PSR-0 class autoloader shim for Elgg 1.8

19-autoloader.php

<?php
/**
 * Enables full PSR-0 class autoloading out of /classes directory
 *
 * Usage in start.php:
 *
 * if (!function_exists('elgg_get_version')) {
 *     require_once __DIR__ . '/19-autoloader.php';
 * }
 */

spl_autoload_register(function ($class) {
	$pieces = explode('\\', ltrim($class, '\\'));
	$pieces[count($pieces) - 1] = strtr($pieces[count($pieces) - 1], '_', '/');
	$file = __DIR__ . '/classes/' . implode('/', $pieces) . '.php';
	is_readable($file) && (require $file);
});