Add .wasParsed() to ArgResults.

pkg/args/lib/src/options.dart

 library options;
 
 import 'package:collection/wrappers.dart';
 
 /// A command-line option. Includes both flags and options which take a value.
 class Option {
   final String name;
   final String abbreviation;
   final List<String> allowed;
   final defaultValue;
   final Function callback;
   final String help;
   final String valueHelp;
   final Map<String, String> allowedHelp;
-  final bool isFlag;
+  final OptionType type;
   final bool negatable;
-  final bool allowMultiple;
   final bool hide;
 
+  /// Whether the option is boolean-valued flag.
+  bool get isFlag => type == OptionType.FLAG;
+
+  /// Whether the option takes a single value.
+  bool get isSingle => type == OptionType.SINGLE;
+
+  /// Whether the option allows multiple values.
+  bool get isMultiple => type == OptionType.MULTIPLE;
+
   Option(this.name, this.abbreviation, this.help, this.valueHelp,
       List<String> allowed, Map<String, String> allowedHelp, this.defaultValue,
-      this.callback, {this.isFlag, this.negatable, this.allowMultiple: false,
-      this.hide: false}) :
+      this.callback, this.type, {this.negatable, this.hide: false}) :
         this.allowed = allowed == null ?
             null : new UnmodifiableListView(allowed),
         this.allowedHelp = allowedHelp == null ?
             null : new UnmodifiableMapView(allowedHelp) {
 
     if (name.isEmpty) {
       throw new ArgumentError('Name cannot be empty.');
     } else if (name.startsWith('-')) {
       throw new ArgumentError('Name $name cannot start with "-".');
     }
 
     // Ensure name does not contain any invalid characters.
     if (_invalidChars.hasMatch(name)) {
       throw new ArgumentError('Name "$name" contains invalid characters.');
     }
 
     if (abbreviation != null) {
       if (abbreviation.length != 1) {
         throw new ArgumentError('Abbreviation must be null or have length 1.');
       } else if(abbreviation == '-') {
         throw new ArgumentError('Abbreviation cannot be "-".');
       }
 
       if (_invalidChars.hasMatch(abbreviation)) {
         throw new ArgumentError('Abbreviation is an invalid character.');
       }
     }
   }
 
+  /// Returns [value] if non-`null`, otherwise returns the default value for
+  /// this option.
+  ///
+  /// For single-valued options, it will be [defaultValue] if set or `null`
+  /// otherwise. For multiple-valued options, it will be an empty list or a
+  /// list containing [defaultValue] if set.
+  dynamic getOrDefault(value) {
+    if (value != null) return value;
+
+    if (!isMultiple) return defaultValue;
+    if (defaultValue != null) return [defaultValue];
+    return [];
+  }
+
   static final _invalidChars = new RegExp(r'''[ \t\r\n"'\\/]''');
 }
+
+/// What kinds of values an option accepts.
+class OptionType {
+  /// An option that can only be `true` or `false`.
+  ///
+  /// The presence of the option name itself in the argument list means `true`.
+  static const FLAG = const OptionType("OptionType.FLAG");
+
+  /// An option that takes a single value.
+  ///
+  /// Examples:
+  ///
+  ///     --mode debug
+  ///     -mdebug
+  ///     --mode=debug
+  ///
+  /// If the option is passed more than once, the last one wins.
+  static const SINGLE = const OptionType("OptionType.SINGLE");
+
+  /// An option that allows multiple values.
+  ///
+  /// Example:
+  ///
+  ///     --output text --output xml
+  ///
+  /// In the parsed [ArgResults], a multiple-valued option will always return
+  /// a list, even if one or no values were passed.
+  static const MULTIPLE = const OptionType("OptionType.MULTIPLE");
+
+  const OptionType(this.name);

[nweiz, 2014/07/14 21:22:34]

This should be private.

[Bob Nystrom, 2014/07/15 21:05:23]

Done.

+
+  final String name;

[nweiz, 2014/07/14 21:22:34]

Nit: fields go above constructors.

[Bob Nystrom, 2014/07/15 21:05:23]

Done.

+}