From b867b58f3761b9f363d382362dd1634b7301ef4e Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Fri, 19 Jan 2024 19:18:18 +0100
Subject: [PATCH 01/22] Implement SELECT and related tags handling

---
 .../html-api/class-wp-html-open-elements.php  |  23 ++-
 .../html-api/class-wp-html-processor.php      | 164 +++++++++++++++++-
 2 files changed, 179 insertions(+), 8 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-open-elements.php b/src/wp-includes/html-api/class-wp-html-open-elements.php
index 15479801dda10..c304ba57a0cca 100644
--- a/src/wp-includes/html-api/class-wp-html-open-elements.php
+++ b/src/wp-includes/html-api/class-wp-html-open-elements.php
@@ -269,19 +269,34 @@ 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;
 	}
 
 	/**
diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index 32800218f6404..cc371519f775b 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -101,7 +101,7 @@
  *
  *  - Containers: ADDRESS, BLOCKQUOTE, DETAILS, DIALOG, DIV, FOOTER, HEADER, MAIN, MENU, SPAN, SUMMARY.
  *  - Custom elements: All custom elements are supported. :)
- *  - Form elements: BUTTON, DATALIST, FIELDSET, INPUT, LABEL, LEGEND, METER, PROGRESS, SEARCH.
+ *  - Form elements: BUTTON, DATALIST, FIELDSET, INPUT, LABEL, LEGEND, METER, OPTGROUP, OPTION, PROGRESS, SEARCH, SELECT.
  *  - Formatting elements: B, BIG, CODE, EM, FONT, I, PRE, SMALL, STRIKE, STRONG, TT, U, WBR.
  *  - Heading elements: H1, H2, H3, H4, H5, H6, HGROUP.
  *  - Links: A.
@@ -757,6 +757,9 @@ public function step( $node_to_process = self::PROCESS_NEXT_NODE ) {
 				case WP_HTML_Processor_State::INSERTION_MODE_IN_BODY:
 					return $this->step_in_body();
 
+				case WP_HTML_Processor_State::INSERTION_MODE_IN_SELECT:
+					return $this->step_in_select();
+
 				default:
 					$this->last_error = self::ERROR_UNSUPPORTED;
 					throw new WP_HTML_Unsupported_Exception( "No support for parsing in the '{$this->state->insertion_mode}' state." );
@@ -1336,6 +1339,50 @@ private function step_in_body() {
 			case '+TRACK':
 				$this->insert_html_element( $this->state->current_token );
 				return true;
+
+			/*
+			 * > A start tag whose tag name is "select"
+			 */
+			case '+SELECT':
+				$this->reconstruct_active_formatting_elements();
+				$this->insert_html_element( $this->state->current_token );
+				$this->state->frameset_ok = false;
+
+				// If the insertion mode is one of
+				// - "in table"
+				// - "in caption"
+				// - "in table body"
+				// - "in row"
+				// - "in cell"
+				// then switch the insertion mode to "in select in table"
+				//
+				// Otherwise, switch the insertion mode to "in select".
+				switch ( $this->state->insertion_mode ) {
+					case WP_HTML_Processor_State::INSERTION_MODE_IN_TABLE:
+					case WP_HTML_Processor_State::INSERTION_MODE_IN_CAPTION:
+					case WP_HTML_Processor_State::INSERTION_MODE_IN_TABLE_BODY:
+					case WP_HTML_Processor_State::INSERTION_MODE_IN_ROW:
+					case WP_HTML_Processor_State::INSERTION_MODE_IN_CELL:
+						$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_SELECT_IN_TABLE;
+						break;
+					default:
+						$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_SELECT;
+						break;
+				}
+				return true;
+
+			/*
+			 * > A start tag whose tag name is one of: "optgroup", "option"
+			 */
+			case '+OPTGROUP':
+			case '+OPTION':
+				$current_node = $this->state->stack_of_open_elements->current_node();
+				if ( $current_node && 'OPTION' === $current_node->node_name ) {
+					$this->state->stack_of_open_elements->pop();
+				}
+				$this->reconstruct_active_formatting_elements();
+				$this->insert_html_element( $this->state->current_token );
+				return true;
 		}
 
 		/*
@@ -1378,8 +1425,6 @@ private function step_in_body() {
 			case 'NOFRAMES':
 			case 'NOSCRIPT':
 			case 'OBJECT':
-			case 'OPTGROUP':
-			case 'OPTION':
 			case 'PLAINTEXT':
 			case 'RB':
 			case 'RP':
@@ -1387,7 +1432,6 @@ private function step_in_body() {
 			case 'RTC':
 			case 'SARCASM':
 			case 'SCRIPT':
-			case 'SELECT':
 			case 'STYLE':
 			case 'SVG':
 			case 'TABLE':
@@ -1448,6 +1492,118 @@ private function step_in_body() {
 		}
 	}
 
