) : 0;
$pagenum = \max( 1, $pagenum );
/*
* Arrange pages into two parts: top level pages and children_pages
* children_pages is two dimensional array, eg.
* children_pages[10][] contains all sub-pages whose parent is 10.
* It only takes O( N ) to arrange this and it takes O( 1 ) for subsequent lookup operations
* If searching, ignore hierarchy and treat everything as top level
*/
if ( empty( $_REQUEST['s'] ) ) {
$top_level_pages = [];
$children_pages = [];
$pages_map = [];
foreach ( $pages as $page ) {
// Catch and repair bad pages.
if ( $page->post_parent === $page->ID ) {
$page->post_parent = 0;
}
if ( $page->post_parent === 0 ) {
$top_level_pages[] = $page;
}
else {
$children_pages[ $page->post_parent ][] = $page;
}
$pages_map[ $page->ID ] = $page;
}
$pages = $top_level_pages;
}
$count = 0;
$start = ( ( $pagenum - 1 ) * $per_page );
$end = ( $start + $per_page );
$to_display = [];
foreach ( $pages as $page ) {
if ( $count >= $end ) {
break;
}
if ( $count >= $start ) {
$to_display[] = $page->ID;
}
++$count;
$this->get_child_page_ids( $children_pages, $count, $page->ID, $start, $end, $to_display, $pages_map );
}
// If it is the last pagenum and there are orphaned pages, display them with paging as well.
if ( isset( $children_pages ) && $count < $end ) {
foreach ( $children_pages as $orphans ) {
foreach ( $orphans as $op ) {
if ( $count >= $end ) {
break;
}
if ( $count >= $start ) {
$to_display[] = $op->ID;
}
++$count;
}
}
}
return $to_display;
}
/**
* Adds all child pages due to be shown on the current page to the $to_display array.
* Copied over with some changes from WP_Posts_List_Table::_page_rows.
*
* @param array $children_pages The full map of child pages.
* @param int $count The number of pages already processed.
* @param int $parent_id The id of the parent that's currently being processed.
* @param int $start The number at which the current overview starts.
* @param int $end The number at which the current overview ends.
* @param int $to_display The page IDs to be shown.
* @param int $pages_map A map of page ID to an object with ID and post_parent.
*
* @return void
*/
private function get_child_page_ids( &$children_pages, &$count, $parent_id, $start, $end, &$to_display, &$pages_map ) {
if ( ! isset( $children_pages[ $parent_id ] ) ) {
return;
}
foreach ( $children_pages[ $parent_id ] as $page ) {
if ( $count >= $end ) {
break;
}
// If the page starts in a subtree, print the parents.
if ( $count === $start && $page->post_parent > 0 ) {
$my_parents = [];
$my_parent = $page->post_parent;
while ( $my_parent ) {
// Get the ID from the list or the attribute if my_parent is an object.
$parent_id = $my_parent;
if ( \is_object( $my_parent ) ) {
$parent_id = $my_parent->ID;
}
$my_parent = $pages_map[ $parent_id ];
$my_parents[] = $my_parent;
if ( ! $my_parent->post_parent ) {
break;
}
$my_parent = $my_parent->post_parent;
}
while ( $my_parent = \array_pop( $my_parents ) ) {
$to_display[] = $my_parent->ID;
}
}
if ( $count >= $start ) {
$to_display[] = $page->ID;
}
++$count;
$this->get_child_page_ids( $children_pages, $count, $page->ID, $start, $end, $to_display, $pages_map );
}
unset( $children_pages[ $parent_id ] ); // Required in order to keep track of orphans.
}
}