Restructure YAML package suitable for pub lish

utils/pub/yaml/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.
-
-part of yaml;
-
-/// This class wraps behaves almost identically to the normal Dart Map
-/// implementation, with the following differences:
-///
-///  *  It allows null, NaN, boolean, list, and map keys.
-///  *  It defines `==` structurally. That is, `yamlMap1 == yamlMap2` if they
-///     have the same contents.
-///  *  It has a compatible [hashCode] method.
-class YamlMap implements Map {
-  Map _map;
-
-  YamlMap() : _map = new Map();
-
-  YamlMap.from(Map map) : _map = new Map.from(map);
-
-  YamlMap._wrap(this._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.mappedBy(_unwrapKey);
-  Iterable get values => _map.values;
-  int get length => _map.length;
-  bool get isEmpty => _map.isEmpty;
-  String toString() => _map.toString();
-
-  int get hashCode => _hashCode(_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.
-  _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 {
-  var value;
-
-  _WrappedHashKey(this.value);
-
-  int get hashCode => _hashCode(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);
-  }
-}
-
-/// Returns the hash code for [obj]. This includes null, true, false, maps, and
-/// lists. Also handles self-referential structures.
-int _hashCode(obj, [List parents]) {
-  if (parents == null) {
-    parents = [];
-  } else if (parents.any((p) => identical(p, obj))) {
-    return -1;
-  }
-
-  parents.add(obj);
-  try {
-    if (obj == null) return 0;
-    if (obj == true) return 1;
-    if (obj == false) return 2;
-    if (obj is Map) {
-      return _hashCode(obj.keys, parents) ^
-        _hashCode(obj.values, parents);
-    }
-    if (obj is Iterable) {
-      // This is probably a really bad hash function, but presumably we'll get
-      // this in the standard library before it actually matters.
-      int hash = 0;
-      for (var e in obj) {
-        hash ^= _hashCode(e, parents);
-      }
-      return hash;
-    }
-    return obj.hashCode;
-  } finally {
-    parents.removeLast();
-  }
-}