From 3c3b76920e7ca5431d116b6bce4b6ff43e8b7061 Mon Sep 17 00:00:00 2001
From: Peter Conrad <conrad@quisquis.de>
Date: Sun, 4 Nov 2018 13:54:05 +0100
Subject: [PATCH 1/2] Use function pointers instead of std::function objects in
 static variant visitors

---
 include/fc/static_variant.hpp | 46 ++++++++++++++++++++---------------
 1 file changed, 26 insertions(+), 20 deletions(-)

diff --git a/include/fc/static_variant.hpp b/include/fc/static_variant.hpp
index 1b2628b..a1f8583 100644
--- a/include/fc/static_variant.hpp
+++ b/include/fc/static_variant.hpp
@@ -178,33 +178,39 @@ struct type_info<> {
 
 } // namespace impl
 
-template<typename Visitor,typename Data>
-std::vector<std::function<typename Visitor::result_type(Visitor&,Data)>> init_wrappers()
+template<int L,typename Visitor,typename Data>
+static const fc::array<typename Visitor::result_type(*)(Visitor&,Data),L>
+      init_wrappers( Visitor& v, Data d, typename Visitor::result_type(**funcs)(Visitor&,Data) = 0)
 {
-   return std::vector<std::function<typename Visitor::result_type(Visitor&,Data)>>();
+   return fc::array<typename Visitor::result_type(*)(Visitor&,Data),L>();
 }
 
-template<typename Visitor,typename Data, typename T, typename ... Types>
-std::vector<std::function<typename Visitor::result_type(Visitor&,Data)>> init_wrappers()
+template<int L,typename Visitor,typename Data,typename T, typename ... Types>
+static const fc::array<typename Visitor::result_type(*)(Visitor&,Data),L>
+      init_wrappers( Visitor& v, Data d, typename Visitor::result_type(**funcs)(Visitor&,Data) = 0 )
 {
-   std::vector<std::function<typename Visitor::result_type(Visitor&,Data)>> result
-        = init_wrappers<Visitor,Data,Types...>();
-   result.insert( result.begin(), [] ( Visitor& v, Data d ) { return v( *reinterpret_cast<T*>( d ) ); } );
+   fc::array<typename Visitor::result_type(*)(Visitor&,Data),L> result;
+   if( !funcs ) funcs = result.begin();
+   *funcs++ = [] ( Visitor& v, Data d ) { return v( *reinterpret_cast<T*>( d ) ); };
+   init_wrappers<L,Visitor,Data,Types...>( v, d, funcs );
    return result;
 }
 
-template<typename Visitor,typename Data>
-std::vector<std::function<typename Visitor::result_type(Visitor&,Data)>> init_const_wrappers()
+template<int L,typename Visitor,typename Data>
+static const fc::array<typename Visitor::result_type(*)(Visitor&,Data),L>
+      init_const_wrappers( Visitor& v, Data d, typename Visitor::result_type(**funcs)(Visitor&,Data) = 0 )
 {
-   return std::vector<std::function<typename Visitor::result_type(Visitor&,Data)>>();
+   return fc::array<typename Visitor::result_type(*)(Visitor&,Data),L>();
 }
 
-template<typename Visitor,typename Data, typename T, typename ... Types>
-std::vector<std::function<typename Visitor::result_type(Visitor&,Data)>> init_const_wrappers()
+template<int L,typename Visitor,typename Data,typename T, typename ... Types>
+static const fc::array<typename Visitor::result_type(*)(Visitor&,Data),L>
+      init_const_wrappers( Visitor& v, Data d, typename Visitor::result_type(**funcs)(Visitor&,Data) = 0 )
 {
-   std::vector<std::function<typename Visitor::result_type(Visitor&,Data)>> result
-        = init_const_wrappers<Visitor,Data,Types...>();
-   result.insert( result.begin(), [] ( Visitor& v, Data d ) { return v( *reinterpret_cast<const T*>( d ) ); } );
+   fc::array<typename Visitor::result_type(*)(Visitor&,Data),L> result;
+   if( !funcs ) funcs = result.begin();
+   *funcs++ = [] ( Visitor& v, Data d ) { return v( *reinterpret_cast<const T*>( d ) ); };
+   init_const_wrappers<L,Visitor,Data,Types...>( v, d, funcs );
    return result;
 }
 
@@ -361,7 +367,7 @@ public:
     template<typename visitor>
     static typename visitor::result_type visit( tag_type tag, visitor& v, void* data )
     {
-        static auto wrappers = init_wrappers<visitor,void*,Types...>();
+        static const auto wrappers = init_wrappers<impl::type_info<Types...>::count,visitor,void*,Types...>( v, data );
         FC_ASSERT( tag >= 0 && tag < count(), "Unsupported type ${tag}!", ("tag",tag) );
         return wrappers[tag]( v, data );
     }
@@ -369,7 +375,7 @@ public:
     template<typename visitor>
     static typename visitor::result_type visit( tag_type tag, const visitor& v, void* data )
     {
-        static auto wrappers = init_wrappers<const visitor,void*,Types...>();
+        static const auto wrappers = init_wrappers<impl::type_info<Types...>::count,const visitor,void*,Types...>( v, data );
         FC_ASSERT( tag >= 0 && tag < count(), "Unsupported type ${tag}!", ("tag",tag) );
         return wrappers[tag]( v, data );
     }
@@ -377,7 +383,7 @@ public:
     template<typename visitor>
     static typename visitor::result_type visit( tag_type tag, visitor& v, const void* data )
     {
-        static auto wrappers = init_const_wrappers<visitor,const void*,Types...>();
+        static const auto wrappers = init_const_wrappers<impl::type_info<Types...>::count,visitor,const void*,Types...>( v, data );
         FC_ASSERT( tag >= 0 && tag < count(), "Unsupported type ${tag}!", ("tag",tag) );
         return wrappers[tag]( v, data );
     }
@@ -385,7 +391,7 @@ public:
     template<typename visitor>
     static typename visitor::result_type visit( tag_type tag, const visitor& v, const void* data )
     {
-        static auto wrappers = init_const_wrappers<const visitor,const void*,Types...>();
+        static const auto wrappers = init_const_wrappers<impl::type_info<Types...>::count,const visitor,const void*,Types...>( v, data );
         FC_ASSERT( tag >= 0 && tag < count(), "Unsupported type ${tag}!", ("tag",tag) );
         return wrappers[tag]( v, data );
     }

From ed4a300fd56a5b1857ce43c17f6d3a39958e7bf5 Mon Sep 17 00:00:00 2001
From: Peter Conrad <conrad@quisquis.de>
Date: Sun, 4 Nov 2018 21:14:29 +0100
Subject: [PATCH 2/2] Added missing include

---
 include/fc/static_variant.hpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/fc/static_variant.hpp b/include/fc/static_variant.hpp
index a1f8583..f5227af 100644
--- a/include/fc/static_variant.hpp
+++ b/include/fc/static_variant.hpp
@@ -14,6 +14,8 @@
 #include <functional>
 #include <stdexcept>
 #include <typeinfo>
+
+#include <fc/array.hpp>
 #include <fc/exception/exception.hpp>
 
 namespace fc {