+	/**
+	 * Parses next element in the 'in select' insertion mode.
+	 *
+	 * This internal function performs the 'in select' insertion mode
+	 * logic for the generalized WP_HTML_Processor::step() function.
+	 *
+	 * @since 6.5.0
+	 *
+	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
+	 *
+	 * @see https://html.spec.whatwg.org/multipage/parsing.html#parsing-main-inselect
+	 * @see WP_HTML_Processor::step
+	 *
+	 * @return bool Whether an element was found.
+	 */
+	private function step_in_select() {
+		$tag_name = $this->get_tag();
+		$op_sigil = $this->is_tag_closer() ? '-' : '+';
+		$op       = "{$op_sigil}{$tag_name}";
+
+		switch ( $op ) {
+			/*
+			 * > A start tag whose tag name is "html"
+			 */
+			case '+HTML':
+				$this->last_error = self::ERROR_UNSUPPORTED;
+				throw new WP_HTML_Unsupported_Exception( "Cannot process {$tag_name} element." );
+
+			/*
+			 * > A start tag whose tag name is "option"
+			 */
+			case '+OPTION':
+				$current_node = $this->state->stack_of_open_elements->current_node();
+				if ( $current_node && 'OPTION' === $current_node->node_name ) {
+					$this->state->stack_of_open_elements->pop();
+				}
+				$this->insert_html_element( $this->state->current_token );
+				return true;
+
+			/*
+			 * > A start tag whose tag name is "optgroup"
+			 * > A start tag whose tag name is "hr"
+			 */
+			case '+OPTGROUP':
+			case '+HR':
+				$current_node = $this->state->stack_of_open_elements->current_node();
+				if ( $current_node && 'OPTION' === $current_node->node_name ) {
+					$this->state->stack_of_open_elements->pop();
+					// If we've popped, update the current_node
+					$current_node = $this->state->stack_of_open_elements->current_node();
+				}
+
+				if ( $current_node && 'OPTGROUP' === $current_node->node_name ) {
+					$this->state->stack_of_open_elements->pop();
+				}
+
+				$this->insert_html_element( $this->state->current_token );
+				return true;
+
+			/*
+			 * > An end tag whose tag name is "optgroup"
+			 */
+			case '-OPTGROUP':
+				$walker       = $this->state->stack_of_open_elements->walk_up();
+				$current_node = $walker->current();
+				if ( ! $current_node ) {
+					return $this->step();
+				}
+				if ( 'OPTGROUP' === $current_node->node_name ) {
+					$this->state->stack_of_open_elements->pop();
+					return true;
+				}
+
+				$walker->next();
+				$current_node_parent = $walker->current();
+				if ( 'OPTION' === $current_node->node_name && 'OPTGROUP' === $current_node_parent->node_name ) {
+					$this->state->stack_of_open_elements->pop();
+					$this->state->stack_of_open_elements->pop();
+					return true;
+				}
+				return $this->step();
+
+			/*
+			 * > An end tag whose tag name is "option"
+			 */
+			case '-OPTION':
+				$current_node = $this->state->stack_of_open_elements->current_node();
+				if ( $current_node && 'OPTION' === $current_node->node_name ) {
+					$this->state->stack_of_open_elements->pop();
+					return true;
+				}
+				return $this->step();
+
+			/*
+			 * > An end tag whose tag name is "select"
+			 * > A start tag whose tag name is "select"
+			 */
+			case '-SELECT':
+			case '+SELECT':
+				if ( ! $this->state->stack_of_open_elements->has_element_in_select_scope( 'SELECT' ) ) {
+					return $this->step();
+				}
+				$this->state->stack_of_open_elements->pop_until( 'SELECT' );
+				$this->state->stack_of_open_elements->pop();
+				$this->reset_insertion_mode();
+				return true;
+		}
+
+		$this->last_error = self::ERROR_UNSUPPORTED;
+		throw new WP_HTML_Unsupported_Exception( "Cannot process {$tag_name} element." );
+	}
+
 	/*
 	 * Internal helpers
 	 */

From 9245930e6d8697a7de47ef1bbb1b75a402e66dbf Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Wed, 3 Jul 2024 20:54:44 +0200
Subject: [PATCH 02/22] Remove SELECT from unsupported elements test

---
 tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php b/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php
index 01dcd9c32d7fb..403f40a1da032 100644
--- a/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php
+++ b/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php
@@ -189,15 +189,12 @@ public static function data_unsupported_elements() {
 			'NOFRAMES', // Neutralized.
 			'NOSCRIPT',
 			'OBJECT',
-			'OPTGROUP',
-			'OPTION',
 			'PLAINTEXT', // Neutralized.
 			'RB', // Neutralized.
 			'RP',
 			'RT',
 			'RTC', // Neutralized.
 			'SCRIPT',
-			'SELECT',
 			'STYLE',
 			'SVG',
 			'TABLE',

From 267a27be1007181eceb06b95aa68de5e7109df18 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Wed, 3 Jul 2024 20:57:11 +0200
Subject: [PATCH 03/22] Remove SELECT scope optgroup/option tests

---
 .../tests/html-api/wpHtmlSupportRequiredOpenElements.php      | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/tests/phpunit/tests/html-api/wpHtmlSupportRequiredOpenElements.php b/tests/phpunit/tests/html-api/wpHtmlSupportRequiredOpenElements.php
index c2e8c697e8156..48255190ad50c 100644
--- a/tests/phpunit/tests/html-api/wpHtmlSupportRequiredOpenElements.php
+++ b/tests/phpunit/tests/html-api/wpHtmlSupportRequiredOpenElements.php
@@ -308,9 +308,5 @@ public function test_has_element_in_select_scope_needs_support() {
 		 * FOREIGNOBJECT, DESC, TITLE.
 		 */
 		$this->ensure_support_is_added_everywhere( 'SVG' );
-
-		// These elements are specific to SELECT scope.
-		$this->ensure_support_is_added_everywhere( 'OPTGROUP' );
-		$this->ensure_support_is_added_everywhere( 'OPTION' );
 	}
 }

From b0475fb11c4c02b9484411764991de1a119c6ead Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Wed, 3 Jul 2024 20:57:57 +0200
Subject: [PATCH 04/22] Remove SELECT, OPTION, OPTGROUP from unsupported tags

