HTML5 cache manifest filter

lib/rake-pipeline-web-filters.rb

@@ -26,4 +26,5 @@ module Filters
 require "rake-pipeline-web-filters/chained_filter"
 require "rake-pipeline-web-filters/less_filter"
 require "rake-pipeline-web-filters/handlebars_filter"
+require "rake-pipeline-web-filters/manifest_filter"
 require "rake-pipeline-web-filters/helpers"

lib/rake-pipeline-web-filters/helpers.rb

@@ -32,7 +32,7 @@ def sass(*args, &block)
       filter(Rake::Pipeline::Web::Filters::SassFilter, *args, &block)
     end
     alias_method :scss, :sass
-    
+
     # Add a new {StylusFilter} to the pipeline.
     # @see StylusFilter#initialize
     def stylus(*args, &block)
@@ -98,6 +98,22 @@ def less(*args, &block)
     def handlebars(*args, &block)
       filter(Rake::Pipeline::Web::Filters::HandlebarsFilter, *args, &block)
     end
+    #
+    # Add a new {ManifestFilter} to the pipeline.
+    # @see ManifestFilter#initialize
+    def manifest(*args, &block)
+      # Duplicate all current items in the pipeline into a new directory.
+      # We must work with duplicates otherwise the initial ones will
+      # be blown away. The manifest filter will strip out the manifest
+      # directory when generating the file.
+      match "**/*" do
+        copy { |name| [name, "manifest/#{name}"] }
+      end
+
+      match "manifest/**/*" do
+        filter(Rake::Pipeline::Web::Filters::ManifestFilter, *args, &block)
+      end
+    end
   end
 
   module ProjectHelpers

lib/rake-pipeline-web-filters/manifest_filter.rb

@@ -0,0 +1,68 @@
+module Rake::Pipeline::Web::Filters
+  # Take all inputs and output an HTML5 cache manifest.
+  #
+  # @example
+  #   !!!ruby
+  #   Rake::Pipeline.build do
+  #     input "app/assets", "**/*.js"
+  #     output "public"
+  #
+  #     # NOTE: You must match and copy othwerise files will be deleted!
+  #     match "**/*" do
+  #       copy { |input| [input, "manifest/#{input}" ]
+  #     end
+  #
+  #     match "manifest/**/*" do
+  #       filter Rake::Pipeline::Web::Filters::UglifyFilter
+  #     end
+  #   end
+  class ManifestFilter < Rake::Pipeline::Filter
+    include Rake::Pipeline::Web::Filters::FilterWithDependencies
+
+    # @param [String] Generated file name
+    # @param [Proc] block a block to use as the Filter's
+    #   {#output_name_generator}.
+    def initialize(name = 'cache.manifest', &block)
+      block ||= proc { |input| name }
+      super(&block)
+    end
+
+    # Implement the {#generate_output} method required by
+    # the {Filter} API. Generates a proper HTML5 cache manifest
+    # with all inputs inside the cache section, a unique tag,
+    # and states that all other requests require internet access.
+    #
+    # @param [Array<FileWrapper>] inputs an Array of
+    #   {FileWrapper} objects representing the inputs to
+    #   this filter.
+    # @param [FileWrapper] output a single {FileWrapper}
+    #   object representing the output.
+    def generate_output(inputs, output)
+      assets = inputs.map { |i| i.path.gsub('manifest/', '') }.join("\n")
+
+      output.write ERB.new(template).result(binding)
+    end
+
+  private
+
+    def external_dependencies
+      [ "erb" ]
+    end
+
+    def template
+      <<-erb
+CACHE MANIFEST
+
+# Automatically generated by rake-pipeline-web-filters
+# Tag: <%= Time.now.to_i %> (<%= Time.now %>)
+
+CACHE:
+<%= assets %>
+
+NETWORK:
+# All other resources require network access
+*
+      erb
+    end
+  end
+end

spec/helpers_spec.rb

@@ -102,6 +102,19 @@ def filter
       filter.should be_kind_of(Rake::Pipeline::Web::Filters::HandlebarsFilter)
     end
   end
+
+  describe "#manifest" do
+    it "setups a proper manifest pipeline" do
+      dsl.manifest
+
+      pipeline.filters.first.should be_kind_of(Rake::Pipeline::Matcher)
+      pipeline.filters.first.glob.should == "**/*"
+
+      filter.should be_kind_of(Rake::Pipeline::Matcher)
+      filter.glob.should == "manifest/**/*"
+      filter.filters.first.should be_kind_of(Rake::Pipeline::Web::Filters::ManifestFilter)
+    end
+  end
 end
 
 describe "ProjectHelpers" do

spec/manifest_filter_spec.rb

@@ -0,0 +1,62 @@
+describe "ManifestFilter" do
+  ManifestFilter ||= Rake::Pipeline::Web::Filters::ManifestFilter
+  MemoryFileWrapper ||= Rake::Pipeline::SpecHelpers::MemoryFileWrapper
+
+  def input_file(name, content)
+    MemoryFileWrapper.new("/path/to/input", name, "UTF-8", content)
+  end
+
+  def output_file(name)
+    MemoryFileWrapper.new("/path/to/output", name, "UTF-8")
+  end
+
+  def setup_filter(filter)
+    filter.file_wrapper_class = MemoryFileWrapper
+    filter.input_files = [
+      input_file("manifest/index.html", ""),
+      input_file("manifest/application.js", ""),
+      input_file("manifest/application.css", "")
+    ]
+    filter.output_root = "/path/to/output"
+    filter.rake_application = Rake::Application.new
+    filter
+  end
+
+  it "generates a proper cache manifest for output" do
+    filter = setup_filter ManifestFilter.new("cache.manifest")
+
+    filter.output_files.should == [output_file("cache.manifest")]
+
+    tasks = filter.generate_rake_tasks
+    tasks.each(&:invoke)
+
+    file = MemoryFileWrapper.files["/path/to/output/cache.manifest"]
+
+    file.encoding.should == "UTF-8"
+
+    file.body.lines.first.chomp.should == 'CACHE MANIFEST'
+
+    file.body.should match(%r{# Tag: \d+})
+
+    file.body.should match(/^index\.html/)
+    file.body.should match(/^application\.css/)
+    file.body.should match(/^application\.js/)
+  end
+
+  describe "naming output files" do
+    it "should use cache.manifest by default" do
+      filter = setup_filter ManifestFilter.new
+      filter.output_files.first.path.should == "cache.manifest"
+    end
+
+    it "accepts a string to set the output file name" do
+      filter = setup_filter(ManifestFilter.new("octopus"))
+      filter.output_files.first.path.should == "octopus"
+    end
+
+    it "accepts a block to customize output file names" do
+      filter = setup_filter(ManifestFilter.new { |input| "octopus" })
+      filter.output_files.first.path.should == "octopus"
+    end
+  end
+end