R3
================

R3 is an URI router library. It compiles your route paths into a radix tree.
By using the constructed radix tree in the start-up time, you may dispatch your
routes efficiently.

Pattern Syntax
-----------------------

    /blog/post/{id}      use [^/]+ regular expression by default.

    /blog/post/{id:\d+}  use `\d+` regular expression instead of default.



Use case in PHP
-----------------------

```php
// Here is the paths data structure
$paths = [
    '/blog/post/{id}' => [ 'controller' => 'PostController' , 'action' => 'item'   , 'method'   => 'GET' ] , 
    '/blog/post'      => [ 'controller' => 'PostController' , 'action' => 'list'   , 'method'   => 'GET' ] , 
    '/blog/post'      => [ 'controller' => 'PostController' , 'action' => 'create' , 'method' => 'POST' ]  , 
    '/blog'           => [ 'controller' => 'BlogController' , 'action' => 'list'   , 'method'   => 'GET' ] , 
];
$rs = r2_compile_radix($paths, 'persisten-table-id');
$ret = r2_dispatch_radix($rs, '/blog/post/3' );
list($complete, $route, $variables) = $ret;

list($error, $message) = r2_validate($route); // validate route conditions
if ( $error ) {
    echo $message; // "Method not allowed", "...";
}
```