Options parsing cleanup.

pkg/analyzer-experimental/lib/options.dart

 // Copyright (c) 2013, 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';
 
 import 'dart:io';
 
@@ skipping 96 matching lines @@
 class _CommandLineParser {
 
   final List<String> _knownFlags;
   final ArgParser _parser;
 
   /** Creates a new command line parser */
   _CommandLineParser()
     : _knownFlags = <String>[],
       _parser = new ArgParser();
 
-
   /**
    * Defines a flag.
    *
    * See [ArgParser.addFlag()].
    */
   void addFlag(String name, {String abbr, String help, bool defaultsTo: false,
       bool negatable: true, void callback(bool value)}) {
     _knownFlags.add(name);
     _parser.addFlag(name, abbr: abbr, help: help, defaultsTo: defaultsTo,
         negatable: negatable, callback: callback);
   }
 
   /**
    * Defines a value-taking option.
    *
    * See [ArgParser.addOption()].
    */
   void addOption(String name, {String abbr, String help, List<String> allowed,
       Map<String, String> allowedHelp, String defaultsTo,
       void callback(value), bool allowMultiple: false}) {
     _parser.addOption(name, abbr: abbr, help: help, allowed: allowed,
         allowedHelp: allowedHelp, defaultsTo: defaultsTo, callback: callback,
         allowMultiple: allowMultiple);
   }
 
-
   /**
    * Generates a string displaying usage information for the defined options.
    *
    * See [ArgParser.getUsage()].
    */
   String getUsage() => _parser.getUsage();
 
   /**
    * Parses [args], a list of command-line arguments, matches them against the
    * flags and options defined by this parser, and returns the result.
    *
    * See [ArgParser].
    */
   ArgResults parse(List<String> args) => _parser.parse(_filterUnknowns(args));
 
   List<String> _filterUnknowns(args) {
 
     // Only filter args if the ignore flag is specified.
     if (!args.contains('--ignore_unrecognized_flags')) {
       return args;
     }
 
     // Filter all unrecognized flags and options.
-    var filtered = <String>[];
-    for (var i=0; i < args.length; ++i) {
-      var arg = args[i];
-      if (arg.startsWith('--') && arg.length > 2) {
-        if (!_knownFlags.contains(arg.substring(2))) {
-          //"eat" params by advancing to the next flag/option
-          i = _getNextFlagIndex(args, i);
-        } else {
-          filtered.add(arg);
-        }
-      } else {
-        filtered.add(arg);
-      }
-    }
+    return args.where((arg) => !arg.startsWith('--') ||
+        _knownFlags.contains(arg.substring(2)));
 
-    return filtered;
-  }
-
-  _getNextFlagIndex(args, i) {
-    for ( ; i < args.length; ++i) {
-      if (args[i].startsWith('--')) {
-        return i;
-      }
-    }
-    return i;
   }
 
 }