(Fix #215) better error printing in editor & extension, adds mapping for editor

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 options;
 
 import 'package:args/args.dart';
 
 class CompilerOptions {
   /** Report warnings as errors. */
@@ skipping 13 matching lines @@
 
   /** File to process by the compiler. */
   String inputFile;
 
   /** Directory where all sources are found. */
   final String baseDir;
 
   /** Directory where all output will be generated. */
   final String outputDir;
 
+  /**
+   * Whether to print error messages using the json format understood by the
+   * Dart editor.
+   */
+  final bool jsonFormat;
+
   // We could make this faster, if it ever matters.
   factory CompilerOptions() => parse(['']);
 
   CompilerOptions.fromArgs(ArgResults args)
     : warningsAsErrors = args['warnings_as_errors'],
       verbose = args['verbose'],
       clean = args['clean'],
       useColors = args['colors'],
       baseDir = args['basedir'],
       outputDir = args['out'],
       forceMangle = args['unique_output_filenames'],
+      jsonFormat = args['json_format'],
       inputFile = args.rest.length > 0 ? args.rest[0] : null;
 
   static CompilerOptions parse(List<String> arguments) {
     var parser = new ArgParser()
       ..addFlag('verbose', abbr: 'v',
           defaultsTo: false, negatable: false)
       ..addFlag('clean', help: 'Remove all generated files',
           defaultsTo: false, negatable: false)
       ..addFlag('warnings_as_errors', abbr: 'e',
           help: 'Warnings handled as errors',
           defaultsTo: false, negatable: false)
       ..addFlag('colors', help: 'Display errors/warnings in colored text',
           defaultsTo: true)
       ..addFlag('unique_output_filenames', abbr: 'u',
           help: 'Use unique names for all generated files, so they will not '
                 'have the same name as your input files, even if they are in a '
                 'different directory',
           defaultsTo: false, negatable: false)
+      ..addFlag('json_format', abbr: 'j',

[Jennifer Messerly, 2012/12/06 04:00:08]

I dunno if this one really needs a short option -- it's pretty advanced.
Presumably only passed when we're debugging build.dart

[Siggi Cherem (dart-lang), 2012/12/06 18:46:42]

Done.

+          help: 'Print error messsages in a json format easy to parse by tools,'
+                ' such as the Dart editor',
+          defaultsTo: false, negatable: false)
       ..addOption('out', abbr: 'o', help: 'Directory where to generate files'
           ' (defaults to the same directory as the source file)')
       ..addOption('basedir', help: 'Base directory where to find all source '
           'files (defaults to the source file\'s directory)')
       ..addFlag('help', abbr: 'h', help: 'Displays this help message',
           defaultsTo: false, negatable: false);
     try {
       var results = parser.parse(arguments);
       if (results['help'] || results.rest.length == 0) {
         showUsage(parser);
         return null;
       }
       return new CompilerOptions.fromArgs(results);
     } on FormatException catch (e) {
       print(e.message);
       showUsage(parser);
       return null;
     }
   }
 
   static showUsage(parser) {
     print('Usage: dwc [options...] input.html');
     print(parser.getUsage());
   }
 }