nearby: snapshot as of cl/296436629

Signed-off-by: Alexey Polyudov <apolyudov@google.com>
Change-Id: I2cf5bf225b76f4c1541954651f3a7544a14e0cec

cpp/platform/exception.h

@@ -0,0 +1,57 @@
+#ifndef PLATFORM_EXCEPTION_H_
+#define PLATFORM_EXCEPTION_H_
+
+namespace location {
+namespace nearby {
+
+struct Exception {
+  enum Value {
+    NONE,
+    IO,
+    INTERRUPTED,
+    INVALID_PROTOCOL_BUFFER,
+    EXECUTION,
+  };
+};
+
+// ExceptionOr models the concept of the return value of a function that might
+// throw an exception.
+//
+// If ok() returns true, result() is a usable return value. Otherwise,
+// exception() explains why such a value is not present.
+//
+// A typical pattern of usage is as follows:
+//
+//      if (!e.ok()) {
+//        if (Exception::EXCEPTION_TYPE_1 == e.exception()) {
+//          // Handle Exception::EXCEPTION_TYPE_1.
+//        } else if (Exception::EXCEPTION_TYPE_2 == e.exception()) {
+//          // Handle Exception::EXCEPTION_TYPE_2.
+//        }
+//
+//         return;
+//      }
+//
+//      // Use e.result().
+template <typename T>
+class ExceptionOr {
+ public:
+  explicit ExceptionOr(T result);
+  explicit ExceptionOr(Exception::Value exception);
+
+  bool ok() const;
+
+  T result() const;
+  Exception::Value exception() const;
+
+ private:
+  T result_;
+  Exception::Value exception_;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#include "platform/exception.cc"
+
+#endif  // PLATFORM_EXCEPTION_H_