<?php
/**
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 */

/**
 * Collation class that's essentially a no-op.
 *
 * Does sorting based on binary value of the string.
 * Like how things were pre 1.17.
 *
 * @since 1.18
 */
class IdentityCollation extends Collation {

	/** @var Language */
	private $contentLanguage;

	/**
	 * @param Language $contentLanguage
	 */
	public function __construct( Language $contentLanguage ) {
		$this->contentLanguage = $contentLanguage;
	}

	public function getSortKey( $string ) {
		return $string;
	}

	public function getFirstLetter( $string ) {
		// Copied from UppercaseCollation.
		// I'm kind of unclear on when this could happen...
		if ( $string[0] == "\0" ) {
			$string = substr( $string, 1 );
		}
		return $this->contentLanguage->firstChar( $string );
	}
}