Class: Rack::Builder

Inherits:
Object
  • Object
show all
Defined in:
lib/rack/builder.rb

Overview

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.

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(&block) ⇒ Builder

Returns a new instance of Builder.


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# File 'lib/rack/builder.rb', line 44

def initialize(&block)
  @ins = []
  instance_eval(&block) if block_given?
end

Class Method Details

.app(&block) ⇒ Object


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# File 'lib/rack/builder.rb', line 49

def self.app(&block)
  self.new(&block).to_app
end

.parse_file(config, opts = Server::Options.new) ⇒ Object


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# File 'lib/rack/builder.rb', line 27

def self.parse_file(config, opts = Server::Options.new)
  options = {}
  if config =~ /\.ru$/
    cfgfile = ::File.read(config)
    if cfgfile[/^#\\(.*)/] && opts
      options = opts.parse! $1.split(/\s+/)
    end
    cfgfile.sub!(/^__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

Instance Method Details

#call(env) ⇒ Object


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# File 'lib/rack/builder.rb', line 76

def call(env)
  to_app.call(env)
end

#map(path, &block) ⇒ Object


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# 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

#run(app) ⇒ Object


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# File 'lib/rack/builder.rb', line 57

def run(app)
  @ins << app #lambda { |nothing| app }
end

#to_appObject


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# 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

#use(middleware, *args, &block) ⇒ Object


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# File 'lib/rack/builder.rb', line 53

def use(middleware, *args, &block)
  @ins << lambda { |app| middleware.new(app, *args, &block) }
end