7 files changed, 1712 insertions, 0 deletions
diff --git a/phpBB/phpbb/extension/base.php b/phpBB/phpbb/extension/base.php
new file mode 100644
index 0000000000..c4462b64d8
--- /dev/null
+++ b/phpBB/phpbb/extension/base.php
@@ -0,0 +1,135 @@
+<?php
+/**
+*
+* @package extension
+* @copyright (c) 2011 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+* A base class for extensions without custom enable/disable/purge code.
+*
+* @package extension
+*/
+class phpbb_extension_base implements phpbb_extension_interface
+{
+	/** @var ContainerInterface */
+	protected $container;
+
+	/** @var phpbb_extension_finder */
+	protected $finder;
+
+	/** @var phpbb_db_migrator */
+	protected $migrator;
+
+	/** @var string */
+	protected $extension_name;
+
+	/** @var string */
+	protected $extension_path;
+
+	/**
+	* Constructor
+	*
+	* @param ContainerInterface $container Container object
+	* @param phpbb_extension_finder $extension_finder
+	* @param string $extension_name Name of this extension (from ext.manager)
+	* @param string $extension_path Relative path to this extension
+	*/
+	public function __construct(ContainerInterface $container, phpbb_extension_finder $extension_finder, phpbb_db_migrator $migrator, $extension_name, $extension_path)
+	{
+		$this->container = $container;
+		$this->extension_finder = $extension_finder;
+		$this->migrator = $migrator;
+
+		$this->extension_name = $extension_name;
+		$this->extension_path = $extension_path;
+	}
+
+	/**
+	* Single enable step that installs any included migrations
+	*
+	* @param mixed $old_state State returned by previous call of this method
+	* @return false Indicates no further steps are required
+	*/
+	public function enable_step($old_state)
+	{
+		$migrations = $this->get_migration_file_list();
+
+		$this->migrator->set_migrations($migrations);
+
+		$this->migrator->update();
+
+		return !$this->migrator->finished();
+	}
+
+	/**
+	* Single disable step that does nothing
+	*
+	* @param mixed $old_state State returned by previous call of this method
+	* @return false Indicates no further steps are required
+	*/
+	public function disable_step($old_state)
+	{
+		return false;
+	}
+
+	/**
+	* Single purge step that reverts any included and installed migrations
+	*
+	* @param mixed $old_state State returned by previous call of this method
+	* @return false Indicates no further steps are required
+	*/
+	public function purge_step($old_state)
+	{
+		$migrations = $this->get_migration_file_list();
+
+		$this->migrator->set_migrations($migrations);
+
+		foreach ($migrations as $migration)
+		{
+			while ($this->migrator->migration_state($migration) !== false)
+			{
+				$this->migrator->revert($migration);
+
+				return true;
+			}
+		}
+
+		return false;
+	}
+
+	/**
+	* Get the list of migration files from this extension
+	*
+	* @return array
+	*/
+	protected function get_migration_file_list()
+	{
+		static $migrations = false;
+
+		if ($migrations !== false)
+		{
+			return $migrations;
+		}
+
+		// Only have the finder search in this extension path directory
+		$migrations = $this->extension_finder
+			->extension_directory('/migrations')
+			->find_from_extension($this->extension_name, $this->extension_path);
+		$migrations = $this->extension_finder->get_classes_from_files($migrations);
+
+		return $migrations;
+	}
+}
diff --git a/phpBB/phpbb/extension/exception.php b/phpBB/phpbb/extension/exception.php
new file mode 100644
index 0000000000..e08a8912ea
--- /dev/null
+++ b/phpBB/phpbb/extension/exception.php
@@ -0,0 +1,27 @@
+<?php
+/**
+*
+* @package extension
+* @copyright (c) 2012 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+ * Exception class for metadata
+ */
+class phpbb_extension_exception extends UnexpectedValueException
+{
+	public function __toString()
+	{
+		return $this->getMessage();
+	}
+}
+\ No newline at end of file
diff --git a/phpBB/phpbb/extension/finder.php b/phpBB/phpbb/extension/finder.php
new file mode 100644
index 0000000000..155a41cda5
--- /dev/null
+++ b/phpBB/phpbb/extension/finder.php
@@ -0,0 +1,523 @@
+<?php
+/**
+*
+* @package extension
+* @copyright (c) 2011 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* The extension finder provides a simple way to locate files in active extensions
+*
+* @package extension
+*/
+class phpbb_extension_finder
+{
+	protected $extension_manager;
+	protected $filesystem;
+	protected $phpbb_root_path;
+	protected $cache;
+	protected $php_ext;
+
+	/**
+	* The cache variable name used to store $this->cached_queries in $this->cache.
+	*
+	* Allows the use of multiple differently configured finders with the same cache.
+	* @var string
+	*/
+	protected $cache_name;
+
+	/**
+	* An associative array, containing all search parameters set in methods.
+	* @var	array
+	*/
+	protected $query;
+
+	/**
+	* A map from md5 hashes of serialized queries to their previously retrieved
+	* results.
+	* @var	array
+	*/
+	protected $cached_queries;
+
+	/**
+	* Creates a new finder instance with its dependencies
+	*
+	* @param phpbb_extension_manager $extension_manager An extension manager
+	*            instance that provides the finder with a list of active
+	*            extensions and their locations
+	* @param phpbb_filesystem $filesystem Filesystem instance
+	* @param string $phpbb_root_path Path to the phpbb root directory
+	* @param phpbb_cache_driver_interface $cache A cache instance or null
+	* @param string $php_ext php file extension
+	* @param string $cache_name The name of the cache variable, defaults to
+	*                           _ext_finder
+	*/
+	public function __construct(phpbb_extension_manager $extension_manager, phpbb_filesystem $filesystem, $phpbb_root_path = '', phpbb_cache_driver_interface $cache = null, $php_ext = 'php', $cache_name = '_ext_finder')
+	{
+		$this->extension_manager = $extension_manager;
+		$this->filesystem = $filesystem;
+		$this->phpbb_root_path = $phpbb_root_path;
+		$this->cache = $cache;
+		$this->php_ext = $php_ext;
+		$this->cache_name = $cache_name;
+
+		$this->query = array(
+			'core_path' => false,
+			'core_suffix' => false,
+			'core_prefix' => false,
+			'core_directory' => false,
+			'extension_suffix' => false,
+			'extension_prefix' => false,
+			'extension_directory' => false,
+		);
+
+		$this->cached_queries = ($this->cache) ? $this->cache->get($this->cache_name) : false;
+	}
+
+	/**
+	* Sets a core path to be searched in addition to extensions
+	*
+	* @param string $core_path The path relative to phpbb_root_path
+	* @return phpbb_extension_finder This object for chaining calls
+	*/
+	public function core_path($core_path)
+	{
+		$this->query['core_path'] = $core_path;
+		return $this;
+	}
+
+	/**
+	* Sets the suffix all files found in extensions and core must match.
