symfony/src/Symfony/Component/Validator/Constraints/LanguageValidator.php

<?php

namespace Symfony\Component\Validator\Constraints;

/*
 * This file is part of the Symfony framework.
 *
 * (c) Fabien Potencier <fabien.potencier@symfony-project.com>
 *
 * This source file is subject to the MIT license that is bundled
 * with this source code in the file LICENSE.
 */

use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;
use Symfony\Component\Validator\Exception\UnexpectedTypeException;
use Symfony\Component\Locale\Locale;

/**
 * Validates whether a value is a valid language code
 *
 * @author Bernhard Schussek <bernhard.schussek@symfony-project.com>
 */
class LanguageValidator extends ConstraintValidator
{
    public function isValid($value, Constraint $constraint)
    {
        if (null === $value || '' === $value) {
            return true;
        }

        if (!is_scalar($value) && !(is_object($value) && method_exists($value, '__toString()'))) {
            throw new UnexpectedTypeException($value, 'string');
        }

        $value = (string)$value;

        if (!in_array($value, Locale::getLanguages())) {
            $this->setMessage($constraint->message, array('{{ value }}' => $value));

            return false;
        }

        return true;
    }
}