module Rack # Rack::Builder implements a small DSL to iteratively construct Rack # applications. # # Example: # # app = Rack::Builder.new { # use Rack::CommonLogger # use Rack::ShowExceptions # map "/lobster" do # use Rack::Lint # run Rack::Lobster.new # end # } # # +use+ adds a middleware to the stack, +run+ dispatches to an application. # You can use +map+ to construct a Rack::URLMap in a convenient way. class Builder def initialize(&block) @ins = [] instance_eval(&block) if block_given? end def use(middleware, *args, &block) @ins << if block_given? lambda { |app| middleware.new(app, *args, &block) } else lambda { |app| middleware.new(app, *args) } end end def run(app) @ins << app #lambda { |nothing| app } end def map(path, &block) if @ins.last.kind_of? Hash @ins.last[path] = Rack::Builder.new(&block).to_app else @ins << {} map(path, &block) end end def to_app @ins[-1] = Rack::URLMap.new(@ins.last) if Hash === @ins.last inner_app = @ins.last @ins[0...-1].reverse.inject(inner_app) { |a, e| e.call(a) } end def call(env) to_app.call(env) end end end