Unifying compiler context

pkg/front_end/lib/src/fasta/command_line.dart

 // Copyright (c) 2016, 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 fasta.command_line;
 
 import 'fasta_codes.dart' show Message, templateFastaCLIArgumentRequired;
 
 import 'deprecated_problems.dart' show deprecated_inputError;
 
 import 'problems.dart' show unhandled;
 
 deprecated_argumentError(Message usage, String message) {
   if (usage != null) print(usage.message);
   deprecated_inputError(null, null, message);
 }
 
 argumentError(Message usage, Message message) {
   if (usage != null) print(usage.message);
   deprecated_inputError(null, null, message.message);
 }
 
 class ParsedArguments {
   final Map<String, dynamic> options = <String, dynamic>{};
   final List<String> arguments = <String>[];
 
   toString() => "ParsedArguments($options, $arguments)";
 }
 
+/// Abstract parser for command-line options.
 class CommandLine {
   final Map<String, dynamic> options;
 
   final List<String> arguments;
 
   final Message usage;
 
   CommandLine.parsed(ParsedArguments p, this.usage)
       : this.options = p.options,
         this.arguments = p.arguments {
@@ skipping 141 matching lines @@
       } else if (argument == "/?" || argument == "/h") {
         result.options[argument] = true;
       } else {
         result.arguments.add(argument);
       }
     }
     result.arguments.addAll(nonOptions);
     return result;
   }
 }