support for nested containers

 - this allows us to support casks for things like "dmg in zip" "zip in
   tar", etc, etc
 - a nested container can be any format that homebrew-cask supports
 - the existing container support is now referred to as a Cask's
   "primary container"
 - use the `nested_container` artifact type to indicate the relative
   path to a nested container that you wanted extracted
 - multiple layers of nesting should work with multiple nested_container
   directives (though this is untested as yet)
 - add SpeedDownload as the first cask to use this feature; refs #602

Casks/speed-download.rb

@@ -0,0 +1,8 @@
+class SpeedDownload < Cask
+  url 'http://mirror.nscocoa.com/~yazsoftc1/files/sd5/sd5.zip'
+  homepage 'http://www.yazsoft.com/products/speed-download'
+  version 'latest'
+  no_checksum
+  nested_container 'Speed Download 5.dmg'
+  link 'Speed Download 5/Speed Download.app'
+end

lib/cask/artifact.rb

@@ -3,12 +3,18 @@ module Cask::Artifact; end
 require 'cask/artifact/base'
 
 require 'cask/artifact/app'
+require 'cask/artifact/nested_container'
 require 'cask/artifact/pkg'
 require 'cask/artifact/prefpane'
 
 module Cask::Artifact
+  #
+  # NOTE: order is important here, since we want to extract nested containers
+  #       before we handle any other artifacts
+  #
   def self.artifacts
     [
+      Cask::Artifact::NestedContainer,
       Cask::Artifact::App,
       Cask::Artifact::Pkg,
       Cask::Artifact::Prefpane,

lib/cask/artifact/nested_container.rb

@@ -0,0 +1,23 @@
+class Cask::Artifact::NestedContainer < Cask::Artifact::Base
+  def self.me?(cask)
+    cask.artifacts[:nested_container].any?
+  end
+
+  def install
+    @cask.artifacts[:nested_container].each { |container| extract(container) }
+  end
+
+  def uninstall
+    # no need to take action; we will get removed by rmtree of parent
+  end
+
+  def extract(container_relative_path)
+    source = @cask.destination_path.join(container_relative_path)
+    container = Cask::Container.for_path(source, @command)
+    unless container
+      raise "aw dang, could not identify nested container at #{source}"
+    end
+    ohai "Extracting nested container #{source.basename}"
+    container.new(@cask, source, @command).extract
+  end
+end

lib/cask/dsl.rb

@@ -36,10 +36,11 @@ def artifacts
     end
 
     ARTIFACT_TYPES = [
+      :install,
       :link,
+      :nested_container,
       :prefpane,
-      :install,
-      :uninstall
+      :uninstall,
     ]
 
     ARTIFACT_TYPES.each do |type|

lib/cask/installer.rb

@@ -12,7 +12,7 @@ def install(force=false)
     end
 
     download
-    extract_container
+    extract_primary_container
     install_artifacts
 
     ohai "Success! #{@cask} installed to #{@cask.destination_path}"
@@ -26,11 +26,11 @@ def download
     @downloaded_path = download.perform
   end
 
-  def extract_container
+  def extract_primary_container
     FileUtils.mkdir_p @cask.destination_path
     container = Cask::Container.for_path(@downloaded_path, @command)
     unless container
-      raise "uh oh, could not identify container for #{@downloaded_path}"
+      raise "uh oh, could not identify primary container for #{@downloaded_path}"
     end
     container.new(@cask, @downloaded_path, @command).extract
   end

test/cask/artifact/nested_container_test.rb

@@ -0,0 +1,17 @@
+require 'test_helper'
+
+describe Cask::Artifact::NestedContainer do
+  describe 'install' do
+    it 'extracts the specified paths as containers' do
+      cask = Cask.load('nested-app').tap do |c|
+        TestHelper.install_without_artifacts(c)
+      end
+
+      shutup do
+        Cask::Artifact::NestedContainer.new(cask).install
+      end
+
+      cask.destination_path.join('MyNestedApp.app').must_be :directory?
+    end
+  end
+end

test/cask/installer_test.rb

@@ -103,6 +103,17 @@
       pkg = dest_path/'Naked.pkg'
       pkg.must_be :file?
     end
+
+    it "works fine with a nested container" do
+      nested_app = Cask.load('nested-app')
+
+      shutup do
+        Cask::Installer.new(nested_app).install
+      end
+
+      dest_path = Cask.appdir/'MyNestedApp.app'
+      TestHelper.valid_alias?(dest_path).must_equal true
+    end
   end
 
   describe "uninstall" do

test/support/Casks/nested-app.rb

@@ -0,0 +1,9 @@
+class NestedApp < TestCask
+  url TestHelper.local_binary('NestedApp.dmg.zip')
+  homepage 'http://example.com/nested-app'
+  version '1.2.3'
+  sha1 'de226f9ced77ae359ddb3c8764c605a391199d5c'
+  nested_container 'NestedApp.dmg'
+  link 'MyNestedApp.app'
+end
+

test/test_helper.rb

@@ -76,7 +76,7 @@ def self.valid_alias?(candidate)
   def self.install_without_artifacts(cask)
     Cask::Installer.new(cask).tap do |i|
       shutup { i.download }
-      i.extract_container
+      i.extract_primary_container
     end
   end
 end