meta: when_all added and minor changes to selection.h

2019-01-29 16:01:02 +02:00
parent bb35115359
commit 8fef779a91
2 changed files with 35 additions and 5 deletions
@@ -67,6 +67,24 @@ namespace meta{
   using if_ = if_c<If::type::value, Args...>;

   //! @}
+
+   /*!
+    * Named type selectors
+    */
+   //! @{
+
+   //! Select the first type of a type sequence
+   template <typename T1, typename ...>
+   struct first_of {
+      using type = T1;
+   };
+   //! Select the second type of a type sequence
+   template <typename T1, typename T2, typename ...>
+   struct second_of {
+      using type = T2;
+   };
+
+   //! @}
 }}

 //! @}