Ticket #31789: 31789.diff

wp-admin/includes/theme.php

@@ -408 +408 @@
  */
 function wp_prepare_themes_for_js( $themes = null ) {
         $current_theme = get_stylesheet();
+        $prepared_themes = array();
 
+        /**
+         * Allow overriding the themes returned. Passing a non-empty array will cause
+         * this function to exit early with that array of theme data. This can allow
+         * for more aggressive caching on installs with a large number of themes.
+         *
+         * @since 4.2.0
+         *
+         * @param array  $prepared_themes  An associative array of theme data.
+         * @param string $current_theme    The current theme slug.
+         *
+         * @return array Default empty array to skip, non-empty array to override.
+         */
+        $prepared_themes = apply_filters( 'pre_wp_prepare_themes_for_js', $prepared_themes, $current_theme );
+        if ( is_array( $prepared_themes ) && ! empty( $prepared_themes ) ) {
+                return $prepared_themes;
+        }
+
         // Make sure the current theme is listed first.
         $prepared_themes = array( $current_theme => array() );