possible to encounter
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* one of the termination elements, they don't need
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* to be listed here. If they were, they would be
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* unreachable and only waste CPU cycles while
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* scanning through HTML.
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*/
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)
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);
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}
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/**
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* Returns whether a particular element is in list item scope.
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*
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* @since 6.4.0
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*
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* @see https://html.spec.whatwg.org/#has-an-element-in-list-item-scope
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*
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* @throws WP_HTML_Unsupported_Exception Always until this function is implemented.
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*
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* @param string $tag_name Name of tag to check.
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* @return bool Whether given element is in scope.
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*/
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public function has_element_in_list_item_scope( $tag_name ) { // phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable
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throw new WP_HTML_Unsupported_Exception( 'Cannot process elements depending on list item scope.' );
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return false; // The linter requires this unreachable code until the function is implemented and can return.
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}
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/**
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* Returns whether a particular element is in button scope.
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*
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* @since 6.4.0
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*
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* @see https://html.spec.whatwg.org/#has-an-element-in-button-scope
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*
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* @param string $tag_name Name of tag to check.
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* @return bool Whether given element is in scope.
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*/
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public function has_element_in_button_scope( $tag_name ) {
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return $this->has_element_in_specific_scope( $tag_name, array( 'BUTTON' ) );
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}
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/**
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* Returns whether a particular element is in table scope.
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*
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* @since 6.4.0
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*
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* @see https://html.spec.whatwg.org/#has-an-element-in-table-scope
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*
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* @throws WP_HTML_Unsupported_Exception Always until this function is implemented.
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*
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* @param string $tag_name Name of tag to check.
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* @return bool Whether given element is in scope.
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*/
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public function has_element_in_table_scope( $tag_name ) { // phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable
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throw new WP_HTML_Unsupported_Exception( 'Cannot process elements depending on table scope.' );
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return false; // The linter requires this unreachable code until the function is implemented and can return.
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}
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/**
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* Returns whether a particular element is in select scope.
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*
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* @since 6.4.0
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*
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* @see https://html.spec.whatwg.org/#has-an-element-in-select-scope
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*
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* @throws WP_HTML_Unsupported_Exception Always until this function is implemented.
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*
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* @param string $tag_name Name of tag to check.
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* @return bool Whether given element is in scope.
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*/
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public function has_element_in_select_scope( $tag_name ) { // phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable
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throw new WP_HTML_Unsupported_Exception( 'Cannot process elements depending on select scope.' );
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return false; // The linter requires this unreachable code until the function is implemented and can return.
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}
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/**
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* Returns whether a P is in BUTTON scope.
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*
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* @since 6.4.0
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*
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* @see https://html.spec.whatwg.org/#has-an-element-in-button-scope
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*
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* @return bool Whether a P is in BUTTON scope.
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*/
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public function has_p_in_button_scope() {
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return $this->has_p_in_button_scope;
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}
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/**
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* Pops a node off of the stack of open elements.
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*
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* @since 6.4.0
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*
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* @see https://html.spec.whatwg.org/#stack-of-open-elements
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*
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* @return bool Whether a node was popped off of the stack.
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*/
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public function pop() {
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$item = array_pop( $this->stack );
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if ( null === $item ) {
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return false;
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}
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$this->after_element_pop( $item );
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return true;
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}
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/**
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* Pops nodes off of the stack of open elements until one with the given tag name has been popped.
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*
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* @since 6.4.0
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*
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* @see WP_HTML_Open_Elements::pop
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*
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* @param string $tag_name Name of tag that needs to be popped off of the stack of open elements.
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* @return bool Whether a tag of the given name was found and popped off of the stack of open elements.
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*/
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public function pop_until( $tag_name ) {
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foreach ( $this->walk_up() as $item ) {
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$this->pop();
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if ( $tag_name === $item->node_name ) {
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return true;
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}
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}
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return false;
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}
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/**
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* Pushes a node onto the stack of open elements.
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*
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* @since 6.4.0
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*
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* @see https://html.spec.whatwg.org/#stack-of-open-elements
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*
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* @param WP_HTML_Token $stack_item Item to add onto stack.
