Adding isNotEmpty property to collection and string.

pkg/yaml/lib/src/yaml_map.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 yaml_map;
 
 import 'deep_equals.dart';
 import 'utils.dart';
 
 /// This class wraps behaves almost identically to the normal Dart Map
@@ skipping 18 matching lines @@
   operator []=(key, value) { _map[_wrapKey(key)] = value; }
   putIfAbsent(key, ifAbsent()) => _map.putIfAbsent(_wrapKey(key), ifAbsent);
   remove(key) => _map.remove(_wrapKey(key));
   void clear() => _map.clear();
   void forEach(void f(key, value)) =>
     _map.forEach((k, v) => f(_unwrapKey(k), v));
   Iterable get keys => _map.keys.map(_unwrapKey);
   Iterable get values => _map.values;
   int get length => _map.length;
   bool get isEmpty => _map.isEmpty;
+  bool get isNotEmpty => map.isNotEmpty;
   String toString() => _map.toString();
 
   int get hashCode => hashCodeFor(_map);
 
   bool operator ==(other) {
     if (other is! YamlMap) return false;
     return deepEquals(this, other);
   }
 
   /// Wraps an object for use as a key in the map.
@@ skipping 22 matching lines @@
   int get hashCode => hashCodeFor(value);
 
   String toString() => value.toString();
 
   /// This is defined as both values being structurally equal.
   bool operator ==(other) {
     if (other is! _WrappedHashKey) return false;
     return deepEquals(this.value, other.value);
   }
 }