---
 tests/phpunit/tests/html-api/wpHtmlProcessor.php | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/tests/phpunit/tests/html-api/wpHtmlProcessor.php b/tests/phpunit/tests/html-api/wpHtmlProcessor.php
index 536f6fdf4dd8f..b842703a7a135 100644
--- a/tests/phpunit/tests/html-api/wpHtmlProcessor.php
+++ b/tests/phpunit/tests/html-api/wpHtmlProcessor.php
@@ -406,8 +406,6 @@ public static function data_unsupported_special_in_body_tags() {
 			'NOFRAMES'  => array( 'NOFRAMES' ),
 			'NOSCRIPT'  => array( 'NOSCRIPT' ),
 			'OBJECT'    => array( 'OBJECT' ),
-			'OPTGROUP'  => array( 'OPTGROUP' ),
-			'OPTION'    => array( 'OPTION' ),
 			'PLAINTEXT' => array( 'PLAINTEXT' ),
 			'RB'        => array( 'RB' ),
 			'RP'        => array( 'RP' ),
@@ -415,7 +413,6 @@ public static function data_unsupported_special_in_body_tags() {
 			'RTC'       => array( 'RTC' ),
 			'SARCASM'   => array( 'SARCASM' ),
 			'SCRIPT'    => array( 'SCRIPT' ),
-			'SELECT'    => array( 'SELECT' ),
 			'STYLE'     => array( 'STYLE' ),
 			'SVG'       => array( 'SVG' ),
 			'TABLE'     => array( 'TABLE' ),

From 1944b6646c5945e75c787284637bbffcd1353cf6 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Wed, 3 Jul 2024 20:58:54 +0200
Subject: [PATCH 05/22] Remove OPTION,OPTGROUP from gen implied end tags
 unsupported  test

---
 .../tests/html-api/wpHtmlSupportRequiredHtmlProcessor.php     | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/tests/phpunit/tests/html-api/wpHtmlSupportRequiredHtmlProcessor.php b/tests/phpunit/tests/html-api/wpHtmlSupportRequiredHtmlProcessor.php
index 2d3cd21ce461b..07943cd62a2f4 100644
--- a/tests/phpunit/tests/html-api/wpHtmlSupportRequiredHtmlProcessor.php
+++ b/tests/phpunit/tests/html-api/wpHtmlSupportRequiredHtmlProcessor.php
@@ -58,8 +58,6 @@ private function ensure_support_is_added_everywhere( $tag_name ) {
 	 * @covers WP_HTML_Processor::generate_implied_end_tags
 	 */
 	public function test_generate_implied_end_tags_needs_support() {
-		$this->ensure_support_is_added_everywhere( 'OPTGROUP' );
-		$this->ensure_support_is_added_everywhere( 'OPTION' );
 		$this->ensure_support_is_added_everywhere( 'RB' );
 		$this->ensure_support_is_added_everywhere( 'RP' );
 		$this->ensure_support_is_added_everywhere( 'RT' );
@@ -79,8 +77,6 @@ public function test_generate_implied_end_tags_needs_support() {
 	public function test_generate_implied_end_tags_thoroughly_needs_support() {
 		$this->ensure_support_is_added_everywhere( 'CAPTION' );
 		$this->ensure_support_is_added_everywhere( 'COLGROUP' );
-		$this->ensure_support_is_added_everywhere( 'OPTGROUP' );
-		$this->ensure_support_is_added_everywhere( 'OPTION' );
 		$this->ensure_support_is_added_everywhere( 'RB' );
 		$this->ensure_support_is_added_everywhere( 'RP' );
 		$this->ensure_support_is_added_everywhere( 'RT' );

From 8d4b4dfd5ef7a550b5d4cfbd2bd3a947a239d899 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Thu, 4 Jul 2024 13:28:22 +0200
Subject: [PATCH 06/22] Add OPTION, OPTGROUP to implied end tags

---
 src/wp-includes/html-api/class-wp-html-processor.php | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index cc371519f775b..509cfb5b164d6 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -2192,6 +2192,7 @@ private function close_a_p_element() {
 	 * Closes elements that have implied end tags.
 	 *
 	 * @since 6.4.0
+	 * @since 6.7.0 Support "option" and "optgroup".
 	 *
 	 * @see https://html.spec.whatwg.org/#generate-implied-end-tags
 	 *
@@ -2202,6 +2203,8 @@ private function generate_implied_end_tags( $except_for_this_element = null ) {
 			'DD',
 			'DT',
 			'LI',
+			'OPTGROUP',
+			'OPTION',
 			'P',
 		);
 
@@ -2230,6 +2233,8 @@ private function generate_implied_end_tags_thoroughly() {
 			'DD',
 			'DT',
 			'LI',
+			'OPTGROUP',
+			'OPTION',
 			'P',
 		);
 

From 140411904e9da10d44878a0f595111111eb828fd Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Thu, 4 Jul 2024 13:44:42 +0200
Subject: [PATCH 07/22] Update step_in_select since tag

---
 src/wp-includes/html-api/class-wp-html-processor.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index 509cfb5b164d6..eb1d092f698e5 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -1498,7 +1498,7 @@ private function step_in_body() {
 	 * This internal function performs the 'in select' insertion mode
 	 * logic for the generalized WP_HTML_Processor::step() function.
 	 *
-	 * @since 6.5.0
+	 * @since 6.7.0
 	 *
 	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
 	 *

From dc0bbb90d8205c24d84287d8292078cf55505457 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Thu, 4 Jul 2024 16:04:09 +0200
Subject: [PATCH 08/22] Update since tags on in_select_scope

