Firestore DatabaseId in C++ (#727)

* Implement DataBaseId in C++

* add database_id_test to project

* fix project

* address changes

* fix style

3 files changed, 137 insertions, 0 deletions

diff --git a/Firestore/core/src/firebase/firestore/model/CMakeLists.txt b/Firestore/core/src/firebase/firestore/model/CMakeLists.txt
index 3af56ec..aee0d86 100644
--- a/Firestore/core/src/firebase/firestore/model/CMakeLists.txt
+++ b/Firestore/core/src/firebase/firestore/model/CMakeLists.txt
@@ -15,9 +15,14 @@
 cc_library(
   firebase_firestore_model
   SOURCES
+    database_id.cc
+    database_id.h
     field_value.cc
+    field_value.h
     timestamp.cc
+    timestamp.h
   DEPENDS
+    absl_strings
     firebase_firestore_util
     firebase_firestore_types
 )
diff --git a/Firestore/core/src/firebase/firestore/model/database_id.cc b/Firestore/core/src/firebase/firestore/model/database_id.cc
new file mode 100644
index 0000000..af12d30
--- /dev/null
+++ b/Firestore/core/src/firebase/firestore/model/database_id.cc
@@ -0,0 +1,40 @@
+/*
+ * 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/database_id.h"
+
+#include "Firestore/core/src/firebase/firestore/util/firebase_assert.h"
+
+namespace firebase {
+namespace firestore {
+namespace model {
+
+constexpr const char* DatabaseId::kDefaultDatabaseId;
+
+DatabaseId::DatabaseId(const absl::string_view project_id,
+                       const absl::string_view database_id)
+    : project_id_(project_id), database_id_(database_id) {
+  FIREBASE_ASSERT(!project_id.empty());
+  FIREBASE_ASSERT(!database_id.empty());
+}
+
+bool DatabaseId::IsDefaultDatabase() {
+  return database_id_ == kDefaultDatabaseId;
+}
+
+}  // namespace model
+}  // namespace firestore
+}  // namespace firebase
diff --git a/Firestore/core/src/firebase/firestore/model/database_id.h b/Firestore/core/src/firebase/firestore/model/database_id.h
new file mode 100644
index 0000000..48c547c
--- /dev/null
+++ b/Firestore/core/src/firebase/firestore/model/database_id.h
@@ -0,0 +1,92 @@
+/*
+ * 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_DATABASE_ID_H_
+#define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_DATABASE_ID_H_
+
+#include <string>
+
+#include "absl/strings/string_view.h"
+
+namespace firebase {
+namespace firestore {
+namespace model {
+
+/** A DatabaseId represents a particular database in the Firestore. */
+class DatabaseId {
+ public:
+  /** The default name for "unset" database ID in resource names. */
+  static constexpr const char* kDefaultDatabaseId = "(default)";
+
+  /**
+   * Creates and returns a new DatabaseId.
+   *
+   * @param project_id The project for the database.
+   * @param database_id The database in the project to use.
+   */
+  DatabaseId(const absl::string_view project_id,
+             const absl::string_view database_id);
+
+  const std::string& project_id() const {
+    return project_id_;
+  }
+
+  const std::string& database_id() const {
+    return database_id_;
+  }
+
+  /** Whether this is the default database of the project. */
+  bool IsDefaultDatabase();
+
+  friend bool operator<(const DatabaseId& lhs, const DatabaseId& rhs);
+
+ private:
+  const std::string project_id_;
+  const std::string database_id_;
+};
+
+/** Compares against another DatabaseId. */
+inline bool operator<(const DatabaseId& lhs, const DatabaseId& rhs) {
+  return lhs.project_id_ < rhs.project_id_ ||
+         (lhs.project_id_ == rhs.project_id_ &&
+          lhs.database_id_ < rhs.database_id_);
+}
+
+inline bool operator>(const DatabaseId& lhs, const DatabaseId& rhs) {
+  return rhs < lhs;
+}
+
+inline bool operator>=(const DatabaseId& lhs, const DatabaseId& rhs) {
+  return !(lhs < rhs);
+}
+
+inline bool operator<=(const DatabaseId& lhs, const DatabaseId& rhs) {
+  return !(lhs > rhs);
+}
+
+inline bool operator!=(const DatabaseId& lhs, const DatabaseId& rhs) {
+  return lhs < rhs || lhs > rhs;
+}
+
+inline bool operator==(const DatabaseId& lhs, const DatabaseId& rhs) {
+  return !(lhs != rhs);
+}
+
+}  // namespace model
+}  // namespace firestore
+}  // namespace firebase
+
+#endif  // FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_DATABASE_ID_H_