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 }
Or
app = Rack::Builder.app do use Rack::CommonLogger lambda { |env| [200, {'Content-Type' => 'text/plain'}, 'OK'] } 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.
# File lib/rack/builder.rb, line 49 def self.app(&block) self.new(&block).to_app end
# File lib/rack/builder.rb, line 44 def initialize(&block) @ins = [] instance_eval(&block) if block_given? end
# File lib/rack/builder.rb, line 27 def self.parse_file(config, opts = Server::Options.new) options = {} if config =~ %r\.ru$/ cfgfile = ::File.read(config) if cfgfile[%r^#\\(.*)/] && opts options = opts.parse! $1.split(%r\s+/) end cfgfile.sub!(%r^__END__\n.*/, '') app = eval "Rack::Builder.new {( " + cfgfile + "\n )}.to_app", TOPLEVEL_BINDING, config else require config app = Object.const_get(::File.basename(config, '.rb').capitalize) end return app, options end
# File lib/rack/builder.rb, line 76 def call(env) to_app.call(env) end
# File lib/rack/builder.rb, line 61 def map(path, &block) if @ins.last.kind_of? Hash @ins.last[path] = self.class.new(&block).to_app else @ins << {} map(path, &block) end end
# File lib/rack/builder.rb, line 57 def run(app) @ins << app #lambda { |nothing| app } end
# File lib/rack/builder.rb, line 70 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
# File lib/rack/builder.rb, line 53 def use(middleware, *args, &block) @ins << lambda { |app| middleware.new(app, *args, &block) } end