gistfile1.php

<?php


class Router
{
    private $uri;
    private $cache = [];

    public function setUri($uri)
    {
        $this->uri = $uri;
    }


    public function parse($notation)
    {
        if (! array_key_exists($notation, $this->cache)) {
            $this->cache[$notation] = $this->transform($notation);
        }

        return $this->apply($this->uri, $this->cache[$notation]);
    }


    private function transform($notation) 
    {
        $map = [
            '{' => '(?P<',
            '}' => '>[^/\\\\.,;?\n]+)',
        ];
        $pattern = strtr($notation, $map);
        $pattern = "#^{$pattern}$#i";
        return $pattern;
    }


    private function apply($uri, $expression)
    {
        $matches = [];

        if (preg_match($expression, $uri, $matches)) {
            return $this->clean($matches);
        }

        return false;
    }


    private function clean($matches)
    {
        $list = [];
        foreach ($matches as $key => $value) {
            if (is_numeric($key) === false && $value !== '') {
                $list[$key] = $value;
            }
        }
        return $list;       
    }

}

$router = new Router;


$router->setUri('user/3');
var_dump($router->parse('user/{id}'));