+	*
+	* There is no default file extension, so to find PHP files only, you will
+	* have to specify .php as a suffix. However when using get_classes, the .php
+	* file extension is automatically added to suffixes.
+	*
+	* @param string $suffix A filename suffix
+	* @return phpbb_extension_finder This object for chaining calls
+	*/
+	public function suffix($suffix)
+	{
+		$this->core_suffix($suffix);
+		$this->extension_suffix($suffix);
+		return $this;
+	}
+
+	/**
+	* Sets a suffix all files found in extensions must match
+	*
+	* There is no default file extension, so to find PHP files only, you will
+	* have to specify .php as a suffix. However when using get_classes, the .php
+	* file extension is automatically added to suffixes.
+	*
+	* @param string $extension_suffix A filename suffix
+	* @return phpbb_extension_finder This object for chaining calls
+	*/
+	public function extension_suffix($extension_suffix)
+	{
+		$this->query['extension_suffix'] = $extension_suffix;
+		return $this;
+	}
+
+	/**
+	* Sets a suffix all files found in the core path must match
+	*
+	* There is no default file extension, so to find PHP files only, you will
+	* have to specify .php as a suffix. However when using get_classes, the .php
+	* file extension is automatically added to suffixes.
+	*
+	* @param string $core_suffix A filename suffix
+	* @return phpbb_extension_finder This object for chaining calls
+	*/
+	public function core_suffix($core_suffix)
+	{
+		$this->query['core_suffix'] = $core_suffix;
+		return $this;
+	}
+
+	/**
+	* Sets the prefix all files found in extensions and core must match
+	*
+	* @param string $prefix A filename prefix
+	* @return phpbb_extension_finder This object for chaining calls
+	*/
+	public function prefix($prefix)
+	{
+		$this->core_prefix($prefix);
+		$this->extension_prefix($prefix);
+		return $this;
+	}
+
+	/**
+	* Sets a prefix all files found in extensions must match
+	*
+	* @param string $extension_prefix A filename prefix
+	* @return phpbb_extension_finder This object for chaining calls
+	*/
+	public function extension_prefix($extension_prefix)
+	{
+		$this->query['extension_prefix'] = $extension_prefix;
+		return $this;
+	}
+
+	/**
+	* Sets a prefix all files found in the core path must match
+	*
+	* @param string $core_prefix A filename prefix
+	* @return phpbb_extension_finder This object for chaining calls
+	*/
+	public function core_prefix($core_prefix)
+	{
+		$this->query['core_prefix'] = $core_prefix;
+		return $this;
+	}
+
+	/**
+	* Sets a directory all files found in extensions and core must be contained in
+	*
+	* Automatically sets the core_directory if its value does not differ from
+	* the current directory.
+	*
+	* @param string $directory
+	* @return phpbb_extension_finder This object for chaining calls
+	*/
+	public function directory($directory)
+	{
+		$this->core_directory($directory);
+		$this->extension_directory($directory);
+		return $this;
+	}
+
+	/**
+	* Sets a directory all files found in extensions must be contained in
+	*
+	* @param string $extension_directory
+	* @return phpbb_extension_finder This object for chaining calls
+	*/
+	public function extension_directory($extension_directory)
+	{
+		$this->query['extension_directory'] = $this->sanitise_directory($extension_directory);
+		return $this;
+	}
+
+	/**
+	* Sets a directory all files found in the core path must be contained in
+	*
+	* @param string $core_directory
+	* @return phpbb_extension_finder This object for chaining calls
+	*/
+	public function core_directory($core_directory)
+	{
+		$this->query['core_directory'] = $this->sanitise_directory($core_directory);
+		return $this;
+	}
+
+	/**
+	* Removes occurances of /./ and makes sure path ends without trailing slash
+	*
+	* @param string $directory A directory pattern
+	* @return string A cleaned up directory pattern
+	*/
+	protected function sanitise_directory($directory)
+	{
+		$directory = $this->filesystem->clean_path($directory);
+		$dir_len = strlen($directory);
+
+		if ($dir_len > 1 && $directory[$dir_len - 1] === '/')
+		{
+			$directory = substr($directory, 0, -1);
+		}
+
+		return $directory;
+	}
+
+	/**
+	* Finds classes matching the configured options if they follow phpBB naming rules.
+	*
+	* The php file extension is automatically added to suffixes.
+	*
+	* Note: If a file is matched but contains a class name not following the
+	* phpBB naming rules an incorrect class name will be returned.
+	*
+	* @param bool $cache Whether the result should be cached
+	* @param bool $use_all_available Use all available instead of just all
+	* 						enabled extensions
+	* @return array An array of found class names
+	*/
+	public function get_classes($cache = true, $use_all_available = false)
+	{
+		$this->query['extension_suffix'] .= '.' . $this->php_ext;
+		$this->query['core_suffix'] .= '.' . $this->php_ext;
+
+		$files = $this->find($cache, false, $use_all_available);
+
+		return $this->get_classes_from_files($files);
+	}
+
+	/**
+	* Get class names from a list of files
+	*
+	* @param array $files Array of files (from find())
+	* @return array Array of class names
+	*/
+	public function get_classes_from_files($files)
+	{
+		$classes = array();
+		foreach ($files as $file => $ext_name)
+		{
+			$file = preg_replace('#^(phpbb|includes)/#', '', $file);
+
+			$classes[] = 'phpbb_' . str_replace('/', '_', substr($file, 0, -strlen('.' . $this->php_ext)));
+		}
+		return $classes;
+	}
+
+	/**
+	* Finds all directories matching the configured options
+	*
+	* @param bool $cache Whether the result should be cached
+	* @param bool $use_all_available Use all available instead of just all
+	* 						enabled extensions
+	* @param bool $extension_keys Whether the result should have extension name as array key
+	* @return array An array of paths to found directories
+	*/
+	public function get_directories($cache = true, $use_all_available = false, $extension_keys = false)
+	{
+		return $this->find_with_root_path($cache, true, $use_all_available, $extension_keys);
+	}
+
+	/**
+	* Finds all files matching the configured options.
