Release based on cl/313536507.

Signed-off-by: Alexey Polyudov <apolyudov@google.com>
Change-Id: I83ec7dee1a7ef6f4bdfd47482c94d03910525b7e

cpp/platform/api/atomic_reference.h

@@ -15,21 +15,48 @@
 #ifndef PLATFORM_API_ATOMIC_REFERENCE_H_
 #define PLATFORM_API_ATOMIC_REFERENCE_H_
 
+#include "platform/api/atomic_reference_def.h"
+#include "platform/api/platform.h"
+#include "platform/ptr.h"
+#include "absl/types/any.h"
+
 namespace location {
 namespace nearby {
 
-// An object reference that may be updated atomically.
-//
-// https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/atomic/AtomicReference.html
+// "Common" part of implementation.
+// Placed here for textual compatibility to minimize scope of changes.
+// Can be (and should be) moved to a separate file outside "api" folder.
+// TODO(apolyudov): for API v2.0
+namespace platform {
+namespace impl {
 template <typename T>
-class AtomicReference {
+class AtomicReferenceImpl : public AtomicReference<T> {
  public:
-  virtual ~AtomicReference() {}
+  explicit AtomicReferenceImpl(T initial_value) {
+    atomic_ = platform::ImplementationPlatform::createAtomicReferenceAny(
+        absl::any(initial_value));
+  }
 
-  virtual T get() = 0;
-  virtual void set(T value) = 0;
+  ~AtomicReferenceImpl() override = default;
+
+  void set(T new_value) override { atomic_->set(absl::any(new_value)); }
+
+  T get() override { return absl::any_cast<T>(atomic_->get()); }
+
+ private:
+  Ptr<AtomicReference<absl::any>> atomic_;
 };
 
+}  // namespace impl
+
+template <typename T>
+Ptr<AtomicReference<T>> ImplementationPlatform::createAtomicReference(
+    T initial_value) {
+  return Ptr<AtomicReference<T>>(
+      new impl::AtomicReferenceImpl<T>{initial_value});
+}
+
+}  // namespace platform
 }  // namespace nearby
 }  // namespace location