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<?php
/*
* This file is part of the Symfony package.
*
* (c) Fabien Potencier <fabien@symfony.com>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace Symfony\Component\Form\Util;
/**
* A hash map which keeps track of deletions and additions.
*
* Like in associative arrays, elements can be mapped to integer or string keys.
* Unlike associative arrays, the map keeps track of the order in which keys
* were added and removed. This order is reflected during iteration.
*
* The map supports concurrent modification during iteration. That means that
* you can insert and remove elements from within a foreach loop and the
* iterator will reflect those changes accordingly.
*
* While elements that are added during the loop are recognized by the iterator,
* changed elements are not. Otherwise the loop could be infinite if each loop
* changes the current element:
*
* $map = new OrderedHashMap();
* $map[1] = 1;
* $map[2] = 2;
* $map[3] = 3;
*
* foreach ($map as $index => $value) {
* echo "$index: $value\n"
* if (1 === $index) {
* $map[1] = 4;
* $map[] = 5;
* }
* }
*
* print_r(iterator_to_array($map));
*
* // => 1: 1
* // 2: 2
* // 3: 3
* // 4: 5
* // Array
* // (
* // [1] => 4
* // [2] => 2
* // [3] => 3
* // [4] => 5
* // )
*
* The map also supports multiple parallel iterators. That means that you can
* nest foreach loops without affecting each other's iteration:
*
* foreach ($map as $index => $value) {
* foreach ($map as $index2 => $value2) {
* // ...
* }
* }
*
* @author Bernhard Schussek <bschussek@gmail.com>
*
* @since 2.2.6
*/
class OrderedHashMap implements \ArrayAccess, \IteratorAggregate, \Countable
{
/**
* The elements of the map, indexed by their keys.
*
* @var array
*/
private $elements = array();
/**
* The keys of the map in the order in which they were inserted or changed.
*
* @var array
*/
private $orderedKeys = array();
/**
* References to the cursors of all open iterators.
*
* @var array
*/
private $managedCursors = array();
/**
* Creates a new map.
*
* @param array $elements The elements to insert initially.
*
* @since 2.2.6
*/
public function __construct(array $elements = array())
{
$this->elements = $elements;
$this->orderedKeys = array_keys($elements);
}
/**
* {@inheritdoc}
*
* @since 2.2.6
*/
public function offsetExists($key)
{
return isset($this->elements[$key]);
}
/**
* {@inheritdoc}
*
* @since 2.2.6
*/
public function offsetGet($key)
{
if (!isset($this->elements[$key])) {
throw new \OutOfBoundsException('The offset "' . $key . '" does not exist.');
}
return $this->elements[$key];
}
/**
* {@inheritdoc}
*
* @since 2.2.6
*/
public function offsetSet($key, $value)
{
if (null === $key || !isset($this->elements[$key])) {
if (null === $key) {
$key = array() === $this->orderedKeys
// If the array is empty, use 0 as key
? 0
// Imitate PHP's behavior of generating a key that equals
// the highest existing integer key + 1
: max($this->orderedKeys) + 1;
}
$this->orderedKeys[] = $key;
}
$this->elements[$key] = $value;
}
/**
* {@inheritdoc}
*
* @since 2.2.6
*/
public function offsetUnset($key)
{
if (false !== ($position = array_search($key, $this->orderedKeys))) {
array_splice($this->orderedKeys, $position, 1);
unset($this->elements[$key]);
foreach ($this->managedCursors as $i => $cursor) {
if ($cursor >= $position) {
--$this->managedCursors[$i];
}
}
}
}
/**
* {@inheritdoc}
*
* @since 2.2.6
*/
public function getIterator()
{
return new OrderedHashMapIterator($this->elements, $this->orderedKeys, $this->managedCursors);
}
/**
* {@inheritdoc}
*
* @since 2.2.6
*/
public function count()
{
return count($this->elements);
}
}