<?php
/**
 * Base class for all objects where only one object should be created
 *
 * @version $Header$
 *
 * Copyright (c) 2004 bitweaver.org
 * All Rights Reserved. See below for details and a complete list of authors.
 * Licensed under the GNU LESSER GENERAL PUBLIC LICENSE. See http://www.gnu.org/copyleft/lesser.html for details
 *
 * Virtual base class (as much as one can have such things in PHP) for all
 * derived tikiwiki classes that require database access.
 *
 * created 2004/8/15
 *
 * @author spider <spider@steelsun.com>
 * @package  kernel
 */

/**
 * required setup
 */
require_once( KERNEL_PKG_PATH . 'BitBase.php' );

/**
 * @package  kernel
 */
abstract class BitSingleton extends BitBase implements BitCacheable {

    protected static $singletons = null;

    function __construct() {
		parent::__construct();
	}

    public static function loadSingleton( $pVarName = NULL ) {
        $class = static::getClass();
		$globalVarName = !empty( $pVarName ) ? $pVarName : 'g'.$class;
		global $$globalVarName;

		if( !($$globalVarName = static::loadFromCache( 'Singleton' )) ) {
			$$globalVarName = new $class;
		}
		if(!isset(static::$singletons[$globalVarName])) {
			static::$singletons[$globalVarName] = $$globalVarName;
			global $gBitSmarty;
			$gBitSmarty->assignByRef( $globalVarName, $$globalVarName );
		}
		return static::$singletons[$globalVarName];
    }

	public function getCacheKey() {
		return 'Singleton';
	}

	public static function isCacheableClass() {
		return true;
	}

	public function isCacheableObject() {
		return true;
	}

}

// I don't remember where I found this, but this is to allow php < 5.3 to use this method.
if (!function_exists('get_called_class')) {
    function get_called_class($bt = false, $l = 1) {
        if (!$bt)
            $bt = debug_backtrace();
        if (!isset($bt[$l]))
            throw new Exception("Cannot find called class -> stack level too deep.");
        if (!isset($bt[$l]['type'])) {
            throw new Exception('type not set');
        }
        else
            switch ($bt[$l]['type']) {
                case '::':
                    $lines = file($bt[$l]['file']);
                    $i = 0;
                    $callerLine = '';
                    do {
                        $i++;
                        $callerLine = $lines[$bt[$l]['line'] - $i] . $callerLine;
                    } while (stripos($callerLine, $bt[$l]['function']) === false);
                    preg_match('/([a-zA-Z0-9\_]+)::' . $bt[$l]['function'] . '/', $callerLine, $matches);
                    if (!isset($matches[1])) {
                        // must be an edge case.
                        throw new Exception("Could not find caller class: originating method call is obscured.");
                    }
                    switch ($matches[1]) {
                        case 'self':
                        case 'parent':
                            return get_called_class($bt, $l + 1);
                        default:
                            return $matches[1];
                    }
                // won't get here.
                case '->': switch ($bt[$l]['function']) {
                        case '__get':
                            // edge case -> get class of calling object
                            if (!is_object($bt[$l]['object']))
                                throw new Exception("Edge case fail. __get called on non object.");
                            return get_class($bt[$l]['object']);
                        default: return $bt[$l]['class'];
                    }

                default: throw new Exception("Unknown backtrace method type");
            }
    }
}