PHP Autoloader

<?php


class AutoLoader
{
    /**
    * The location where all the classes are stored.
    *
    * @var string
    */
    protected static $_rootDir = '';

    /**
    * Variables to say whether you're already setup the autoloader
    *
    * @var boolean
    */
    protected static $_setup = false;

    /**
    * Initializes the auto loader.
    *
    * @param string $rootDir The directory all the classes are located
    */
    public static function setupAutoloader($rootDir)
    {
        if(AutoLoader::$_setup) {
            return;
        }

        AutoLoader::$_rootDir = $rootDir;
        spl_autoload_register('AutoLoader::autoload');

        AutoLoader::$_setup = true;
    }

    /**
    * Will auto load a class by the name of the class.
    *
    * @param string $class The name of the class you're going to be loading.
    *
    * @return boolean
    */
    public static function autoload($class)
    {
        if(class_exists($class)) {
            return true;
        }

        $classFile = AutoLoader::classToFile($class);

        if(!$classFile) {
            return false;
        }

        if(file_exists($classFile)) {
            require_once $classFile;
            return class_exists($class);
        }

        return false;
    }

    /**
    * Converts the class name to a file path.
    *
    * @param string $class The name of the class you want to resolve the file for.
    */
    public static function classToFile($class)
    {
        return AutoLoader::$_rootDir . '/' . strtolower($class) . '.php';
    }
}