+	*
+	* @param bool $cache Whether the result should be cached
+	* @param bool $use_all_available Use all available instead of just all
+	* 						enabled extensions
+	* @return array An array of paths to found files
+	*/
+	public function get_files($cache = true, $use_all_available = false)
+	{
+		return $this->find_with_root_path($cache, false, $use_all_available);
+	}
+
+	/**
+	* A wrapper around the general find which prepends a root path to results
+	*
+	* @param bool $cache Whether the result should be cached
+	* @param bool $is_dir Directories will be returned when true, only files
+	*                     otherwise
+	* @param bool $use_all_available Use all available instead of just all
+	* 						enabled extensions
+	* @param bool $extension_keys If true, result will be associative array
+	*					with extension name as key
+	* @return array An array of paths to found items
+	*/
+	protected function find_with_root_path($cache = true, $is_dir = false, $use_all_available = false, $extension_keys = false)
+	{
+		$items = $this->find($cache, $is_dir, $use_all_available);
+
+		$result = array();
+		foreach ($items as $item => $ext_name)
+		{
+			if ($extension_keys)
+			{
+				$result[$ext_name] = $this->phpbb_root_path . $item;
+			}
+			else
+			{
+				$result[] = $this->phpbb_root_path . $item;
+			}
+		}
+
+		return $result;
+	}
+
+	/**
+	* Finds all file system entries matching the configured options
+	*
+	* @param bool $cache Whether the result should be cached
+	* @param bool $is_dir Directories will be returned when true, only files
+	*                     otherwise
+	* @param bool $use_all_available Use all available instead of just all
+	* 						enabled extensions
+	* @return array An array of paths to found items
+	*/
+	public function find($cache = true, $is_dir = false, $use_all_available = false)
+	{
+		if ($use_all_available)
+		{
+			$extensions = $this->extension_manager->all_available();
+		}
+		else
+		{
+			$extensions = $this->extension_manager->all_enabled();
+		}
+
+		if ($this->query['core_path'])
+		{
+			$extensions['/'] = $this->phpbb_root_path . $this->query['core_path'];
+		}
+
+		$files = array();
+		$file_list = $this->find_from_paths($extensions, $cache, $is_dir);
+
+		foreach ($file_list as $file)
+		{
+			$files[$file['named_path']] = $file['ext_name'];
+		}
+
+		return $files;
+	}
+
+	/**
+	* Finds all file system entries matching the configured options for one
+	* specific extension
+	*
+	* @param string $extension_name Name of the extension
+	* @param string $extension_path Relative path to the extension root directory
+	* @param bool $cache Whether the result should be cached
+	* @param bool $is_dir Directories will be returned when true, only files
+	*                     otherwise
+	* @return array An array of paths to found items
+	*/
+	public function find_from_extension($extension_name, $extension_path, $cache = true, $is_dir = false)
+	{
+		$extensions = array(
+			$extension_name => $extension_path,
+		);
+
+		$files = array();
+		$file_list = $this->find_from_paths($extensions, $cache, $is_dir);
+
+		foreach ($file_list as $file)
+		{
+			$files[$file['named_path']] = $file['ext_name'];
+		}
+
+		return $files;
+	}
+
+	/**
+	* Finds all file system entries matching the configured options from
+	* an array of paths
+	*
+	* @param array $extensions Array of extensions (name => full relative path)
+	* @param bool $cache Whether the result should be cached
+	* @param bool $is_dir Directories will be returned when true, only files
+	*                     otherwise
+	* @return array An array of paths to found items
+	*/
+	public function find_from_paths($extensions, $cache = true, $is_dir = false)
+	{
+		$this->query['is_dir'] = $is_dir;
+		$query = md5(serialize($this->query) . serialize($extensions));
+
+		if (!defined('DEBUG') && $cache && isset($this->cached_queries[$query]))
+		{
+			return $this->cached_queries[$query];
+		}
+
+		$files = array();
+
+		foreach ($extensions as $name => $path)
+		{
+			$ext_name = $name;
+
+			if (!file_exists($path))
+			{
+				continue;
+			}
+
+			if ($name === '/')
+			{
+				$location = $this->query['core_path'];
+				$name = '';
+				$suffix = $this->query['core_suffix'];
+				$prefix = $this->query['core_prefix'];
+				$directory = $this->query['core_directory'];
+			}
+			else
+			{
+				$location = 'ext/';
+				$name .= '/';
+				$suffix = $this->query['extension_suffix'];
+				$prefix = $this->query['extension_prefix'];
+				$directory = $this->query['extension_directory'];
+			}
+
+			// match only first directory if leading slash is given
+			if ($directory === '/')
+			{
+				$directory_pattern = '^' . preg_quote(DIRECTORY_SEPARATOR, '#');
+			}
+			else if ($directory && $directory[0] === '/')
+			{
+				$directory_pattern = '^' . preg_quote(str_replace('/', DIRECTORY_SEPARATOR, $directory) . DIRECTORY_SEPARATOR, '#');
+			}
+			else
+			{
+				$directory_pattern = preg_quote(DIRECTORY_SEPARATOR . str_replace('/', DIRECTORY_SEPARATOR, $directory) . DIRECTORY_SEPARATOR, '#');
+			}
+			if ($is_dir)
+			{
+				$directory_pattern .= '$';
+			}
+			$directory_pattern = '#' . $directory_pattern . '#';
+
+			$iterator = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($path), RecursiveIteratorIterator::SELF_FIRST);
+			foreach ($iterator as $file_info)
+			{
+				$filename = $file_info->getFilename();
+				if ($filename == '.' || $filename == '..')
