[PLUGINS] Add StemWord plugin, which stems words, given a language. Currently used for tags

plugins/StemWord/StemWord.php

@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types = 1);
+
+// {{{ License
+
+// This file is part of GNU social - https://www.gnu.org/software/social
+//
+// GNU social is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// GNU social 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 Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with GNU social.  If not, see <http://www.gnu.org/licenses/>.
+
+// }}}
+
+namespace Plugin\StemWord;
+
+use App\Core\Event;
+use App\Core\Modules\Plugin;
+use Wamania\Snowball\StemmerFactory;
+
+class StemWord extends Plugin
+{
+    public function onStemWord(string $language, string $word, string &$out)
+    {
+        $out = StemmerFactory::create($language)->stem($word);
+        return Event::stop;
+    }
+}

plugins/StemWord/composer.json

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+{
+  "require": {
+    "wamania/php-stemmer": "^3.0"
+  }
+}