gistfile1.php

    protected static function getConstantValues($prefix = '')
    {
        $refl = new ReflectionClass(get_called_class());
        $allConstants = $refl->getConstants();

        if ($prefix != '') {
            $prefixLength = strlen($prefix);
            $filteredList = array();
            foreach ($allConstants as $key => $value) {
                if (substr($key, 0, $prefixLength) == $prefix) {
                    $filteredList[$key] = $value;
                }
            }
            return $filteredList;
        } else {
            return $allConstants;
        }
    }