Refactor (and improve) traits

albatross/cereal/traits.h

@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2018 Swift Navigation Inc.
+ * Contact: Swift Navigation <[email protected]>
+ *
+ * This source is subject to the license found in the file 'LICENSE' which must
+ * be distributed together with this source. All other rights reserved.
+ *
+ * THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND,
+ * EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE.
+ */
+
+#ifndef ALBATROSS_CEREAL_TRAITS_H
+#define ALBATROSS_CEREAL_TRAITS_H
+
+#include "cereal/details/traits.hpp"
+
+namespace albatross {
+
+/*
+ * This little trick was borrowed from cereal, you an think of it as
+ * a function that will always return false ... but that doesn't
+ * get resolved until template instantiation, which when combined
+ * with a static assert let's you include a static assert that
+ * only triggers with a particular template parameter is used.
+ */
+template <class T> struct delay_static_assert : std::false_type {};
+
+/*
+ * The following helper functions let you inspect a type and cereal Archive
+ * and determine if the type has a valid serialization method for that Archive
+ * type.
+ */
+template <typename X, typename Archive> class valid_output_serializer {
+  template <typename T>
+  static typename std::enable_if<
+      1 == cereal::traits::detail::count_output_serializers<T, Archive>::value,
+      std::true_type>::type
+  test(int);
+  template <typename T> static std::false_type test(...);
+
+public:
+  static constexpr bool value = decltype(test<X>(0))::value;
+};
+
+template <typename X, typename Archive> class valid_input_serializer {
+  template <typename T>
+  static typename std::enable_if<
+      1 == cereal::traits::detail::count_input_serializers<T, Archive>::value,
+      std::true_type>::type
+  test(int);
+  template <typename T> static std::false_type test(...);
+
+public:
+  static constexpr bool value = decltype(test<X>(0))::value;
+};
+
+template <typename X, typename Archive> class valid_in_out_serializer {
+  template <typename T>
+  static typename std::enable_if<valid_input_serializer<T, Archive>::value &&
+                                     valid_output_serializer<T, Archive>::value,
+                                 std::true_type>::type
+  test(int);
+  template <typename T> static std::false_type test(...);
+
+public:
+  static constexpr bool value = decltype(test<X>(0))::value;
+};
+}
+
+#endif