+				{
+					continue;
+				}
+
+				if ($file_info->isDir() == $is_dir)
+				{
+					if ($is_dir)
+					{
+						$relative_path = $iterator->getInnerIterator()->getSubPath() . DIRECTORY_SEPARATOR . basename($filename) . DIRECTORY_SEPARATOR;
+						if ($relative_path[0] !== DIRECTORY_SEPARATOR)
+						{
+							$relative_path = DIRECTORY_SEPARATOR . $relative_path;
+						}
+					}
+					else
+					{
+						$relative_path = DIRECTORY_SEPARATOR . $iterator->getInnerIterator()->getSubPathname();
+					}
+
+					if ((!$suffix || substr($relative_path, -strlen($suffix)) === $suffix) &&
+						(!$prefix || substr($filename, 0, strlen($prefix)) === $prefix) &&
+						(!$directory || preg_match($directory_pattern, $relative_path)))
+					{
+						$files[] = array(
+							'named_path'	=> str_replace(DIRECTORY_SEPARATOR, '/', $location . $name . substr($relative_path, 1)),
+							'ext_name'		=> $ext_name,
+							'path'			=> str_replace(array(DIRECTORY_SEPARATOR, $this->phpbb_root_path), array('/', ''), $file_info->getPath()) . '/',
+							'filename'		=> $filename,
+						);
+					}
+				}
+			}
+		}
+
+		if ($cache && $this->cache)
+		{
+			$this->cached_queries[$query] = $files;
+			$this->cache->put($this->cache_name, $this->cached_queries);
+		}
+
+		return $files;
+	}
+}
diff --git a/phpBB/phpbb/extension/interface.php b/phpBB/phpbb/extension/interface.php
new file mode 100644
index 0000000000..7b36a12bf6
--- /dev/null
+++ b/phpBB/phpbb/extension/interface.php
@@ -0,0 +1,67 @@
+<?php
+/**
+*
+* @package extension
+* @copyright (c) 2011 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* The interface extension meta classes have to implement to run custom code
+* on enable/disable/purge.
+*
+* @package extension
+*/
+interface phpbb_extension_interface
+{
+	/**
+	* enable_step is executed on enabling an extension until it returns false.
+	*
+	* Calls to this function can be made in subsequent requests, when the
+	* function is invoked through a webserver with a too low max_execution_time.
+	*
+	* @param	mixed	$old_state	The return value of the previous call
+	*								of this method, or false on the first call
+	* @return	mixed				Returns false after last step, otherwise
+	*								temporary state which is passed as an
+	*								argument to the next step
+	*/
+	public function enable_step($old_state);
+
+	/**
+	* Disables the extension.
+	*
+	* Calls to this function can be made in subsequent requests, when the
+	* function is invoked through a webserver with a too low max_execution_time.
+	*
+	* @param	mixed	$old_state	The return value of the previous call
+	*								of this method, or false on the first call
+	* @return	mixed				Returns false after last step, otherwise
+	*								temporary state which is passed as an
+	*								argument to the next step
+	*/
+	public function disable_step($old_state);
+
+	/**
+	* purge_step is executed on purging an extension until it returns false.
+	*
+	* Calls to this function can be made in subsequent requests, when the
+	* function is invoked through a webserver with a too low max_execution_time.
+	*
+	* @param	mixed	$old_state	The return value of the previous call
+	*								of this method, or false on the first call
+	* @return	mixed				Returns false after last step, otherwise
+	*								temporary state which is passed as an
+	*								argument to the next step
+	*/
+	public function purge_step($old_state);
+}
diff --git a/phpBB/phpbb/extension/manager.php b/phpBB/phpbb/extension/manager.php
new file mode 100644
index 0000000000..4451049d04
--- /dev/null
+++ b/phpBB/phpbb/extension/manager.php
@@ -0,0 +1,513 @@
+<?php
+/**
+*
+* @package extension
+* @copyright (c) 2011 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+* The extension manager provides means to activate/deactivate extensions.
+*
+* @package extension
+*/
+class phpbb_extension_manager
+{
+	/** @var ContainerInterface */
+	protected $container;
+
+	protected $db;
+	protected $config;
+	protected $cache;
+	protected $php_ext;
+	protected $extensions;
+	protected $extension_table;
+	protected $phpbb_root_path;
+	protected $cache_name;
+
+	/**
+	* Creates a manager and loads information from database
+	*
+	* @param ContainerInterface $container A container
+	* @param phpbb_db_driver $db A database connection
+	* @param phpbb_config $config phpbb_config
+	* @param phpbb_filesystem $filesystem
+	* @param string $extension_table The name of the table holding extensions
+	* @param string $phpbb_root_path Path to the phpbb includes directory.
