Add Immutable SortedSet in C++ (#1206)

* Add SortedSet

* Add document_key_set.h

* Add equality to SortedSet

1 files changed, 34 insertions, 0 deletions

diff --git a/Firestore/core/src/firebase/firestore/model/document_key_set.h b/Firestore/core/src/firebase/firestore/model/document_key_set.h
new file mode 100644
index 0000000..1301bf5
--- /dev/null
+++ b/Firestore/core/src/firebase/firestore/model/document_key_set.h
@@ -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.
+ */
+
+#ifndef FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_DOCUMENT_KEY_SET_H_
+#define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_DOCUMENT_KEY_SET_H_
+
+#include "Firestore/core/src/firebase/firestore/immutable/sorted_set.h"
+#include "Firestore/core/src/firebase/firestore/model/document_key.h"
+
+namespace firebase {
+namespace firestore {
+namespace model {
+
+/** Convenience type for a set of keys, since they are so common. */
+using DocumentKeySet = immutable::SortedSet<DocumentKey>;
+
+}  // namespace model
+}  // namespace firestore
+}  // namespace firebase
+
+#endif  // FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_DOCUMENT_KEY_SET_H_