opal · Mar 23, 2014 · Mar 23, 2014
Showing with 54 additions and 23 deletions.

+54 −23 lib/opal/util.rb
diff --git a/lib/opal/util.rb b/lib/opal/util.rb
@@ -2,36 +2,67 @@ module Opal
   module Util
     extend self
 
-    def null
-      if (/mswin|mingw/ =~ RUBY_PLATFORM).nil?
-        '/dev/null'
-      else
-        'nul'
-      end
-    end
-
     # Used for uglifying source to minify
     def uglify(str)
-      IO.popen('uglifyjs 2> ' + null, 'r+') do |i|
-        i.puts str
-        i.close_write
-        return i.read
-      end
-    rescue Errno::ENOENT, Errno::EPIPE, Errno::EINVAL
-      $stderr.puts '"uglifyjs" command not found (install with: "npm install -g uglify-js")'
-      nil
+      uglifyjs = DigestSourceCommand.new(:uglifyjs, nil, ' (install with: "npm install -g uglify-js")')
+      uglifyjs.digest(str)
     end
 
     # Gzip code to check file size
     def gzip(str)
-      IO.popen('gzip -f 2> ' + null, 'r+') do |i|
-        i.puts str
-        i.close_write
-        return i.read
+      gzip = DigestSourceCommand.new(:gzip, '-f', ', it is required to produce the .gz version')
+      gzip.digest(str)
+    end
+
+
+    class DigestSourceCommand
+      def initialize(command, options, message)
+        @command, @options, @message = command, options, message
+      end
+      attr_reader :command, :options, :message
+
+      def digest(source)
+        return unless command_installed? command, message
+        IO.popen("#{command} #{options} #{hide_stderr}", 'r+') do |i|
+          i.puts source
+          i.close_write
+          i.read
+        end
+      end
+
+
+      private
+
+      def hide_stderr
+        if (/mswin|mingw/ =~ RUBY_PLATFORM).nil?
+          '2> /dev/null'
+        else
+          '2> nul'
+        end
+      end
+
+      # Code from http://stackoverflow.com/questions/2108727/which-in-ruby-checking-if-program-exists-in-path-from-ruby
+      def which(cmd)
+        exts = ENV['PATHEXT'] ? ENV['PATHEXT'].split(';') : ['']
+        ENV['PATH'].split(File::PATH_SEPARATOR).each do |path|
+          exts.each { |ext|
+            exe = File.join(path, "#{cmd}#{ext}")
+            return exe if File.executable? exe
+          }
+        end
+        nil
+      end
+
+      INSTALLED = {}
+      def command_installed?(cmd, install_comment)
+        cmd = cmd.to_s
+        INSTALLED.fetch(cmd) do
+          unless INSTALLED[cmd] = which(cmd) != nil
+            $stderr.puts %Q("#{cmd}" command not found#{install_comment})
+          end
+        end
       end
-    rescue Errno::ENOENT, Errno::EPIPE, Errno::EINVAL
-      $stderr.puts '"gzip" command not found, it is required to produce the .gz version'
-      nil
     end
+
   end
 end