Ticket #10852: new_get_page_children.3.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;
 }
 
 /**

new file tests/phpunit/tests/post/getPageChildren.php

@@ +1 @@
+<?php
+
+/**
+ * @group post
+ */
+
+class Tests_Post_getPageChildren extends WP_UnitTestCase {
+        function setUp() {
+                parent::setUp();
+        }
+
+        function test_get_hierarchical_ordering() {
+        $page_1 = $this->factory->post->create( array( 'post_type' => 'page' ) );
+        $page_2 = $this->factory->post->create( array( 'post_type' => 'page', 'post_parent' => $page_1 ) );
+        $page_3 = $this->factory->post->create( array( 'post_type' => 'page', 'post_parent' => $page_1 ) );
+        $page_4 = $this->factory->post->create( array( 'post_type' => 'page', 'post_parent' => $page_2 ) );
+
+        /*
+         * Here's the tree we are testing:
+         *
+         * page 1
+         * - page 2
+         * -- page 4
+         * - page 3
+         *
+         * If hierarchical => true works, the order will be 1,2,4,3.
+         * If it doesn't, they will be in the creation order, 1,2,3,4.
+         */
+
+        $pages = get_pages();
+
+        $ordered_pages = get_page_children( 0, $pages );
+        $this->assertEqualSets( array($page_1, $page_2, $page_4, $page_3 ), wp_list_pluck( $ordered_pages, 'ID' ) );
+        $ordered_pages = get_page_children( $page_1, $pages );
+        $this->assertEqualSets( array($page_2, $page_4, $page_3 ), wp_list_pluck( $ordered_pages, 'ID' ) );
+        $ordered_pages = get_page_children( $page_2, $pages );
+        $this->assertEqualSets( array( $page_4 ), wp_list_pluck( $ordered_pages, 'ID' ) );
+        $ordered_pages = get_page_children( $page_4, $pages );
+        $this->assertEqualSets( array(), wp_list_pluck( $ordered_pages, 'ID' ) );
+        }
+
+    function test_get_missing_parent() {
+        $page_1 = $this->factory->post->create( array( 'post_type' => 'page' ) );
+        $page_2 = $this->factory->post->create( array( 'post_type' => 'page', 'post_parent' => $page_1 ) );
+        $page_3 = $this->factory->post->create( array( 'post_type' => 'page', 'post_parent' => $page_1 ) );
+        $page_4 = $this->factory->post->create( array( 'post_type' => 'page', 'post_parent' => $page_2 ) );
+
+        $pages = get_pages();
+
+        $ordered_pages = get_page_children( -1, $pages );
+        $this->assertEqualSets( array(), $ordered_pages );
+
+    }
+
+    function test_get_outside_parent() {
+        $page_1 = $this->factory->post->create( array( 'post_type' => 'page' ) );
+        $page_2 = $this->factory->post->create( array( 'post_type' => 'page', 'post_parent' => $page_1 ) );
+        $page_3 = $this->factory->post->create( array( 'post_type' => 'page', 'post_parent' => $page_1 ) );
+        $page_4 = $this->factory->post->create( array( 'post_type' => 'page', 'post_parent' => $page_2 ) );
+
+        $pages = get_posts( array( $page_2, $page_4 ) );
+
+        $ordered_pages = get_page_children($page_3, $pages );
+        $this->assertEqualSets( array(), $ordered_pages );
+    }
+}