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yaml/lib/src/yaml_node_wrapper.dart

-// 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 yaml.yaml_node_wrapper;
-
-import 'dart:collection';
-
-import 'package:collection/collection.dart' as pkg_collection;
-import 'package:source_span/source_span.dart';
-
-import 'null_span.dart';
-import 'style.dart';
-import 'yaml_node.dart';
-
-/// A wrapper that makes a normal Dart map behave like a [YamlMap].
-class YamlMapWrapper extends MapBase
-    with pkg_collection.UnmodifiableMapMixin
-    implements YamlMap {
-  final CollectionStyle style = CollectionStyle.ANY;
-
-  final Map _dartMap;
-
-  final SourceSpan span;
-
-  final Map<dynamic, YamlNode> nodes;
-
-  Map get value => this;
-
-  Iterable get keys => _dartMap.keys;
-
-  YamlMapWrapper(Map dartMap, sourceUrl)
-      : this._(dartMap, new NullSpan(sourceUrl));
-
-  YamlMapWrapper._(Map dartMap, SourceSpan span)
-      : _dartMap = dartMap,
-        span = span,
-        nodes = new _YamlMapNodes(dartMap, span);
-
-  operator [](Object key) {
-    var value = _dartMap[key];
-    if (value is Map) return new YamlMapWrapper._(value, span);
-    if (value is List) return new YamlListWrapper._(value, span);
-    return value;
-  }
-
-  int get hashCode => _dartMap.hashCode;
-
-  operator ==(Object other) =>
-      other is YamlMapWrapper && other._dartMap == _dartMap;
-}
-
-/// The implementation of [YamlMapWrapper.nodes] as a wrapper around the Dart
-/// map.
-class _YamlMapNodes extends MapBase<dynamic, YamlNode>
-    with pkg_collection.UnmodifiableMapMixin<dynamic, YamlNode> {
-  final Map _dartMap;
-
-  final SourceSpan _span;
-
-  Iterable get keys => _dartMap.keys.map((key) =>
-      new YamlScalar.internalWithSpan(key, _span));
-
-  _YamlMapNodes(this._dartMap, this._span);
-
-  YamlNode operator [](Object key) {
-    // Use "as" here because key being assigned to invalidates type propagation.
-    if (key is YamlScalar) key = (key as YamlScalar).value;
-    if (!_dartMap.containsKey(key)) return null;
-    return _nodeForValue(_dartMap[key], _span);
-  }
-
-  int get hashCode => _dartMap.hashCode;
-
-  operator ==(Object other) =>
-      other is _YamlMapNodes && other._dartMap == _dartMap;
-}
-
-// TODO(nweiz): Use UnmodifiableListMixin when issue 18970 is fixed.
-/// A wrapper that makes a normal Dart list behave like a [YamlList].
-class YamlListWrapper extends ListBase implements YamlList {
-  final CollectionStyle style = CollectionStyle.ANY;
-
-  final List _dartList;
-
-  final SourceSpan span;
-
-  final List<YamlNode> nodes;
-
-  List get value => this;
-
-  int get length => _dartList.length;
-
-  set length(int index) {
-    throw new UnsupportedError("Cannot modify an unmodifiable List.");
-  }
-
-  YamlListWrapper(List dartList, sourceUrl)
-      : this._(dartList, new NullSpan(sourceUrl));
-
-  YamlListWrapper._(List dartList, SourceSpan span)
-      : _dartList = dartList,
-        span = span,
-        nodes = new _YamlListNodes(dartList, span);
-
-  operator [](int index) {
-    var value = _dartList[index];
-    if (value is Map) return new YamlMapWrapper._(value, span);
-    if (value is List) return new YamlListWrapper._(value, span);
-    return value;
-  }
-
-  operator []=(int index, value) {
-    throw new UnsupportedError("Cannot modify an unmodifiable List.");
-  }
-
-  int get hashCode => _dartList.hashCode;
-
-  operator ==(Object other) =>
-      other is YamlListWrapper && other._dartList == _dartList;
-}
-
-// TODO(nweiz): Use UnmodifiableListMixin when issue 18970 is fixed.
-/// The implementation of [YamlListWrapper.nodes] as a wrapper around the Dart
-/// list.
-class _YamlListNodes extends ListBase<YamlNode> {
-  final List _dartList;
-
-  final SourceSpan _span;
-
-  int get length => _dartList.length;
-
-  set length(int index) {
-    throw new UnsupportedError("Cannot modify an unmodifiable List.");
-  }
-
-  _YamlListNodes(this._dartList, this._span);
-
-  YamlNode operator [](int index) => _nodeForValue(_dartList[index], _span);
-
-  operator []=(int index, value) {
-    throw new UnsupportedError("Cannot modify an unmodifiable List.");
-  }
-
-  int get hashCode => _dartList.hashCode;
-
-  operator ==(Object other) =>
-      other is _YamlListNodes && other._dartList == _dartList;
-}
-
-YamlNode _nodeForValue(value, SourceSpan span) {
-  if (value is Map) return new YamlMapWrapper._(value, span);
-  if (value is List) return new YamlListWrapper._(value, span);
-  return new YamlScalar.internalWithSpan(value, span);
-}