Add throwaway full-text search feature in a dedicated Database class

- Add explicit return type to UserDefinedChannels->current() to help IDE auto-completion

src/Content/Conversation/Collection/UserDefinedChannels.php

@@ -21,6 +21,12 @@
 
 namespace Friendica\Content\Conversation\Collection;
 
+use Friendica\Content\Conversation\Entity;
+
 class UserDefinedChannels extends Timelines
 {
+	public function current(): Entity\UserDefinedChannel
+	{
+		return parent::current();
+	}
 }

src/Database/DisposableFullTextSearch.php

@@ -0,0 +1,59 @@
+<?php
+/**
+ * @copyright Copyright (C) 2010-2024, the Friendica project
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program 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.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace Friendica\Database;
+
+/**
+ * Full-text search on a haystack string that isn't present in the database.
+ * The haystack is inserted in a temporary table with a FULLTEXT index, then any number of
+ * matches can be performed on it before the row is deleted when the class instance is destroyed,
+ * either manually or at the end of the script at the latest.
+ */
+class DisposableFullTextSearch
+{
+	private Database $db;
+	private int $identifier;
+
+	public function __construct(Database $database, string $haystack)
+	{
+		$this->db = $database;
+
+		// Maximum value is indicated by the INT UNSIGNED type of the check-full-text-search.pid field
+		$this->identifier = random_int(0, pow(2, 32) - 1);
+
+		$this->db->insert('check-full-text-search', ['pid' => $this->identifier, 'searchtext' => $haystack], Database::INSERT_UPDATE);
+	}
+
+	public function __destruct()
+	{
+		$this->db->delete('check-full-text-search', ['pid' => $this->identifier]);
+	}
+
+	/**
+	 * @param string $needle Boolean mode search string
+	 * @return bool
+	 * @throws \Exception
+	 */
+	public function match(string $needle): bool
+	{
+		return $this->db->exists('check-full-text-search', ["`pid` = ? AND MATCH (`searchtext`) AGAINST (? IN BOOLEAN MODE)", $this->identifier, $needle]);
+	}
+}