<?php
/**
* CakePHP(tm) : Rapid Development Framework (https://cakephp.org)
* Copyright (c) Cake Software Foundation, Inc. (https://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. (https://cakefoundation.org)
* @link https://cakephp.org CakePHP(tm) Project
* @since 3.0.5
* @license https://opensource.org/licenses/mit-license.php MIT License
*/
namespace Cake\Collection\Iterator;
use Cake\Collection\Collection;
use Cake\Collection\CollectionInterface;
use Cake\Collection\CollectionTrait;
use MultipleIterator;
use Serializable;
/**
* Creates an iterator that returns elements grouped in pairs
*
* ### Example
*
* ```
* $iterator = new ZipIterator([[1, 2], [3, 4]]);
* $iterator->toList(); // Returns [[1, 3], [2, 4]]
* ```
*
* You can also chose a custom function to zip the elements together, such
* as doing a sum by index:
*
* ### Example
*
* ```
* $iterator = new ZipIterator([[1, 2], [3, 4]], function ($a, $b) {
* return $a + $b;
* });
* $iterator->toList(); // Returns [4, 6]
* ```
*/
class ZipIterator extends MultipleIterator implements CollectionInterface, Serializable
{
use CollectionTrait;
/**
* The function to use for zipping items together
*
* @var callable
*/
protected $_callback;
/**
* Contains the original iterator objects that were attached
*
* @var array
*/
protected $_iterators = [];
/**
* Creates the iterator to merge together the values by for all the passed
* iterators by their corresponding index.
*
* @param array $sets The list of array or iterators to be zipped.
* @param callable|null $callable The function to use for zipping the elements of each iterator.
*/
public function __construct(array $sets, $callable = null)
{
$sets = array_map(function ($items) {
return (new Collection($items))->unwrap();
}, $sets);
$this->_callback = $callable;
parent::__construct(MultipleIterator::MIT_NEED_ALL | MultipleIterator::MIT_KEYS_NUMERIC);
foreach ($sets as $set) {
$this->_iterators[] = $set;
$this->attachIterator($set);
}
}
/**
* Returns the value resulting out of zipping all the elements for all the
* iterators with the same positional index.
*
* @return mixed
*/
public function current()
{
if ($this->_callback === null) {
return parent::current();
}
return call_user_func_array($this->_callback, parent::current());
}
/**
* Returns a string representation of this object that can be used
* to reconstruct it
*
* @return string
*/
public function serialize()
{
return serialize($this->_iterators);
}
/**
* Unserializes the passed string and rebuilds the ZipIterator instance
*
* @param string $iterators The serialized iterators
* @return void
*/
public function unserialize($iterators)
{
parent::__construct(MultipleIterator::MIT_NEED_ALL | MultipleIterator::MIT_KEYS_NUMERIC);
$this->_iterators = unserialize($iterators);
foreach ($this->_iterators as $it) {
$this->attachIterator($it);
}
}
}