Interactivity API: Implement directive caching to optimize data-wp-each processing.

Previous attempts to optimize `WP_Interactivity_API::data_wp_each_processor` included a "pre-compute and cache" strategy. Instead of re-parsing the template on every iteration, we can build a "blueprint" of the template once, cache it, and then use it to efficiently process each item. However, this solution did not consider how the WP_HTML_Tag_Processor is designed.

The WP_HTML_Tag_Processor architecture works by:

- Sequentially scanning HTML to find tags (via strpos, strcspn, etc.)
- Tracking positions as byte offsets
- Modifying HTML through WP_HTML_Text_Replacement objects

There's no way to "jump to position X" without scanning from the beginning. Byte offsets shift as HTML is modified, and bookmarks are designed for single-pass processing, not cross-rendering reuse.

Looking more carefully at the bottleneck, the real issue is that for EACH item in the array, we:

1. Create a new WP_Interactivity_API_Directives_Processor
2. Call $p->next_tag() repeatedly (which does expensive string scanning)
3. Call get_attribute_names_with_prefix('data-wp-') for each tag
4. Parse directive names and extract values
5. Evaluate directives

The optimization opportunity is steps 2-4, not step 5. We can't avoid re-scanning the HTML (that's how the Tag Processor works), but we can cache what we learned about where directives are and what they are.

This commit introduces the `WP_Interactivity_API_Directive_Cache` class to cache pre-parsed directive information, significantly reducing the O(N×M) complexity of rendering templates with multiple items. The caching mechanism stores directive metadata, improving performance during repeated template rendering.

Additionally, the `_process_directives` method is updated to utilize this cache, enhancing efficiency. Tests are added to ensure the correctness of the caching mechanism and its integration with existing functionality.

Author: Michelleeby

src/wp-includes/assets/script-loader-packages.min.php

@@ -1 +1 @@
-<?php return array('interactivity/index.min.js' => array('dependencies' => array(), 'version' => '441cab46d043b0a45f6f', 'type' => 'module'), 'interactivity/debug.min.js' => array('dependencies' => array(), 'version' => '4b216ecdeb745ab1b420', 'type' => 'module'), 'interactivity-router/index.min.js' => array('dependencies' => array('@wordpress/interactivity', array('id' => '@wordpress/a11y', 'import' => 'dynamic')), 'version' => '765a6ee8162122b48e6c', 'type' => 'module'), 'interactivity-router/full-page.min.js' => array('dependencies' => array(array('id' => '@wordpress/interactivity-router', 'import' => 'dynamic')), 'version' => 'ac76172d5956969e2227', 'type' => 'module'), 'a11y/index.min.js' => array('dependencies' => array(), 'version' => 'b7d06936b8bc23cff2ad', 'type' => 'module'), 'block-library/accordion/view.min.js' => array('dependencies' => array('@wordpress/interactivity'), 'version' => '5fa6ee20ae87460b9868', 'type' => 'module'), 'block-library/file/view.min.js' => array('dependencies' => array('@wordpress/interactivity'), 'version' => 'f9665632b48682075277', 'type' => 'module'), 'block-library/form/view.min.js' => array('dependencies' => array(), 'version' => 'baaf25398238b4f2a821', 'type' => 'module'), 'block-library/image/view.min.js' => array('dependencies' => array('@wordpress/interactivity'), 'version' => '26816800d42394b0a5f5', 'type' => 'module'), 'block-library/navigation/view.min.js' => array('dependencies' => array('@wordpress/interactivity'), 'version' => '3d4d582d5a6b3cf1185b', 'type' => 'module'), 'block-library/query/view.min.js' => array('dependencies' => array('@wordpress/interactivity', array('id' => '@wordpress/interactivity-router', 'import' => 'dynamic')), 'version' => 'f55e93a1ad4806e91785', 'type' => 'module'), 'block-library/search/view.min.js' => array('dependencies' => array('@wordpress/interactivity'), 'version' => '208bf143e4074549fa89', 'type' => 'module'), 'block-editor/utils/fit-text-frontend.min.js' => array('dependencies' => array(), 'version' => '6e035d66824ec76d9de1', 'type' => 'module'));
+<?php return array('interactivity/index.min.js' => array('dependencies' => array(), 'version' => '441cab46d043b0a45f6f', 'type' => 'module'), 'interactivity/debug.min.js' => array('dependencies' => array(), 'version' => '4b216ecdeb745ab1b420', 'type' => 'module'), 'interactivity-router/index.min.js' => array('dependencies' => array('@wordpress/interactivity', array('id' => '@wordpress/a11y', 'import' => 'dynamic')), 'version' => '765a6ee8162122b48e6c', 'type' => 'module'), 'a11y/index.min.js' => array('dependencies' => array(), 'version' => 'b7d06936b8bc23cff2ad', 'type' => 'module'), 'block-library/file/view.min.js' => array('dependencies' => array('@wordpress/interactivity'), 'version' => 'f9665632b48682075277', 'type' => 'module'), 'block-library/form/view.min.js' => array('dependencies' => array(), 'version' => 'baaf25398238b4f2a821', 'type' => 'module'), 'block-library/image/view.min.js' => array('dependencies' => array('@wordpress/interactivity'), 'version' => '26816800d42394b0a5f5', 'type' => 'module'), 'block-library/navigation/view.min.js' => array('dependencies' => array('@wordpress/interactivity'), 'version' => '3d4d582d5a6b3cf1185b', 'type' => 'module'), 'block-library/query/view.min.js' => array('dependencies' => array('@wordpress/interactivity', array('id' => '@wordpress/interactivity-router', 'import' => 'dynamic')), 'version' => 'f55e93a1ad4806e91785', 'type' => 'module'), 'block-library/search/view.min.js' => array('dependencies' => array('@wordpress/interactivity'), 'version' => '208bf143e4074549fa89', 'type' => 'module'));

