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diff --git a/Firestore/Source/Local/FSTLocalViewChanges.mm b/Firestore/Source/Local/FSTLocalViewChanges.mm
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+++ b/Firestore/Source/Local/FSTLocalViewChanges.mm
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+/*
+ * Copyright 2017 Google
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#import "Firestore/Source/Local/FSTLocalViewChanges.h"
+
+#import "Firestore/Source/Core/FSTViewSnapshot.h"
+#import "Firestore/Source/Model/FSTDocument.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface FSTLocalViewChanges ()
+- (instancetype)initWithQuery:(FSTQuery *)query
+                    addedKeys:(FSTDocumentKeySet *)addedKeys
+                  removedKeys:(FSTDocumentKeySet *)removedKeys NS_DESIGNATED_INITIALIZER;
+@end
+
+@implementation FSTLocalViewChanges
+
++ (instancetype)changesForViewSnapshot:(FSTViewSnapshot *)viewSnapshot {
+  FSTDocumentKeySet *addedKeys = [FSTDocumentKeySet keySet];
+  FSTDocumentKeySet *removedKeys = [FSTDocumentKeySet keySet];
+
+  for (FSTDocumentViewChange *docChange in viewSnapshot.documentChanges) {
+    switch (docChange.type) {
+      case FSTDocumentViewChangeTypeAdded:
+        addedKeys = [addedKeys setByAddingObject:docChange.document.key];
+        break;
+
+      case FSTDocumentViewChangeTypeRemoved:
+        removedKeys = [removedKeys setByAddingObject:docChange.document.key];
+        break;
+
+      default:
+        // Do nothing.
+        break;
+    }
+  }
+
+  return [self changesForQuery:viewSnapshot.query addedKeys:addedKeys removedKeys:removedKeys];
+}
+
++ (instancetype)changesForQuery:(FSTQuery *)query
+                      addedKeys:(FSTDocumentKeySet *)addedKeys
+                    removedKeys:(FSTDocumentKeySet *)removedKeys {
+  return
+      [[FSTLocalViewChanges alloc] initWithQuery:query addedKeys:addedKeys removedKeys:removedKeys];
+}
+
+- (instancetype)initWithQuery:(FSTQuery *)query
+                    addedKeys:(FSTDocumentKeySet *)addedKeys
+                  removedKeys:(FSTDocumentKeySet *)removedKeys {
+  self = [super init];
+  if (self) {
+    _query = query;
+    _addedKeys = addedKeys;
+    _removedKeys = removedKeys;
+  }
+  return self;
+}
+
+@end
+
+NS_ASSUME_NONNULL_END