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

7 files changed, 336 insertions, 2 deletions

diff --git a/Firestore/core/src/firebase/firestore/model/CMakeLists.txt b/Firestore/core/src/firebase/firestore/model/CMakeLists.txt
index 95310ec..1b0e6a4 100644
--- a/Firestore/core/src/firebase/firestore/model/CMakeLists.txt
+++ b/Firestore/core/src/firebase/firestore/model/CMakeLists.txt
@@ -18,16 +18,22 @@ cc_library(
     base_path.h
     database_id.cc
     database_id.h
+    document.cc
+    document.h
     document_key.cc
     document_key.h
     field_path.cc
     field_path.h
     field_value.cc
     field_value.h
-    snapshot_version.cc
-    snapshot_version.h
+    maybe_document.cc
+    maybe_document.h
+    no_document.cc
+    no_document.h
     resource_path.cc
     resource_path.h
+    snapshot_version.cc
+    snapshot_version.h
     timestamp.cc
     timestamp.h
   DEPENDS
diff --git a/Firestore/core/src/firebase/firestore/model/document.cc b/Firestore/core/src/firebase/firestore/model/document.cc
new file mode 100644
index 0000000..16548cd
--- /dev/null
+++ b/Firestore/core/src/firebase/firestore/model/document.cc
@@ -0,0 +1,50 @@
+/*
+ * 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 <utility>
+
+#include "Firestore/core/src/firebase/firestore/util/firebase_assert.h"
+
+namespace firebase {
+namespace firestore {
+namespace model {
+
+Document::Document(FieldValue&& data,
+                   DocumentKey key,
+                   SnapshotVersion version,
+                   bool has_local_mutations)
+    : MaybeDocument(std::move(key), std::move(version)),
+      data_(std::move(data)),
+      has_local_mutations_(has_local_mutations) {
+  set_type(Type::Document);
+  FIREBASE_ASSERT(FieldValue::Type::Object == data.type());
+}
+
+bool Document::Equals(const MaybeDocument& other) const {
+  if (other.type() != Type::Document) {
+    return false;
+  }
+  const Document& other_doc = static_cast<const Document&>(other);
+  return MaybeDocument::Equals(other) &&
+         has_local_mutations_ == other_doc.has_local_mutations_ &&
+         data_ == other_doc.data_;
+}
+
+}  // namespace model
+}  // namespace firestore
+}  // namespace firebase
diff --git a/Firestore/core/src/firebase/firestore/model/document.h b/Firestore/core/src/firebase/firestore/model/document.h
new file mode 100644
index 0000000..50a7b90
--- /dev/null
+++ b/Firestore/core/src/firebase/firestore/model/document.h
@@ -0,0 +1,72 @@
+/*
+ * 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_DOCUMENT_H_
+#define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_DOCUMENT_H_
+
+#include "Firestore/core/src/firebase/firestore/model/field_value.h"
+#include "Firestore/core/src/firebase/firestore/model/maybe_document.h"
+
+namespace firebase {
+namespace firestore {
+namespace model {
+
+/**
+ * Represents a document in Firestore with a key, version, data and whether the
+ * data has local mutations applied to it.
+ */
+class Document : public MaybeDocument {
+ public:
+  /**
+   * Construct a document. FieldValue must be passed by rvalue.
+   */
+  Document(FieldValue&& data,
+           DocumentKey key,
+           SnapshotVersion version,
+           bool has_local_mutations);
+
+  const FieldValue& data() const {
+    return data_;
+  }
+
+  bool has_local_mutations() const {
+    return has_local_mutations_;
+  }
+
+ protected:
+  bool Equals(const MaybeDocument& other) const override;
+
+ private:
+  FieldValue data_;  // This is of type Object.