---
 src/wp-includes/html-api/class-wp-html-open-elements.php | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-open-elements.php b/src/wp-includes/html-api/class-wp-html-open-elements.php
index c304ba57a0cca..117bfb4a04eac 100644
--- a/src/wp-includes/html-api/class-wp-html-open-elements.php
+++ b/src/wp-includes/html-api/class-wp-html-open-elements.php
@@ -269,8 +269,8 @@ public function has_element_in_table_scope( $tag_name ) {
 	/**
 	 * Returns whether a particular element is in select scope.
 	 *
-	 * @since 6.4.0 - Stub, always throws.
-	 * @since 6.5.0 - Implemented.
+	 * @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
 	 *

From 9d9984463dac791c28fab4434c6e26a24d9d4b43 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Thu, 4 Jul 2024 16:14:32 +0200
Subject: [PATCH 09/22] =?UTF-8?q?Implement=20in=5Fselect=5Fscope=20via=20?=
 =?UTF-8?q?=E2=80=A6in=5Fspecific=5Fscope?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../html-api/class-wp-html-open-elements.php  | 34 +++++++++----------
 1 file changed, 16 insertions(+), 18 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-open-elements.php b/src/wp-includes/html-api/class-wp-html-open-elements.php
index 117bfb4a04eac..0fd8ae43b0c42 100644
--- a/src/wp-includes/html-api/class-wp-html-open-elements.php
+++ b/src/wp-includes/html-api/class-wp-html-open-elements.php
@@ -156,11 +156,15 @@ public function current_node() {
 	 *
 	 * @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.
+	 * @param string   $tag_name             Name of tag check.
+	 * @param string[] $termination_list     List of elements that terminate the search.
+	 * @param string   $termination_behavior Optional. "include" or "exclude". If "include"
+	 *                                       (default), the terminate when any tag in
+	 *                                       `$termination_list` is reached. Otherwise,
+	 *                                       terminate when any _other_ tag is reached.
 	 * @return bool Whether the element was found in a specific scope.
 	 */
-	public function has_element_in_specific_scope( $tag_name, $termination_list ) {
+	public function has_element_in_specific_scope( $tag_name, $termination_list, $termination_behavior = 'include' ) {
 		foreach ( $this->walk_up() as $node ) {
 			if ( $node->node_name === $tag_name ) {
 				return true;
@@ -178,7 +182,10 @@ public function has_element_in_specific_scope( $tag_name, $termination_list ) {
 					return false;
 			}
 
-			if ( in_array( $node->node_name, $termination_list, true ) ) {
+			$terminate = 'include' === $termination_behavior
+				? in_array( $node->node_name, $termination_list, true )
+				: ! in_array( $node->node_name, $termination_list, true );
+			if ( $terminate ) {
 				return false;
 			}
 		}
@@ -283,20 +290,11 @@ public function has_element_in_table_scope( $tag_name ) {
 	 * @return bool Whether given element is in scope.
 	 */
 	public function has_element_in_select_scope( $tag_name ) {
-		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;
+		return $this->has_element_in_specific_scope(
+			$tag_name,
+			array( 'OPTION', 'OPTGROUP' ),
+			'exclude'
+		);
 	}
 
 	/**

From 30854052ac646e75965e491736f25d8958b44d38 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Thu, 4 Jul 2024 19:02:39 +0200
Subject: [PATCH 10/22] =?UTF-8?q?Revert=20"Implement=20in=5Fselect=5Fscope?=
 =?UTF-8?q?=20via=20=E2=80=A6in=5Fspecific=5Fscope"?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This reverts commit 9d9984463dac791c28fab4434c6e26a24d9d4b43.
---
 .../html-api/class-wp-html-open-elements.php  | 34 ++++++++++---------
 1 file changed, 18 insertions(+), 16 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-open-elements.php b/src/wp-includes/html-api/class-wp-html-open-elements.php
index 0fd8ae43b0c42..117bfb4a04eac 100644
--- a/src/wp-includes/html-api/class-wp-html-open-elements.php
+++ b/src/wp-includes/html-api/class-wp-html-open-elements.php
@@ -156,15 +156,11 @@ public function current_node() {
 	 *
 	 * @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.
-	 * @param string   $termination_behavior Optional. "include" or "exclude". If "include"
-	 *                                       (default), the terminate when any tag in
-	 *                                       `$termination_list` is reached. Otherwise,
-	 *                                       terminate when any _other_ tag is reached.
+	 * @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, $termination_behavior = 'include' ) {
+	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;
@@ -182,10 +178,7 @@ public function has_element_in_specific_scope( $tag_name, $termination_list, $te
 					return false;
 			}
 
-			$terminate = 'include' === $termination_behavior
-				? in_array( $node->node_name, $termination_list, true )
-				: ! in_array( $node->node_name, $termination_list, true );
-			if ( $terminate ) {
+			if ( in_array( $node->node_name, $termination_list, true ) ) {
 				return false;
 			}
 		}
@@ -290,11 +283,20 @@ public function has_element_in_table_scope( $tag_name ) {
 	 * @return bool Whether given element is in scope.
 	 */
 	public function has_element_in_select_scope( $tag_name ) {
-		return $this->has_element_in_specific_scope(
-			$tag_name,
-			array( 'OPTION', 'OPTGROUP' ),
-			'exclude'
-		);
+		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;
 	}
 
 	/**

From e095c6206c3a32279016e35c8f909eb270ce3fd7 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Thu, 4 Jul 2024 20:36:01 +0200
Subject: [PATCH 11/22] Add current_node_is method

---
 .../html-api/class-wp-html-open-elements.php  | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/src/wp-includes/html-api/class-wp-html-open-elements.php b/src/wp-includes/html-api/class-wp-html-open-elements.php
index 15479801dda10..9ba5a0cf4aa70 100644
--- a/src/wp-includes/html-api/class-wp-html-open-elements.php
+++ b/src/wp-includes/html-api/class-wp-html-open-elements.php
@@ -144,6 +144,28 @@ public function current_node() {
 		return $current_node ? $current_node : null;
 	}
 
