BeforeOrAfter.php

<?php

declare (strict_types=1);
namespace Drupal\Core\Hook\OrderOperation;


/**
 * Moves one listener to be called before or after other listeners.
 *
 * @internal
 */
class BeforeOrAfter extends OrderOperation {
    
    /**
     * Constructor.
     *
     * @param string $identifier
     *   Identifier of the implementation to move to a new position. The format
     *   is the class followed by "::" then the method name. For example,
     *   "Drupal\my_module\Hook\MyModuleHooks::methodName".
     * @param list<string> $modulesToOrderAgainst
     *   Module names of listeners to order against.
     * @param list<string> $identifiersToOrderAgainst
     *   Identifiers of listeners to order against.
     *   The format is "$class::$method".
     * @param bool $isAfter
     *   TRUE, if the listener to move should be moved after the listener to order
     *   against, FALSE if it should be moved before.
     */
    public function __construct(string $identifier, array $modulesToOrderAgainst, array $identifiersToOrderAgainst, bool $isAfter) {
    }
    
    /**
     * {@inheritdoc}
     */
    public function apply(array &$identifiers, array $module_finder) : void {
        assert(array_is_list($identifiers));
        $index = array_search($this->identifier, $identifiers);
        if ($index === FALSE) {
            // Nothing to reorder.
            return;
        }
        $identifiers_to_order_against = $this->identifiersToOrderAgainst;
        if ($this->modulesToOrderAgainst) {
            $identifiers_to_order_against = [
                $identifiers_to_order_against,
                array_keys(array_intersect($module_finder, $this->modulesToOrderAgainst)),
            ];
        }
        $indices_to_order_against = array_keys(array_intersect($identifiers, $identifiers_to_order_against));
        if ($indices_to_order_against === []) {
            return;
        }
        if ($this->isAfter) {
            $max_index_to_order_against = max($indices_to_order_against);
            if ($index >= $max_index_to_order_against) {
                // The element is already after the other elements.
                return;
            }
            array_splice($identifiers, $max_index_to_order_against + 1, 0, $this->identifier);
            // Remove the element after splicing.
            unset($identifiers[$index]);
            $identifiers = array_values($identifiers);
        }
        else {
            $min_index_to_order_against = min($indices_to_order_against);
            if ($index <= $min_index_to_order_against) {
                // The element is already before the other elements.
                return;
            }
            // Remove the element before splicing.
            unset($identifiers[$index]);
            array_splice($identifiers, $min_index_to_order_against, 0, $this->identifier);
        }
    }

}