Support for @mixin, @include and @extend

pkg/csslib/lib/src/options.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library csslib.src.options;
 
 import 'package:args/args.dart';
 
 class PreprocessorOptions {
+  /** Generate polyfill code (e.g., var, etc.) */
+  final bool polyfill;
+
   /** Report warnings as errors. */
   final bool warningsAsErrors;
 
   /** Throw an exception on warnings (not used by command line tool). */
   final bool throwOnWarnings;
 
   /** Throw an exception on errors (not used by command line tool). */
   final bool throwOnErrors;
 
   /** True to show informational messages. The `--verbose` flag. */
@@ skipping 21 matching lines @@
   factory PreprocessorOptions() => parse(['']);
 
   PreprocessorOptions.fromArgs(ArgResults args)
     : warningsAsErrors = args['warnings_as_errors'],
       throwOnWarnings = args['throw_on_warnings'],
       throwOnErrors = args['throw_on_errors'],
       verbose = args['verbose'],
       checked = args['checked'],
       lessSupport = args['less'],
       useColors = args['colors'],
+      polyfill = args['polyfill'],
       inputFile = args.rest.length > 0 ? args.rest[0] : null;
 
   // tool.dart [options...] <css file>
   static PreprocessorOptions parse(List<String> arguments) {
     var parser = new ArgParser()
       ..addFlag('verbose', abbr: 'v', defaultsTo: false, negatable: false,
           help: 'Display detail info')
       ..addFlag('checked', defaultsTo: false, negatable: false,
           help: 'Validate CSS values invalid value display a warning message')
       ..addFlag('less', defaultsTo: true, negatable: true,
           help: 'Supports subset of Less syntax')
       ..addFlag('suppress_warnings', defaultsTo: true,
           help: 'Warnings not displayed')
       ..addFlag('warnings_as_errors', defaultsTo: false,
           help: 'Warning handled as errors')
       ..addFlag('throw_on_errors', defaultsTo: false,
           help: 'Throw on errors encountered')
       ..addFlag('throw_on_warnings', defaultsTo: false,
           help: 'Throw on warnings encountered')
       ..addFlag('colors', defaultsTo: true,
           help: 'Display errors/warnings in colored text')
+      ..addFlag('polyfill', defaultsTo: false,
+          help: 'Generate polyfill for new CSS features')
       ..addFlag('help', abbr: 'h', defaultsTo: false, negatable: false,
           help: 'Displays this help message');
 
     try {
       var results = parser.parse(arguments);
       if (results['help'] || results.rest.length == 0) {
         showUsage(parser);
         return null;
       }
       return new PreprocessorOptions.fromArgs(results);
     } on FormatException catch (e) {
       print(e.message);
       showUsage(parser);
       return null;
     }
   }
 
   static showUsage(parser) {
     print('Usage: css [options...] input.css');
     print(parser.getUsage());
   }
 
 }