Core_Route::uri

public static function uri(array $params = null)
{
    if (!isset(Route::$regex[Core::$project]))
    {
        # 构造路由正则
        Route::init_regex();
    }

    $current_route = Core::config('route.'.Route::$current_route);

    if (!isset($current_route['default']) || !is_array($current_route['default']))$current_route['default'] = array();

    if (null===$params)
    {
        // 使用默认参数
        $params = $current_route['default'];
    }
    else
    {
        // 覆盖默认参数
        $params += $current_route['default'];
    }

    // 获取URI
    $uri = $current_route['uri'];

    if (strpos($uri, '<') === false && strpos($uri, '(') === false)
    {
        // This is a static route, no need to replace anything
        return $uri;
    }

    $provided_optional = false;

    while (preg_match('#\([^()]++\)#', $uri, $match))
    {
        // Search for the matched value
        $search = $match[0];

        // Remove the parenthesis from the match as the replace
        $replace = substr($match[0], 1, -1);

        while (preg_match('#' . Route::REGEX_KEY . '#', $replace, $match))
        {
            list ($key, $param) = $match;

            if (isset($params[$param]) && ($params[$param]!==Route::arr_get($current_route['default'],$param)))
            {
                $provided_optional = true;

                // Replace the key with the parameter value
                $replace = str_replace($key, $params[$param], $replace);
            }
            elseif ($provided_optional)
            {
                // Look for a default
                if (isset($current_route['default'][$param]))
                {
                    $replace = str_replace($key, $current_route['default'][$param], $replace);
                }
                else
                {
                    // Ungrouped parameters are required
                    throw new Exception(__('Required route parameter not passed: :param', array(':param' => $param)));
                }
            }
            else
            {
                // This group has missing parameters
                $replace = '';
                break;
            }
        }

        // Replace the group in the URI
        $uri = str_replace($search, $replace, $uri);
    }

    while (preg_match('#' . Route::REGEX_KEY . '#', $uri, $match))
    {
        list($key, $param) = $match;

        if ( !isset($params[$param]) )
        {
            if (isset($current_route['default'][$param]))
            {
                $params[$param] = $current_route['default'][$param];
            }
            else
            {
                // Ungrouped parameters are required
                throw new Exception(__('Required route parameter not passed: :param', array(':param' => $param)));
            }
        }

        $uri = str_replace($key, $params[$param], $uri);
    }

    // Trim all extra slashes from the URI
    $uri = preg_replace('#//+#', '/', rtrim($uri, '/'));

    if (isset($current_route['defaults']['host']))
    {
        if (false===strpos($current_route['defaults']['host'], '://'))
        {
            $host = HttpIO::PROTOCOL.$host;
        }

        $uri = rtrim($host, '/') . '/' . $uri;
    }

    return $uri;
}