Finds hierarchy loops using a callback function that maps object IDs to parent IDs.

Parameters

$callbackcallablerequired

Function that accepts ( ID, $callback_args ) and outputs parent_ID.

$startintrequired

The ID to start the loop check at.

$start_parentintrequired

The parent_ID of $start to use instead of calling $callback( $start ).
Use null to always use $callback.

$callback_argsarrayoptional

Additional arguments to send to $callback.

Default:array()

Return

Source

function wp_find_hierarchy_loop( $callback, $start, $start_parent, $callback_args = array() ) {
	$override = is_null( $start_parent ) ? array() : array( $start => $start_parent );

	$arbitrary_loop_member = wp_find_hierarchy_loop_tortoise_hare( $callback, $start, $override, $callback_args );
	if ( ! $arbitrary_loop_member ) {
		return array();
	}

	return wp_find_hierarchy_loop_tortoise_hare( $callback, $arbitrary_loop_member, $override, $callback_args, true );
}

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