Blocks: Introduce helper function to retrieve hooked blocks

In order to implement Block Hooks (see #59313), we added block_hooks field to the WP_Block_Type class, as well as to block registration related functions. In this follow-up, new helper function gets introduced that is going to compute the list of hooked blocks by other registered blocks for a given block type.

Extracted from WordPress/wordpress-develop#5158 and covered with unit tests.

Props ockham.
Fixes #59383.


Built from https://develop.svn.wordpress.org/trunk@56610


git-svn-id: https://core.svn.wordpress.org/trunk@56122 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/blocks.php

@@ -739,6 +739,27 @@ function get_dynamic_block_names() {
 	return $dynamic_block_names;
 }
 
+/**
+ * Retrieves block types (and positions) hooked into the given block.
+ *
+ * @since 6.4.0
+ *
+ * @param string $name Block type name including namespace.
+ * @return array Associative array of `$block_type_name => $position` pairs.
+ */
+function get_hooked_blocks( $name ) {
+	$block_types = WP_Block_Type_Registry::get_instance()->get_all_registered();
+	$hooked_blocks = array();
+	foreach ( $block_types as $block_type ) {
+		foreach ( $block_type->block_hooks as $anchor_block_type => $relative_position ) {
+			if ( $anchor_block_type === $name ) {
+				$hooked_blocks[ $block_type->name ] = $relative_position;
+			}
+		}
+	}
+	return $hooked_blocks;
+}
+
 /**
  * Given an array of attributes, returns a string in the serialized attributes
  * format prepared for post content.

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.4-alpha-56609';
+$wp_version = '6.4-alpha-56610';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.