Bring the YAML package's style up to modern standards.

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;
+library yaml.map;
+
+import 'dart:collection';
+
+import 'package:collection/collection.dart';
 
 import 'deep_equals.dart';
 import 'utils.dart';
 
-/// This class wraps behaves almost identically to the normal Dart Map
+/// This class behaves almost identically to the normal Dart [Map]
 /// implementation, with the following differences:
 ///
-///  *  It allows null, NaN, boolean, list, and map keys.
+///  *  It NaN, list, and map keys.

[Bob Nystrom, 2014/05/09 00:18:56]

"It NaN" -> "It allows NaN".

[nweiz, 2014/05/20 00:15:07]

Done.

 ///  *  It defines `==` structurally. That is, `yamlMap1 == yamlMap2` if they
 ///     have the same contents.
 ///  *  It has a compatible [hashCode] method.
-class YamlMap implements Map {
-  final Map _map;
+///
+/// This class is deprecated. In future releases, this package will use
+/// a [HashMap] with a custom equality operation rather than a custom class.
+@Deprecated('1.0.0')
+class YamlMap extends DelegatingMap {
+  YamlMap()
+      : super(new HashMap(equals: deepEquals, hashCode: hashCodeFor));
 
-  YamlMap() : _map = new Map();
-
-  YamlMap.from(Map map) : _map = new Map.from(map);
-
-  YamlMap._wrap(this._map);
-
-  void addAll(Map other) {
-    other.forEach((key, value) {
-      this[key] = value;
-    });
+  YamlMap.from(Map map)
+      : super(new HashMap(equals: deepEquals, hashCode: hashCodeFor)) {
+    addAll(map);
   }
 
-  bool containsValue(value) => _map.containsValue(value);
-  bool containsKey(key) => _map.containsKey(_wrapKey(key));
-  operator [](key) => _map[_wrapKey(key)];
-  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);
+  int get hashCode => hashCodeFor(this);
 
   bool operator ==(other) {
     if (other is! YamlMap) return false;
     return deepEquals(this, other);
   }
-
-  /// Wraps an object for use as a key in the map.
-  _wrapKey(obj) {
-    if (obj != null && obj is! bool && obj is! List &&
-        (obj is! double || !obj.isNan) &&
-        (obj is! Map || obj is YamlMap)) {
-      return obj;
-    } else if (obj is Map) {
-      return new YamlMap._wrap(obj);
-    }
-    return new _WrappedHashKey(obj);
-  }
-
-  /// Unwraps an object that was used as a key in the map.
-  _unwrapKey(obj) => obj is _WrappedHashKey ? obj.value : obj;
 }
-
-/// A class for wrapping normally-unhashable objects that are being used as keys
-/// in a YamlMap.
-class _WrappedHashKey {
-  final value;
-
-  _WrappedHashKey(this.value);
-
-  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);
-  }
-}