src/wp-includes/assets/script-modules-packages.min.php

@@ -0,0 +1,153 @@
+<?php
+/**
+ * Interactivity API: WP_Interactivity_API_Directive_Cache class
+ *
+ * @package WordPress
+ * @subpackage Interactivity API
+ * @since 6.10.0
+ */
+
+/**
+ * Caches pre-parsed directive information for efficient template re-rendering.
+ *
+ * This class addresses a performance bottleneck in `data-wp-each` processing where
+ * the same template is rendered N times (once per array item), causing O(N×M)
+ * complexity. By caching the directive parsing results, we reduce redundant work.
+ *
+ * The cache maps tag occurrence indices to pre-parsed directive data. Since the
+ * WP_HTML_Tag_Processor requires sequential scanning, we use tag index to identify
+ * which tag's metadata to retrieve.
+ *
+ * What gets cached:
+ * - Parsed directive names (prefix, suffix, unique_id)
+ * - Extracted directive values (namespace, value)
+ * - Directive entries for each prefix type
+ *
+ * What does NOT get cached:
+ * - Directive evaluation results (these depend on context)
+ * - Modified HTML (each iteration needs a fresh template)
+ * - The HTML scanning itself (unavoidable with Tag Processor architecture)
+ *
+ * @since 6.10.0
+ *
+ * @access private
+ *
+ * @see WP_Interactivity_API::data_wp_each_processor()
+ */
+class WP_Interactivity_API_Directive_Cache {
+	/**
+	 * Cached directive entries organized by tag index and directive prefix.
+	 *
+	 * Structure:
+	 * [
+	 *   '{tag_index}:{directive_prefix}' => [
+	 *     ['namespace' => 'plugin', 'value' => 'context.foo', 'suffix' => null, 'unique_id' => null],
+	 *     ...
+	 *   ],
+	 *   ...
+	 * ]
+	 *
+	 * @since 6.10.0
+	 * @var array
+	 */
+	private $cache = array();
+
+	/**
+	 * Cached attribute names with 'data-wp-' prefix for each tag.
+	 *
+	 * Structure:
+	 * [
+	 *   {tag_index} => ['data-wp-text', 'data-wp-class--active', ...],
+	 *   ...
+	 * ]
+	 *
+	 * @since 6.10.0
+	 * @var array
+	 */
+	private $directive_attributes_cache = array();
+
+	/**
+	 * Gets directive entries for a specific tag and prefix.
+	 *
+	 * If cached, returns the cached value. Otherwise, calls the parser function,
+	 * caches the result, and returns it.
+	 *
+	 * @since 6.10.0
+	 *
+	 * @param int      $tag_index The tag occurrence index (0-based, increments with each tag that has directives).
+	 * @param string   $prefix    The directive prefix (e.g., 'text', 'bind', 'class').
+	 * @param callable $parser    Function to call if not cached. Signature: function($tag_index, $prefix): array
+	 * @return array The directive entries for this tag and prefix.
+	 */
+	public function get_or_parse_entries( int $tag_index, string $prefix, callable $parser ): array {
+		$cache_key = "{$tag_index}:{$prefix}";
+
+		if ( ! isset( $this->cache[ $cache_key ] ) ) {
+			$this->cache[ $cache_key ] = $parser( $tag_index, $prefix );
+		}
+
+		return $this->cache[ $cache_key ];
+	}
+
+	/**
+	 * Caches the list of directive attribute names for a tag.
+	 *
+	 * @since 6.10.0
+	 *
+	 * @param int   $tag_index           The tag occurrence index.
+	 * @param array $directive_attributes The array of directive attribute names.
+	 */
+	public function cache_directive_attributes( int $tag_index, array $directive_attributes ): void {
+		$this->directive_attributes_cache[ $tag_index ] = $directive_attributes;
+	}
+
+	/**
+	 * Gets cached directive attribute names for a tag.
+	 *
+	 * @since 6.10.0
+	 *
+	 * @param int $tag_index The tag occurrence index.
+	 * @return array|null The directive attribute names, or null if not cached.
+	 */
+	public function get_directive_attributes( int $tag_index ): ?array {
+		return $this->directive_attributes_cache[ $tag_index ] ?? null;
+	}
+
+	/**
+	 * Checks if directive entries are cached for a specific tag and prefix.
+	 *
+	 * @since 6.10.0
+	 *
+	 * @param int    $tag_index The tag occurrence index.
+	 * @param string $prefix    The directive prefix.
+	 * @return bool Whether the entries are cached.
+	 */
+	public function has_cached_entries( int $tag_index, string $prefix ): bool {
+		$cache_key = "{$tag_index}:{$prefix}";
+		return isset( $this->cache[ $cache_key ] );
+	}
+
+	/**
+	 * Clears all cached data.
+	 *
+	 * @since 6.10.0
+	 */
+	public function clear(): void {
+		$this->cache                      = array();
+		$this->directive_attributes_cache = array();
+	}
+
+	/**
+	 * Gets the total number of cached entries.
+	 *
+	 * Useful for debugging and testing.
+	 *
+	 * @since 6.10.0
+	 *
+	 * @return int The number of cached directive entry sets.
+	 */
+	public function get_cache_size(): int {
+		return count( $this->cache );
+	}
+}
+