port Firestore SnapshotVersion in C++ (#767)

* implement SnapshotVersion and test

Author: zxu123

Firestore/Example/Firestore.xcodeproj/project.pbxproj

@@ -141,6 +141,7 @@
 		AB380D04201BC6E400D97691 /* ordered_code_test.cc in Sources */ = {isa = PBXBuildFile; fileRef = AB380D03201BC6E400D97691 /* ordered_code_test.cc */; };
 		AB38D93020236E21000A432D /* database_info_test.cc in Sources */ = {isa = PBXBuildFile; fileRef = AB38D92E20235D22000A432D /* database_info_test.cc */; };
 		AB7BAB342012B519001E0872 /* geo_point_test.cc in Sources */ = {isa = PBXBuildFile; fileRef = AB7BAB332012B519001E0872 /* geo_point_test.cc */; };
+		ABA495BB202B7E80008A7851 /* snapshot_version_test.cc in Sources */ = {isa = PBXBuildFile; fileRef = ABA495B9202B7E79008A7851 /* snapshot_version_test.cc */; };
 		ABC1D7DC2023A04B00BA84F0 /* credentials_provider_test.cc in Sources */ = {isa = PBXBuildFile; fileRef = AB38D9342023966E000A432D /* credentials_provider_test.cc */; };
 		ABC1D7DD2023A04F00BA84F0 /* empty_credentials_provider_test.cc in Sources */ = {isa = PBXBuildFile; fileRef = AB38D93620239689000A432D /* empty_credentials_provider_test.cc */; };
 		ABC1D7DE2023A05300BA84F0 /* user_test.cc in Sources */ = {isa = PBXBuildFile; fileRef = AB38D93220239654000A432D /* user_test.cc */; };
@@ -346,6 +347,7 @@
 		AB38D93620239689000A432D /* empty_credentials_provider_test.cc */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = empty_credentials_provider_test.cc; sourceTree = "<group>"; };
 		AB71064B201FA60300344F18 /* database_id_test.cc */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = database_id_test.cc; sourceTree = "<group>"; };
 		AB7BAB332012B519001E0872 /* geo_point_test.cc */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = geo_point_test.cc; path = ../../core/test/firebase/firestore/geo_point_test.cc; sourceTree = "<group>"; };
+		ABA495B9202B7E79008A7851 /* snapshot_version_test.cc */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = snapshot_version_test.cc; sourceTree = "<group>"; };
 		ABC1D7DF2023A3EF00BA84F0 /* token_test.cc */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = token_test.cc; sourceTree = "<group>"; };
 		ABC1D7E22023CDC500BA84F0 /* firebase_credentials_provider_test.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = firebase_credentials_provider_test.mm; sourceTree = "<group>"; };
 		ABF6506B201131F8005F2C74 /* timestamp_test.cc */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = timestamp_test.cc; sourceTree = "<group>"; };
@@ -584,6 +586,7 @@
 				B686F2AD2023DDB20028D6BE /* field_path_test.cc */,
 				AB71064B201FA60300344F18 /* database_id_test.cc */,
 				AB356EF6200EA5EB0089B766 /* field_value_test.cc */,
+				ABA495B9202B7E79008A7851 /* snapshot_version_test.cc */,
 				ABF6506B201131F8005F2C74 /* timestamp_test.cc */,
 			);
 			name = model;
@@ -1329,6 +1332,7 @@
 				ABC1D7DC2023A04B00BA84F0 /* credentials_provider_test.cc in Sources */,
 				5492E059202154AB00B64F25 /* FIRQuerySnapshotTests.mm in Sources */,
 				5492E050202154AA00B64F25 /* FIRCollectionReferenceTests.mm in Sources */,
+				ABA495BB202B7E80008A7851 /* snapshot_version_test.cc in Sources */,
 				5492E0A02021552D00B64F25 /* FSTLevelDBMutationQueueTests.mm in Sources */,
 				54EB764D202277B30088B8F3 /* array_sorted_map_test.cc in Sources */,
 				5492E03420213FFC00B64F25 /* FSTMemorySpecTests.mm in Sources */,

Firestore/core/src/firebase/firestore/model/CMakeLists.txt

@@ -22,6 +22,8 @@ cc_library(
     field_path.h
     field_value.cc
     field_value.h
+    snapshot_version.cc
+    snapshot_version.h
     resource_path.cc
     resource_path.h
     timestamp.cc

Firestore/core/src/firebase/firestore/model/snapshot_version.cc

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2018 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.
+ */
+
+#include "Firestore/core/src/firebase/firestore/model/snapshot_version.h"
+
+namespace firebase {
+namespace firestore {
+namespace model {
+
+SnapshotVersion::SnapshotVersion(const Timestamp& timestamp)
+    : timestamp_(timestamp) {
+}
+
+const SnapshotVersion& SnapshotVersion::None() {
+  static const SnapshotVersion kNone(Timestamp{});
+  return kNone;
+}
+
+}  // namespace model
+}  // namespace firestore
+}  // namespace firebase

