simple string-based array access

Config.php

<?php
class Config
{
    protected $data;
    public function __construct(array $data)
    {
        $this->data = $data;
    }
    public function get($alias)
    {
        $keys = explode('.', $alias);
        $data = $this->data;
        foreach ($keys as $key) {
            if (empty($key)) {
                throw new \InvalidArgumentException('Empty key provided');
            }
            if (!isset($data[$key])) {
                $message = sprintf(
                    'Key %s hasn\'t been found in config',
                    $key
                );
                throw new \BadMethodCallException($message);
            }
            $data = $data[$key];
        }
        return $data;
    }
}

test.php

require 'Config.php';
$data = array(
    'app' => array(
        'params' => array(
            'db' => array(
                'user' => 'underdog',
            ),
        ),
    ),
);
$config = new Config($data);
var_dump($config->get('app.params.db.user'), $config->get('app.params'));
/*
string(8) "underdog"
array(1) {
  'db' =>
  array(1) {
    'user' =>
    string(8) "underdog"
  }
}
*/