Consolidate has_data and has_data_v

btas/tensor_traits.h

@@ -9,20 +9,6 @@
 
 namespace btas {
 
-/// test T has data() member
-/// this will be used to detect whether or not the storage is consecutive
-template<class T>
-class has_data {
- /// true case
- template<class U>
- static auto __test(U* p) -> decltype(p->data(), std::true_type());
- /// false case
- template<class>
- static std::false_type __test(...);
-public:
- static constexpr const bool value = std::is_same<std::true_type, decltype(__test<T>(0))>::value;
-};
-
 /// test T has range_type
 template<class T>
 class has_range_type {

btas/type_traits.h

@@ -125,10 +125,22 @@ namespace btas {
  template <typename T>
  constexpr inline bool has_squarebraket_v = has_squarebraket<T>::value;
 
- template <typename S, typename Enabler = void>
- constexpr static bool has_data_v = false;
- template <typename S>
- constexpr static bool has_data_v<S, std::void_t<decltype(std::declval<S&>().data())>> = true;
+ /// test T has data() member
+ /// this will be used to detect whether or not the storage is consecutive
+ template<class T>
+ class has_data {
+ /// true case
+ template<class U>
+ static auto __test(U* p) -> decltype(p->data(), std::true_type());
+ /// false case
+ template<class>
+ static std::false_type __test(...);
+ public:
+ static constexpr const bool value = std::is_same<std::true_type, decltype(__test<T>(0))>::value;
+ };
+
+ template <typename T>
+ inline constexpr bool has_data_v = has_data<T>::value;
 
  template <typename S, typename Enabler = void>
  constexpr static bool has_size_v = false;