Firestore/core/src/firebase/firestore/model/snapshot_version.h

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2018 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.
+ */
+
+#ifndef FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_SNAPSHOT_VERSION_H_
+#define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_SNAPSHOT_VERSION_H_
+
+#include "Firestore/core/src/firebase/firestore/model/timestamp.h"
+
+namespace firebase {
+namespace firestore {
+namespace model {
+
+/**
+ * A version of a document in Firestore. This corresponds to the version
+ * timestamp, such as update_time or read_time.
+ */
+class SnapshotVersion {
+ public:
+  explicit SnapshotVersion(const Timestamp& timestamp);
+
+  const Timestamp& timestamp() const {
+    return timestamp_;
+  }
+
+  /** Creates a new version that is smaller than all other versions. */
+  static const SnapshotVersion& None();
+
+ private:
+  Timestamp timestamp_;
+};
+
+/** Compares against another SnapshotVersion. */
+inline bool operator<(const SnapshotVersion& lhs, const SnapshotVersion& rhs) {
+  return lhs.timestamp() < rhs.timestamp();
+}
+
+inline bool operator>(const SnapshotVersion& lhs, const SnapshotVersion& rhs) {
+  return lhs.timestamp() > rhs.timestamp();
+}
+
+inline bool operator>=(const SnapshotVersion& lhs, const SnapshotVersion& rhs) {
+  return lhs.timestamp() >= rhs.timestamp();
+}
+
+inline bool operator<=(const SnapshotVersion& lhs, const SnapshotVersion& rhs) {
+  return lhs.timestamp() <= rhs.timestamp();
+}
+
+inline bool operator!=(const SnapshotVersion& lhs, const SnapshotVersion& rhs) {
+  return lhs.timestamp() != rhs.timestamp();
+}
+
+inline bool operator==(const SnapshotVersion& lhs, const SnapshotVersion& rhs) {
+  return lhs.timestamp() == rhs.timestamp();
+}
+
+}  // namespace model
+}  // namespace firestore
+}  // namespace firebase
+
+#endif  // FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_SNAPSHOT_VERSION_H_

Firestore/core/test/firebase/firestore/model/CMakeLists.txt

@@ -18,6 +18,7 @@ cc_test(
     database_id_test.cc
     field_path_test.cc
     field_value_test.cc
+    snapshot_version_test.cc
     timestamp_test.cc
     resource_path_test.cc
   DEPENDS

Firestore/core/test/firebase/firestore/model/snapshot_version_test.cc

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2018 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.
+ */
+
+#include "Firestore/core/src/firebase/firestore/model/snapshot_version.h"
+
+#include "gtest/gtest.h"
+
+namespace firebase {
+namespace firestore {
+namespace model {
+
+TEST(SnapshotVersion, Getter) {
+  SnapshotVersion version(Timestamp(123, 456));
+  EXPECT_EQ(Timestamp(123, 456), version.timestamp());
+
+  const SnapshotVersion& no_version = SnapshotVersion::None();
+  EXPECT_EQ(Timestamp(), no_version.timestamp());
+}
+
+TEST(SnapshotVersion, Comparison) {
+  EXPECT_LT(SnapshotVersion::None(), SnapshotVersion(Timestamp(123, 456)));
+
+  EXPECT_LT(SnapshotVersion(Timestamp(123, 456)),
+            SnapshotVersion(Timestamp(456, 123)));
+  EXPECT_GT(SnapshotVersion(Timestamp(456, 123)),
+            SnapshotVersion(Timestamp(123, 456)));
+  EXPECT_LE(SnapshotVersion(Timestamp(123, 456)),
+            SnapshotVersion(Timestamp(456, 123)));
+  EXPECT_LE(SnapshotVersion(Timestamp(123, 456)),
+            SnapshotVersion(Timestamp(123, 456)));
+  EXPECT_GE(SnapshotVersion(Timestamp(456, 123)),
+            SnapshotVersion(Timestamp(123, 456)));
+  EXPECT_GE(SnapshotVersion(Timestamp(123, 456)),
+            SnapshotVersion(Timestamp(123, 456)));
+  EXPECT_EQ(SnapshotVersion(Timestamp(123, 456)),
+            SnapshotVersion(Timestamp(123, 456)));
+  EXPECT_NE(SnapshotVersion(Timestamp(123, 456)),
+            SnapshotVersion(Timestamp(456, 123)));
+}
+
+}  //  namespace model
+}  //  namespace firestore
+}  //  namespace firebase