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HTML API: Implement the _reset insertion mode appropriately_ algorithm.
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In order to add support for the SELECT and TABLE tags in the HTML Processor, it
needs to implement the HTML algorithm named "reset the insertion mode
appropriately".

This patch implements that algorithm to unblock the additional tag support. The
algorithm resets the parsing mode after specific state changes in complicated
situations where alternative rules are in effect (such as rules governing how
the parser handles tags found within a TABLE element).

Developed in WordPress/wordpress-develop#6020
Discussed in https://core.trac.wordpress.org/ticket/61549

Props dmsnell, jonsurrell.
Fixes #61549.

Built from https://develop.svn.wordpress.org/trunk@58656


git-svn-id: http://core.svn.wordpress.org/trunk@58070 1a063a9b-81f0-0310-95a4-ce76da25c4cd
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@dmsnell
dmsnell committed Jul 3, 2024
1 parent 5569a5c commit eda0d41
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22 changes: 22 additions & 0 deletions wp-includes/html-api/class-wp-html-processor-state.php
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Original file line number Diff line number Diff line change
Expand Up @@ -215,6 +215,17 @@ class WP_HTML_Processor_State {
*/
const INSERTION_MODE_IN_TEMPLATE = 'insertion-mode-in-template';

/**
* The stack of template insertion modes.
*
* @since 6.7.0
*
* @see https://html.spec.whatwg.org/#the-insertion-mode:stack-of-template-insertion-modes
*
* @var array<string>
*/
public $stack_of_template_insertion_modes = array();

/**
* Tracks open elements while scanning HTML.
*
Expand Down Expand Up @@ -272,6 +283,17 @@ class WP_HTML_Processor_State {
*/
public $context_node = null;

/**
* HEAD element pointer.
*
* @since 6.7.0
*
* @see https://html.spec.whatwg.org/multipage/parsing.html#head-element-pointer
*
* @var WP_HTML_Token|null
*/
public $head_element = null;

/**
* The frameset-ok flag indicates if a `FRAMESET` element is allowed in the current state.
*
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183 changes: 183 additions & 0 deletions wp-includes/html-api/class-wp-html-processor.php
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Original file line number Diff line number Diff line change
Expand Up @@ -2129,6 +2129,189 @@ private function reconstruct_active_formatting_elements() {
throw new WP_HTML_Unsupported_Exception( 'Cannot reconstruct active formatting elements when advancing and rewinding is required.' );
}

/**
* Runs the reset the insertion mode appropriately algorithm.
*
* @since 6.7.0
*
* @see https://html.spec.whatwg.org/multipage/parsing.html#reset-the-insertion-mode-appropriately
*/
public function reset_insertion_mode(): void {
// Set the first node.
$first_node = null;
foreach ( $this->state->stack_of_open_elements->walk_down() as $first_node ) {
break;
}

/*
* > 1. Let _last_ be false.
*/
$last = false;
foreach ( $this->state->stack_of_open_elements->walk_up() as $node ) {
/*
* > 2. Let _node_ be the last node in the stack of open elements.
* > 3. _Loop_: If _node_ is the first node in the stack of open elements, then set _last_
* > to true, and, if the parser was created as part of the HTML fragment parsing
* > algorithm (fragment case), set node to the context element passed to
* > that algorithm.
* > …
*/
if ( $node === $first_node ) {
$last = true;
if ( isset( $this->context_node ) ) {
$node = $this->context_node;
}
}

switch ( $node->node_name ) {
/*
* > 4. If node is a `select` element, run these substeps:
* > 1. If _last_ is true, jump to the step below labeled done.
* > 2. Let _ancestor_ be _node_.
* > 3. _Loop_: If _ancestor_ is the first node in the stack of open elements,
* > jump to the step below labeled done.
* > 4. Let ancestor be the node before ancestor in the stack of open elements.
* > …
* > 7. Jump back to the step labeled _loop_.
* > 8. _Done_: Switch the insertion mode to "in select" and return.
*/
case 'SELECT':
if ( ! $last ) {
foreach ( $this->state->stack_of_open_elements->walk_up( $node ) as $ancestor ) {
switch ( $ancestor->node_name ) {
/*
* > 5. If _ancestor_ is a `template` node, jump to the step below
* > labeled _done_.
*/
case 'TEMPLATE':
break 2;

/*
* > 6. If _ancestor_ is a `table` node, switch the insertion mode to
* > "in select in table" and return.
*/
case 'TABLE':
$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_SELECT_IN_TABLE;
return;
}
}
}
$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_SELECT;
return;

/*
* > 5. If _node_ is a `td` or `th` element and _last_ is false, then switch the
* > insertion mode to "in cell" and return.
*/
case 'TD':
case 'TH':
if ( ! $last ) {
$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_CELL;
return;
}
break;

/*
* > 6. If _node_ is a `tr` element, then switch the insertion mode to "in row"
* > and return.
*/
case 'TR':
$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_ROW;
return;

/*
* > 7. If _node_ is a `tbody`, `thead`, or `tfoot` element, then switch the
* > insertion mode to "in table body" and return.
*/
case 'TBODY':
case 'THEAD':
case 'TFOOT':
$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_TABLE_BODY;
return;

/*
* > 8. If _node_ is a `caption` element, then switch the insertion mode to
* > "in caption" and return.
*/
case 'CAPTION':
$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_CAPTION;
return;

/*
* > 9. If _node_ is a `colgroup` element, then switch the insertion mode to
* > "in column group" and return.
*/
case 'COLGROUP':
$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_COLUMN_GROUP;
return;

/*
* > 10. If _node_ is a `table` element, then switch the insertion mode to
* > "in table" and return.
*/
case 'TABLE':
$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_TABLE;
return;

/*
* > 11. If _node_ is a `template` element, then switch the insertion mode to the
* > current template insertion mode and return.
*/
case 'TEMPLATE':
$this->state->insertion_mode = end( $this->state->stack_of_template_insertion_modes );
return;

/*
* > 12. If _node_ is a `head` element and _last_ is false, then switch the
* > insertion mode to "in head" and return.
*/
case 'HEAD':
if ( ! $last ) {
$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_HEAD;
return;
}
break;

/*
* > 13. If _node_ is a `body` element, then switch the insertion mode to "in body"
* > and return.
*/
case 'BODY':
$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_BODY;
return;

/*
* > 14. If _node_ is a `frameset` element, then switch the insertion mode to
* > "in frameset" and return. (fragment case)
*/
case 'FRAMESET':
$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_FRAMESET;
return;

/*
* > 15. If _node_ is an `html` element, run these substeps:
* > 1. If the head element pointer is null, switch the insertion mode to
* > "before head" and return. (fragment case)
* > 2. Otherwise, the head element pointer is not null, switch the insertion
* > mode to "after head" and return.
*/
case 'HTML':
$this->state->insertion_mode = isset( $this->state->head_element )
? WP_HTML_Processor_State::INSERTION_MODE_AFTER_HEAD
: WP_HTML_Processor_State::INSERTION_MODE_BEFORE_HEAD;
return;
}
}

/*
* > 16. If _last_ is true, then switch the insertion mode to "in body"
* > and return. (fragment case)
*
* This is only reachable if `$last` is true, as per the fragment parsing case.
*/
$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_BODY;
}

/**
* Runs the adoption agency algorithm.
*
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2 changes: 1 addition & 1 deletion wp-includes/version.php
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@
*
* @global string $wp_version
*/
$wp_version = '6.7-alpha-58654';
$wp_version = '6.7-alpha-58656';

/**
* Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.
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