Adding Django formatter

This will enable the creation of Django formated translation files as described here: https://docs.djangoproject.com/en/dev/topics/i18n/translation/

lib/twine/formatters/django.rb

@@ -0,0 +1,143 @@
+module Twine
+  module Formatters
+    class Django < Abstract
+      FORMAT_NAME = 'django'
+      EXTENSION = '.po'
+      DEFAULT_FILE_NAME = 'strings.po'
+
+      def self.can_handle_directory?(path)
+      Dir.entries(path).any? { |item| /^.+\.po$/.match(item) }
+      end
+
+      def default_file_name
+        return DEFAULT_FILE_NAME
+      end
+
+      def determine_language_given_path(path)
+          path_arr = path.split(File::SEPARATOR)
+          path_arr.each do |segment|
+              match = /(..)\.po$/.match(segment)
+              if match
+                  return match[1]
+              end
+          end
+          
+        return
+      end
+
+      def read_file(path, lang)
+        comment_regex = /#.? *"(.*)"$/
+        key_regex = /msgid *"(.*)"$/
+        value_regex = /msgstr *"(.*)"$/m
+
+        encoding = Twine::Encoding.encoding_for_path(path)
+        sep = nil
+        if !encoding.respond_to?(:encode)
+          # This code is not necessary in 1.9.3 and does not work as it did in 1.8.7.
+          if encoding.end_with? 'LE'
+            sep = "\x0a\x00"
+          elsif encoding.end_with? 'BE'
+            sep = "\x00\x0a"
+          else
+            sep = "\n"
+          end
+        end
+
+        if encoding.index('UTF-16')
+          mode = "rb:#{encoding}"
+        else
+          mode = "r:#{encoding}"
+        end
+
+        File.open(path, mode) do |f|
+          last_comment = nil
+          while line = (sep) ? f.gets(sep) : f.gets
+            if encoding.index('UTF-16')
+              if line.respond_to? :encode!
+                line.encode!('UTF-8')
+              else
+                require 'iconv'
+                line = Iconv.iconv('UTF-8', encoding, line).join
+              end
+            end
+            if @options[:consume_comments]
+               comment_match = comment_regex.match(line)
+               if comment_match
+                   comment = comment_match[1]
+               end
+            else
+                comment = nil
+            end
+            key_match = key_regex.match(line)
+            if key_match
+                key = key_match[1].gsub('\\"', '"')
+            end
+            value_match = value_regex.match(line)
+            if value_match
+                value = value_match[1].gsub(/"\n"/, '').gsub('\\"', '"')
+            end
+
+
+            if key and key.length > 0 and value and value.length > 0
+                set_translation_for_key(key, lang, value)
+                if comment and comment.length > 0 and !comment.start_with?("--------- ")
+                    set_comment_for_key(key, comment)
+                end
+                comment = nil
+            end
+
+          end
+        end
+      end
+
+      def write_file(path, lang)
+        default_lang = @strings.language_codes[0]
+        encoding = @options[:output_encoding] || 'UTF-8'
+        File.open(path, "w:#{encoding}") do |f|
+          f.puts "##\n # Django Strings File\n # Generated by Twine #{Twine::VERSION}\n # Language: #{lang}\n "
+          @strings.sections.each do |section|
+            printed_section = false
+            section.rows.each do |row|
+              if row.matches_tags?(@options[:tags], @options[:untagged])
+                f.puts ''
+                if !printed_section
+                  if section.name && section.name.length > 0
+                    f.print "#--------- #{section.name} ---------#\n\n"
+                  end
+                  printed_section = true
+                end
+                
+                basetrans = row.translated_string_for_lang(default_lang)
+
+                key = row.key
+                key = key.gsub('"', '\\\\"')
+
+                value = row.translated_string_for_lang(lang, default_lang)
+                if value
+                  value = value.gsub('"', '\\\\"')
+
+                  comment = row.comment
+
+                  if comment
+                     comment = comment.gsub('"', '\\\\"')
+                  end
+
+                  if comment && comment.length > 0
+                    f.print "#. #{comment} \n"
+                  end
+
+                  if basetrans && basetrans.length > 0
+                    f.print "# base translation: \"#{basetrans}\"\n"
+                  end
+
+                  f.print "msgid \"#{key}\"\n"
+                  f.print "msgstr \"#{value}\"\n"
+                end
+              end
+            end
+          end
+        end
+      end
+    end
+  end
+end