lithium\action\Dispatcher

class

Dispatcher is the outermost layer of the framework, responsible for both receiving the initial HTTP request and sending back a response at the end of the request's life cycle.

After either receiving or instantiating a Request object instance, the Dispatcher passes that instance to the Router, which produces the parameters necessary to dispatch the request (unless no route matches, in which case an exception is thrown).

Using these parameters, the Dispatcher loads and instantiates the correct Controller object, and passes it the Request object instance. The Controller returns a Response object to the Dispatcher, where the headers and content are rendered and sent to the browser.

Source

class Dispatcher extends \lithium\core\StaticObjectDeprecated {

	/**
	 * Fully-namespaced router class reference.  Class must implement a `parse()` method,
	 * which must return an array with (at a minimum) 'controller' and 'action' keys.
	 *
	 * @see lithium\net\http\Router::parse()
	 * @var array
	 */
	protected static $_classes = [
		'router' => 'lithium\net\http\Router'
	];

	/**
	 * Contains pre-process format strings for changing Dispatcher's behavior based on `'rules'`.
	 *
	 * Each key in the array represents a 'rule'; if a key that matches the rule is present
	 * (and not empty) in a route, (i.e. the result of `Router::parse()`) then the rule's
	 * value will be applied to the route before it is dispatched. When applying a rule, any
	 * array elements of the flag which are present in the route will be modified using a
	 * `Text::insert()`-formatted string. Alternatively, a callback can be used to do custom
	 * transformations other than the default `Text::insert()`.
	 *
	 * For example, to implement action prefixes (i.e. `admin_index`), set a rule named
	 * `'admin'`, with a value array containing a modifier key for the `action` element of
	 * a route, i.e.: `array('action' => 'admin_{:action}')`. Now, if the `'admin'` key is
	 * present and not empty in the parameters returned from routing, the value of `'action'`
	 * will be rewritten per the settings in the rule:
	 * ```
	 * Dispatcher::config([
	 *	'rules' => [
	 *		'admin' => 'admin_{:action}'
	 *	]
	 * ]);
	 * ```
	 *
	 * The following example shows two rules that continuously or independently transform the
	 * action parameter in order to allow any variations i.e. `'admin_index'`, `'api_index'`
	 * and `'admin_api_index'`.
	 * ```
	 * // ...
	 *		'api' => 'api_{:action}',
	 *		'admin' => 'admin_{:action}'
	 * // ...
	 * ```
	 *
	 * Here's another example. To support normalizing actions, set a rule named `'action'` with
	 * a value array containing a callback that uses `Inflector` to camelize the
	 * action:
	 * ```
	 * // ...
	 *		'action' => ['action' => function($params) {
	 *			return Inflector::camelize(strtolower($params['action']), false);
	 *		}]
	 * // ...
	 * ```
	 *
	 * The entires rules can become a callback as well:
	 * ```
	 * Dispatcher::config([
	 *	'rules' => function($params) {
	 *		// ...
	 *	}
	 * ]);
	 * ```
	 *
	 * @see lithium\action\Dispatcher::config()
	 * @see lithium\util\Text::insert()
	 * @see lithium\util\Inflector
	 * @var array
	 */
	protected static $_rules = [];

	/**
	 * Used to set configuration parameters for the `Dispatcher`.
	 *
	 * @see lithium\action\Dispatcher::$_rules
	 * @param array $config Possible key settings are `'classes'` which sets the class dependencies
	 *              for `Dispatcher` (i.e. `'request'` or `'router'`) and `'rules'`, which sets the
	 *              pre-processing rules for routing parameters. For more information on the
	 *              `'rules'` setting, see the `$_rules` property.
	 * @return array If no parameters are passed, returns an associative array with the current
	 *         configuration, otherwise returns `null`.
	 */
	public static function config(array $config = []) {
		if (!$config) {
			return ['rules' => static::$_rules];
		}

		foreach ($config as $key => $val) {
			$key = "_{$key}";
			if (!is_array($val)) {
				static::${$key} = $val;
				continue;
			}
			if (isset(static::${$key})) {
				static::${$key} = $val + static::${$key};
			}
		}
	}

	/**
	 * Dispatches a request based on a request object (an instance or subclass of
	 * `lithium\net\http\Request`).
	 *
	 * @see lithium\action\Request
	 * @see lithium\action\Response
	 * @param object $request An instance of a request object (usually `lithium\action\Request`)
	 *               with HTTP request information.
	 * @param array $options
	 * @return mixed Returns the value returned from the callable object retrieved from
	 *         `Dispatcher::_callable()`, which is either a string or an instance of
	 *         `lithium\action\Response`.
	 * @filter Allows to perform actions very early or late in the request.
	 */
	public static function run($request, array $options = []) {
		$params = compact('request', 'options');

		return Filters::run(get_called_class(), __FUNCTION__, $params, function($params) {
			$router = static::$_classes['router'];

