Add aidl::nullable type for nullable in AIDL
This provides source-level compatibility between new(std::optional) and
old(std::unique_ptr).
Bug: 144773267
Test: m
Change-Id: I378dbf848a51a705a9e06f9cd4b0def9728c3bff
diff --git a/libs/binder/include/binder/Nullable.h b/libs/binder/include/binder/Nullable.h
new file mode 100644
index 0000000..a98583d
--- /dev/null
+++ b/libs/binder/include/binder/Nullable.h
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * 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.
+ */
+#pragma once
+
+#include <optional>
+#include <utility>
+
+namespace android {
+
+namespace aidl {
+
+// nullable/make_nullable provide source-level compatibility between std::opional and std::unique_ptr
+// usage:
+// nullable<Foo> a;
+// nullable<Foo> b = make_nullable<Foo>(...);
+// auto c = make_nullable<Foo>(...);
+// c.reset();
+// c = make_nullable<Foo>(...);
+// c = std::move(a);
+
+template <typename T>
+using nullable = std::optional<T>;
+
+template <typename T, typename... Args>
+inline nullable<T> make_nullable(Args&&... args) {
+ return std::make_optional<T>(std::forward<Args>(args)...);
+}
+
+} // namespace aidl
+
+} // namespace android
\ No newline at end of file
