StoppableIterator.php

<?php
/**
 * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
 * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 *
 * Licensed under The MIT License
 * For full copyright and license information, please see the LICENSE.txt
 * Redistributions of files must retain the above copyright notice.
 *
 * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 * @link          http://cakephp.org CakePHP(tm) Project
 * @since         3.0.0
 * @license       http://www.opensource.org/licenses/mit-license.php MIT License
 */
namespace Cake\Collection\Iterator;

use Cake\Collection\Collection;

/**
 * Creates an iterator from another iterator that will verify a condition on each
 * step. If the condition evaluates to false, the iterator will not yield more
 * results.
 *
 * @internal
 * @see Collection::stopWhen()
 */
class StoppableIterator extends Collection {

/**
 * The condition to evaluate for each item of the collection
 *
 * @var callable
 */
	protected $_condition;

/**
 * Creates an iterator that can be stopped based on a condition provided by a callback.
 *
 * Each time the condition callback is executed it will receive the value of the element
 * in the current iteration, the key of the element and the passed $items iterator
 * as arguments, in that order.
 *
 * @param array|\Traversable $items The list of values to iterate
 * @param callable $condition A function that will be called for each item in
 * the collection, if the result evaluates to false, no more items will be
 * yielded from this iterator.
 */
	public function __construct($items, callable $condition) {
		$this->_condition = $condition;
		parent::__construct($items);
	}

/**
 * Evaluates the condition and returns its result, this controls
 * whether or not more results will be yielded.
 *
 * @return bool
 */
	public function valid() {
		if (!parent::valid()) {
			return false;
		}

		$current = $this->current();
		$key = $this->key();
		$condition = $this->_condition;
		return !$condition($current, $key, $this);
	}

}