Changeset 56941

Timestamp:

10/16/2023 02:00:01 PM (14 months ago)

Author:

SergeyBiryukov

Message:

HTML API: Avoid calling subclass method while internally scanning in Tag Processor.

After modifying tags in the HTML API, the Tag Processor backs up to before the tag being modified and then re-parses its attributes. This saves on the code complexity involved in applying updates, which have already been transformed to “lexical updates” by the time they are applied.

In order to do that, ::get_updated_html() called ::next_tag() to reuse its logic. However, as a public method, subclasses may change the behavior of that method, and the HTML Processor does just this. It maintains an HTML stack of open elements and when the Tag Processor calls this method to re-scan a tag and its attributes, it leads to a broken stack.

This commit replaces the call to ::next_tag() with a more appropriate reapplication of its internal parsing logic to rescan the tag name and its attributes. Given the limited nature of what's occurring in ::get_updated_html(), this should bring with it certain guarantees that no HTML structure is being changed (that structure will only be changed by subclasses like the HTML Processor).

Follow-up to [56274], [56702].

Props dmsnell, zieladam, nicolefurlan.
Fixes #59607.

Location:

trunk

Files:

• src/wp-includes/html-api/class-wp-html-tag-processor.php (modified) (2 diffs)
• tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php (modified) (2 diffs)

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

@@ -2271 +2271 @@
      * @since 6.2.0
      * @since 6.2.1 Shifts the internal cursor corresponding to the applied updates.
+     * @since 6.4.0 No longer calls subclass method `next_tag()` after updating HTML.
      *
      * @return string The processed HTML.
@@ -2304 +2305 @@
          * move; a call to `next_tag()` will reparse the recently-updated attributes
          * and additional calls to modify the attributes will apply at this same
-         * location.
+         * location, but in order to avoid issues with subclasses that might add
+         * behaviors to `next_tag()`, the internal methods should be called here
+         * instead.
+         *
+         * It's important to note that in this specific place there will be no change
+         * because the processor was already at a tag when this was called and it's
+         * rewinding only to the beginning of this very tag before reprocessing it
+         * and its attributes.
          *
          * <p>Previous HTML<em>More HTML</em></p>
-         *                 ^  | back up by the length of the tag name plus the opening <
-         *                 \<-/ back up by strlen("em") + 1 ==> 3
-         */
-
-        // Store existing state so it can be restored after reparsing.
-        $previous_parsed_byte_count = $this->bytes_already_parsed;
-        $previous_query             = $this->last_query;
-
-        // Reparse attributes.
+         *                 ↑  │ back up by the length of the tag name plus the opening <
+         *                 └←─┘ back up by strlen("em") + 1 ==> 3
+         */
         $this->bytes_already_parsed = $before_current_tag;
-        $this->next_tag();
-
-        // Restore previous state.
-        $this->bytes_already_parsed = $previous_parsed_byte_count;
-        $this->parse_query( $previous_query );
+        $this->parse_next_tag();
+        // Reparse the attributes.
+        while ( $this->parse_next_attribute() ) {
+            continue;
+        }
 
         return $this->html;

trunk/tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php

@@ -412 +412 @@
 
     /**
+     * Ensures that updating tag's attributes doesn't shift the current position
+     * in the input HTML document.
+     *
+     * @since 6.4.0
+     *
+     * @ticket 59607
+     *
+     * @covers WP_HTML_Tag_Processor::get_updated_html
+     */
+    public function test_remains_stable_when_editing_attributes() {
+        $p = WP_HTML_Processor::create_fragment( '<div><button>First<button><b here>Second' );
+        $p->next_tag( array( 'breadcrumbs' => array( 'BUTTON', 'B' ) ) );
+
+        $this->assertSame(
+            array( 'HTML', 'BODY', 'DIV', 'BUTTON', 'B' ),
+            $p->get_breadcrumbs(),
+            'Found the wrong nested structure at the matched tag.'
+        );
+
+        $p->set_attribute( 'a-name', 'a-value' );
+
+        $this->assertTrue(
+            $p->get_attribute( 'here' ),
+            'Should have found the B tag but could not find expected "here" attribute.'
+        );
+
+        $this->assertSame(
+            array( 'HTML', 'BODY', 'DIV', 'BUTTON', 'B' ),
+            $p->get_breadcrumbs(),
+            'Found the wrong nested structure at the matched tag.'
+        );
+
+        $p->get_updated_html();
+
+        $this->assertTrue(
+            $p->get_attribute( 'here' ),
+            'Should have stayed at the B tag but could not find expected "here" attribute.'
+        );
+
+        $this->assertSame(
+            array( 'HTML', 'BODY', 'DIV', 'BUTTON', 'B' ),
+            $p->get_breadcrumbs(),
+            'Found the wrong nested structure at the matched tag after updating attributes.'
+        );
+    }
+
+    /**
      * Ensures that the ability to set attributes isn't broken by the HTML Processor.
      *
@@ -418 +465 @@
      * @ticket 58517
      *
-     * @covers WP_HTML_Processor::set_attribute
+     * @covers WP_HTML_Tag_Processor::set_attribute
      */
     public function test_can_modify_attributes_after_finding_tag() {