class AssetCollectionFilterIterator

AssetCollection.php in drupal/core/vendor/kriswallsmith/assetic/src/Assetic/Asset/AssetCollection.php

class AssetCollectionFilterIterator extends \RecursiveFilterIterator {
  private $visited;
  private $sources;

  /**
   * Constructor.
   *
   * @param AssetCollectionIterator $iterator The inner iterator
   * @param array                   $visited  An array of visited asset objects
   * @param array                   $sources  An array of visited source strings
   */
  public function __construct(AssetCollectionIterator $iterator, array $visited = array(), array $sources = array()) {
    parent::__construct($iterator);
    $this->visited = $visited;
    $this->sources = $sources;
  }

  /**
   * Determines whether the current asset is a duplicate.
   *
   * De-duplication is performed based on either strict equality or by
   * matching sources.
   *
   * @return Boolean Returns true if we have not seen this asset yet
   */
  public function accept() {
    $asset = $this
      ->getInnerIterator()
      ->current(true);
    $duplicate = false;

    // check strict equality
    if (in_array($asset, $this->visited, true)) {
      $duplicate = true;
    }
    else {
      $this->visited[] = $asset;
    }

    // check source
    $sourceRoot = $asset
      ->getSourceRoot();
    $sourcePath = $asset
      ->getSourcePath();
    if ($sourceRoot && $sourcePath) {
      $source = $sourceRoot . '/' . $sourcePath;
      if (in_array($source, $this->sources)) {
        $duplicate = true;
      }
      else {
        $this->sources[] = $source;
      }
    }
    return !$duplicate;
  }

  /**
   * Passes visited objects and source URLs to the child iterator.
   */
  public function getChildren() {
    return new self($this
      ->getInnerIterator()
      ->getChildren(), $this->visited, $this->sources);
  }

}