+	* @param string $php_ext php file extension
+	* @param phpbb_cache_driver_interface $cache A cache instance or null
+	* @param string $cache_name The name of the cache variable, defaults to _ext
+	*/
+	public function __construct(ContainerInterface $container, phpbb_db_driver $db, phpbb_config $config, phpbb_filesystem $filesystem, $extension_table, $phpbb_root_path, $php_ext = 'php', phpbb_cache_driver_interface $cache = null, $cache_name = '_ext')
+	{
+		$this->container = $container;
+		$this->phpbb_root_path = $phpbb_root_path;
+		$this->db = $db;
+		$this->config = $config;
+		$this->cache = $cache;
+		$this->filesystem = $filesystem;
+		$this->php_ext = $php_ext;
+		$this->extension_table = $extension_table;
+		$this->cache_name = $cache_name;
+
+		$this->extensions = ($this->cache) ? $this->cache->get($this->cache_name) : false;
+
+		if ($this->extensions === false)
+		{
+			$this->load_extensions();
+		}
+	}
+
+	/**
+	* Loads all extension information from the database
+	*
+	* @return null
+	*/
+	public function load_extensions()
+	{
+		$this->extensions = array();
+
+		// Do not try to load any extensions when installing or updating
+		// Note: database updater invokes this code, and in 3.0
+		// there is no extension table therefore the rest of this function
+		// fails
+		if (defined('IN_INSTALL'))
+		{
+			return;
+		}
+
+		$sql = 'SELECT *
+			FROM ' . $this->extension_table;
+
+		$result = $this->db->sql_query($sql);
+		$extensions = $this->db->sql_fetchrowset($result);
+		$this->db->sql_freeresult($result);
+
+		foreach ($extensions as $extension)
+		{
+			$extension['ext_path'] = $this->get_extension_path($extension['ext_name']);
+			$this->extensions[$extension['ext_name']] = $extension;
+		}
+
+		ksort($this->extensions);
+
+		if ($this->cache)
+		{
+			$this->cache->put($this->cache_name, $this->extensions);
+		}
+	}
+
+	/**
+	* Generates the path to an extension
+	*
+	* @param string $name The name of the extension
+	* @param bool $phpbb_relative Whether the path should be relative to phpbb root
+	* @return string Path to an extension
+	*/
+	public function get_extension_path($name, $phpbb_relative = false)
+	{
+		$name = str_replace('.', '', $name);
+
+		return (($phpbb_relative) ? $this->phpbb_root_path : '') . 'ext/' . $name . '/';
+	}
+
+	/**
+	* Instantiates the extension meta class for the extension with the given name
+	*
+	* @param string $name The extension name
+	* @return phpbb_extension_interface Instance of the extension meta class or
+	*                     phpbb_extension_base if the class does not exist
+	*/
+	public function get_extension($name)
+	{
+		$extension_class_name = 'phpbb_ext_' . str_replace('/', '_', $name) . '_ext';
+
+		$migrator = $this->container->get('migrator');
+
+		if (class_exists($extension_class_name))
+		{
+			return new $extension_class_name($this->container, $this->get_finder(), $migrator, $name, $this->get_extension_path($name, true));
+		}
+		else
+		{
+			return new phpbb_extension_base($this->container, $this->get_finder(), $migrator, $name, $this->get_extension_path($name, true));
+		}
+	}
+
+	/**
+	* Instantiates the metadata manager for the extension with the given name
+	*
+	* @param string $name The extension name
+	* @param string $template The template manager
+	* @return phpbb_extension_metadata_manager Instance of the metadata manager
+	*/
+	public function create_extension_metadata_manager($name, phpbb_template $template)
+	{
+		return new phpbb_extension_metadata_manager($name, $this->config, $this, $template, $this->phpbb_root_path);
+	}
+
+	/**
+	* Runs a step of the extension enabling process.
+	*
+	* Allows the exentension to enable in a long running script that works
+	* in multiple steps across requests. State is kept for the extension
+	* in the extensions table.
+	*
+	* @param	string	$name	The extension's name
+	* @return	bool			False if enabling is finished, true otherwise
+	*/
+	public function enable_step($name)
+	{
+		// ignore extensions that are already enabled
+		if (isset($this->extensions[$name]) && $this->extensions[$name]['ext_active'])
+		{
+			return false;
+		}
+
+		$old_state = (isset($this->extensions[$name]['ext_state'])) ? unserialize($this->extensions[$name]['ext_state']) : false;
+
+		$extension = $this->get_extension($name);
+		$state = $extension->enable_step($old_state);
+
+		$active = ($state === false);
+
+		$extension_data = array(
+			'ext_name'		=> $name,
+			'ext_active'	=> $active,
+			'ext_state'		=> serialize($state),
+		);
+
+		$this->extensions[$name] = $extension_data;
+		$this->extensions[$name]['ext_path'] = $this->get_extension_path($extension_data['ext_name']);
+		ksort($this->extensions);
+
+		$sql = 'SELECT COUNT(ext_name) as row_count
+			FROM ' . $this->extension_table . "
+			WHERE ext_name = '" . $this->db->sql_escape($name) . "'";
+		$result = $this->db->sql_query($sql);
+		$count = $this->db->sql_fetchfield('row_count');
+		$this->db->sql_freeresult($result);
+
+		if ($count)
+		{
+			$sql = 'UPDATE ' . $this->extension_table . '
+				SET ' . $this->db->sql_build_array('UPDATE', $extension_data) . "
+				WHERE ext_name = '" . $this->db->sql_escape($name) . "'";
+			$this->db->sql_query($sql);
+		}
+		else
+		{
+			$sql = 'INSERT INTO ' . $this->extension_table . '
+				' . $this->db->sql_build_array('INSERT', $extension_data);
+			$this->db->sql_query($sql);
+		}
+
+		if ($this->cache)
+		{
+			$this->cache->purge();
+		}
+
+		return !$active;
+	}
+
+	/**
+	* Enables an extension
+	*
+	* This method completely enables an extension. But it could be long running
+	* so never call this in a script that has a max_execution time.
+	*
+	* @param string $name The extension's name
+	* @return null
+	*/
+	public function enable($name)
+	{
+		while ($this->enable_step($name));
+	}
+
+	/**
+	* Disables an extension
+	*
+	* Calls the disable method on the extension's meta class to allow it to
+	* process the event.
+	*
+	* @param string $name The extension's name
+	* @return bool False if disabling is finished, true otherwise
+	*/
+	public function disable_step($name)
+	{
+		// ignore extensions that are already disabled
+		if (!isset($this->extensions[$name]) || !$this->extensions[$name]['ext_active'])
+		{
+			return false;
+		}
+
+		$old_state = unserialize($this->extensions[$name]['ext_state']);
+
+		$extension = $this->get_extension($name);
+		$state = $extension->disable_step($old_state);
+
+		// continue until the state is false
+		if ($state !== false)
+		{
+			$extension_data = array(
+				'ext_state'		=> serialize($state),
+			);
+			$this->extensions[$name]['ext_state'] = serialize($state);
+
+			$sql = 'UPDATE ' . $this->extension_table . '
+				SET ' . $this->db->sql_build_array('UPDATE', $extension_data) . "
+				WHERE ext_name = '" . $this->db->sql_escape($name) . "'";
+			$this->db->sql_query($sql);
+
+			if ($this->cache)
+			{
+				$this->cache->purge();
+			}
+
+			return true;
+		}
+
+		$extension_data = array(
+			'ext_active'	=> false,
+			'ext_state'		=> serialize(false),
+		);
+		$this->extensions[$name]['ext_active'] = false;
+		$this->extensions[$name]['ext_state'] = serialize(false);
+
+		$sql = 'UPDATE ' . $this->extension_table . '
+			SET ' . $this->db->sql_build_array('UPDATE', $extension_data) . "
+			WHERE ext_name = '" . $this->db->sql_escape($name) . "'";
+		$this->db->sql_query($sql);
+
+		if ($this->cache)
+		{
+			$this->cache->purge();
+		}
+
+		return false;
+	}
+
+	/**
+	* Disables an extension
+	*
+	* Disables an extension completely at once. This process could run for a
+	* while so never call this in a script that has a max_execution time.
