Traversal Router

traba.php

<?php

// This was the first test to create what then became Traba.
//
// https://github.com/guide42/traba
//

$request = array(
    'path_info' => '/user/123/edit',
    'query' => array(
        'name' => 'John Doe',
        'age' => 42,
    ),
);

// {{{ Fast an ugly traversal implementation

function split_path_info($path)
{
    $parts = array();

    foreach (explode('/', $path) as $part) {
        if (empty($part) || $part === '.') {
            continue;
        }

        if ($part === '..') {
            if ($parts) {
                unset($parts[count($parts) - 1]);
                continue;
            }

            throw new RuntimeException('');
        }

        $parts[] = $part;
    }

    return $parts;
}

function get_path_info($context)
{
    if (isset($context['request']['path_info'])) {
        return $context['request']['path_info'];
    }

    return '/';
}

function traverser($context, $root)
{
    $path = get_path_info($context);

    if ($path === '/') {
        return array(
            'context' => $root,
            'name' => null,
            'subpath' => array(),
            'traversed' => array(),
        );
    }

    $parts = split_path_info($path);
    foreach($parts as $i => $segment) {
        if (!(is_array($root) || $root instanceof \ArrayAccess) || !isset($root[$segment])) {
            return array(
                'context' => $root,
                'name' => $segment,
                'subpath' => array_slice($parts, $i + 1),
                'traversed' => array_slice($parts, 0, $i),
            );
        }

        $root = $root[$segment];
    }

    return array(
        'context' => $root,
        'name' => null,
        'subpath' => array(),
        'traversed' => $parts,
    );
}

// }}}

// {{{ Example of utilization of the traversal algorithm

class User {
    public $name;
    public $age;
    public function __construct($name, $age) {
        $this->name = $name;
        $this->age = $age;
    }
}

class UserDispatcher implements \ArrayAccess
{
    private $users = null;

    public function init() {
        if ($this->users === null) {
            $this->users = array(
                123 => new User('Not John', 24),
            );
        }
    }

    public function offsetExists($offset) {
        $this->init();
        return isset($this->users[$offset]);
    }

    public function offsetGet($offset) {
        $this->init();
        return $this->users[$offset];
    }

    public function offsetSet($offset, $value) {}

    public function offsetUnset($offset) {}
}

$context = array('request' => $request);
$root = array(
    'user' => new UserDispatcher(),
);

$matched = traverser($context, $root);

// }}}

// {{{ Implementation of the matcher

function matcher(array $registry, array $matched)
{
    $context = $matched['context'];
    $name = $matched['name'] ? $matched['name'] : 'index';

    foreach ($registry as $view) {
        if ($view[0] === $name && $context instanceof $view[1]) {
            return $view[2];
        }
    }

    return null;
}

// }}}

// {{{ Use the matcher

function user_edit($request, User $user)
{
    $user->name = $request['query']['name'];
    $user->age = $request['query']['age'];

    return 'OK';
}

function user_index($request, User $user)
{
    return 'Name=' . $user->name . '; Age=' . $user->age;
}

function not_found($request, $context)
{
    return '404';
}

$registry = array(
    //   | name   | context type | callback     |
    array( 'index', 'User'       , 'user_index' ),
    array( 'edit' , 'User'       , 'user_edit'  ),
);

$view = matcher($registry, $matched);

if ($view === null) {
    $view = 'not_found';
}

// }}}

// {{{

$response = call_user_func($view, $request, $matched['context']);

echo $response . PHP_EOL;

// }}}

// Hope nobody will kill me for so ugly code