Add observatory_pub_packages snapshot to third_party

observatory_pub_packages/observe/src/observable_map.dart

+// Copyright (c) 2013, 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 observe.src.observable_map;
+
+import 'dart:collection';
+import 'package:observe/observe.dart';
+
+
+// TODO(jmesserly): this needs to be faster. We currently require multiple
+// lookups per key to get the old value.
+// TODO(jmesserly): this doesn't implement the precise interfaces like
+// LinkedHashMap, SplayTreeMap or HashMap. However it can use them for the
+// backing store.
+
+// TODO(jmesserly): should we summarize map changes like we do for list changes?
+class MapChangeRecord<K, V> extends ChangeRecord {
+  // TODO(jmesserly): we could store this more compactly if it matters, with
+  // subtypes for inserted and removed.
+
+  /// The map key that changed.
+  final K key;
+
+  /// The previous value associated with this key.
+  final V oldValue;
+
+  /// The new value associated with this key.
+  final V newValue;
+
+  /// True if this key was inserted.
+  final bool isInsert;
+
+  /// True if this key was removed.
+  final bool isRemove;
+
+  MapChangeRecord(this.key, this.oldValue, this.newValue)
+      : isInsert = false, isRemove = false;
+
+  MapChangeRecord.insert(this.key, this.newValue)
+      : isInsert = true, isRemove = false, oldValue = null;
+
+  MapChangeRecord.remove(this.key, this.oldValue)
+      : isInsert = false, isRemove = true, newValue = null;
+
+  String toString() {
+    var kind = isInsert ? 'insert' : isRemove ? 'remove' : 'set';
+    return '#<MapChangeRecord $kind $key from: $oldValue to: $newValue>';
+  }
+}
+
+/// Represents an observable map of model values. If any items are added,
+/// removed, or replaced, then observers that are listening to [changes]
+/// will be notified.
+class ObservableMap<K, V> extends ChangeNotifier implements Map<K, V> {
+  final Map<K, V> _map;
+
+  /// Creates an observable map.
+  ObservableMap() : _map = new HashMap<K, V>();
+
+  /// Creates a new observable map using a [LinkedHashMap].
+  ObservableMap.linked() : _map = new LinkedHashMap<K, V>();
+
+  /// Creates a new observable map using a [SplayTreeMap].
+  ObservableMap.sorted() : _map = new SplayTreeMap<K, V>();
+
+  /// Creates an observable map that contains all key value pairs of [other].
+  /// It will attempt to use the same backing map type if the other map is a
+  /// [LinkedHashMap], [SplayTreeMap], or [HashMap]. Otherwise it defaults to
+  /// [HashMap].
+  ///
+  /// Note this will perform a shallow conversion. If you want a deep conversion
+  /// you should use [toObservable].
+  factory ObservableMap.from(Map<K, V> other) {
+    return new ObservableMap<K, V>.createFromType(other)..addAll(other);
+  }
+
+  /// Like [ObservableMap.from], but creates an empty map.
+  factory ObservableMap.createFromType(Map<K, V> other) {
+    ObservableMap result;
+    if (other is SplayTreeMap) {
+      result = new ObservableMap<K, V>.sorted();
+    } else if (other is LinkedHashMap) {
+      result = new ObservableMap<K, V>.linked();
+    } else {
+      result = new ObservableMap<K, V>();
+    }
+    return result;
+  }
+
+  @reflectable Iterable<K> get keys => _map.keys;
+
+  @reflectable Iterable<V> get values => _map.values;
+
+  @reflectable int get length =>_map.length;
+
+  @reflectable bool get isEmpty => length == 0;
+
+  @reflectable bool get isNotEmpty => !isEmpty;
+
+  @reflectable bool containsValue(Object value) => _map.containsValue(value);
+
+  @reflectable bool containsKey(Object key) => _map.containsKey(key);
+
+  @reflectable V operator [](Object key) => _map[key];
+
+  @reflectable void operator []=(K key, V value) {
+    if (!hasObservers) {
+      _map[key] = value;
+      return;
+    }
+
+    int len = _map.length;
+    V oldValue = _map[key];
+
+    _map[key] = value;
+
+    if (len != _map.length) {
+      notifyPropertyChange(#length, len, _map.length);
+      notifyChange(new MapChangeRecord.insert(key, value));
+      _notifyKeysValuesChanged();
+    } else if (oldValue != value) {
+      notifyChange(new MapChangeRecord(key, oldValue, value));
+      _notifyValuesChanged();
+    }
+  }
+
+  void addAll(Map<K, V> other) {
+    other.forEach((K key, V value) { this[key] = value; });
+  }
+
+  V putIfAbsent(K key, V ifAbsent()) {
+    int len = _map.length;
+    V result = _map.putIfAbsent(key, ifAbsent);
+    if (hasObservers && len != _map.length) {
+      notifyPropertyChange(#length, len, _map.length);
+      notifyChange(new MapChangeRecord.insert(key, result));
+      _notifyKeysValuesChanged();
+    }
+    return result;
+  }
+
+  V remove(Object key) {
+    int len = _map.length;
+    V result =  _map.remove(key);
+    if (hasObservers && len != _map.length) {
+      notifyChange(new MapChangeRecord.remove(key, result));
+      notifyPropertyChange(#length, len, _map.length);
+      _notifyKeysValuesChanged();
+    }
+    return result;
+  }
+
+  void clear() {
+    int len = _map.length;
+    if (hasObservers && len > 0) {
+      _map.forEach((key, value) {
+        notifyChange(new MapChangeRecord.remove(key, value));
+      });
+      notifyPropertyChange(#length, len, 0);
+      _notifyKeysValuesChanged();
+    }
+    _map.clear();
+  }
+
+  void forEach(void f(K key, V value)) => _map.forEach(f);
+
+  String toString() => Maps.mapToString(this);
+
+  // Note: we don't really have a reasonable old/new value to use here.
+  // But this should fix "keys" and "values" in templates with minimal overhead.
+  void _notifyKeysValuesChanged() {
+    notifyChange(new PropertyChangeRecord(this, #keys, null, null));
+    _notifyValuesChanged();
+  }
+
+  void _notifyValuesChanged() {
+    notifyChange(new PropertyChangeRecord(this, #values, null, null));
+  }
+}