Port Firestore Document to C++ (#777)

* implement SnapshotVersion and test

* update project

* implement MaybeDocument and test

* move snapshot-version from core to model

* fix a bug

* implement Document and test

* implement NoDocument

* adding type tag and fix style

* fix a few bugs, discovered after merging and test run.

* add assert to check FieldValue type and more test for comparision.

* address changes

* allow moving FieldValue to construct Document.

* address changes

* add document tests to project

* use std::less convention

* make Type::Unknown static initializer

4 files changed, 197 insertions, 1 deletions

diff --git a/Firestore/core/test/firebase/firestore/model/CMakeLists.txt b/Firestore/core/test/firebase/firestore/model/CMakeLists.txt
index e73be98..0d581bc 100644
--- a/Firestore/core/test/firebase/firestore/model/CMakeLists.txt
+++ b/Firestore/core/test/firebase/firestore/model/CMakeLists.txt
@@ -17,11 +17,14 @@ cc_test(
   SOURCES
     database_id_test.cc
     document_key_test.cc
+    document_test.cc
     field_path_test.cc
     field_value_test.cc
+    maybe_document_test.cc
+    no_document_test.cc
+    resource_path_test.cc
     snapshot_version_test.cc
     timestamp_test.cc
-    resource_path_test.cc
   DEPENDS
     firebase_firestore_model
 )
diff --git a/Firestore/core/test/firebase/firestore/model/document_test.cc b/Firestore/core/test/firebase/firestore/model/document_test.cc
new file mode 100644
index 0000000..6b72360
--- /dev/null
+++ b/Firestore/core/test/firebase/firestore/model/document_test.cc
@@ -0,0 +1,76 @@
+/*
+ * 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/document.h"
+
+#include "absl/strings/string_view.h"
+#include "gtest/gtest.h"
+
+namespace firebase {
+namespace firestore {
+namespace model {
+
+namespace {
+
+inline Document MakeDocument(const absl::string_view data,
+                             const absl::string_view path,
+                             const Timestamp& timestamp,
+                             bool has_local_mutations) {
+  return Document(FieldValue::ObjectValue(
+                      {{"field", FieldValue::StringValue(data.data())}}),
+                  DocumentKey::FromPathString(path.data()),
+                  SnapshotVersion(timestamp), has_local_mutations);
+}
+
+}  // anonymous namespace
+
+TEST(Document, Getter) {
+  const Document& doc =
+      MakeDocument("foo", "i/am/a/path", Timestamp(123, 456), true);
+  EXPECT_EQ(MaybeDocument::Type::Document, doc.type());
+  EXPECT_EQ(
+      FieldValue::ObjectValue({{"field", FieldValue::StringValue("foo")}}),
+      doc.data());
+  EXPECT_EQ(DocumentKey::FromPathString("i/am/a/path"), doc.key());
+  EXPECT_EQ(SnapshotVersion(Timestamp(123, 456)), doc.version());
+  EXPECT_TRUE(doc.has_local_mutations());
+}
+
+TEST(Document, Comparison) {
+  EXPECT_EQ(MakeDocument("foo", "i/am/a/path", Timestamp(123, 456), true),
+            MakeDocument("foo", "i/am/a/path", Timestamp(123, 456), true));
+  EXPECT_NE(MakeDocument("foo", "i/am/a/path", Timestamp(123, 456), true),
+            MakeDocument("bar", "i/am/a/path", Timestamp(123, 456), true));
+  EXPECT_NE(
+      MakeDocument("foo", "i/am/a/path", Timestamp(123, 456), true),
+      MakeDocument("foo", "i/am/another/path", Timestamp(123, 456), true));
+  EXPECT_NE(MakeDocument("foo", "i/am/a/path", Timestamp(123, 456), true),
+            MakeDocument("foo", "i/am/a/path", Timestamp(456, 123), true));
+  EXPECT_NE(MakeDocument("foo", "i/am/a/path", Timestamp(123, 456), true),
+            MakeDocument("foo", "i/am/a/path", Timestamp(123, 456), false));
+
+  // Document and MaybeDocument will not equal. In particular, Document and
+  // NoDocument will not equal, which I won't test here.
+  EXPECT_NE(Document(FieldValue::ObjectValue({}),
+                     DocumentKey::FromPathString("same/path"),
