MediaWiki 1.30.2

[autoinstallsdev/mediawiki.git] / includes / collation / Collation.php

diff --git a/includes/collation/Collation.php b/includes/collation/Collation.php
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+<?php
+/**
+ * Database row sorting.
+ *
+ * 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
+ */
+
+/**
+ * @since 1.16.3
+ * @author Tim Starling
+ */
+abstract class Collation {
+       private static $instance;
+
+       /**
+        * @since 1.16.3
+        * @return Collation
+        */
+       public static function singleton() {
+               if ( !self::$instance ) {
+                       global $wgCategoryCollation;
+                       self::$instance = self::factory( $wgCategoryCollation );
+               }
+               return self::$instance;
+       }
+
+       /**
+        * @since 1.16.3
+        * @throws MWException
+        * @param string $collationName
+        * @return Collation
+        */
+       public static function factory( $collationName ) {
+               global $wgContLang;
+
+               switch ( $collationName ) {
+                       case 'uppercase':
+                               return new UppercaseCollation;
+                       case 'numeric':
+                               return new NumericUppercaseCollation( $wgContLang );
+                       case 'identity':
+                               return new IdentityCollation;
+                       case 'uca-default':
+                               return new IcuCollation( 'root' );
+                       case 'uca-default-u-kn':
+                               return new IcuCollation( 'root-u-kn' );
+                       case 'xx-uca-ckb':
+                               return new CollationCkb;
+                       case 'xx-uca-et':
+                               return new CollationEt;
+                       case 'xx-uca-fa':
+                               return new CollationFa;
+                       case 'uppercase-ba':
+                               return new BashkirUppercaseCollation;
+                       default:
+                               $match = [];
+                               if ( preg_match( '/^uca-([A-Za-z@=-]+)$/', $collationName, $match ) ) {
+                                       return new IcuCollation( $match[1] );
+                               }
+
+                               # Provide a mechanism for extensions to hook in.
+                               $collationObject = null;
+                               Hooks::run( 'Collation::factory', [ $collationName, &$collationObject ] );
+
+                               if ( $collationObject instanceof Collation ) {
+                                       return $collationObject;
+                               }
+
+                               // If all else fails...
+                               throw new MWException( __METHOD__ . ": unknown collation type \"$collationName\"" );
+               }
+       }
+
+       /**
+        * Given a string, convert it to a (hopefully short) key that can be used
+        * for efficient sorting.  A binary sort according to the sortkeys
+        * corresponds to a logical sort of the corresponding strings.  Current
+        * code expects that a line feed character should sort before all others, but
+        * has no other particular expectations (and that one can be changed if
+        * necessary).
+        *
+        * @since 1.16.3
+        *
+        * @param string $string UTF-8 string
+        * @return string Binary sortkey
+        */
+       abstract function getSortKey( $string );
+
+       /**
+        * Given a string, return the logical "first letter" to be used for
+        * grouping on category pages and so on.  This has to be coordinated
+        * carefully with convertToSortkey(), or else the sorted list might jump
+        * back and forth between the same "initial letters" or other pathological
+        * behavior.  For instance, if you just return the first character, but "a"
+        * sorts the same as "A" based on getSortKey(), then you might get a
+        * list like
+        *
+        * == A ==
+        * * [[Aardvark]]
+        *
+        * == a ==
+        * * [[antelope]]
+        *
+        * == A ==
+        * * [[Ape]]
+        *
+        * etc., assuming for the sake of argument that $wgCapitalLinks is false.
+        *
+        * @since 1.16.3
+        *
+        * @param string $string UTF-8 string
+        * @return string UTF-8 string corresponding to the first letter of input
+        */
+       abstract function getFirstLetter( $string );
+
+}