nearby: snapshot of cl/304428753

Signed-off-by: Alexey Polyudov <apolyudov@google.com>
Change-Id: I0023ac6e40456fc4a8169c3173bcbff3b5ccc476

cpp/platform/api2/submittable_executor.h

@@ -0,0 +1,42 @@
+#ifndef PLATFORM_API2_SUBMITTABLE_EXECUTOR_H_
+#define PLATFORM_API2_SUBMITTABLE_EXECUTOR_H_
+
+#include <memory>
+
+#include "platform/api2/executor.h"
+#include "platform/api2/future.h"
+#include "platform/callable.h"
+
+namespace location {
+namespace nearby {
+
+// Each per-platform concrete implementation is expected to extend from
+// SubmittableExecutor and provide an override of its submit() method.
+//
+// e.g.
+// class XyzSubmittableExecutor
+//                      : public SubmittableExecutor<XyzSubmittableExecutor> {
+//  public:
+//   template <typename T>
+//   std::unique_ptr<Future<T>> submit(std::unique_ptr<Callable<T>> callable) {
+//     ...
+//   }
+// }
+template <typename ConcreteSubmittableExecutor>
+class SubmittableExecutor : public Executor {
+ public:
+  ~SubmittableExecutor() override {}
+
+  template <typename T>
+  std::unique_ptr<Future<T>> Submit(std::unique_ptr<Callable<T>> callable) {
+    static_assert(
+        std::is_base_of_v<SubmittableExecutor, ConcreteSubmittableExecutor>,
+        "Class template type is not derived from SubmittableExecutor");
+    return static_cast<ConcreteSubmittableExecutor*>(this)->submit(callable);
+  }
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_SUBMITTABLE_EXECUTOR_H_