+                     SnapshotVersion(Timestamp()), false),
+            MaybeDocument(DocumentKey::FromPathString("same/path"),
+                          SnapshotVersion(Timestamp())));
+}
+
+}  // namespace model
+}  // namespace firestore
+}  // namespace firebase
diff --git a/Firestore/core/test/firebase/firestore/model/maybe_document_test.cc b/Firestore/core/test/firebase/firestore/model/maybe_document_test.cc
new file mode 100644
index 0000000..005798a
--- /dev/null
+++ b/Firestore/core/test/firebase/firestore/model/maybe_document_test.cc
@@ -0,0 +1,66 @@
+/*
+ * 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/maybe_document.h"
+
+#include "absl/strings/string_view.h"
+#include "gtest/gtest.h"
+
+namespace firebase {
+namespace firestore {
+namespace model {
+
+namespace {
+
+inline MaybeDocument MakeMaybeDocument(const absl::string_view path,
+                                       const Timestamp& timestamp) {
+  return MaybeDocument(DocumentKey::FromPathString(path.data()),
+                       SnapshotVersion(timestamp));
+}
+
+inline bool operator<(const MaybeDocument& lhs, const MaybeDocument& rhs) {
+  static const DocumentKeyComparator less;
+  return less(lhs, rhs);
+}
+
+}  // anonymous namespace
+
+TEST(MaybeDocument, Getter) {
+  const MaybeDocument& doc =
+      MakeMaybeDocument("i/am/a/path", Timestamp(123, 456));
+  EXPECT_EQ(MaybeDocument::Type::Unknown, doc.type());
+  EXPECT_EQ(DocumentKey::FromPathString("i/am/a/path"), doc.key());
+  EXPECT_EQ(SnapshotVersion(Timestamp(123, 456)), doc.version());
+}
+
+TEST(MaybeDocument, Comparison) {
+  EXPECT_TRUE(MakeMaybeDocument("root/123", Timestamp(456, 123)) <
+              MakeMaybeDocument("root/456", Timestamp(123, 456)));
+  // MaybeDocument comparision is purely key-based.
+  EXPECT_FALSE(MakeMaybeDocument("root/123", Timestamp(111, 111)) <
+               MakeMaybeDocument("root/123", Timestamp(222, 222)));
+
+  EXPECT_EQ(MakeMaybeDocument("root/123", Timestamp(456, 123)),
+            MakeMaybeDocument("root/123", Timestamp(456, 123)));
+  EXPECT_NE(MakeMaybeDocument("root/123", Timestamp(456, 123)),
+            MakeMaybeDocument("root/456", Timestamp(456, 123)));
+  EXPECT_NE(MakeMaybeDocument("root/123", Timestamp(456, 123)),
+            MakeMaybeDocument("root/123", Timestamp(123, 456)));
+}
+
+}  // namespace model
+}  // namespace firestore
+}  // namespace firebase
diff --git a/Firestore/core/test/firebase/firestore/model/no_document_test.cc b/Firestore/core/test/firebase/firestore/model/no_document_test.cc
new file mode 100644
index 0000000..825820f
--- /dev/null
+++ b/Firestore/core/test/firebase/firestore/model/no_document_test.cc
@@ -0,0 +1,51 @@
+/*
+ * 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/no_document.h"
+
+#include "absl/strings/string_view.h"
+#include "gtest/gtest.h"
+
+namespace firebase {
+namespace firestore {
+namespace model {
+
+namespace {
+
+inline NoDocument MakeNoDocument(const absl::string_view path,
+                                 const Timestamp& timestamp) {
+  return NoDocument(DocumentKey::FromPathString(path.data()),
+                    SnapshotVersion(timestamp));
+}
+
+}  // anonymous namespace
+
+TEST(NoDocument, Getter) {
+  const NoDocument& doc = MakeNoDocument("i/am/a/path", Timestamp(123, 456));
+  EXPECT_EQ(MaybeDocument::Type::NoDocument, doc.type());
+  EXPECT_EQ(DocumentKey::FromPathString("i/am/a/path"), doc.key());
+  EXPECT_EQ(SnapshotVersion(Timestamp(123, 456)), doc.version());
+
+  // NoDocument and MaybeDocument will not equal.
+  EXPECT_NE(NoDocument(DocumentKey::FromPathString("same/path"),
+                       SnapshotVersion(Timestamp())),
+            MaybeDocument(DocumentKey::FromPathString("same/path"),
+                          SnapshotVersion(Timestamp())));
+}
+
+}  // namespace model
+}  // namespace firestore
+}  // namespace firebase