--- /dev/null
+<?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
+ *
+ * @since 1.30
+ *
+ * @file
+ */
+
+/**
+ * Resort normal UTF-8 order by putting a bunch of stuff in PUA
+ *
+ * This takes a bunch of characters (The alphabet) that should,
+ * be together, and converts them all to private-use-area characters
+ * so that they are all sorted in the right order relative to each
+ * other.
+ *
+ * This renumbers characters starting at U+F3000 (Chosen to avoid
+ * conflicts with other people using private use area)
+ *
+ * This does not support fancy things like secondary differences, etc.
+ *
+ * It is expected most people will subclass this and just override the
+ * constructor to hard-code an alphabet.
+ */
+class CustomUppercaseCollation extends NumericUppercaseCollation {
+
+ /** @var array $alphabet Sorted array of letters */
+ private $alphabet;
+
+ /** @var array $puaSubset List of private use area codes */
+ private $puaSubset;
+
+ /**
+ * @note This assumes $alphabet does not contain U+F3000-U+F303F
+ *
+ * @param array $alphabet Sorted array of uppercase characters.
+ * @param Language $lang What language for number sorting.
+ */
+ public function __construct( array $alphabet, Language $lang ) {
+ // It'd be trivial to extend this past 64, you'd just
+ // need a bit of bit-fiddling. Doesn't seem necessary right
+ // now.
+ if ( count( $alphabet ) < 1 || count( $alphabet ) >= 64 ) {
+ throw new UnexpectedValueException( "Alphabet must be < 64 items" );
+ }
+ $this->alphabet = $alphabet;
+
+ $this->puaSubset = [];
+ $len = count( $alphabet );
+ for ( $i = 0; $i < $len; $i++ ) {
+ $this->puaSubset[] = "\xF3\xB3\x80" . chr( $i + 128 );
+ }
+ parent::__construct( $lang );
+ }
+
+ private function convertToPua( $string ) {
+ return str_replace( $this->alphabet, $this->puaSubset, $string );
+ }
+
+ public function getSortKey( $string ) {
+ return $this->convertToPua( parent::getSortKey( $string ) );
+ }
+
+ public function getFirstLetter( $string ) {
+ // In case a title has a PUA code in it, make it sort
+ // under the header for the character it would replace
+ // to avoid inconsistent behaviour. This class mostly
+ // assumes that people will not use PUA codes.
+ return parent::getFirstLetter(
+ str_replace( $this->puaSubset, $this->alphabet, $string )
+ );
+ }
+}