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wp_find_hierarchy_loop_tortoise_hare ›

Od3.1.0
Przestarzałyn/a
wp_find_hierarchy_loop_tortoise_hare ( $callback, $start, $override = array(), $callback_args = array(), $_return_loop = false )
Dostęp:
  • private
Parametry: (5)
  • (callable) $callback Function that accepts ( ID, callback_arg, ... ) and outputs parent_ID.
    Wymagane: Tak
  • (int) $start The ID to start the loop check at.
    Wymagane: Tak
  • (array) $override Optional. An array of ( ID => parent_ID, ... ) to use instead of $callback. Default empty array.
    Wymagane: Nie
    Domyślny: array()
  • (array) $callback_args Optional. Additional arguments to send to $callback. Default empty array.
    Wymagane: Nie
    Domyślny: array()
  • (bool) $_return_loop Optional. Return loop members or just detect presence of loop? Only set to true if you already know the given $start is part of a loop (otherwise the returned array might include branches). Default false.
    Wymagane: Nie
    Domyślny: false
Powrót:
  • (mixed) Scalar ID of some arbitrary member of the loop, or array of IDs of all members of loop if $_return_loop
Zdefiniowane na:
Codex:

Use the "The Tortoise and the Hare" algorithm to detect loops.

For every step of the algorithm, the hare takes two steps and the tortoise one. If the hare ever laps the tortoise, there must be a loop.



Źródło

function wp_find_hierarchy_loop_tortoise_hare( $callback, $start, $override = array(), $callback_args = array(), $_return_loop = false ) {
	$tortoise        = $start;
	$hare            = $start;
	$evanescent_hare = $start;
	$return          = array();

	// Set evanescent_hare to one past hare
	// Increment hare two steps
	while (
		$tortoise
	&&
		( $evanescent_hare = isset( $override[ $hare ] ) ? $override[ $hare ] : call_user_func_array( $callback, array_merge( array( $hare ), $callback_args ) ) )
	&&
		( $hare = isset( $override[ $evanescent_hare ] ) ? $override[ $evanescent_hare ] : call_user_func_array( $callback, array_merge( array( $evanescent_hare ), $callback_args ) ) )
	) {
		if ( $_return_loop ) {
			$return[ $tortoise ]        = true;
			$return[ $evanescent_hare ] = true;
			$return[ $hare ]            = true;
		}

		// tortoise got lapped - must be a loop
		if ( $tortoise == $evanescent_hare || $tortoise == $hare ) {
			return $_return_loop ? $return : $tortoise;
		}

		// Increment tortoise by one step
		$tortoise = isset( $override[ $tortoise ] ) ? $override[ $tortoise ] : call_user_func_array( $callback, array_merge( array( $tortoise ), $callback_args ) );
	}

	return false;
}