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FastRoute - Fast request router for PHP

This library provides a fast implementation of a regular expression based router. Blog post explaining how the implementation works and why it is fast.

Install

To install with composer:

Requires PHP 8.1 or newer.

Usage

Here's a basic usage example:

Defining routes

The routes are defined by calling the FastRoute\simpleDispatcher() function, which accepts a callable taking a FastRoute\ConfigureRoutes instance. The routes are added by calling addRoute() on the collector instance:

The $method is an uppercase HTTP method string for which a certain route should match. It is possible to specify multiple valid methods using an array:

By default, the $routePattern uses a syntax where {foo} specifies a placeholder with name foo and matching the regex [^/]+. To adjust the pattern the placeholder matches, you can specify a custom pattern by writing {bar:[0-9]+}. Some examples:

Custom patterns for route placeholders cannot use capturing groups. For example {lang:(en|de)} is not a valid placeholder, because () is a capturing group. Instead you can use either {lang:en|de} or {lang:(?:en|de)}.

Furthermore, parts of the route enclosed in [...] are considered optional, so that /foo[bar] will match both /foo and /foobar. Optional parts are only supported in a trailing position, not in the middle of a route.

The $handler parameter does not necessarily have to be a callback, it could also be a controller class name or any other kind of data you wish to associate with the route. FastRoute only tells you which handler corresponds to your URI, how you interpret it is up to you.

Shortcut methods for common request methods

For the GET, POST, PUT, PATCH, DELETE and HEAD request methods shortcut methods are available. For example:

Is equivalent to:

Route Groups

Additionally, you can specify routes inside a group. All routes defined inside a group will have a common prefix.

For example, defining your routes as:

Will have the same result as:

Nested groups are also supported, in which case the prefixes of all the nested groups are combined.

Caching

The reason simpleDispatcher accepts a callback for defining the routes is to allow seamless caching. By using cachedDispatcher instead of simpleDispatcher you can cache the generated routing data and construct the dispatcher from the cached information:

The second parameter to the function is an options array, which can be used to specify the cache key (e.g. file location when using files for caching), caching driver, among other things.

Dispatching a URI

A URI is dispatched by calling the dispatch() method of the created dispatcher. This method accepts the HTTP method and a URI. Getting those two bits of information (and normalizing them appropriately) is your job - this library is not bound to the PHP web SAPIs.

The dispatch() method returns an array whose first element contains a status code. It is one of Dispatcher::NOT_FOUND, Dispatcher::METHOD_NOT_ALLOWED and Dispatcher::FOUND. For the method not allowed status the second array element contains a list of HTTP methods allowed for the supplied URI. For example:

[FastRoute\Dispatcher::METHOD_NOT_ALLOWED, ['GET', 'POST']]

NOTE: The HTTP specification requires that a 405 Method Not Allowed response include the Allow: header to detail available methods for the requested resource. Applications using FastRoute should use the second array element to add this header when relaying a 405 response.

For the found status the second array element is the handler that was associated with the route and the third array element is a dictionary of placeholder names to their values. For example:

/* Routing against GET /user/nikic/42 */

[FastRoute\Dispatcher::FOUND, 'handler0', ['name' => 'nikic', 'id' => '42']]

Overriding the route parser and dispatcher

The routing process makes use of three components: A route parser, a data generator and a dispatcher. The three components adhere to the following interfaces:

The route parser takes a route pattern string and converts it into an array of route infos, where each route info is again an array of its parts. The structure is best understood using an example:

/* The route /user/{id:\d+}[/{name}] converts to the following array: */
[
    [
        '/user/',
        ['id', '\d+'],
    ],
    [
        '/user/',
        ['id', '\d+'],
        '/',
        ['name', '[^/]+'],
    ],
]

This array can then be passed to the addRoute() method of a data generator. After all routes have been added the getData() of the generator is invoked, which returns all the routing data required by the dispatcher. The format of this data is not further specified - it is tightly coupled to the corresponding dispatcher.

The dispatcher accepts the routing data via a constructor and provides a dispatch() method, which you're already familiar with.

The route parser can be overwritten individually (to make use of some different pattern syntax), however the data generator and dispatcher should always be changed as a pair, as the output from the former is tightly coupled to the input of the latter. The reason the generator and the dispatcher are separate is that only the latter is needed when using caching (as the output of the former is what is being cached.)

When using the simpleDispatcher / cachedDispatcher functions from above the override happens through the options array:

The above options array corresponds to the defaults. By replacing MarkBased with GroupCountBased you could switch to a different dispatching strategy.

A Note on HEAD Requests

The HTTP spec requires servers to support both GET and HEAD methods:

The methods GET and HEAD MUST be supported by all general-purpose servers

To avoid forcing users to manually register HEAD routes for each resource we fallback to matching an available GET route for a given resource. The PHP web SAPI transparently removes the entity body from HEAD responses so this behavior has no effect on the vast majority of users.

However, implementers using FastRoute outside the web SAPI environment (e.g. a custom server) MUST NOT send entity bodies generated in response to HEAD requests. If you are a non-SAPI user this is your responsibility; FastRoute has no purview to prevent you from breaking HTTP in such cases.

Finally, note that applications MAY always specify their own HEAD method route for a given resource to bypass this behavior entirely.

Credits

This library is based on a router that Levi Morrison implemented for the Aerys server.

A large number of tests, as well as HTTP compliance considerations, were provided by Daniel Lowrey.