PHP PSR-0 Autoload (with Phar)

index.php

/**
 * Enhanced PSR-0 autoloader with Phar-Support
 *
 * @param $class string Name of the class (with namespace)
 *
 * @author    Ralf Mike Pretzlaw <kontakt@mike-pretzlaw.de>
 * @copyright 2012 Ralf Mike Pretzlaw
 *
 * @throws Exception
 */
function autoloadPSR ( $class )
{
    /**
     * PSR-0
     * https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-0.md
     */
    $className = ltrim($class, '\\');
    $fileName  = '';
    $namespace = '';
    if ( $lastNsPos = strripos($className, '\\') )
    {
        $namespace = substr($className, 0, $lastNsPos);
        $className = substr($className, $lastNsPos + 1);
        $fileName  = str_replace('\\', DIRECTORY_SEPARATOR, $namespace) . DIRECTORY_SEPARATOR;
    }

    $fileName .= str_replace('_', DIRECTORY_SEPARATOR, $className) . '.php';

    /**
     * PHAR-Part
     */
    $pharFile = Phar::running() . DIRECTORY_SEPARATOR . $fileName;

    if ( false !== stream_resolve_include_path($fileName) )
    { // exists in at least one include-path: require it
        require_once $fileName;
    }
    else if ( file_exists($pharFile) )
    { // is in phar archive: require the phar file
        require_once $pharFile;
    }
    else
    { // neither phar nor in include-path: that's bad
        throw new \Exception( 'File with definition of ' . $class . ' could not be found.' );
    }

    if ( false == class_exists($class, false) && false == interface_exists($class, false) )
    { // class doesn't exists after including a file: bad too
        throw new \Exception( 'Definition for ' . $class . ' not found.' );
    }
}

spl_autoload_register('autoloadPSR', true, true);