Do not match untagged strings when tags are specified.

In addition, add a --untagged option for force-selecting all untagged
strings.

lib/twine/cli.rb

@@ -36,9 +36,12 @@ module Twine
         opts.on('-l', '--lang LANGUAGES', Array, 'The language code(s) to use for the specified action.') do |langs|
           @options[:languages] = langs
         end
-        opts.on('-t', '--tags TAGS', Array, 'The tag(s) to use for the specified action. Only strings with that tag will be processed.') do |tags|
+        opts.on('-t', '--tags TAGS', Array, 'The tag(s) to use for the specified action. Only strings with that tag will be processed. Do not specify any tags to match all strings in the strings data file.') do |tags|
           @options[:tags] = tags
         end
+        opts.on('-u', '--untagged', 'If you have specified tags using the --tags flag, then only those tags will be selected. If you also want to select all strings that are untagged, then you can specify this option to do so.') do |u|
+          @options[:untagged] = true
+        end
         formats = []
         Formatters::FORMATTERS.each do |formatter|
           formats << formatter::FORMAT_NAME

lib/twine/formatters/android.rb

@@ -77,7 +77,7 @@ module Twine
           @strings.sections.each do |section|
             printed_section = false
             section.rows.each do |row|
-              if row.matches_tags?(@options[:tags])
+              if row.matches_tags?(@options[:tags], @options[:untagged])
                 if !printed_section
                   f.puts ''
                   if section.name && section.name.length > 0

lib/twine/formatters/apple.rb

@@ -75,7 +75,7 @@ module Twine
           @strings.sections.each do |section|
             printed_section = false
             section.rows.each do |row|
-              if row.matches_tags?(@options[:tags])
+              if row.matches_tags?(@options[:tags], @options[:untagged])
                 if !printed_section
                   f.puts ''
                   if section.name && section.name.length > 0

lib/twine/stringsfile.rb

@@ -22,13 +22,13 @@ module Twine
       @translations = {}
     end
     
-    def matches_tags?(tags)
+    def matches_tags?(tags, include_untagged)
       if tags == nil || tags.length == 0
         # The user did not specify any tags. Everything passes.
         return true
       elsif @tags == nil || @tags.length == 0
-        # This row has no tags. Never match
-        return false
+        # This row has no tags.
+        return (include_untagged) ? true : false
       else
         tags.each do |tag|
           if @tags.include? tag

test/fixtures/test-output-1.txt

@@ -7,4 +7,5 @@
 	<string name="key1">key1-french</string>
 	<string name="key2">key2-french</string>
 	<string name="key3">key3-english</string>
+	<string name="key4">key4-english</string>
 </resources>