Weak-referenced data structures for PHP

This library is based on php-weak PHP extension and provides various weak data structures:

• class Weak\WeakKeyMap
• class Weak\WeakValueMap
• class Weak\WeakKeyValueMap

Requirements

php-weak PHP extension required. PHP 7 only (due to php-weak).

Installation:

composer require pinepain/php-weak-lib

Docs:

Class Weak\WeakKeyMap

Mapping class that references keys weakly. Entries will be discarded when there is no longer a reference to the key. This can be used to associate additional data with an object owned by other parts of an application without adding attributes to those objects. This can be especially useful with objects that override attribute accesses. Built on top of SplObjectStorage.

Caution

Because a Weak\WeakKeyMap is built on top of a SplObjectStorage, it must not change size when iterating over it. This can be difficult to ensure for a Weakref\WeakKeyMap because actions performed by the program during iteration may cause items in the storage to vanish "by magic" (as a side effect of garbage collection).

Example

<?php

require __DIR__ . '/../vendor/autoload.php';

use Weak\WeakKeyMap;

$map = new WeakKeyMap();

$obj1 = new stdClass();
$inf1 = new stdClass();

$obj2 = new stdClass();
$inf2 = new stdClass();

$map->attach($obj1, $inf1);
$map->attach($obj2, $inf2);

var_dump($map->count()); // 2

// Let's destroy key
$obj1 = null;

var_dump($map->count()); // 1

Class Weak\WeakValueMap

Mapping class that references values weakly. Entries will be discarded when reference to the value exists any more. Built on top of SplObjectStorage.

Caution

Because a Weak\WeakValueMap is built on top of a SplObjectStorage, it must not change size when iterating over it. This can be difficult to ensure for a Weakref\WeakValueMap because actions performed by the program during iteration may cause items in the storage to vanish "by magic" (as a side effect of garbage collection).

Example

<?php

require __DIR__ . '/../vendor/autoload.php';

use Weak\WeakValueMap;

$map = new WeakValueMap();

$obj1 = new stdClass();
$inf1 = new stdClass();

$obj2 = new stdClass();
$inf2 = new stdClass();

$map->attach($obj1, $inf1);
$map->attach($obj2, $inf2);

var_dump($map->count()); // 2

// Let's destroy value
$inf1 = null;

var_dump($map->count()); // 1

Class Weak\WeakKeyValueMap

Mapping class that references values weakly. Entries will be discarded when reference to the key or value exists any more. Built on top of SplObjectStorage.

Caution

Because a Weak\WeakKeyValueMap is built on top of a SplObjectStorage, it must not change size when iterating over it. This can be difficult to ensure for a Weakref\WeakKeyValueMap because actions performed by the program during iteration may cause items in the storage to vanish "by magic" (as a side effect of garbage collection).

Example

<?php

require __DIR__ . '/../vendor/autoload.php';

use Weak\WeakValueMap;

$map = new WeakKeyValueMap();

$obj1 = new stdClass();
$inf1 = new stdClass();

$obj2 = new stdClass();
$inf2 = new stdClass();

$map->attach($obj1, $inf1);
$map->attach($obj2, $inf2);

var_dump($map->count()); // 2

// Let's destroy key
$obj1 = null;

var_dump($map->count()); // 1

// Let's destroy value
$inf2 = null;

var_dump($map->count()); // 0

License

php-weak-lib PHP library is licensed under the MIT license.