[ticket/12466] Move classes from acp_database.php to their own files

* Moving classes from acp_database.php to phpbb/db/extractor namespace,
   also into separate files
 * Adding DocBlocks and property visibility to classes
 * Removing globals from code
 * Passing former globals to base_extractor's constructor
 * Adding DB extractor as a service, also implementing the extractor interface
   as well as the extractor factory.

PHPBB3-12466

phpBB/phpbb/db/extractor/extractor_interface.php

@@ -0,0 +1,80 @@
+<?php
+/**
+*
+* This file is part of the phpBB Forum Software package.
+*
+* @copyright (c) phpBB Limited <https://www.phpbb.com>
+* @license GNU General Public License, version 2 (GPL-2.0)
+*
+* For full copyright and license information, please see
+* the docs/CREDITS.txt file.
+*
+*/
+
+namespace phpbb\db\extractor;
+
+/**
+* Database extractor interface
+*/
+interface extractor_interface
+{
+	/**
+	* Start the extraction of the database
+	*
+	* This function initialize the database extraction. It is required to call this
+	* function before calling any other extractor functions.
+	*
+	* @param string	$format
+	* @param string	$filename
+	* @param int	$time
+	* @param bool	$download
+	* @param bool	$store
+	* @return null
+	* @throws \phpbb\db\extractor\exception\invalid_format_exception when $format is invalid
+	*/
+	public function init_extractor($format, $filename, $time, $download = false, $store = false);
+
+	/**
+	* Writes header comments to the database backup
+	*
+	* @param	string	$table_prefix	prefix of phpBB database tables
+	* @return null
+	* @throws \phpbb\db\extractor\exception\extractor_not_initialized_exception when calling this function before init_extractor()
+	*/
+	public function write_start($table_prefix);
+
+	/**
+	* Closes file and/or dumps download data
+	*
+	* @return null
+	* @throws \phpbb\db\extractor\exception\extractor_not_initialized_exception when calling this function before init_extractor()
+	*/
+	public function write_end();
+
+	/**
+	* Extracts database table structure
+	*
+	* @param	string	$table_name	name of the database table
+	* @return null
+	* @throws \phpbb\db\extractor\exception\extractor_not_initialized_exception when calling this function before init_extractor()
+	*/
+	public function write_table($table_name);
+
+	/**
+	* Extracts data from database table
+	*
+	* @param	string	$table_name	name of the database table
+	* @return null
+	* @throws \phpbb\db\extractor\exception\extractor_not_initialized_exception when calling this function before init_extractor()
+	*/
+	public function write_data($table_name);
+
+	/**
+	* Writes data to file/download content
+	*
+	* @param string	$data
+	* @return null
+	* @throws \phpbb\db\extractor\exception\extractor_not_initialized_exception when calling this function before init_extractor()
+	*/
+	public function flush($data);
+}