blob: c6041a4ff788c554295f2b1a38c5ddf13a1cf1bb [file] [log] [blame]
// Copyright (c) 2016, 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 observable.src.differs;
/// Determines differences between two maps, returning [MapChangeRecord]s.
/// While [MapChangeRecord] has more information and can be replayed they carry
/// a more significant cost to calculate and create and should only be used when
/// the details in the record will actually be used.
/// See also [EqualityDiffer] for a simpler comparison.
class MapDiffer<K, V> implements Differ<Map<K, V>> {
const MapDiffer();
List<MapChangeRecord<K, V>> diff(Map<K, V> oldValue, Map<K, V> newValue) {
if (identical(oldValue, newValue)) {
return ChangeRecord.NONE;
final changes = <MapChangeRecord<K, V>>[];
oldValue.forEach((oldK, oldV) {
final newV = newValue[oldK];
if (newV == null && !newValue.containsKey(oldK)) {
changes.add(new MapChangeRecord<K, V>.remove(oldK, oldV));
} else if (newV != oldV) {
changes.add(new MapChangeRecord<K, V>(oldK, oldV, newV));
newValue.forEach((newK, newV) {
if (!oldValue.containsKey(newK)) {
changes.add(new MapChangeRecord<K, V>.insert(newK, newV));
return freezeInDevMode(changes);