+	/**
+	 * Checks if the node at the top of the stack matches provided node name.
+	 *
+	 * @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' );
+	 *
+	 * @since 6.7.0
+	 *
+	 * @param  string $node_name The node name to match. Provide a tag name for tags or a
+	 *                           token name for other types of tokens.
+	 * @return bool True if there are nodes on the stack and the top node has
+	 *              a matching node_name.
+	 */
+	public function current_node_is( string $node_name ): bool {
+		$current_node = end( $this->stack );
+		return $current_node && $current_node->node_name === $node_name;
+	}
+
 	/**
 	 * Returns whether an element is in a specific scope.
 	 *

From 76c899a2d8bb9d43d8bae9d0eebac805a2a746dc Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Thu, 4 Jul 2024 21:23:20 +0200
Subject: [PATCH 12/22] Add text, comment, doctype handling

---
 .../html-api/class-wp-html-processor.php      | 30 +++++++++++++++++--
 1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index eb1d092f698e5..bb0564233f66c 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -1508,11 +1508,35 @@ private function step_in_body() {
 	 * @return bool Whether an element was found.
 	 */
 	private function step_in_select() {
-		$tag_name = $this->get_tag();
-		$op_sigil = $this->is_tag_closer() ? '-' : '+';
-		$op       = "{$op_sigil}{$tag_name}";
+		$token_name = $this->get_token_name();
+		$token_type = $this->get_token_type();
+		$op_sigil   = '#tag' === $token_type ? ( parent::is_tag_closer() ? '-' : '+' ) : '';
+		$op         = "{$op_sigil}{$token_name}";
 
 		switch ( $op ) {
+			/*
+			 * > Any other character token
+			 */
+			case '#text':
+				$this->insert_html_element( $this->state->current_token );
+				return true;
+
+			/*
+			 * > A comment token
+			 */
+			case '#comment':
+			case '#funky-comment':
+			case '#presumptuous-tag':
+				$this->insert_html_element( $this->state->current_token );
+				return true;
+
+			/*
+			 * > A DOCTYPE token
+			 */
+			case 'html':
+				// Parse error. Ignore the token.
+				return $this->step();
+
 			/*
 			 * > A start tag whose tag name is "html"
 			 */

From 52fd8e58027edc16eb2bdb90ba7035e31fdb9e20 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Thu, 4 Jul 2024 21:23:49 +0200
Subject: [PATCH 13/22] Handle +HTML case

---
 src/wp-includes/html-api/class-wp-html-processor.php | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index bb0564233f66c..2f5f2468a132d 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -1541,8 +1541,7 @@ private function step_in_select() {
 			 * > A start tag whose tag name is "html"
 			 */
 			case '+HTML':
-				$this->last_error = self::ERROR_UNSUPPORTED;
-				throw new WP_HTML_Unsupported_Exception( "Cannot process {$tag_name} element." );
+				return $this->step_in_body();
 
 			/*
 			 * > A start tag whose tag name is "option"

From 6a10eb0222d462ac8d7e6f7ce19630d9e9ad7689 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Thu, 4 Jul 2024 21:25:07 +0200
Subject: [PATCH 14/22] Update several cases to use current_node_is

---
 .../html-api/class-wp-html-processor.php        | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index 2f5f2468a132d..d772eb38739dd 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -1547,8 +1547,7 @@ private function step_in_select() {
 			 * > A start tag whose tag name is "option"
 			 */
 			case '+OPTION':
-				$current_node = $this->state->stack_of_open_elements->current_node();
-				if ( $current_node && 'OPTION' === $current_node->node_name ) {
+				if ( $this->state->stack_of_open_elements->current_node_is( 'OPTION' ) ) {
 					$this->state->stack_of_open_elements->pop();
 				}
 				$this->insert_html_element( $this->state->current_token );
@@ -1557,17 +1556,17 @@ private function step_in_select() {
 			/*
 			 * > A start tag whose tag name is "optgroup"
 			 * > A start tag whose tag name is "hr"
+			 *
+			 * These rules are identical except for the treatment of the self-closing flag and
+			 * the subsequent pop of the HR void element, all of which is handled elsewhere in the processor.
 			 */
 			case '+OPTGROUP':
 			case '+HR':
-				$current_node = $this->state->stack_of_open_elements->current_node();
-				if ( $current_node && 'OPTION' === $current_node->node_name ) {
+				if ( $this->state->stack_of_open_elements->current_node_is( 'OPTION' ) ) {
 					$this->state->stack_of_open_elements->pop();
-					// If we've popped, update the current_node
-					$current_node = $this->state->stack_of_open_elements->current_node();
 				}
 
-				if ( $current_node && 'OPTGROUP' === $current_node->node_name ) {
+				if ( $this->state->stack_of_open_elements->current_node_is( 'OPTGROUP' ) ) {
 					$this->state->stack_of_open_elements->pop();
 				}
 
@@ -1601,11 +1600,11 @@ private function step_in_select() {
 			 * > An end tag whose tag name is "option"
 			 */
 			case '-OPTION':
-				$current_node = $this->state->stack_of_open_elements->current_node();
-				if ( $current_node && 'OPTION' === $current_node->node_name ) {
+				if ( $this->state->stack_of_open_elements->current_node_is( 'OPTION' ) ) {
 					$this->state->stack_of_open_elements->pop();
 					return true;
 				}
+				// Parse error: ignore the token.
 				return $this->step();
 
 			/*

From 8b3a9e43eee325f70ae95e49ed1568a13a1c58ca Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Thu, 4 Jul 2024 21:25:29 +0200
Subject: [PATCH 15/22] Simplify -OPTGROUP handling implementation