+	*
+	* @param string $name The extension's name
+	* @return null
+	*/
+	public function disable($name)
+	{
+		while ($this->disable_step($name));
+	}
+
+	/**
+	* Purge an extension
+	*
+	* Disables the extension first if active, and then calls purge on the
+	* extension's meta class to delete the extension's database content.
+	*
+	* @param string $name The extension's name
+	* @return bool False if purging is finished, true otherwise
+	*/
+	public function purge_step($name)
+	{
+		// ignore extensions that do not exist
+		if (!isset($this->extensions[$name]))
+		{
+			return false;
+		}
+
+		// disable first if necessary
+		if ($this->extensions[$name]['ext_active'])
+		{
+			$this->disable($name);
+		}
+
+		$old_state = unserialize($this->extensions[$name]['ext_state']);
+
+		$extension = $this->get_extension($name);
+		$state = $extension->purge_step($old_state);
+
+		// continue until the state is false
+		if ($state !== false)
+		{
+			$extension_data = array(
+				'ext_state'		=> serialize($state),
+			);
+			$this->extensions[$name]['ext_state'] = serialize($state);
+
+			$sql = 'UPDATE ' . $this->extension_table . '
+				SET ' . $this->db->sql_build_array('UPDATE', $extension_data) . "
+				WHERE ext_name = '" . $this->db->sql_escape($name) . "'";
+			$this->db->sql_query($sql);
+
+			if ($this->cache)
+			{
+				$this->cache->purge();
+			}
+
+			return true;
+		}
+
+		unset($this->extensions[$name]);
+
+		$sql = 'DELETE FROM ' . $this->extension_table . "
+			WHERE ext_name = '" . $this->db->sql_escape($name) . "'";
+		$this->db->sql_query($sql);
+
+		if ($this->cache)
+		{
+			$this->cache->purge();
+		}
+
+		return false;
+	}
+
+	/**
+	* Purge an extension
+	*
+	* Purges an extension completely at once. This process could run for a while
+	* so never call this in a script that has a max_execution time.
+	*
+	* @param string $name The extension's name
+	* @return null
+	*/
+	public function purge($name)
+	{
+		while ($this->purge_step($name));
+	}
+
+	/**
+	* Retrieves a list of all available extensions on the filesystem
+	*
+	* @return array An array with extension names as keys and paths to the
+	*               extension as values
+	*/
+	public function all_available()
+	{
+		$available = array();
+		if (!is_dir($this->phpbb_root_path . 'ext/'))
+		{
+			return $available;
+		}
+
+		$iterator = new RecursiveIteratorIterator(
+			new RecursiveDirectoryIterator($this->phpbb_root_path . 'ext/', FilesystemIterator::NEW_CURRENT_AND_KEY | FilesystemIterator::FOLLOW_SYMLINKS),
+			RecursiveIteratorIterator::SELF_FIRST);
+		foreach ($iterator as $file_info)
+		{
+			if ($file_info->isFile() && $file_info->getFilename() == 'ext.' . $this->php_ext)
+			{
+				$ext_name = $iterator->getInnerIterator()->getSubPath();
+
+				$ext_name = str_replace(DIRECTORY_SEPARATOR, '/', $ext_name);
+
+				$available[$ext_name] = $this->phpbb_root_path . 'ext/' . $ext_name . '/';
+			}
+		}
+		ksort($available);
+		return $available;
+	}
+
+	/**
+	* Retrieves all configured extensions.
+	*
+	* All enabled and disabled extensions are considered configured. A purged
+	* extension that is no longer in the database is not configured.
+	*
+	* @return array An array with extension names as keys and and the
+	*               database stored extension information as values
+	*/
+	public function all_configured()
+	{
+		$configured = array();
+		foreach ($this->extensions as $name => $data)
+		{
+			$data['ext_path'] = $this->phpbb_root_path . $data['ext_path'];
+			$configured[$name] = $data;
+		}
+		return $configured;
+	}
+
+	/**
+	* Retrieves all enabled extensions.
+	*
+	* @return array An array with extension names as keys and and the
+	*               database stored extension information as values
+	*/
+	public function all_enabled()
+	{
+		$enabled = array();
+		foreach ($this->extensions as $name => $data)
+		{
+			if ($data['ext_active'])
+			{
+				$enabled[$name] = $this->phpbb_root_path . $data['ext_path'];
+			}
+		}
+		return $enabled;
+	}
+
+	/**
+	* Retrieves all disabled extensions.
+	*
+	* @return array An array with extension names as keys and and the
+	*               database stored extension information as values
+	*/
+	public function all_disabled()
+	{
+		$disabled = array();
+		foreach ($this->extensions as $name => $data)
+		{
+			if (!$data['ext_active'])
+			{
+				$disabled[$name] = $this->phpbb_root_path . $data['ext_path'];
+			}
+		}
+		return $disabled;
+	}
+
+	/**
+	* Check to see if a given extension is available on the filesystem
+	*
+	* @param string $name Extension name to check NOTE: Can be user input
+	* @return bool Depending on whether or not the extension is available
+	*/
+	public function available($name)
+	{
+		return file_exists($this->get_extension_path($name, true));
+	}
+
+	/**
+	* Check to see if a given extension is enabled
+	*
+	* @param string $name Extension name to check
+	* @return bool Depending on whether or not the extension is enabled
+	*/
+	public function enabled($name)
+	{
+		return isset($this->extensions[$name]) && $this->extensions[$name]['ext_active'];
+	}
+
+	/**
+	* Instantiates a phpbb_extension_finder.
