work in progress: observable implementation using detailed change records

lib/observe/set.dart

Index: lib/observe/set.dart
diff --git a/lib/observe/set.dart b/lib/observe/set.dart
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+// 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 web_ui.observe.set;
+
+import 'dart:collection';
+import 'dart:collection-dev';
+import 'package:web_ui/observe.dart';
+
+/**
+ * Represents an observable map of model values. If any items are added,
+ * removed, or replaced, then observers that are registered with
+ * [observe] will be notified.
+ */
+abstract class ObservableSet<E> implements Observable, Set<E> {
+  /**
+   * Creates a map with the default implementation.
+   */
+  factory ObservableSet() => new ObservableHashSet<E>();
+
+  /**
+   * Creates a [Map] that contains all key value pairs of [other].
+   */
+  factory ObservableSet.from(Iterable<E> other) =>
+      new ObservableHashSet<E>.from(other);
+}
+
+
+/**
+ * Represents an observable [HashSet] of model values. If any items are added,
+ * removed, or replaced, then observers that are registered with
+ * [observe] will be notified.
+ */
+// Note: this code is similar to HashSet, but adding notify calls.
+// TODO(jmesserly): also this shold extend Collection<E>, so we can delete
+// copy+paste code. Fix once we have mixins.
+class ObservableHashSet<E> extends Observable implements ObservableSet<E> {
+  // The map backing this set. The associations in this map are all
+  // of the form element -> element. If a value is not in the map,
+  // then it is not in the set.
+  final HashMap<E, E> _backingMap;
+
+  ObservableHashSet() : _backingMap = new HashMap<E, E>();
+
+  /**
+   * Creates a [Set] that contains all elements of [other].
+   */
+  factory ObservableHashSet.from(Iterable<E> other) =>
+      new ObservableHashSet<E>()..addAll(other);
+
+  void clear() {
+    if (hasObservers) {
+      for (var key in _backingMap.keys) {
+        notifyChange(ChangeRecord.REMOVE, key, key, null);
+      }
+      notifyChange(ChangeRecord.FIELD, 'length', _backingMap.length, 0);
+    }
+    _backingMap.clear();
+  }
+
+  void add(E value) {
+    int oldLen = _backingMap.length;
+    _backingMap[value] = value;
+    int newLen = _backingMap.length;
+    if (hasObservers && oldLen != newLen) {
+      notifyChange(ChangeRecord.FIELD, 'length', oldLen, newLen);
+      notifyChange(ChangeRecord.INSERT, value, null, value);
+    }
+  }
+
+  bool remove(Object value) {
+    if (observeReads) notifyRead(ChangeRecord.INDEX, value);
+    if (!_backingMap.containsKey(value)) return false;
+    _backingMap.remove(value);
+    notifyChange(ChangeRecord.REMOVE, value, value, null);
+    int len = _backingMap.length;
+    notifyChange(ChangeRecord.FIELD, 'length', len + 1, len);
+    return true;
+  }
+
+  bool contains(E value) {
+    if (observeReads) notifyRead(ChangeRecord.INDEX, value);
+    return _backingMap.containsKey(value);
+  }
+
+  Set<E> intersection(Collection<E> collection) {
+    Set<E> result = new Set<E>();
+    collection.forEach((E value) {
+      if (contains(value)) result.add(value);
+    });
+    return result;
+  }
+
+  bool isSubsetOf(Collection<E> other) {
+    return new Set<E>.from(other).containsAll(this);
+  }
+
+  bool containsAll(Collection<E> collection) {
+    return collection.every((E value) {
+      return contains(value);
+    });
+  }
+
+  bool get isEmpty => length == 0;
+
+  int get length {
+    if (observeReads) notifyRead(ChangeRecord.FIELD, 'length');
+    return _backingMap.length;
+  }
+
+  Iterator<E> get iterator => new _HashSetIterator<E>(this);
+
+  String toString() {
+    return Collections.collectionToString(this);
+  }
+
+
+  // ---------------------------------------------------------------------------
+  // Note: below this comment, methods are copy+paste from Collection<E> and
+  // Iterable<E>. Remove when we have mixins.
+  // ---------------------------------------------------------------------------
+  void addAll(Iterable<E> elements) {
+    for (E element in elements) add(element);
+  }
+
+  // TODO(jmesserly): mappedByList, takeList, skipList are not right.
+
+  void removeAll(Iterable elements) =>
+    IterableMixinWorkaround.removeAll(this, elements);
+  void retainAll(Iterable elements) =>
+      IterableMixinWorkaround.retainAll(this, elements);
+  void removeMatching(bool test(E element)) =>
+      IterableMixinWorkaround.removeMatching(this, test);
+  void retainMatching(bool test(E element)) =>
+    IterableMixinWorkaround.retainMatching(this, test);
+  Iterable mappedBy(f(E element)) =>
+      IterableMixinWorkaround.mappedByList(toList(), f);
+  Iterable<E> where(bool f(E element)) =>
+      IterableMixinWorkaround.where(this, f);
+  void forEach(void f(E element)) => IterableMixinWorkaround.forEach(this, f);
+  dynamic reduce(var initialValue,
+                 dynamic combine(var previousValue, E element)) =>
+      IterableMixinWorkaround.reduce(this, initialValue, combine);
+  bool every(bool f(E element)) => IterableMixinWorkaround.every(this, f);
+  String join([String separator]) =>
+      IterableMixinWorkaround.join(this, separator);
+  bool any(bool f(E element)) => IterableMixinWorkaround.any(this, f);
+  List<E> toList() => new List<E>.from(this);
+  Set<E> toSet() => new Set<E>.from(this);
+  E min([int compare(E a, E b)]) => IterableMixinWorkaround.min(this, compare);
+  E max([int compare(E a, E b)]) => IterableMixinWorkaround.max(this, compare);
+  Iterable<E> take(int n) => IterableMixinWorkaround.takeList(toList(), n);
+  Iterable<E> takeWhile(bool test(E value))
+      => IterableMixinWorkaround.takeWhile(this, test);
+  Iterable<E> skip(int n) => IterableMixinWorkaround.skipList(toList(), n);
+  Iterable<E> skipWhile(bool test(E value)) =>
+      IterableMixinWorkaround.skipWhile(this, test);
+  E get single => IterableMixinWorkaround.single(this);
+  E get first => IterableMixinWorkaround.first(this);
+  E get last => IterableMixinWorkaround.last(this);
+  E firstMatching(bool test(E value), { E orElse() }) =>
+      IterableMixinWorkaround.firstMatching(this, test, orElse);
+  E lastMatching(bool test(E value), {E orElse()}) =>
+      IterableMixinWorkaround.lastMatching(this, test, orElse);
+  E singleMatching(bool test(E value)) =>
+      IterableMixinWorkaround.singleMatching(this, test);
+  E elementAt(int index) => IterableMixinWorkaround.elementAt(this, index);
+}
+
+class _HashSetIterator<E> implements Iterator<E> {
+  final ObservableHashSet<E> _set;
+  final Iterator _keysIterator;
+
+  _HashSetIterator(ObservableHashSet<E> set)
+    : _set = set,
+      _keysIterator = set._backingMap.keys.iterator;
+
+  E get current {
+    E result = _keysIterator.current;
+    if (observeReads) _set.notifyRead(ChangeRecord.INDEX, result);
+    return result;
+  }
+
+  bool moveNext() {
+    if (observeReads) _set.notifyRead(ChangeRecord.FIELD, 'length');
+    bool result = _keysIterator.moveNext();
+    return result;
+  }
+}