---
 .../html-api/class-wp-html-processor.php      | 22 +++++++++----------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index d772eb38739dd..d8c0e9016d737 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -1577,23 +1577,21 @@ private function step_in_select() {
 			 * > An end tag whose tag name is "optgroup"
 			 */
 			case '-OPTGROUP':
-				$walker       = $this->state->stack_of_open_elements->walk_up();
-				$current_node = $walker->current();
-				if ( ! $current_node ) {
-					return $this->step();
-				}
-				if ( 'OPTGROUP' === $current_node->node_name ) {
-					$this->state->stack_of_open_elements->pop();
-					return true;
+				$current_node = $this->state->stack_of_open_elements->current_node();
+				if ( $current_node && 'OPTION' === $current_node->node_name ) {
+					foreach ( $this->state->stack_of_open_elements->walk_up( $current_node ) as $parent ) {
+						break;
+					}
+					if ( $parent && 'OPTGROUP' === $parent->node_name ) {
+						$this->state->stack_of_open_elements->pop();
+					}
 				}
 
-				$walker->next();
-				$current_node_parent = $walker->current();
-				if ( 'OPTION' === $current_node->node_name && 'OPTGROUP' === $current_node_parent->node_name ) {
-					$this->state->stack_of_open_elements->pop();
+				if ( $this->state->stack_of_open_elements->current_node_is( 'OPTGROUP' ) ) {
 					$this->state->stack_of_open_elements->pop();
 					return true;
 				}
+				// Parse error: ignore the token.
 				return $this->step();
 
 			/*

From 87c65969b965ad313e9e49097232c9f26537bd23 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Thu, 4 Jul 2024 21:25:50 +0200
Subject: [PATCH 16/22] Add input,keygen,textarea,script,template handling

---
 .../html-api/class-wp-html-processor.php      | 23 +++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index d8c0e9016d737..166847c9f7231 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -1618,6 +1618,29 @@ private function step_in_select() {
 				$this->state->stack_of_open_elements->pop();
 				$this->reset_insertion_mode();
 				return true;
+
+			/*
+			 * > A start tag whose tag name is one of: "input", "keygen", "textarea"
+			 */
+			case '+INPUT':
+			case '+KEYGEN':
+			case '+TEXTAREA':
+				// Parse error.
+				if ( ! $this->state->stack_of_open_elements->has_element_in_select_scope( 'SELECT' ) ) {
+					return $this->step();
+				}
+				$this->state->stack_of_open_elements->pop_until( 'SELECT' );
+				$this->reset_insertion_mode();
+				return $this->step( self::REPROCESS_CURRENT_NODE );
+
+			/*
+			 * > A start tag whose tag name is one of: "script", "template"
+			 * > An end tag whose tag name is "template"
+			 */
+			case '+SCRIPT':
+			case '+TEMPLATE':
+			case '-TEMPLATE':
+				return $this->step_in_head();
 		}
 
 		$this->last_error = self::ERROR_UNSUPPORTED;

From d46433071552a0e3b5c740dff3de1f59a4f63f55 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Thu, 4 Jul 2024 21:26:02 +0200
Subject: [PATCH 17/22] Add "anything else" handling

---
 src/wp-includes/html-api/class-wp-html-processor.php | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index 166847c9f7231..bb6bb1057d56a 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -1643,8 +1643,11 @@ private function step_in_select() {
 				return $this->step_in_head();
 		}
 
-		$this->last_error = self::ERROR_UNSUPPORTED;
-		throw new WP_HTML_Unsupported_Exception( "Cannot process {$tag_name} element." );
+		/*
+		 * > Anything else
+		 * >   Parse error: ignore the token.
+		 */
+		return $this->step();
 	}
 
 	/*

From ddbd676d5e33ed032cb513c0b4d3201f782f4009 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Thu, 4 Jul 2024 21:28:01 +0200
Subject: [PATCH 18/22] Add step_in_head stub

---
 .../html-api/class-wp-html-processor.php      | 23 +++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index bb6bb1057d56a..6ba85262f3a1d 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -757,6 +757,9 @@ public function step( $node_to_process = self::PROCESS_NEXT_NODE ) {
 				case WP_HTML_Processor_State::INSERTION_MODE_IN_BODY:
 					return $this->step_in_body();
 
+				case WP_HTML_Processor_State::INSERTION_MODE_IN_HEAD:
+					return $this->step_in_head();
+
 				case WP_HTML_Processor_State::INSERTION_MODE_IN_SELECT:
 					return $this->step_in_select();
 
@@ -1492,6 +1495,26 @@ private function step_in_body() {
 		}
 	}
 
+	/**
+	 * Parses next element in the 'in head' insertion mode.
+	 *
+	 * this internal function performs the 'in select' insertion mode
+	 * logic for the generalized wp_html_processor::step() function.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @throws wp_html_unsupported_exception when encountering unsupported html input.
+	 *
+	 * @see https://html.spec.whatwg.org/multipage/parsing.html#parsing-main-inselect
+	 * @see wp_html_processor::step
+	 *
+	 * @return bool whether an element was found.
+	 */
+	private function step_in_head() {
+		$this->last_error = self::ERROR_UNSUPPORTED;
+		throw new WP_HTML_Unsupported_Exception( "No support for parsing in the '{$this->state->insertion_mode}' state." );
+	}
+
 	/**
 	 * Parses next element in the 'in select' insertion mode.
 	 *

From f6d686d396535fb754de9f0078f79ca645a342c1 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Thu, 4 Jul 2024 21:29:35 +0200
Subject: [PATCH 19/22] Multi-line comments should be block comments

