Concise, expressive string-matching in PHP

<?php
// simple tasks should be concise
$input = new Literal($_GET['password']);
if ($input->matches($user->password)) {
    $user->login();
}

// hard tasks should be clear
$shell = new Pcre('{a,ba,k,z}sh');
$file  = new SubjectFile('/etc/group');
$shell->foundIn($file->column(':', 7));