Pendragon

Pendragon provides an HTTP router and its toolkit for use in Rack. As a Rack application, it makes it easy to define complicated routing. Algorithms of the router are used in Padrino and Grape, it's fast, flexible and robust.

If you want to use in Ruby-1.9, you can do it by using mustermann19.

Pendragon.new do
  get('/') { [200, {}, ['hello world']] }
  namespace :users do
    get('/',    to: -> { [200, {}, ['User page index']] })
    get('/:id', to: -> (id) { [200, {}, [id]] })
    get('/:id/comments') { |id| [200, {}, [User.find_by(id: id).comments.to_json]] }
  end
end

Router Patterns

Type	Description	Note
liner	Linear search, Optimized Mustermann patterns
realism	First route is detected by union regexps (Actually, O(1) in ruby level), routes since the first time will be retected by linear search	this algorithm is using in Grape
radix	Radix Tree, not using Mustermann and regexp	requires C++11

Installation

Add this line to your application's Gemfile:

gem 'pendragon'

And then execute:

$ bundle

Or install it yourself as:

$ gem install pendragon

Usage

Selects router pattern

You can select router pattern as following code.

# Gets Linear router class by passing type in `Pendragon.[]`
Pendragon[:linear] #=> Pendragon::Linear

# Specify :type to construction of Pendragon.
Pendragon.new(type: :linear) { ... }

Registers a route

It has some methods to register a route. For example, #get, #post and #delete are so. This section introduces all those methods.

route(method, path, **options, &block)

The method is the basis of the registration method of all. In comparison with other registration methods, one argument is increased.

Pendragon.new do
  route('GET', ?/){ [200, {}, ['hello']] }
end

get(path, **options, &block), post, delete, put and head

Basically the usage is the same with #route. You may as well use those methods instead of #route because those methods are easy to understand.

Pendragon.new do
  get   (?/) { [200, {}, ['hello']] }
  post  (?/) { [200, {}, ['hello']] }
  delete(?/) { [200, {}, ['hello']] }
  put   (?/) { [200, {}, ['hello']] }
  head  (?/) { [200, {}, ['hello']] }
end

Mounts Rack Application

You can easily mount your rack application onto Pendragon.

Please note that pendragon distinguishes between processing Proc and Rack Application.

class RackApp
  def call(env)
    puts env #=> rack default env
    [200, {}, ['hello']]
  end
end

Pendragon.new do
  get '/ids/:id', to: -> (id) { p id } # Block parameters are available
  get '/rack/:id', to: RackApp.new # RackApp#call will be called, `id` is not passed and `env` is passed instead.
end

Halt

You can halt to processing by calling throw :halt inside your route.

Pendragon.new do
  get ?/ do
    throw :halt, [404, {}, ['not found']]
    [200, {}, ['failed to halt']]
  end
end

Cascading

A route can punt to the next matching route by using X-Cascade header.

pendragon = Pendragon.new do
  foo = 1
  get ?/ do
    [200, { 'X-Cascade' => 'pass' }, ['']]
  end

  get ?/ do
    [200, {}, ['goal!']]
  end
end

env = Rack::MockRequest.env_for(?/)
pendragon.call(env) #=> [200, {}, ['goal!']]

Contributing

1. fork the project.
2. create your feature branch. (git checkout -b my-feature)
3. commit your changes. (git commit -am 'commit message')
4. push to the branch. (git push origin my-feature)
5. send pull request.

License

the MIT License