+	*
+	* @return phpbb_extension_finder An extension finder instance
+	*/
+	public function get_finder()
+	{
+		return new phpbb_extension_finder($this, $this->filesystem, $this->phpbb_root_path, $this->cache, $this->php_ext, $this->cache_name . '_finder');
+	}
+}
diff --git a/phpBB/phpbb/extension/metadata_manager.php b/phpBB/phpbb/extension/metadata_manager.php
new file mode 100644
index 0000000000..14b77c085b
--- /dev/null
+++ b/phpBB/phpbb/extension/metadata_manager.php
@@ -0,0 +1,371 @@
+<?php
+/**
+*
+* @package extension
+* @copyright (c) 2012 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* The extension metadata manager validates and gets meta-data for extensions
+*
+* @package extension
+*/
+class phpbb_extension_metadata_manager
+{
+	/**
+	* phpBB Config instance
+	* @var phpbb_config
+	*/
+	protected $config;
+
+	/**
+	* phpBB Extension Manager
+	* @var phpbb_extension_manager
+	*/
+	protected $extension_manager;
+
+	/**
+	* phpBB Template instance
+	* @var phpbb_template
+	*/
+	protected $template;
+
+	/**
+	* phpBB root path
+	* @var string
+	*/
+	protected $phpbb_root_path;
+
+	/**
+	* Name (including vendor) of the extension
+	* @var string
+	*/
+	protected $ext_name;
+
+	/**
+	* Metadata from the composer.json file
+	* @var array
+	*/
+	protected $metadata;
+
+	/**
+	* Link (including root path) to the metadata file
+	* @var string
+	*/
+	protected $metadata_file;
+
+	/**
+	* Creates the metadata manager
+	*
+	* @param string				$ext_name			Name (including vendor) of the extension
+	* @param phpbb_config		$config				phpBB Config instance
+	* @param phpbb_extension_manager	$extension_manager An instance of the phpBBb extension manager
+	* @param phpbb_template		$template			phpBB Template instance
+	* @param string				$phpbb_root_path	Path to the phpbb includes directory.
+	*/
+	public function __construct($ext_name, phpbb_config $config, phpbb_extension_manager $extension_manager, phpbb_template $template, $phpbb_root_path)
+	{
+		$this->config = $config;
+		$this->extension_manager = $extension_manager;
+		$this->template = $template;
+		$this->phpbb_root_path = $phpbb_root_path;
+
+		$this->ext_name = $ext_name;
+		$this->metadata = array();
+		$this->metadata_file = '';
+	}
+
+	/**
+	 * Processes and gets the metadata requested
+	 *
+	 * @param  string $element			All for all metadata that it has and is valid, otherwise specify which section you want by its shorthand term.
+	 * @return array					Contains all of the requested metadata, throws an exception on failure
+	 */
+	public function get_metadata($element = 'all')
+	{
+		$this->set_metadata_file();
+
+		// Fetch the metadata
+		$this->fetch_metadata();
+
+		// Clean the metadata
+		$this->clean_metadata_array();
+
+		switch ($element)
+		{
+			case 'all':
+			default:
+				// Validate the metadata
+				if (!$this->validate())
+				{
+					return false;
+				}
+
+				return $this->metadata;
+			break;
+
+			case 'name':
+				return ($this->validate('name')) ? $this->metadata['name'] : false;
+			break;
+
+			case 'display-name':
+				if (isset($this->metadata['extra']['display-name']))
+				{
+					return $this->metadata['extra']['display-name'];
+				}
+				else
+				{
+					return ($this->validate('name')) ? $this->metadata['name'] : false;
+				}
+			break;
+		}
+	}
+
+	/**
+	 * Sets the filepath of the metadata file
+	 *
+	 * @return boolean  Set to true if it exists, throws an exception on failure
+	 */
+	private function set_metadata_file()
+	{
+		$ext_filepath = $this->extension_manager->get_extension_path($this->ext_name);
+		$metadata_filepath = $this->phpbb_root_path . $ext_filepath . 'composer.json';
+
+		$this->metadata_file = $metadata_filepath;
+
+		if (!file_exists($this->metadata_file))
+		{
+    		throw new phpbb_extension_exception('The required file does not exist: ' . $this->metadata_file);
+		}
+	}
+
+	/**
+	 * Gets the contents of the composer.json file
+	 *
+	 * @return bool True if success, throws an exception on failure
+	 */
+	private function fetch_metadata()
+	{
+		if (!file_exists($this->metadata_file))
+		{
+			throw new phpbb_extension_exception('The required file does not exist: ' . $this->metadata_file);
+		}
+		else
+		{
+			if (!($file_contents = file_get_contents($this->metadata_file)))
+			{
+    			throw new phpbb_extension_exception('file_get_contents failed on ' . $this->metadata_file);
+			}
+
+			if (($metadata = json_decode($file_contents, true)) === NULL)
+			{
+    			throw new phpbb_extension_exception('json_decode failed on ' . $this->metadata_file);
+			}
+
+			$this->metadata = $metadata;
+
+			return true;
+		}
+	}
+
+	/**
+	 * This array handles the cleaning of the array
+	 *
+	 * @return array Contains the cleaned metadata array
+	 */
+	private function clean_metadata_array()
+	{
+		return $this->metadata;
+	}
+
+	/**
+	* Validate fields
+	*
+	* @param string $name  ("all" for display and enable validation
+	* 						"display" for name, type, and authors
+	* 						"name", "type")
+	* @return Bool True if valid, throws an exception if invalid
+	*/
+	public function validate($name = 'display')
+    {
+    	// Basic fields
+    	$fields = array(
+    		'name'		=> '#^[a-zA-Z0-9_\x7f-\xff]{2,}/[a-zA-Z0-9_\x7f-\xff]{2,}$#',
+    		'type'		=> '#^phpbb3-extension$#',
+    		'licence'	=> '#.+#',
+    		'version'	=> '#.+#',
+    	);
+
+    	switch ($name)
+    	{
+    		case 'all':
+    			$this->validate('display');
+
+				$this->validate_enable();
+    		break;
+
+    		case 'display':
+    			foreach ($fields as $field => $data)
+				{
+					$this->validate($field);
+				}
+
+				$this->validate_authors();
+    		break;
+
+    		default:
+    			if (isset($fields[$name]))
+    			{
+    				if (!isset($this->metadata[$name]))
+    				{
+    					throw new phpbb_extension_exception("Required meta field '$name' has not been set.");
+					}
+
+					if (!preg_match($fields[$name], $this->metadata[$name]))
+					{
+    					throw new phpbb_extension_exception("Meta field '$name' is invalid.");
