Add .wasParsed() to ArgResults.

pkg/args/lib/src/arg_results.dart

Index: pkg/args/lib/src/arg_results.dart
diff --git a/pkg/args/lib/src/arg_results.dart b/pkg/args/lib/src/arg_results.dart
new file mode 100644
index 0000000000000000000000000000000000000000..2e47a8e907b724f41982b7177976d8d7dd6fda54
--- /dev/null
+++ b/pkg/args/lib/src/arg_results.dart
@@ -0,0 +1,91 @@
+// Copyright (c) 2014, 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 args.src.arg_results;
+
+import 'package:collection/wrappers.dart';
+
+import 'arg_parser.dart';
+
+/// Creates a new [ArgResults].
+///
+/// Since [ArgResults] doesn't have a public constructor, this lets [Parser]
+/// get to it. This function isn't exported to the public API of the package.
+ArgResults newArgResults(ArgParser parser, Map<String, dynamic> parsed,
+      String name, ArgResults command, List<String> rest) {
+  return new ArgResults._(parser, parsed, name, command, rest);
+}
+
+/// The results of parsing a series of command line arguments using
+/// [ArgParser.parse()].
+///
+/// Includes the parsed options and any remaining unparsed command line
+/// arguments.
+class ArgResults {
+  /// The [ArgParser] whose options were parsed for these results.
+  final ArgParser _parser;
+
+  /// The option values that were parsed from arguments.
+  final Map<String, dynamic> _parsed;
+
+  /// If these are the results for parsing a command's options, this will be the
+  /// name of the command. For top-level results, this returns `null`.
+  final String name;
+
+  /// The command that was selected, or `null` if none was.
+  ///
+  /// This will contain the options that were selected for that command.
+  final ArgResults command;
+
+  /// The remaining command-line arguments that were not parsed as options or
+  /// flags.
+  ///
+  /// If `--` was used to separate the options from the remaining arguments,
+  /// it will not be included in this list unless parsing stopped before the
+  /// `--` was reached.
+  final List<String> rest;
+
+  /// Creates a new [ArgResults].
+  ArgResults._(this._parser, this._parsed, this.name, this.command,
+      List<String> rest)
+      : this.rest = new UnmodifiableListView(rest);
+
+  /// Gets the parsed command-line option named [name].
+  operator [](String name) {
+    if (!_parser.options.containsKey(name)) {
+      throw new ArgumentError('Could not find an option named "$name".');
+    }
+
+    return _parser.options[name].getOrDefault(_parsed[name]);
+  }
+
+  /// Get the names of the available options as an [Iterable].
+  ///
+  /// This includes the options whose values were parsed or that have defaults.
+  /// Options that weren't present and have no default will be omitted.
+  Iterable<String> get options {
+    var result = new Set.from(_parsed.keys);
+
+    // Include the options that have defaults.
+    _parser.options.forEach((name, option) {
+      if (option.defaultValue != null) result.add(name);
+    });
+
+    return result;
+  }
+
+  /// Returns `true` if the option with [name] was parsed from an actual
+  /// argument.
+  ///
+  /// Returns `false` if it wasn't provided and the default value or no default
+  /// value would be used instead.
+  bool wasParsed(String name) {
+    var option = _parser.options[name];
+    if (option == null) {
+      throw new ArgumentError('Could not find an option named "$name".');
+    }
+
+    return _parsed.containsKey(name);
+  }
+}