Class abstract extended from FilterIterator and implements RecursiveIterator.

RecursiveMultiFilterIterator.php

<?php

/**
 * @file    RecursiveMultiFilterIterator.php
 * @brief   Class abstract extended from RecursiveFilterIterator.
 * @author  Joon Park (joon@dvessel.com)
 */

/**
 * This is an abstract class. Extended it with a custom accept() and/or
 * acceptChildren() method to make it useful.
 */
abstract class RecursiveMultiFilterIterator extends RecursiveFilterIterator {

  private $parent;
  private $depth = 0;

  /**
   * Called after the creation of a new child instance. This is useful for
   * carrying over the state of properties from parent iterators. Use
   * getParent() to get all parent methods and properties.
   */
  public function initChild() {
    // do something...
  }

  /**
   * Accept function to decide whether an element of the inner iterator
   * should be accessible through the Filteriterator.
   *
   * @return
   *  Whether or not to expose the current element of the inner iterator.
   */
  public function accept() {
    return TRUE;
  }

  /**
   * When the current element has passed accept() and contains children,
   * further checks can be made here to allow or prevent further processing of
   * child elements.
   */
  public function acceptChildren() {
    return TRUE;
  }

  /**
   * @return
   *  The current depth.
   */
  public function getDepth() {
    return $this->depth;
  }

  /**
   * @return
   *  The immediate parent instance.
   */
  public function getParent() {
    return $this->parent;
  }

  /**
   * Called from getChildren() to pass parents into children.
   */
  public function pushParent($parent) {
    $this->parent = $parent;
    $this->depth  = $parent->depth + 1;
    return $this;
  }

  /**
   * Checks if the current element contains children. It must also pass the
   * acceptChildren() method.
   *
   * @return
   *  Whether the current element has children.
   */
  public function hasChildren() {
    return $this->getInnerIterator()->hasChildren() && $this->acceptChildren();
  }

  /**
   * Gets called when hasChildren() returns TRUE.
   *
   * @return
   *  An iterator for the elements children in the same class as $this.
   */
  public function getChildren() {
    $child = new $this($this->getInnerIterator()->getChildren());
    $child->pushParent($this)->initChild();
    return $child;
  }
}