+  bool has_local_mutations_;
+};
+
+/** Compares against another Document. */
+inline bool operator==(const Document& lhs, const Document& rhs) {
+  return lhs.version() == rhs.version() && lhs.key() == rhs.key() &&
+         lhs.has_local_mutations() == rhs.has_local_mutations() &&
+         lhs.data() == rhs.data();
+}
+
+inline bool operator!=(const Document& lhs, const Document& rhs) {
+  return !(lhs == rhs);
+}
+
+}  // namespace model
+}  // namespace firestore
+}  // namespace firebase
+
+#endif  // FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_DOCUMENT_H_
diff --git a/Firestore/core/src/firebase/firestore/model/maybe_document.cc b/Firestore/core/src/firebase/firestore/model/maybe_document.cc
new file mode 100644
index 0000000..4f3be1d
--- /dev/null
+++ b/Firestore/core/src/firebase/firestore/model/maybe_document.cc
@@ -0,0 +1,38 @@
+/*
+ * 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 <utility>
+
+#include "Firestore/core/src/firebase/firestore/util/firebase_assert.h"
+
+namespace firebase {
+namespace firestore {
+namespace model {
+
+MaybeDocument::MaybeDocument(DocumentKey key, SnapshotVersion version)
+    : key_(std::move(key)), version_(std::move(version)) {
+}
+
+bool MaybeDocument::Equals(const MaybeDocument& other) const {
+  return type_ == other.type_ && version_ == other.version_ &&
+         key_ == other.key_;
+}
+
+}  // namespace model
+}  // namespace firestore
+}  // namespace firebase
diff --git a/Firestore/core/src/firebase/firestore/model/maybe_document.h b/Firestore/core/src/firebase/firestore/model/maybe_document.h
new file mode 100644
index 0000000..71bd3ef
--- /dev/null
+++ b/Firestore/core/src/firebase/firestore/model/maybe_document.h
@@ -0,0 +1,100 @@
+/*
+ * 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_MAYBE_DOCUMENT_H_
+#define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_MAYBE_DOCUMENT_H_
+
+#include <functional>
+
+#include "Firestore/core/src/firebase/firestore/model/document_key.h"
+#include "Firestore/core/src/firebase/firestore/model/snapshot_version.h"
+
+namespace firebase {
+namespace firestore {
+namespace model {
+
+/**
+ * The result of a lookup for a given path may be an existing document or a
+ * tombstone that marks the path deleted.
+ */
+class MaybeDocument {
+ public:
+  /**
+   * All the different kinds of documents, including MaybeDocument and its
+   * subclasses. This is used to provide RTTI for documents.
+   */
+  enum class Type {
+    Unknown,
+    Document,
+    NoDocument,
+  };
+
+  MaybeDocument(DocumentKey key, SnapshotVersion version);
+
+  /** The runtime type of this document. */
+  Type type() const {
+    return type_;
+  }
+
+  /** The key for this document. */
+  const DocumentKey& key() const {
+    return key_;
+  }
+
+  /**
+   * Returns the version of this document if it exists or a version at which
+   * this document was guaranteed to not exist.
+   */
+  const SnapshotVersion& version() const {
+    return version_;
+  }
+
+ protected:
+  // Only allow subclass to set their types.
+  void set_type(Type type) {
+    type_ = type;
+  }
+
+  virtual bool Equals(const MaybeDocument& other) const;
+
+  friend bool operator==(const MaybeDocument& lhs, const MaybeDocument& rhs);
+
+ private:
+  Type type_ = Type::Unknown;
+  DocumentKey key_;
+  SnapshotVersion version_;
+};
+
+inline bool operator==(const MaybeDocument& lhs, const MaybeDocument& rhs) {
+  return lhs.Equals(rhs);
+}
+
+inline bool operator!=(const MaybeDocument& lhs, const MaybeDocument& rhs) {
+  return !(lhs == rhs);
+}
+
+/** Compares against another MaybeDocument by keys only. */
+struct DocumentKeyComparator : public std::less<MaybeDocument> {
+  bool operator()(const MaybeDocument& lhs, const MaybeDocument& rhs) const {
+    return lhs.key() < rhs.key();
+  }
+};
+
+}  // namespace model
+}  // namespace firestore
+}  // namespace firebase
+
+#endif  // FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_MAYBE_DOCUMENT_H_
diff --git a/Firestore/core/src/firebase/firestore/model/no_document.cc b/Firestore/core/src/firebase/firestore/model/no_document.cc
new file mode 100644
index 0000000..98cb428
--- /dev/null
+++ b/Firestore/core/src/firebase/firestore/model/no_document.cc
@@ -0,0 +1,32 @@
+/*
+ * 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 <utility>
+
+namespace firebase {
+namespace firestore {
+namespace model {
+
+NoDocument::NoDocument(DocumentKey key, SnapshotVersion version)
+    : MaybeDocument(std::move(key), std::move(version)) {
+  set_type(Type::NoDocument);
+}
+
+}  // namespace model
+}  // namespace firestore
+}  // namespace firebase
diff --git a/Firestore/core/src/firebase/firestore/model/no_document.h b/Firestore/core/src/firebase/firestore/model/no_document.h
new file mode 100644
index 0000000..7cfd47c
--- /dev/null
+++ b/Firestore/core/src/firebase/firestore/model/no_document.h
@@ -0,0 +1,36 @@
+/*
+ * 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_NO_DOCUMENT_H_
+#define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_NO_DOCUMENT_H_
+
+#include "Firestore/core/src/firebase/firestore/model/maybe_document.h"
+
+namespace firebase {
+namespace firestore {
+namespace model {
+
+/** Represents that no documents exists for the key at the given version. */
+class NoDocument : public MaybeDocument {
+ public:
+  NoDocument(DocumentKey key, SnapshotVersion version);
+};
+
+}  // namespace model
+}  // namespace firestore
+}  // namespace firebase
+
+#endif  // FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_NO_DOCUMENT_H_