NumberInterface.php

<?php

/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2021 Niklas Ekman
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

declare(strict_types=1);

namespace Nekman\LuhnAlgorithm\Contract;

/**
 * Describes the structure of a number in the Luhn Algorithm.
 */
interface NumberInterface
{
    /**
     * Get the number, without check digit.
     * @return string
     */
    public function getNumber(): string;

    /**
     * Get the check digit for the number.
     * @return int|null The check digit or null if it has not been calculated yet.
     */
    public function getCheckDigit(): ?int;
}