STL Support: extends type_traits for future developments

Utilities/std/cm/type_traits

@@ -33,6 +33,8 @@ using std::bool_constant;
 using std::invoke_result;
 using std::invoke_result_t;
 
+using std::void_t;
+
 #else
 
 // Helper classes
@@ -46,6 +48,14 @@ using invoke_result = std::result_of<F(ArgTypes...)>;
 template <class F, typename... ArgTypes>
 using invoke_result_t = typename invoke_result<F, ArgTypes...>::type;
 
+template <typename... ArgTypes>
+struct make_void
+{
+  typedef void type;
+};
+template <typename... ArgTypes>
+using void_t = typename make_void<ArgTypes...>::type;
+
 #endif
 
 } // namespace cm

Utilities/std/cmext/type_traits

@@ -0,0 +1,68 @@
+// -*-c++-*-
+// vim: set ft=cpp:
+
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#ifndef cmext_type_traits
+#define cmext_type_traits
+
+#include <cm/type_traits>
+
+namespace cm {
+
+// type traits for managed pointer types
+template <typename>
+struct is_unique_ptr : std::false_type
+{
+};
+template <typename T>
+struct is_unique_ptr<std::unique_ptr<T>> : std::true_type
+{
+};
+
+// type traits for containers
+template <typename, typename = void_t<>>
+struct is_container : std::false_type
+{
+};
+template <typename T>
+struct is_container<
+  T,
+  cm::void_t<typename T::value_type, typename T::size_type,
+             typename T::difference_type, typename T::iterator>>
+  : std::true_type
+{
+};
+
+template <typename, typename = void_t<>>
+struct is_associative_container : std::false_type
+{
+};
+template <typename T>
+struct is_associative_container<
+  T, cm::void_t<typename T::key_type, typename T::key_compare>>
+  : cm::is_container<T>
+{
+};
+
+template <typename, typename = void_t<>>
+struct is_unordered_associative_container : std::false_type
+{
+};
+template <typename T>
+struct is_unordered_associative_container<
+  T,
+  cm::void_t<typename T::key_type, typename T::hasher, typename T::key_equal,
+             typename T::local_iterator>> : cm::is_container<T>
+{
+};
+
+template <typename T>
+using is_sequence_container =
+  cm::bool_constant<cm::is_container<T>::value &&
+                    !cm::is_associative_container<T>::value &&
+                    !cm::is_unordered_associative_container<T>::value>;
+
+} // namespace cm
+
+#endif