like_to_regex.php

<?php

function likeToRegex($like)
{
    // replace all % characters that are not escaped with .*
    $regex = preg_replace('/(?<!\\\)%/', '.*', $like);
    // replace all escaped % characters with %
    $regex = str_replace('\%', '%', $regex);
    // replace all unescaped _ characters with .{1}
    $regex = preg_replace('/(?<!\\\)_/', '.{1}', $regex);
    // replace all escaped _ characters with _
    $regex = str_replace('\_', '_', $regex);
    // add delimiters
    return '/' . str_replace('/', '\\/', $regex) . '/';
}