Ticket #10852: new_get_page_children.2.diff

src/wp-includes/post.php

@@ -4311 +4311 @@
  * children for the same to retrieve all children of a page. Does not make any
  * SQL queries to get the children.
  *
+ * It uses auxiliary structure to hold parent-children relationships and
+ * runs in O(N) complexity
+ *
  * @since 1.5.1
  *
  * @param int   $page_id    Page ID.
@@ -4318 +4321 @@
  * @return array List of page children.
  */
 function get_page_children( $page_id, $pages ) {
-        $page_list = array();
-        foreach ( (array) $pages as $page ) {
-                if ( $page->post_parent == $page_id ) {
-                        $page_list[] = $page;
-                        if ( $children = get_page_children( $page->ID, $pages ) ) {
-                                $page_list = array_merge( $page_list, $children );
+        // build a hash of ID -> children
+        $children = array();
+        foreach ( (array) $pages as $p ) {
+                $children[ intval( $p->post_parent ) ][] = $p;
+        }
+
+        $post_list = array();
+        if( array_key_exists( $page_id, $children ) ) {
+                $to_look = array_reverse( $children[ $page_id ] );
+                // while we still have posts to_look add them to the list
+                while ( $to_look ) {
+                        $p = array_pop( $to_look );
+                        $post_list[] = $p;
+                        if ( array_key_exists( $p->ID, $children ) ) {
+                                foreach ( array_reverse( $children[ $p->ID ] ) as $child ) {
+                                        $to_look[] = $child;
+                                }
                         }
                 }
         }
 
-        return $page_list;
+        return $post_list;
 }
 
 /**