Usher

Tree-based router library. Useful for (specifically) for Rails and Rack, but probably generally useful for anyone interested in doing routing. Based on Ilya Grigorik suggestion, turns out looking up in a hash and following a tree is faster than Krauter's massive regex approach.

Features

  • Understands single and path-globbing variables
  • Understands arbitrary regex variables
  • Arbitrary HTTP header requirements
  • No optimization phase, so routes are always alterable after the fact
  • Understands Proc and Regex transformations, validations
  • Really, really fast
  • Relatively light and happy code-base, should be easy and fun to alter (it hovers around 1,000 LOC, 800 for the core)
  • Interface and implementation are separate, encouraging cross-pollination
  • Works in 1.9!

Projects using or other references to Usher

Any probably more!

Route format

From the rdoc:

Creates a route from path and options

path

A path consists a mix of dynamic and static parts delimited by /

Dynamic

Dynamic parts are prefixed with either :, *. :variable matches only one part of the path, whereas *variable can match one or more parts.

Example: /path/:variable/path would match

  • /path/test/path
  • /path/something_else/path
  • /path/one_more/path

In the above examples, test, something_else and one_more respectively would be bound to the key :variable. However, /path/test/one_more/path would not be matched.

Example: /path/*variable/path would match

  • /path/one/two/three/path
  • /path/four/five/path

In the above examples, ['one', 'two', 'three'] and ['four', 'five'] respectively would be bound to the key :variable.

As well, variables can have a regex matcher.

Example: /product/{:id,\d+} would match

  • /product/123
  • /product/4521

But not

  • /product/AE-35

As well, the same logic applies for * variables as well, where only parts matchable by the supplied regex will actually be bound to the variable

Variables can also have a greedy regex matcher. These matchers ignore all delimiters, and continue matching for as long as much as their regex allows.

Example: /product/{!id,hello/world|hello} would match

  • /product/hello/world
  • /product/hello

Static

Static parts of literal character sequences. For instance, /path/something.html would match only the same path. As well, static parts can have a regex pattern in them as well, such as /path/something.{html|xml} which would match only /path/something.html and /path/something.xml

Optional sections

Sections of a route can be marked as optional by surrounding it with brackets. For instance, in the above static example, /path/something(.html) would match both /path/something and /path/something.html.

One and only one sections

Sections of a route can be marked as "one and only one" by surrounding it with brackets and separating parts of the route with pipes. For instance, the path, /path/something(.xml|.html) would only match /path/something.xml and /path/something.html. Generally its more efficent to use one and only sections over using regex.

options

  • requirements - After transformation, tests the condition using #===. If it returns false, it raises an Usher::ValidationException
  • conditions - Accepts any of the request_methods specificied in the construction of Usher. This can be either a string or a regular expression.
  • default_values - Provides values for variables in your route for generation. If you're using URL generation, then any values supplied here that aren't included in your path will be appended to the query string.
  • priority - If there are two routes which equally match, the route with the highest priority will match first.
  • Any other key is interpreted as a requirement for the variable of its name.

Rails

script/plugin install git://github.com/joshbuddy/usher.git

In your config/initializers/usher.rb (create if it doesn't exist) add:

Usher::Util::Rails.activate

Rack

config.ru

require 'usher'
app # proc do |env|
  body # "Hi there #{env['usher.params'][:name]}"
  [
    200,          # Status code
    {             # Response headers
      'Content-Type' #> 'text/plain',
      'Content-Length' #> body.size.to_s,
    },
    [body]        # Response body
  ]
end

routes # Usher::Interface.for(:rack) do
  add('/hello/:name').to(app)
end

run routes

>> curl http://127.0.0.1:3000/hello/samueltanders
<< Hi there samueltanders

Sinatra

In Sinatra, you get the extra method, generate, which lets you generate a url. Name your routes with :name when you define them.

require 'rubygems'
require 'usher'
require 'sinatra'

Usher::Interface.for(:sinatra)

get '/hi', :name #> :hi do
  "Hello World! #{generate(:hi)}"
end

(Let me show you to your request)