staylor / WordPress

 * @param int $post_ID     ID of the post we're checking.

 * @return int The new post_parent for the post, 0 otherwise.

 */

function wp_check_post_hierarchy_for_loops( $post_parent, $post_ID ) {

	// Nothing fancy here - bail.

	if ( !$post_parent )

		return 0;

	// New post can't cause a loop.

	if ( empty( $post_ID ) )

		return $post_parent;

	// Can't be its own parent.

	if ( $post_parent == $post_ID )

		return 0;

	// Now look for larger loops.

	if ( !$loop = wp_find_hierarchy_loop( 'wp_get_post_parent_id', $post_ID, $post_parent ) )

		return $post_parent; // No loop

	// Setting $post_parent to the given value causes a loop.

	if ( isset( $loop[$post_ID] ) )

		return 0;

	// There's a loop, but it doesn't contain $post_ID. Break the loop.

	foreach ( array_keys( $loop ) as $loop_member )

		wp_update_post( array( 'ID' => $loop_member, 'post_parent' => 0 ) );

	return $post_parent;

}

/**

 * Set a post thumbnail.

 *

 * @return int The new parent for the term.

 */

function wp_check_term_hierarchy_for_loops( $parent, $term_id, $taxonomy ) {

	// Nothing fancy here - bail

	if ( !$parent )

		return 0;

	// Can't be its own parent.

	if ( $parent == $term_id )

		return 0;

	// Now look for larger loops.

	if ( !$loop = wp_find_hierarchy_loop( 'wp_get_term_taxonomy_parent_id', $term_id, $parent, array( $taxonomy ) ) )

		return $parent; // No loop

	// Setting $parent to the given value causes a loop.

	if ( isset( $loop[$term_id] ) )

		return 0;

	// There's a loop, but it doesn't contain $term_id. Break the loop.

	foreach ( array_keys( $loop ) as $loop_member )

		wp_update_term( $loop_member, $taxonomy, array( 'parent' => 0 ) );

	return $parent;

}