Improve internal generic _allToAll and _exchange methods

One use variadic templates to ensure that generic array types are used

src/utils/Messenger.hpp

@@ -99,14 +99,15 @@ class Messenger
 #endif // PASTIS_HAS_MPI
   }
 
-
-  template <typename SendArrayType,
-            typename RecvArrayType>
-  RecvArrayType _allToAll(const SendArrayType& sent_array, RecvArrayType& recv_array) const
+  template <template <typename ...SendT> typename SendArrayType,
+            template <typename ...RecvT> typename RecvArrayType,
+            typename ...SendT, typename ...RecvT>
+  RecvArrayType<RecvT...> _allToAll(const SendArrayType<SendT...>& sent_array,
+                                    RecvArrayType<RecvT...>& recv_array) const
   {
 #ifdef PASTIS_HAS_MPI
-    using SendDataType = typename SendArrayType::data_type;
-    using RecvDataType = typename RecvArrayType::data_type;
+    using SendDataType = typename SendArrayType<SendT...>::data_type;
+    using RecvDataType = typename RecvArrayType<RecvT...>::data_type;
 
     static_assert(std::is_same_v<std::remove_const_t<SendDataType>,RecvDataType>);
     static_assert(std::is_arithmetic_v<SendDataType>);
@@ -128,13 +129,14 @@ class Messenger
     return recv_array;
   }
 
-  template <typename SendArrayType,
-            typename RecvArrayType>
-  void _exchange(const std::vector<SendArrayType>& sent_array_list,
-                 std::vector<RecvArrayType>& recv_array_list) const
+  template <template <typename ...SendT> typename SendArrayType,
+            template <typename ...RecvT> typename RecvArrayType,
+            typename ...SendT, typename ...RecvT>
+  void _exchange(const std::vector<SendArrayType<SendT...>>& sent_array_list,
+                 std::vector<RecvArrayType<RecvT...>>& recv_array_list) const
   {
-    using SendDataType = typename SendArrayType::data_type;
-    using RecvDataType = typename RecvArrayType::data_type;
+    using SendDataType = typename SendArrayType<SendT...>::data_type;
+    using RecvDataType = typename RecvArrayType<RecvT...>::data_type;
 
     static_assert(std::is_same_v<std::remove_const_t<SendDataType>,RecvDataType>);
     static_assert(std::is_arithmetic_v<SendDataType>);
@@ -146,7 +148,7 @@ class Messenger
         = Messenger::helper::mpiType<SendDataType>();
 
     for (size_t i_send=0; i_send<sent_array_list.size(); ++i_send) {
-      const SendArrayType sent_array = sent_array_list[i_send];
+      const auto sent_array = sent_array_list[i_send];
       if (sent_array.size()>0) {
         MPI_Request request;
         MPI_Isend(&(sent_array[0]), sent_array.size(), mpi_datatype, i_send, 0, MPI_COMM_WORLD, &request);
@@ -155,7 +157,7 @@ class Messenger
     }
 
     for (size_t i_recv=0; i_recv<recv_array_list.size(); ++i_recv) {
-      RecvArrayType recv_array = recv_array_list[i_recv];
+      auto recv_array = recv_array_list[i_recv];
       if (recv_array.size()>0) {
         MPI_Request request;
         MPI_Irecv(&(recv_array[0]), recv_array.size(), mpi_datatype, i_recv, 0, MPI_COMM_WORLD, &request);