respect-validation/library/Rules/Lowercase.php

<?php

/*
 * Copyright (c) Alexandre Gomes Gaigalas <alganet@gmail.com>
 * SPDX-License-Identifier: MIT
 */

declare(strict_types=1);

namespace Respect\Validation\Rules;

use function is_string;
use function mb_strtolower;

/**
 * Validates whether the characters in the input are lowercase.
 *
 * @author Alexandre Gomes Gaigalas <alganet@gmail.com>
 * @author Danilo Benevides <danilobenevides01@gmail.com>
 * @author Henrique Moody <henriquemoody@gmail.com>
 * @author Jean Pimentel <jeanfap@gmail.com>
 */
final class Lowercase extends AbstractRule
{
    /**
     * {@inheritDoc}
     */
    public function validate($input): bool
    {
        if (!is_string($input)) {
            return false;
        }

        return $input === mb_strtolower($input);
    }
}