PSR-0 PHP autoloader

autoloader.php

<?php

/**
 * PSR-0 autoloader
 * @param string $className
 *
 * @see http://www.php-fig.org/psr/psr-0/
 */
function autoload($className)
{
    $className = ltrim($className, '\\');
    $fileName  = '';

    if ($lastNsPos = strrpos($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';

    require $fileName;
}

/**
 * Register the PSR-0 autoloader we created above
 */
spl_autoload_register('autoload');