---
 .../html-api/class-wp-html-processor.php      | 20 ++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index 6ba85262f3a1d..1ecce27b9487d 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -1351,15 +1351,17 @@ private function step_in_body() {
 				$this->insert_html_element( $this->state->current_token );
 				$this->state->frameset_ok = false;
 
-				// If the insertion mode is one of
-				// - "in table"
-				// - "in caption"
-				// - "in table body"
-				// - "in row"
-				// - "in cell"
-				// then switch the insertion mode to "in select in table"
-				//
-				// Otherwise, switch the insertion mode to "in select".
+				/*
+				 * If the insertion mode is one of
+				 * - "in table"
+				 * - "in caption"
+				 * - "in table body"
+				 * - "in row"
+				 * - "in cell"
+				 * then switch the insertion mode to "in select in table"
+				 *
+				 * Otherwise, switch the insertion mode to "in select".
+				 */
 				switch ( $this->state->insertion_mode ) {
 					case WP_HTML_Processor_State::INSERTION_MODE_IN_TABLE:
 					case WP_HTML_Processor_State::INSERTION_MODE_IN_CAPTION:

From 783cef63fe13c3b31a3ecdbe2f060f8761593e96 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Thu, 4 Jul 2024 21:32:40 +0200
Subject: [PATCH 20/22] fixup! Update several cases to use current_node_is

---
 src/wp-includes/html-api/class-wp-html-processor.php | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index 1ecce27b9487d..e6ed1decea45c 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -1381,8 +1381,7 @@ private function step_in_body() {
 			 */
 			case '+OPTGROUP':
 			case '+OPTION':
-				$current_node = $this->state->stack_of_open_elements->current_node();
-				if ( $current_node && 'OPTION' === $current_node->node_name ) {
+				if ( $this->state->stack_of_open_elements->current_node_is( 'OPTION' ) ) {
 					$this->state->stack_of_open_elements->pop();
 				}
 				$this->reconstruct_active_formatting_elements();

From 3222275610c5770bcddd3535a659b5dc6149e633 Mon Sep 17 00:00:00 2001
From: Jon Surrell <sirreal@users.noreply.github.com>
Date: Thu, 4 Jul 2024 21:35:25 +0200
Subject: [PATCH 21/22] Fix step_in_head documentation block

---
 .../html-api/class-wp-html-processor.php           | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index e6ed1decea45c..49634d8571f12 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -1496,20 +1496,20 @@ private function step_in_body() {
 		}
 	}
 
-	/**
+	/*
 	 * Parses next element in the 'in head' insertion mode.
 	 *
-	 * this internal function performs the 'in select' insertion mode
-	 * logic for the generalized wp_html_processor::step() function.
+	 * This internal function performs the 'in head' insertion mode
+	 * logic for the generalized WP_HTML_Processor::step() function.
 	 *
 	 * @since 6.7.0
 	 *
-	 * @throws wp_html_unsupported_exception when encountering unsupported html input.
+	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
 	 *
-	 * @see https://html.spec.whatwg.org/multipage/parsing.html#parsing-main-inselect
-	 * @see wp_html_processor::step
+	 * @see https://html.spec.whatwg.org/multipage/parsing.html#parsing-main-inhead
+	 * @see WP_HTML_Processor::step
 	 *
-	 * @return bool whether an element was found.
+	 * @return bool Whether an element was found.
 	 */
 	private function step_in_head() {
 		$this->last_error = self::ERROR_UNSUPPORTED;

From f2e1d036c730ac81127caa9044b0bb874f5e78c8 Mon Sep 17 00:00:00 2001
From: Dennis Snell <dennis.snell@automattic.com>
Date: Thu, 4 Jul 2024 17:03:36 -0700
Subject: [PATCH 22/22] Apply feedback requests.

---
 .../html-api/class-wp-html-open-elements.php  | 21 +++--
 .../html-api/class-wp-html-processor.php      | 76 ++++++++++++++-----
 2 files changed, 67 insertions(+), 30 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-open-elements.php b/src/wp-includes/html-api/class-wp-html-open-elements.php
index f0b0fcb595f56..d1585cdea5bf5 100644
--- a/src/wp-includes/html-api/class-wp-html-open-elements.php
+++ b/src/wp-includes/html-api/class-wp-html-open-elements.php
@@ -189,11 +189,6 @@ public function current_node_is( string $identity ): bool {
 	/**
 	 * 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
@@ -311,18 +306,22 @@ public function has_element_in_table_scope( $tag_name ) {
 	/**
 	 * 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
 	 *
-	 * > 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.
+	 * @return bool Whether the given element is in SELECT scope.
 	 */
 	public function has_element_in_select_scope( $tag_name ) {
 		foreach ( $this->walk_up() as $node ) {
diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index 2c2baadd2ce26..40538491152ad 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -1351,18 +1351,11 @@ private function step_in_body() {
 				$this->insert_html_element( $this->state->current_token );
 				$this->state->frameset_ok = false;
 
-				/*
-				 * If the insertion mode is one of
-				 * - "in table"
-				 * - "in caption"
-				 * - "in table body"
-				 * - "in row"
-				 * - "in cell"
-				 * then switch the insertion mode to "in select in table"
-				 *
-				 * Otherwise, switch the insertion mode to "in select".
-				 */
 				switch ( $this->state->insertion_mode ) {
+					/*
+					 * > If the insertion mode is one of "in table", "in caption", "in table body", "in row",
+					 * > or "in cell", then switch the insertion mode to "in select in table".
+					 */
 					case WP_HTML_Processor_State::INSERTION_MODE_IN_TABLE:
 					case WP_HTML_Processor_State::INSERTION_MODE_IN_CAPTION:
 					case WP_HTML_Processor_State::INSERTION_MODE_IN_TABLE_BODY:
@@ -1370,6 +1363,10 @@ private function step_in_body() {
 					case WP_HTML_Processor_State::INSERTION_MODE_IN_CELL:
 						$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_SELECT_IN_TABLE;
 						break;
+
+					/*
+					 * > Otherwise, switch the insertion mode to "in select".
+					 */
 					default:
 						$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_SELECT;
 						break;
@@ -1496,13 +1493,13 @@ private function step_in_body() {
 		}
 	}
 
