HTML API: Ensure that full processor can seek to earlier bookmarks

src/wp-includes/html-api/class-wp-html-active-formatting-elements.php

@@ -41,7 +41,7 @@ class WP_HTML_Active_Formatting_Elements {
 	 *
 	 * @var WP_HTML_Token[]
 	 */
-	private $stack = array();
+	public $stack = array();
 
 	/**
 	 * Reports if a specific node is in the stack of active formatting elements.

src/wp-includes/html-api/class-wp-html-open-elements.php

@@ -49,7 +49,7 @@ class WP_HTML_Open_Elements {
 	 *
 	 * @var bool
 	 */
-	private $has_p_in_button_scope = false;
+	public $has_p_in_button_scope = false;
 
 	/**
 	 * A function that will be called when an item is popped off the stack of open elements.

src/wp-includes/html-api/class-wp-html-processor.php

@@ -5324,8 +5324,7 @@ public function seek( $bookmark_name ): bool {
 		 */
 		if ( 'backward' === $direction ) {
 			/*
-			 * Instead of clearing the parser state and starting fresh, calling the stack methods
-			 * maintains the proper flags in the parser.
+			 * When moving backward, stateful stacks should be cleared.
 			 */
 			foreach ( $this->state->stack_of_open_elements->walk_up() as $item ) {
 				if ( 'context-node' === $item->bookmark_name ) {
@@ -5343,32 +5342,65 @@ public function seek( $bookmark_name ): bool {
 				$this->state->active_formatting_elements->remove_node( $item );
 			}
 
-			parent::seek( 'context-node' );
-			$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_BODY;
-			$this->state->frameset_ok    = true;
-			$this->element_queue         = array();
-			$this->current_element       = null;
+			/*
+			 * **After** clearing stacks, more processor state can be reset.
+			 * This must be done after clearing the stack because those stacks generate events that
+			 * would appear on a subsequent call to `next_token()`.
+			 */
+			$this->state->frameset_ok                       = true;
+			$this->state->stack_of_template_insertion_modes = array();
+			$this->state->head_element                      = null;
+			$this->state->form_element                      = null;
+			$this->state->current_token                     = null;
+			$this->current_element                          = null;
+			$this->element_queue                            = array();
 
-			if ( isset( $this->context_node ) ) {
-				$this->breadcrumbs = array_slice( $this->breadcrumbs, 0, 2 );
+			/*
+			 * The absence of a context node indicates a full parse.
+			 * The presence of a context node indicates a fragment parser.
+			 */
+			if ( null === $this->context_node ) {
+				$this->change_parsing_namespace( 'html' );
+				$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_INITIAL;
+				$this->breadcrumbs           = array();
+
+				$this->bytes_already_parsed = 0;
+				$this->parser_state         = self::STATE_READY;
+				$this->next_token();
 			} else {
-				$this->breadcrumbs = array();
-			}
-		}
+				$this->change_parsing_namespace(
+					$this->context_node->integration_node_type
+						? 'html'
+						: $this->context_node->namespace
+				);
+
+				if ( 'TEMPLATE' === $this->context_node->node_name ) {
+					$this->state->stack_of_template_insertion_modes[] = WP_HTML_Processor_State::INSERTION_MODE_IN_TEMPLATE;
+				}
 
-		// When moving forwards, reparse the document until reaching the same location as the original bookmark.
-		if ( $bookmark_starts_at === $this->bookmarks[ $this->state->current_token->bookmark_name ]->start ) {
-			return true;
+				$this->reset_insertion_mode_appropriately();
+				$this->breadcrumbs = array_slice( $this->breadcrumbs, 0, 2 );
+				parent::seek( $this->context_node->bookmark_name );
+			}
 		}
 
-		while ( $this->next_token() ) {
+		/*
+		 * Here, the processor moves forward through the document until it matches the bookmark.
+		 * do-while is used here because the processor is expected to already be stopped on
+		 * a token than may match the bookmarked location.
+		 */
+		do {
+			/*
+			 * The processor will stop on virtual tokens, but bookmarks may not be set on them.
+			 * They should not be matched when seeking a bookmark, skip them.
+			 */
+			if ( $this->is_virtual() ) {
+				continue;
+			}
 			if ( $bookmark_starts_at === $this->bookmarks[ $this->state->current_token->bookmark_name ]->start ) {
-				while ( isset( $this->current_element ) && WP_HTML_Stack_Event::POP === $this->current_element->operation ) {
-					$this->current_element = array_shift( $this->element_queue );
-				}
 				return true;
 			}
-		}
+		} while ( $this->next_token() );
 
 		return false;
 	}

src/wp-includes/html-api/class-wp-html-tag-processor.php

@@ -591,7 +591,7 @@ class WP_HTML_Tag_Processor {
 	 * @since 6.2.0
 	 * @var int
 	 */
-	private $bytes_already_parsed = 0;
+	protected $bytes_already_parsed = 0;
 
 	/**
 	 * Byte offset in input document where current token starts.

tests/phpunit/tests/html-api/wpHtmlProcessor-bookmark.php

@@ -0,0 +1,34 @@
+<?php
+/**
+ * Unit tests covering WP_HTML_Processor bookmark functionality.
+ *
+ * @package WordPress
+ * @subpackage HTML-API
+ */
+
+/**
+ * @group html-api
+ *
+ * @coversDefaultClass WP_HTML_Processor
+ */
+class Tests_HtmlApi_WpHtmlProcessor_Bookmark extends WP_UnitTestCase {
+	/**
+	 * Ensures that bookmarks can be set and seeked to for the full processor.
+	 *
+	 * @ticket 62290
+	 */
+	public function test_full_processor_seek() {
+		$bookmark_name = 'the-bookmark';
+		$processor     = WP_HTML_Processor::create_full_parser( '<html><body><div>' );
+		$this->assertTrue( $processor->next_tag( 'BODY' ) );
+		$this->assertTrue( $processor->set_bookmark( $bookmark_name ), 'Failed to set bookmark.' );
+		$this->assertTrue( $processor->has_bookmark( $bookmark_name ), 'Failed has_bookmark check.' );
+
+		// Move past the bookmark so it must scan backwards.
+		$this->assertTrue( $processor->next_tag( 'DIV' ) );
+
+		// Confirm the bookmark works.
+		$this->assertTrue( $processor->seek( $bookmark_name ), 'Failed to seek to bookmark.' );
+		$this->assertSame( 'BODY', $processor->get_tag() );
+	}
+}

tests/phpunit/tests/html-api/wpHtmlProcessor.php

@@ -133,7 +133,7 @@ public function test_clear_to_navigate_after_seeking() {
 
 			// Create a bookmark inside of that stack.
 			if ( null !== $processor->get_attribute( 'two' ) ) {
-				$processor->set_bookmark( 'two' );
+				$this->assertTrue( $processor->set_bookmark( 'two' ) );
 				break;
 			}
 		}