			$request = $params['request'];
			$options = $params['options'];

			if (($result = $router::process($request)) instanceof Response) {
				return $result;
			}
			$params = static::applyRules($result->params);

			if (!$params) {
				throw new DispatchException('Could not route request.');
			}
			$callable = static::_callable($result, $params, $options);
			return static::_call($callable, $result, $params);
		});
	}

	/**
	 * Attempts to apply a set of formatting rules from `$_rules` to a `$params` array, where each
	 * formatting rule is applied if the key of the rule in `$_rules` is present and not empty in
	 * `$params`.  Also performs sanity checking against `$params` to ensure that no value
	 * matching a rule is present unless the rule check passes.
	 *
	 * @param array $params An array of route parameters to which rules will be applied.
	 * @return array Returns the `$params` array with formatting rules applied to array values.
	 */
	public static function applyRules(&$params) {
		$values = [];
		$rules = static::$_rules;

		if (!$params) {
			return false;
		}

		if (isset($params['controller']) && is_string($params['controller'])) {
			$controller = $params['controller'];

			if (strpos($controller, '.') !== false) {
				list($library, $controller) = explode('.', $controller);
				$controller = $library . '.' . Inflector::camelize($controller);
				$params += compact('library');
			} elseif (strpos($controller, '\\') === false) {
				$controller = Inflector::camelize($controller);

				if (isset($params['library'])) {
					$controller = "{$params['library']}.{$controller}";
				}
			}
			$values = compact('controller');
		}
		$values += $params;

		if (is_callable($rules)) {
			$rules = $rules($params);
		}
		foreach ($rules as $rule => $value) {
			if (!isset($values[$rule])) {
				continue;
			}
			foreach ($value as $k => $v) {
				if (is_callable($v)) {
					$values[$k] = $v($values);
					continue;
				}
				$match = preg_replace('/\{:\w+\}/', '@', $v);
				$match = preg_replace('/@/', '.+', preg_quote($match, '/'));

				if (preg_match('/' . $match . '/i', $values[$k])) {
					continue;
				}
				$values[$k] = Text::insert($v, $values);
			}
		}
		return $values;
	}

	/**
	 * Accepts parameters generated by the `Router` class in `Dispatcher::run()`, and produces a
	 * callable controller object. By default, this method uses the `'controller'` path lookup
	 * configuration in `Libraries::locate()` to return a callable object.
	 *
	 * @param object $request The instance of the `Request` class either passed into or generated by
	 *               `Dispatcher::run()`.
	 * @param array $params The parameter array generated by routing the request.
	 * @param array $options Not currently implemented.
	 * @return object Returns a callable object which the request will be routed to.
	 * @filter
	 */
	protected static function _callable($request, $params, $options) {
		$params = compact('request', 'params', 'options');

		return Filters::run(get_called_class(), __FUNCTION__, $params, function($params) {
			$options = ['request' => $params['request']] + $params['options'];
			$controller = $params['params']['controller'];

			try {
				return Libraries::instance('controllers', $controller, $options);
			} catch (ClassNotFoundException $e) {
				throw new DispatchException("Controller `{$controller}` not found.", null, $e);
			}
		});
	}

	/**
	 * Invokes the callable object returned by `_callable()`, and returns the results, usually a
	 * `Response` object instance.
	 *
	 * @see lithium\action
	 * @param object $callable Typically a closure or instance of `lithium\action\Controller`.
	 * @param object $request An instance of `lithium\action\Request`.
	 * @param array $params An array of parameters to pass to `$callable`, along with `$request`.
	 * @return mixed Returns the return value of `$callable`, usually an instance of
	 *         `lithium\action\Response`.
	 * @throws lithium\action\DispatchException Throws an exception if `$callable` is not a
	 *         `Closure`, or does not declare the PHP magic `__invoke()` method.
	 * @filter
	 */
	protected static function _call($callable, $request, $params) {
		$params = compact('callable', 'request', 'params');
		return Filters::run(get_called_class(), __FUNCTION__, $params, function($params) {
			if (is_callable($callable = $params['callable'])) {
				return $callable($params['request'], $params['params']);
			}
			throw new DispatchException('Result not callable.');
		});
	}
}