class AssetCollectionIterator

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

class AssetCollectionIterator implements \RecursiveIterator {
  private $assets;
  private $filters;
  private $output;
  private $clones;
  public function __construct(AssetCollectionInterface $coll, \SplObjectStorage $clones) {
    $this->assets = $coll
      ->all();
    $this->filters = $coll
      ->getFilters();
    $this->output = $coll
      ->getTargetPath();
    $this->clones = $clones;
    if (false === ($pos = strpos($this->output, '.'))) {
      $this->output .= '_*';
    }
    else {
      $this->output = substr($this->output, 0, $pos) . '_*' . substr($this->output, $pos);
    }
  }

  /**
   * Returns a copy of the current asset with filters and a target URL applied.
   *
   * @param Boolean $raw Returns the unmodified asset if true
   */
  public function current($raw = false) {
    $asset = current($this->assets);
    if ($raw) {
      return $asset;
    }

    // clone once
    if (!isset($this->clones[$asset])) {
      $clone = $this->clones[$asset] = clone $asset;

      // generate a target path based on asset name
      $name = sprintf('%s_%d', pathinfo($asset
        ->getSourcePath(), PATHINFO_FILENAME) ?: 'part', $this
        ->key() + 1);
      $clone
        ->setTargetPath(str_replace('*', $name, $this->output));
    }
    else {
      $clone = $this->clones[$asset];
    }

    // cascade filters
    foreach ($this->filters as $filter) {
      $clone
        ->ensureFilter($filter);
    }
    return $clone;
  }
  public function key() {
    return key($this->assets);
  }
  public function next() {
    return next($this->assets);
  }
  public function rewind() {
    return reset($this->assets);
  }
  public function valid() {
    return false !== current($this->assets);
  }
  public function hasChildren() {
    return current($this->assets) instanceof AssetCollectionInterface;
  }

  /**
   * @uses current()
   */
  public function getChildren() {
    return new self($this
      ->current(), $this->clones);
  }

}