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*/
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public function push( $stack_item ) {
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$this->stack[] = $stack_item;
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$this->after_element_push( $stack_item );
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}
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/**
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* Removes a specific node from the stack of open elements.
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*
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* @since 6.4.0
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*
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* @param WP_HTML_Token $token The node to remove from the stack of open elements.
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* @return bool Whether the node was found and removed from the stack of open elements.
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*/
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public function remove_node( $token ) {
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foreach ( $this->walk_up() as $position_from_end => $item ) {
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if ( $token->bookmark_name !== $item->bookmark_name ) {
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continue;
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}
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$position_from_start = $this->count() - $position_from_end - 1;
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array_splice( $this->stack, $position_from_start, 1 );
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$this->after_element_pop( $item );
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return true;
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}
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return false;
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}
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/**
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* Steps through the stack of open elements, starting with the top element
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* (added first) and walking downwards to the one added last.
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*
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* This generator function is designed to be used inside a "foreach" loop.
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*
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* Example:
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*
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* $html = '<em><strong><a>We are here';
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* foreach ( $stack->walk_down() as $node ) {
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* echo "{$node->node_name} -> ";
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* }
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* > EM -> STRONG -> A ->
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*
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* To start with the most-recently added element and walk towards the top,
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* see WP_HTML_Open_Elements::walk_up().
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*
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* @since 6.4.0
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*/
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public function walk_down() {
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$count = count( $this->stack );
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for ( $i = 0; $i < $count; $i++ ) {
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yield $this->stack[ $i ];
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}
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}
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/**
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* Steps through the stack of open elements, starting with the bottom element
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* (added last) and walking upwards to the one added first.
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*
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* This generator function is designed to be used inside a "foreach" loop.
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*
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* Example:
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*
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* $html = '<em><strong><a>We are here';
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* foreach ( $stack->walk_up() as $node ) {
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* echo "{$node->node_name} -> ";
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* }
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* > A -> STRONG -> EM ->
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*
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* To start with the first added element and walk towards the bottom,
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* see WP_HTML_Open_Elements::walk_down().
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*
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* @since 6.4.0
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*/
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public function walk_up() {
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for ( $i = count( $this->stack ) - 1; $i >= 0; $i-- ) {
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yield $this->stack[ $i ];
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}
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}
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/*
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* Internal helpers.
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*/
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/**
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* Updates internal flags after adding an element.
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*
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* Certain conditions (such as "has_p_in_button_scope") are maintained here as
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* flags that are only modified when adding and removing elements. This allows
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* the HTML Processor to quickly check for these conditions instead of iterating
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* over the open stack elements upon each new tag it encounters. These flags,
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* however, need to be maintained as items are added and removed from the stack.
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*
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* @since 6.4.0
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*
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* @param WP_HTML_Token $item Element that was added to the stack of open elements.
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*/
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public function after_element_push( $item ) {
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/*
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* When adding support for new elements, expand this switch to trap
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* cases where the precalculated value needs to change.
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*/
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switch ( $item->node_name ) {
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case 'BUTTON':
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$this->has_p_in_button_scope = false;
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break;
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case 'P':
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$this->has_p_in_button_scope = true;
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break;
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}
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}
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/**
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* Updates internal flags after removing an element.
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*
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* Certain conditions (such as "has_p_in_button_scope") are maintained here as
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* flags that are only modified when adding and removing elements. This allows
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* the HTML Processor to quickly check for these conditions instead of iterating
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* over the open stack elements upon each new tag it encounters. These flags,
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* however, need to be maintained as items are added and removed from the stack.
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*
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* @since 6.4.0
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*
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* @param WP_HTML_Token $item Element that was removed from the stack of open elements.
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*/
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public function after_element_pop( $item ) {
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/*
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* When adding support for new elements, expand this switch to trap
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* cases where the precalculated value needs to change.
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*/
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switch ( $item->node_name ) {
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case 'BUTTON':
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$this->has_p_in_button_scope = $this->has_element_in_button_scope( 'P' );
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break;
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case 'P':
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$this->has_p_in_button_scope = $this->has_element_in_button_scope( 'P' );
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break;
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}
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}
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}
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