-	/*
+	/**
 	 * Parses next element in the 'in head' insertion mode.
 	 *
 	 * This internal function performs the 'in head' insertion mode
 	 * logic for the generalized WP_HTML_Processor::step() function.
 	 *
-	 * @since 6.7.0
+	 * @since 6.7.0 Stub implementation.
 	 *
 	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
 	 *
@@ -1542,6 +1539,23 @@ private function step_in_select() {
 			 * > Any other character token
 			 */
 			case '#text':
+				$current_token = $this->bookmarks[ $this->state->current_token->bookmark_name ];
+
+				/*
+				 * > A character token that is U+0000 NULL
+				 *
+				 * If a text node only comprises null bytes then it should be
+				 * entirely ignored and should not return to calling code.
+				 */
+				if (
+					1 <= $current_token->length &&
+					"\x00" === $this->html[ $current_token->start ] &&
+					strspn( $this->html, "\x00", $current_token->start, $current_token->length ) === $current_token->length
+				) {
+					// Parse error: ignore the token.
+					return $this->step();
+				}
+
 				$this->insert_html_element( $this->state->current_token );
 				return true;
 
@@ -1558,7 +1572,7 @@ private function step_in_select() {
 			 * > A DOCTYPE token
 			 */
 			case 'html':
-				// Parse error. Ignore the token.
+				// Parse error: ignore the token.
 				return $this->step();
 
 			/*
@@ -1615,6 +1629,7 @@ private function step_in_select() {
 					$this->state->stack_of_open_elements->pop();
 					return true;
 				}
+
 				// Parse error: ignore the token.
 				return $this->step();
 
@@ -1626,31 +1641,36 @@ private function step_in_select() {
 					$this->state->stack_of_open_elements->pop();
 					return true;
 				}
+
 				// Parse error: ignore the token.
 				return $this->step();
 
 			/*
 			 * > An end tag whose tag name is "select"
 			 * > A start tag whose tag name is "select"
+			 *
+			 * > It just gets treated like an end tag.
 			 */
 			case '-SELECT':
 			case '+SELECT':
 				if ( ! $this->state->stack_of_open_elements->has_element_in_select_scope( 'SELECT' ) ) {
+					// Parse error: ignore the token.
 					return $this->step();
 				}
 				$this->state->stack_of_open_elements->pop_until( 'SELECT' );
-				$this->state->stack_of_open_elements->pop();
 				$this->reset_insertion_mode();
 				return true;
 
 			/*
 			 * > A start tag whose tag name is one of: "input", "keygen", "textarea"
+			 *
+			 * All three of these tags are considered a parse error when found in this insertion mode.
 			 */
 			case '+INPUT':
 			case '+KEYGEN':
 			case '+TEXTAREA':
-				// Parse error.
 				if ( ! $this->state->stack_of_open_elements->has_element_in_select_scope( 'SELECT' ) ) {
+					// Ignore the token.
 					return $this->step();
 				}
 				$this->state->stack_of_open_elements->pop_until( 'SELECT' );
@@ -2262,7 +2282,7 @@ private function close_a_p_element() {
 	 * Closes elements that have implied end tags.
 	 *
 	 * @since 6.4.0
-	 * @since 6.7.0 Support "option" and "optgroup".
+	 * @since 6.7.0 Full spec support.
 	 *
 	 * @see https://html.spec.whatwg.org/#generate-implied-end-tags
 	 *
@@ -2276,11 +2296,16 @@ private function generate_implied_end_tags( $except_for_this_element = null ) {
 			'OPTGROUP',
 			'OPTION',
 			'P',
+			'RB',
+			'RP',
+			'RT',
+			'RTC',
 		);
 
-		$current_node = $this->state->stack_of_open_elements->current_node();
+		$no_exclusions = ! isset( $except_for_this_element );
+
 		while (
-			$current_node && $current_node->node_name !== $except_for_this_element &&
+			( $no_exclusions || ! $this->state->stack_of_open_elements->current_node_is( $except_for_this_element ) ) &&
 			in_array( $this->state->stack_of_open_elements->current_node(), $elements_with_implied_end_tags, true )
 		) {
 			$this->state->stack_of_open_elements->pop();
@@ -2294,18 +2319,31 @@ private function generate_implied_end_tags( $except_for_this_element = null ) {
 	 * different from generating end tags in the normal sense.
 	 *
 	 * @since 6.4.0
+	 * @since 6.7.0 Full spec support.
 	 *
 	 * @see WP_HTML_Processor::generate_implied_end_tags
 	 * @see https://html.spec.whatwg.org/#generate-implied-end-tags
 	 */
 	private function generate_implied_end_tags_thoroughly() {
 		$elements_with_implied_end_tags = array(
+			'CAPTION',
+			'COLGROUP',
 			'DD',
 			'DT',
 			'LI',
 			'OPTGROUP',
 			'OPTION',
 			'P',
+			'RB',
+			'RP',
+			'RT',
+			'RTC',
+			'TBODY',
+			'TD',
+			'TFOOT',
+			'TH',
+			'THEAD',
+			'TR',
 		);
 
 		while ( in_array( $this->state->stack_of_open_elements->current_node(), $elements_with_implied_end_tags, true ) ) {