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   1  <?php
   2  
   3  /*
   4   * This file is part of Twig.
   5   *
   6   * (c) Fabien Potencier
   7   *
   8   * For the full copyright and license information, please view the LICENSE
   9   * file that was distributed with this source code.
  10   */
  11  
  12  namespace Twig;
  13  
  14  use Twig\NodeVisitor\NodeVisitorInterface;
  15  
  16  /**
  17   * A node traverser.
  18   *
  19   * It visits all nodes and their children and calls the given visitor for each.
  20   *
  21   * @final
  22   *
  23   * @author Fabien Potencier <fabien@symfony.com>
  24   */
  25  class NodeTraverser
  26  {
  27      protected $env;
  28      protected $visitors = [];
  29  
  30      /**
  31       * @param NodeVisitorInterface[] $visitors
  32       */
  33      public function __construct(Environment $env, array $visitors = [])
  34      {
  35          $this->env = $env;
  36          foreach ($visitors as $visitor) {
  37              $this->addVisitor($visitor);
  38          }
  39      }
  40  
  41      public function addVisitor(NodeVisitorInterface $visitor)
  42      {
  43          $this->visitors[$visitor->getPriority()][] = $visitor;
  44      }
  45  
  46      /**
  47       * Traverses a node and calls the registered visitors.
  48       *
  49       * @return \Twig_NodeInterface
  50       */
  51      public function traverse(\Twig_NodeInterface $node)
  52      {
  53          ksort($this->visitors);
  54          foreach ($this->visitors as $visitors) {
  55              foreach ($visitors as $visitor) {
  56                  $node = $this->traverseForVisitor($visitor, $node);
  57              }
  58          }
  59  
  60          return $node;
  61      }
  62  
  63      protected function traverseForVisitor(NodeVisitorInterface $visitor, \Twig_NodeInterface $node = null)
  64      {
  65          if (null === $node) {
  66              return;
  67          }
  68  
  69          $node = $visitor->enterNode($node, $this->env);
  70  
  71          foreach ($node as $k => $n) {
  72              if (null === $n) {
  73                  continue;
  74              }
  75  
  76              if (false !== ($m = $this->traverseForVisitor($visitor, $n)) && null !== $m) {
  77                  if ($m !== $n) {
  78                      $node->setNode($k, $m);
  79                  }
  80              } else {
  81                  $node->removeNode($k);
  82              }
  83          }
  84  
  85          return $visitor->leaveNode($node, $this->env);
  86      }
  87  }
  88  
  89  class_alias('Twig\NodeTraverser', 'Twig_NodeTraverser');