gistfile1.rb

# To be used with http://github.com/setepo/asset-pocket
#
#    require 'clousure_compressor'
#    compressor :clousure, :handler => ClousureCompressor.new
#
#    js "public/javascripts/application.js" do
#      compress :clousure
#      use "app/views/js/*"
#    end

class ClousureCompressor
  def compress(content)

    if ENV["JS_COMPRESS"] == "skip"
      STDERR.puts "Skipping JavaScript compressor"
      return content
    end

    if `which java`.empty?
      STDERR.puts "*** Java was not found in your path."
      STDERR.puts "*** You can install it with openjdk-6-jre-headless"
      STDERR.puts "*** Java is needed for Google Clousure Compressor was not found."
      STDERR.puts "*** The JavaScript code will be generated without any compression."
      return content
    end

    jar_file = File.expand_path("~/.javascript_closure_compiler/compiler.jar")
    if not File.exist?(jar_file)
      STDERR.puts "*** Google Clousure Compressor was not found."
      STDERR.puts "*** You still can generate the JavaScript files, but they can not be compressed."
      STDERR.puts "*** It is recommended to download http://closure-compiler.googlecode.com/files/compiler-latest.zip and extract the compiler.jar file into #{jar_file}"
      return content
    end

    require "open3"
    stdin, stdout, stderr = Open3.popen3("java", "-jar", jar_file, "--compilation_level", "SIMPLE_OPTIMIZATIONS")
    stdin.write content
    stdin.close

    STDERR.write stderr.read
    compressed = stdout.read

    compressed
  end
end