wcfsetup/install/files/lib/system/SingletonFactory.class.php

   1 <?php
   2 namespace wcf\system;
   3 use wcf\system\exception\SystemException;
   4
   5 /**
   6  * Base class for singleton factories.
   7  *
   8  * @author      Alexander Ebert
   9  * @copyright   2001-2018 WoltLab GmbH
  10  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  11  * @package     WoltLabSuite\Core\System
  12  */
  13 abstract class SingletonFactory {
  14         /**
  15          * list of singletons
  16          * @var SingletonFactory[]
  17          */
  18         protected static $__singletonObjects = [];
  19
  20         /**
  21          * Singletons do not support a public constructor. Override init() if
  22          * your class needs to initialize components on creation.
  23          */
  24         protected final function __construct() {
  25                 $this->init();
  26         }
  27
  28         /**
  29          * Called within __construct(), override if necessary.
  30          */
  31         protected function init() { }
  32
  33         /**
  34          * Object cloning is disallowed.
  35          */
  36         protected final function __clone() { }
  37
  38         /**
  39          * Object serializing is disallowed.
  40          */
  41         public final function __sleep() {
  42                 throw new SystemException('Serializing of Singletons is not allowed');
  43         }
  44
  45         /**
  46          * Returns an unique instance of current child class.
  47          *
  48          * @return      static
  49          * @throws      SystemException
  50          */
  51         public static final function getInstance() {
  52                 $className = get_called_class();
  53                 if (!array_key_exists($className, self::$__singletonObjects)) {
  54                         self::$__singletonObjects[$className] = null;
  55                         self::$__singletonObjects[$className] = new $className();
  56                 }
  57                 else if (self::$__singletonObjects[$className] === null) {
  58                         throw new SystemException("Infinite loop detected while trying to retrieve object for '".$className."'");
  59                 }
  60
  61                 return self::$__singletonObjects[$className];
  62         }
  63
  64         /**
  65          * Returns whether this singleton is already initialized.
  66          *
  67          * @return      boolean
  68          */
  69         public static final function isInitialized() {
  70                 $className = get_called_class();
  71
  72                 return isset(self::$__singletonObjects[$className]);
  73         }
  74 }