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diff --git a/Firestore/Source/Core/FSTViewSnapshot.h b/Firestore/Source/Core/FSTViewSnapshot.h
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+++ b/Firestore/Source/Core/FSTViewSnapshot.h
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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 <Foundation/Foundation.h>
+
+@class FSTDocument;
+@class FSTQuery;
+@class FSTDocumentSet;
+@class FSTViewSnapshot;
+
+NS_ASSUME_NONNULL_BEGIN
+
+#pragma mark - FSTDocumentViewChange
+
+/**
+ * The types of changes that can happen to a document with respect to a view.
+ * NOTE: We sort document changes by their type, so the ordering of this enum is significant.
+ */
+typedef NS_ENUM(NSInteger, FSTDocumentViewChangeType) {
+  FSTDocumentViewChangeTypeRemoved = 0,
+  FSTDocumentViewChangeTypeAdded,
+  FSTDocumentViewChangeTypeModified,
+  FSTDocumentViewChangeTypeMetadata,
+};
+
+/** A change to a single document's state within a view. */
+@interface FSTDocumentViewChange : NSObject
+
+- (id)init __attribute__((unavailable("Use a static constructor method.")));
+
++ (instancetype)changeWithDocument:(FSTDocument *)document type:(FSTDocumentViewChangeType)type;
+
+/** The type of change for the document. */
+@property(nonatomic, assign, readonly) FSTDocumentViewChangeType type;
+/** The document whose status changed. */
+@property(nonatomic, strong, readonly) FSTDocument *document;
+
+@end
+
+#pragma mark - FSTDocumentChangeSet
+
+/** The possibly states a document can be in w.r.t syncing from local storage to the backend. */
+typedef NS_ENUM(NSInteger, FSTSyncState) {
+  FSTSyncStateNone = 0,
+  FSTSyncStateLocal,
+  FSTSyncStateSynced,
+};
+
+/** A set of changes to documents with respect to a view. This set is mutable. */
+@interface FSTDocumentViewChangeSet : NSObject
+
+/** Returns a new empty change set. */
++ (instancetype)changeSet;
+
+/** Takes a new change and applies it to the set. */
+- (void)addChange:(FSTDocumentViewChange *)change;
+
+/** Returns the set of all changes tracked in this set. */
+- (NSArray<FSTDocumentViewChange *> *)changes;
+
+@end
+
+#pragma mark - FSTViewSnapshot
+
+typedef void (^FSTViewSnapshotHandler)(FSTViewSnapshot *_Nullable snapshot,
+                                       NSError *_Nullable error);
+
+/** A view snapshot is an immutable capture of the results of a query and the changes to them. */
+@interface FSTViewSnapshot : NSObject
+
+- (instancetype)initWithQuery:(FSTQuery *)query
+                    documents:(FSTDocumentSet *)documents
+                 oldDocuments:(FSTDocumentSet *)oldDocuments
+              documentChanges:(NSArray<FSTDocumentViewChange *> *)documentChanges
+                    fromCache:(BOOL)fromCache
+             hasPendingWrites:(BOOL)hasPendingWrites
+             syncStateChanged:(BOOL)syncStateChanged NS_DESIGNATED_INITIALIZER;
+
+- (instancetype)init NS_UNAVAILABLE;
+
+/** The query this view is tracking the results for. */
+@property(nonatomic, strong, readonly) FSTQuery *query;
+
+/** The documents currently known to be results of the query. */
+@property(nonatomic, strong, readonly) FSTDocumentSet *documents;
+
+/** The documents of the last snapshot. */
+@property(nonatomic, strong, readonly) FSTDocumentSet *oldDocuments;
+
+/** The set of changes that have been applied to the documents. */
+@property(nonatomic, strong, readonly) NSArray<FSTDocumentViewChange *> *documentChanges;
+
+/** Whether any document in the snapshot was served from the local cache. */
+@property(nonatomic, assign, readonly, getter=isFromCache) BOOL fromCache;
+
+/** Whether any document in the snapshot has pending local writes. */
+@property(nonatomic, assign, readonly) BOOL hasPendingWrites;
+
+/** Whether the sync state changed as part of this snapshot. */
+@property(nonatomic, assign, readonly) BOOL syncStateChanged;
+
+@end
+
+NS_ASSUME_NONNULL_END