Initial commit

.gitignore

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+*.gem
+*.rbc
+.bundle
+.config
+.yardoc
+Gemfile.lock
+InstalledFiles
+_yardoc
+coverage
+doc/
+lib/bundler/man
+pkg
+rdoc
+spec/reports
+test/tmp
+test/version_tmp
+tmp

.rspec

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+--color
+--format documentation

Gemfile

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+source "http://rubygems.org"
+
+gemspec

LICENSE

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+Copyright (c) 2012 Nick Sieger
+
+MIT License
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

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+# Rack::Chain
+
+TODO: Write a gem description
+
+## Installation
+
+Add this line to your application's Gemfile:
+
+    gem 'rack-chain'
+
+And then execute:
+
+    $ bundle
+
+Or install it yourself as:
+
+    $ gem install rack-chain
+
+## Usage
+
+TODO: Write usage instructions here
+
+## Contributing
+
+1. Fork it
+2. Create your feature branch (`git checkout -b my-new-feature`)
+3. Commit your changes (`git commit -am 'Added some feature'`)
+4. Push to the branch (`git push origin my-new-feature`)
+5. Create new Pull Request

Rakefile

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+require 'bundler/gem_tasks'
+
+require 'rspec/core/rake_task'
+RSpec::Core::RakeTask.new
+
+task :default => :spec

lib/rack-chain.rb

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+require 'rack-chain/version'
+require 'rack/chain'

lib/rack-chain/version.rb

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+module Rack
+  class Chain
+    VERSION = "0.0.1"
+  end
+end

lib/rack/chain.rb

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+require 'rack'
+require 'rack/builder'
+require 'fiber'
+
+class Rack::Chain
+  attr_reader   :endpoint
+  attr_accessor :filters
+
+  class Link
+    def initialize(to)
+      @to = to
+    end
+
+    def call(env)
+      Fiber.new do
+        Fiber.yield @to.call(env)
+      end.resume
+    end
+  end
+
+  def initialize(endpoint, filters = [])
+    @endpoint = endpoint
+    @filters  = filters
+  end
+
+  def call(env)
+    Link.new(filters.reverse.inject(endpoint) do |endpt,filter|
+               if filter.respond_to?(:[])
+                 filter[Link.new(endpt)]
+               else
+                 filter.new(Link.new(endpt))
+               end
+             end).call(env)
+  end
+
+  # Include this module in Rack::Builder to make all apps use Rack::Chain.
+  #
+  # Alternatively, extend Rack::Builder in config.ru to use
+  # Rack::Chain for that particular config.ru. Example:
+  #
+  # <pre>
+  # require 'rack/chain'
+  # extend Rack::Chain::Linker
+  # use Middleware1
+  # use Middleware2
+  # run App
+  # </pre>
+  module Linker
+    def to_app
+      app = @map ? generate_map(@run, @map) : @run
+      fail "missing run or map statement" unless app
+      Rack::Chain.new(app, @use)
+    end
+  end
+end
+

rack-chain.gemspec

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+# -*- encoding: utf-8 -*-
+require File.expand_path('../lib/rack-chain/version', __FILE__)
+
+Gem::Specification.new do |gem|
+  gem.authors       = ["Nick Sieger"]
+  gem.email         = ["nick@nicksieger.com"]
+  gem.description   = %q{TODO: Write a gem description}
+  gem.summary       = %q{TODO: Write a gem summary}
+  gem.homepage      = ""
+
+  gem.files         = `git ls-files`.split($\)
+  gem.executables   = gem.files.grep(%r{^bin/}).map{ |f| File.basename(f) }
+  gem.test_files    = gem.files.grep(%r{^(test|spec|features)/})
+  gem.name          = "rack-chain"
+  gem.require_paths = ["lib"]
+  gem.version       = Rack::Chain::VERSION
+
+  gem.add_runtime_dependency "rack", [">= 1.4.0"]
+  gem.add_development_dependency "rspec", [">= 2.8.0"]
+end

spec/rack/chain_spec.rb

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+require File.expand_path('../../spec_helper', __FILE__)
+
+describe Rack::Chain do
+  let(:env) { Hash.new }
+
+  let(:app) { app_dummy.new }
+
+  let(:chain) { Rack::Chain.new(app) }
+
+  let(:filter_names) { %w(Foo Bar Baz) }
+
+  let(:filters) { filter_names.map {|x| filter_dummy(x) } }
+
+  let(:full_chain) { chain.tap {|c| c.filters += filters } }
+
+  it "has an ordered list of filters" do
+    full_chain.filters.should == filters
+  end
+
+  it "calls each filter in order" do
+    full_chain.call(env)[2].should == ["App", *filter_names.reverse]
+  end
+
+  context Rack::Chain::Linker, "#to_app" do
+    let(:builder) do
+      Rack::Builder.new do
+        extend Rack::Chain::Linker
+      end.tap do |builder|
+        filters.each do |filter|
+          builder.use filter
+        end
+        builder.run app
+      end
+    end
+
+    it "overrides Rack::Builder#to_app to create a Rack::Chain" do
+      builder.to_app.should be_instance_of(Rack::Chain)
+    end
+
+    it "calls each filter in order" do
+      builder.to_app.call(env)[2].should == ["App", *filter_names.reverse]
+    end
+  end
+
+  context "with a large set of middleware" do
+    let(:number_of_filters) { 100 }
+
+    let(:filter_names) { (1..number_of_filters).map {|n| "Filter#{n}" } }
+
+    let(:filters) { filter_names.map {|x| filter_dummy(x) { caller.size } } }
+
+    # Skip the call stack size for the app
+    let(:app) { app_dummy { nil }.new }
+
+    it "the call stack size stays constant" do
+      call_stack_sizes = full_chain.call(env)[2].compact
+      call_stack_sizes.max.should == call_stack_sizes.min
+    end
+
+    context "but using normal Rack::Builder" do
+      let(:builder) do
+        Rack::Builder.new.tap {|builder|
+          filters.each do |filter|
+            builder.use filter
+          end
+          builder.run app
+        }
+      end
+
+      it "the call stack size grows with each layer" do
+        call_stack_sizes = builder.call(env)[2].compact
+        call_stack_sizes.max.should > number_of_filters
+      end
+    end
+  end
+end

spec/spec_helper.rb

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+require 'bundler/setup'
+require 'rspec'
+require 'rack/chain'
+
+module Rack::Chain::Fixtures
+  class FilterDummy
+    def initialize(app)
+      @app = app
+    end
+
+    def call(env)
+      @app.call(env).tap do |result|
+        result[2] ||= []
+        result[2] << body if body
+      end
+    end
+
+    def body
+      self.class.name.split(/::/)[-1]
+    end
+  end
+
+  class AppDummy
+    def call(env)
+      [200, {"Content-Type" => "text/plain"}, [body]]
+    end
+
+    def body
+      self.class.name.split(/::/)[-1]
+    end
+  end
+
+  module Dummies
+  end
+
+  def reset_fixtures
+    Dummies.class_eval do
+      constants.each {|c| remove_const(c) }
+    end
+  end
+
+  def filter_dummy(name = "Foo", &block)
+    Dummies.const_set(name, Class.new(FilterDummy) do
+                        define_method(:body, &block) if block
+                      end)
+  end
+
+  def app_dummy(name = "App", &block)
+    Dummies.const_set(name, Class.new(AppDummy) do
+                        define_method(:body, &block) if block
+                      end)
+  end
+end
+
+RSpec.configure do |config|
+  config.include Rack::Chain::Fixtures
+  config.after :each do
+    reset_fixtures
+  end
+end