How FastRoute Supercharges PHP Routing with One‑Pass Regex

Overview

FastRoute is a lightweight, high‑performance PHP routing library that compiles all route definitions into a single regular expression, enabling a single preg_match call per request.

Architecture

The library consists of two main components:

Router – collects route definitions such as GET /post/{id:\d+} and stores the associated handler.

Dispatcher – builds a static prefix tree and hashes dynamic parts to match the incoming HTTP method and URI in constant time.

Key Features

High performance – benchmarks show routing speed significantly faster than comparable libraries.

Simplicity – a clean API allows route setup in a few lines of code.

Flexibility – supports regular‑expression constraints, custom variable rules, named routes and per‑route middleware.

No external dependencies – the library is small and easy to integrate.

Dynamic routes – e.g., /api/users/{id}.

HTTP method handling – GET, POST, PUT, DELETE for RESTful APIs.

Route Compilation

FastRoute transforms each route into a regular expression and then combines all patterns into one large expression using alternation, so only one regex evaluation is required per request.

Individual patterns

~^/users/([^/]+)$
~^/users/([^/]+)/([^/]+)$
~^/users/([^/]+)/posts/([^/]+)$

Combined pattern

~^(?:
    (/users/([^/]+))
  | (/users/([^/]+)/([^/]+))
  | (/users/([^/]+)/posts/([^/]+))
)$~x

Mapping between routes and captured groups can be stored in an array, for example:

[
    ['pattern' => '/users/{id}', 'params' => ['id']],
    ['pattern' => '/users/{id}/{name}', 'params' => ['id', 'name']],
    ['pattern' => '/users/{uid}/posts/{pid}', 'params' => ['uid', 'pid']]
]

Example PHP dispatcher using the combined regex:

<?php
declare(strict_types=1);
$pattern = '~^(?:(/users/([^/]+))|(/users/([^/]+)/([^/]+))|(/users/([^/]+)/posts/([^/]+)))$~x';
$route = '/users/42/john';
if (preg_match($pattern, $route, $m)) {
    // $m[1]..$m[8] contain captured groups; determine which route matched
    var_dump($m);
}

Real‑World Usage

Webman, a high‑performance PHP framework, uses FastRoute as its core router. The dependency is declared in composer.json:

{
    "require": {
        "php": ">=8.0",
        "ext-json": "*",
        "workerman/workerman": "^4.0.4 || ^5.0.0 || dev-master",
        "nikic/fast-route": "^1.3",
        "psr/container": ">=1.0"
    }
}

Typical route definitions in a Webman project:

Route::group('/console', function () {
    Route::group('/v1', function () {
        Route::group('/schedule', function () {
            Route::get('/{organizationId}', [ScheduleController::class, 'list']);
            Route::post('', [ScheduleController::class, 'create']);
            Route::put('/{scheduleId}', [ScheduleController::class, 'edit']);
            Route::delete('/{scheduleId}', [ScheduleController::class, 'delete']);
        });
        Route::group('/department', function () {
            Route::get('/department-list/{organizationId}', [DepartmentController::class, 'departmentList']);
            Route::post('', [DepartmentController::class, 'departmentCreate']);
            Route::put('/{id}', [DepartmentController::class, 'departmentUpdate']);
            Route::delete('', [DepartmentController::class, 'departmentDelete']);
        });
    });
});

Further technical details are described in the author's analysis article:

https://www.npopov.com/2014/02/18/Fast-request-routing-using-regular-expressions.html