rewrite meta::ForEach using boost::mp11

Author: bernhardmgruber

include/pmacc/PMaccConfig.cmake

@@ -296,7 +296,7 @@ endif(MPI_CXX_FOUND)
 # Find Boost
 ################################################################################
 
-find_package(Boost 1.65.1 REQUIRED COMPONENTS filesystem system math_tr1)
+find_package(Boost 1.66 REQUIRED COMPONENTS filesystem system math_tr1)
 if(TARGET Boost::filesystem)
     set(PMacc_LIBRARIES ${PMacc_LIBRARIES} Boost::boost Boost::filesystem
                                            Boost::system Boost::math_tr1)

include/pmacc/meta/ForEach.hpp

@@ -23,68 +23,21 @@
 
 #include "pmacc/meta/accessors/Identity.hpp"
 
+#include <boost/mp11.hpp>
 #include <boost/mpl/apply.hpp>
-#include <boost/mpl/begin_end.hpp>
-#include <boost/mpl/deref.hpp>
+#include <boost/mpl/copy.hpp>
 #include <boost/mpl/transform.hpp>
 
 #include <type_traits>
-#include <utility>
-
 
 namespace pmacc
 {
     namespace meta
     {
         namespace detail
         {
-            /** call the functor were itBegin points to
-             *
-             *  @tparam itBegin iterator to an element in a mpl sequence
-             *  @tparam itEnd iterator to the end of a mpl sequence
-             *  @tparam isEnd true if itBegin == itEnd, else false
-             */
-            template<typename itBegin, typename itEnd, bool isEnd = std::is_same<itBegin, itEnd>::value>
-            struct CallFunctorOfIterator
-            {
-                using nextIt = typename boost::mpl::next<itBegin>::type;
-                using Functor = typename boost::mpl::deref<itBegin>::type;
-                using NextCall = CallFunctorOfIterator<nextIt, itEnd>;
-
-                PMACC_NO_NVCC_HDWARNING
-                template<typename... T_Types>
-                HDINLINE void operator()(T_Types&&... ts) const
-                {
-                    Functor()(std::forward<T_Types>(ts)...);
-                    NextCall()(ts...);
-                }
-
-                PMACC_NO_NVCC_HDWARNING
-                template<typename... T_Types>
-                HDINLINE void operator()(T_Types&&... ts)
-                {
-                    Functor()(std::forward<T_Types>(ts)...);
-                    NextCall()(ts...);
-                }
-            };
-
-            /** Recursion end of ForEach */
-            template<typename itBegin, typename itEnd>
-            struct CallFunctorOfIterator<itBegin, itEnd, true>
-            {
-                PMACC_NO_NVCC_HDWARNING
-                template<typename... T_Types>
-                HDINLINE void operator()(T_Types&&...) const
-                {
-                }
-
-                PMACC_NO_NVCC_HDWARNING
-                template<typename... T_Types>
-                HDINLINE void operator()(T_Types&&...)
-                {
-                }
-            };
-
+            template<typename Seq>
+            using SeqToList = typename boost::mpl::copy<Seq, boost::mpl::back_inserter<boost::mp11::mp_list<>>>::type;
         } // namespace detail
 
         /** Compile-Time for each for Boost::MPL Type Lists
@@ -110,36 +63,19 @@ namespace pmacc
         template<typename T_MPLSeq, typename T_Functor, typename T_Accessor = meta::accessors::Identity<>>
         struct ForEach
         {
-            template<typename X>
-            struct ReplacePlaceholder : bmpl::apply1<T_Functor, typename bmpl::apply1<T_Accessor, X>::type>
-            {
-            };
+            using List = detail::SeqToList<T_MPLSeq>;
 
-            using SolvedFunctors = typename bmpl::transform<T_MPLSeq, ReplacePlaceholder<bmpl::_1>>::type;
-
-            using begin = typename boost::mpl::begin<SolvedFunctors>::type;
-            using end = typename boost::mpl::end<SolvedFunctors>::type;
-
-
-            using NextCall = detail::CallFunctorOfIterator<begin, end>;
+            template<typename X>
+            using ReplacePlaceholder =
+                typename bmpl::apply1<T_Functor, typename bmpl::apply1<T_Accessor, X>::type>::type;
 
-            /* this functor does nothing */
-            using Functor = detail::CallFunctorOfIterator<end, end>;
+            using SolvedFunctors = boost::mp11::mp_transform<ReplacePlaceholder, List>;
 
             PMACC_NO_NVCC_HDWARNING
             template<typename... T_Types>
             HDINLINE void operator()(T_Types&&... ts) const
             {
-                Functor()(std::forward<T_Types>(ts)...);
-                NextCall()(ts...);
-            }
-
-            PMACC_NO_NVCC_HDWARNING
-            template<typename... T_Types>
-            HDINLINE void operator()(T_Types&&... ts)
-            {
-                Functor()(std::forward<T_Types>(ts)...);
-                NextCall()(ts...);
+                boost::mp11::mp_for_each<SolvedFunctors>([&](auto functor) { functor(std::forward<T_Types>(ts)...); });
             }
         };