CheckCircularReferencesPass.php

<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */
namespace Symfony\Component\DependencyInjection\Compiler;

use Symfony\Component\DependencyInjection\Exception\ServiceCircularReferenceException;
use Symfony\Component\DependencyInjection\ContainerBuilder;

/**
 * Checks your services for circular references
 *
 * References from method calls are ignored since we might be able to resolve
 * these references depending on the order in which services are called.
 *
 * Circular reference from method calls will only be detected at run-time.
 *
 * @author Johannes M. Schmitt <schmittjoh@gmail.com>
 */
class CheckCircularReferencesPass implements CompilerPassInterface {
  private $currentId;
  private $currentPath;

  /**
   * Checks the ContainerBuilder object for circular references.
   *
   * @param ContainerBuilder $container The ContainerBuilder instances
   */
  public function process(ContainerBuilder $container) {
    $graph = $container
      ->getCompiler()
      ->getServiceReferenceGraph();
    foreach ($graph
      ->getNodes() as $id => $node) {
      $this->currentId = $id;
      $this->currentPath = array(
        $id,
      );
      $this
        ->checkOutEdges($node
        ->getOutEdges());
    }
  }

  /**
   * Checks for circular references.
   *
   * @param array $edges An array of Nodes
   *
   * @throws ServiceCircularReferenceException When a circular reference is found.
   */
  private function checkOutEdges(array $edges) {
    foreach ($edges as $edge) {
      $node = $edge
        ->getDestNode();
      $this->currentPath[] = $id = $node
        ->getId();
      if ($this->currentId === $id) {
        throw new ServiceCircularReferenceException($this->currentId, $this->currentPath);
      }
      $this
        ->checkOutEdges($node
        ->getOutEdges());
      array_pop($this->currentPath);
    }
  }

}