+					}
+				}
+			break;
+		}
+
+		return true;
+    }
+
+	/**
+	 * Validates the contents of the authors field
+	 *
+	 * @return boolean True when passes validation, throws exception if invalid
+	 */
+	public function validate_authors()
+	{
+		if (empty($this->metadata['authors']))
+		{
+    		throw new phpbb_extension_exception("Required meta field 'authors' has not been set.");
+		}
+
+		foreach ($this->metadata['authors'] as $author)
+		{
+			if (!isset($author['name']))
+			{
+    			throw new phpbb_extension_exception("Required meta field 'author name' has not been set.");
+			}
+		}
+
+		return true;
+	}
+
+	/**
+	 * This array handles the verification that this extension can be enabled on this board
+	 *
+	 * @return bool True if validation succeeded, False if failed
+	 */
+	public function validate_enable()
+	{
+		// Check for phpBB, PHP versions
+		if (!$this->validate_require_phpbb() || !$this->validate_require_php())
+		{
+			return false;
+		}
+
+		return true;
+	}
+
+
+	/**
+	 * Validates the contents of the phpbb requirement field
+	 *
+	 * @return boolean True when passes validation
+	 */
+	public function validate_require_phpbb()
+	{
+		if (!isset($this->metadata['require']['phpbb']))
+		{
+			return true;
+		}
+
+		return $this->_validate_version($this->metadata['require']['phpbb'], $this->config['version']);
+	}
+
+	/**
+	 * Validates the contents of the php requirement field
+	 *
+	 * @return boolean True when passes validation
+	 */
+	public function validate_require_php()
+	{
+		if (!isset($this->metadata['require']['php']))
+		{
+			return true;
+		}
+
+		return $this->_validate_version($this->metadata['require']['php'], phpversion());
+	}
+
+	/**
+	* Version validation helper
+	*
+	* @param string $string The string for comparing to a version
+	* @param string $current_version The version to compare to
+	* @return bool True/False if meets version requirements
+	*/
+	private function _validate_version($string, $current_version)
+	{
+		// Allow them to specify their own comparison operator (ex: <3.1.2, >=3.1.0)
+		$comparison_matches = false;
+		preg_match('#[=<>]+#', $string, $comparison_matches);
+
+		if (!empty($comparison_matches))
+		{
+			return version_compare($current_version, str_replace(array($comparison_matches[0], ' '), '', $string), $comparison_matches[0]);
+		}
+
+		return version_compare($current_version, $string, '>=');
+	}
+
+	/**
+	 * Outputs the metadata into the template
+	 *
+	 * @return null
+	 */
+	public function output_template_data()
+	{
+		$this->template->assign_vars(array(
+			'META_NAME'			=> htmlspecialchars($this->metadata['name']),
+			'META_TYPE'			=> htmlspecialchars($this->metadata['type']),
+			'META_DESCRIPTION'	=> (isset($this->metadata['description'])) ? htmlspecialchars($this->metadata['description']) : '',
+			'META_HOMEPAGE'		=> (isset($this->metadata['homepage'])) ? $this->metadata['homepage'] : '',
+			'META_VERSION'		=> (isset($this->metadata['version'])) ? htmlspecialchars($this->metadata['version']) : '',
+			'META_TIME'			=> (isset($this->metadata['time'])) ? htmlspecialchars($this->metadata['time']) : '',
+			'META_LICENCE'		=> htmlspecialchars($this->metadata['licence']),
+
+			'META_REQUIRE_PHP'		=> (isset($this->metadata['require']['php'])) ? htmlspecialchars($this->metadata['require']['php']) : '',
+			'META_REQUIRE_PHP_FAIL'	=> !$this->validate_require_php(),
+
+			'META_REQUIRE_PHPBB'		=> (isset($this->metadata['require']['phpbb'])) ? htmlspecialchars($this->metadata['require']['phpbb']) : '',
+			'META_REQUIRE_PHPBB_FAIL'	=> !$this->validate_require_phpbb(),
+
+			'META_DISPLAY_NAME'	=> (isset($this->metadata['extra']['display-name'])) ? htmlspecialchars($this->metadata['extra']['display-name']) : '',
+		));
+
+		foreach ($this->metadata['authors'] as $author)
+		{
+			$this->template->assign_block_vars('meta_authors', array(
+				'AUTHOR_NAME'		=> htmlspecialchars($author['name']),
+				'AUTHOR_EMAIL'		=> (isset($author['email'])) ? $author['email'] : '',
+				'AUTHOR_HOMEPAGE'	=> (isset($author['homepage'])) ? $author['homepage'] : '',
+				'AUTHOR_ROLE'		=> (isset($author['role'])) ? htmlspecialchars($author['role']) : '',
+			));
+		}
+	}
+}
diff --git a/phpBB/phpbb/extension/provider.php b/phpBB/phpbb/extension/provider.php
new file mode 100644
index 0000000000..45b55e5cab
--- /dev/null
+++ b/phpBB/phpbb/extension/provider.php
@@ -0,0 +1,76 @@
+<?php
+/**
+*
+* @package extension
+* @copyright (c) 2011 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* Provides a set of items found in extensions.
+*
+* This abstract class is essentially a wrapper around item-specific
+* finding logic. It handles storing the extension manager via constructor
+* for the finding logic to use to find the items, and provides an
+* iterator interface over the items found by the finding logic.
+*
+* Items could be anything, for example template paths or cron task names.
+* Derived classes completely define what the items are.
+*
+* @package extension
+*/
+abstract class phpbb_extension_provider implements IteratorAggregate
+{
+	/**
+	* Array holding all found items
+	* @var array|null
+	*/
+	protected $items = null;
+
+	/**
+	* An extension manager to search for items in extensions
+	* @var phpbb_extension_manager
+	*/
+	protected $extension_manager;
+
+	/**
+	* Constructor. Loads all available items.
+	*
+	* @param phpbb_extension_manager $extension_manager phpBB extension manager
+	*/
+	public function __construct(phpbb_extension_manager $extension_manager)
+	{
+		$this->extension_manager = $extension_manager;
+	}
+
+	/**
+	* Finds items using the extension manager.
+	*
+	* @return array     List of task names
+	*/
+	abstract protected function find();
+
+	/**
+	* Retrieve an iterator over all items
+	*
+	* @return ArrayIterator An iterator for the array of template paths
+	*/
+	public function getIterator()
+	{
+		if ($this->items === null)
+		{
+			$this->items = $this->find();
+		}
+
+		return new ArrayIterator($this->items);
+	}
+}