PHPOffice/PHPPresentation

<?php
/**
 * This file is part of PHPPresentation - A pure PHP library for reading and writing
 * presentations documents.
 *
 * PHPPresentation is free software distributed under the terms of the GNU Lesser
 * General Public License version 3 as published by the Free Software Foundation.
 *
 * For the full copyright and license information, please read the LICENSE
 * file that was distributed with this source code. For the full list of
 * contributors, visit https://github.com/PHPOffice/PHPPresentation/contributors.
 *
 * @see        https://github.com/PHPOffice/PHPPresentation
 *
 * @license     http://www.gnu.org/licenses/lgpl.txt LGPL version 3
 */

declare(strict_types=1);

namespace PhpOffice\PhpPresentation;

/**
 * PhpOffice\PhpPresentation\ComparableInterface.
 */
interface ComparableInterface
{
    /**
     * Get hash code.
     *
     * @return string Hash code
     */
    public function getHashCode(): string;

    /**
     * Get hash index.
     *
     * Note that this index may vary during script execution! Only reliable moment is
     * while doing a write of a workbook and when changes are not allowed.
     *
     * @return null|int Hash index
     */
    public function getHashIndex(): ?int;

    /**
     * Set hash index.
     *
     * Note that this index may vary during script execution! Only reliable moment is
     * while doing a write of a workbook and when changes are not allowed.
     *
     * @param int $value Hash index
     *
     * @return $this
     */
    public function setHashIndex(int $value);
}