Add trait for compatible values of any type

Author: zauguin

hdr/sqlite_modern_cpp.h

@@ -127,50 +127,14 @@ namespace sqlite {
 
 		friend class row_iterator;
 	};
-	namespace detail {
-		template <typename Type>
-		struct is_sqlite_value : public std::integral_constant<
-			bool,
-			std::is_floating_point<Type>::value
-			|| std::is_integral<Type>::value
-			|| std::is_same<std::string, Type>::value
-			|| std::is_same<std::u16string, Type>::value
-			|| std::is_same<sqlite_int64, Type>::value
-		> { };
-		template <typename Type, typename Allocator>
-		struct is_sqlite_value< std::vector<Type, Allocator> > : public std::integral_constant<
-			bool,
-			std::is_floating_point<Type>::value
-			|| std::is_integral<Type>::value
-			|| std::is_same<sqlite_int64, Type>::value
-		> { };
-		template <typename T>
-		struct is_sqlite_value< std::unique_ptr<T> > : public is_sqlite_value<T> {};
-#ifdef MODERN_SQLITE_STD_VARIANT_SUPPORT
-		template <typename ...Args>
-		struct is_sqlite_value< std::variant<Args...> > : public std::integral_constant<
-			bool,
-			true
-		> { };
-#endif
-#ifdef MODERN_SQLITE_STD_OPTIONAL_SUPPORT
-		template <typename T>
-		struct is_sqlite_value< optional<T> > : public is_sqlite_value<T> {};
-#endif
-
-#ifdef _MODERN_SQLITE_BOOST_OPTIONAL_SUPPORT
-		template <typename T>
-		struct is_sqlite_value< boost::optional<T> > : public is_sqlite_value<T> {};
-#endif
-	}
 
 	class row_iterator {
 	public:
 		class value_type {
 		public:
 			value_type(database_binder *_binder): _binder(_binder) {};
 			template<class T>
-			typename std::enable_if<detail::is_sqlite_value<T>::value, value_type &>::type operator >>(T &result) {
+			typename std::enable_if<is_sqlite_value<T>::value, value_type &>::type operator >>(T &result) {
 				get_col_from_db(_binder->_stmt.get(), next_index++, result);
 				return *this;
 			}

hdr/sqlite_modern_cpp/type_wrapper.h

@@ -38,6 +38,15 @@
 namespace sqlite {
 	template<class T, int Type, class = void>
 	struct has_sqlite_type : std::false_type {};
+	
+	template<class T>
+	using is_sqlite_value = std::integral_constant<bool, false
+		|| has_sqlite_type<T, SQLITE_NULL>::value
+		|| has_sqlite_type<T, SQLITE_INTEGER>::value
+		|| has_sqlite_type<T, SQLITE_FLOAT>::value
+		|| has_sqlite_type<T, SQLITE_TEXT>::value
+		|| has_sqlite_type<T, SQLITE_BLOB>::value
+	>;
 
 	template<class T, int Type>
 	struct has_sqlite_type<T&, Type> : has_sqlite_type<T, Type> {};