From 8822eb5ff883bf267f55d24e1791d99a00ab31b5 Mon Sep 17 00:00:00 2001
From: Dmytro <33125344+smay1613@users.noreply.github.com>
Date: Tue, 19 May 2020 16:05:34 +0300
Subject: [PATCH 1/2] Implement with c++11

---
 headers/invoke.hpp/invoke.hpp | 77 +++++++++++++++++++++++------------
 1 file changed, 51 insertions(+), 26 deletions(-)

diff --git a/headers/invoke.hpp/invoke.hpp b/headers/invoke.hpp/invoke.hpp
index 8dfb861..4c6a646 100644
--- a/headers/invoke.hpp/invoke.hpp
+++ b/headers/invoke.hpp/invoke.hpp
@@ -54,7 +54,7 @@ namespace invoke_hpp
 
     template < typename T >
     struct is_reference_wrapper
-    : impl::is_reference_wrapper_impl<std::remove_cv_t<T>> {};
+    : impl::is_reference_wrapper_impl<typename std::remove_cv<T>::type> {};
 }
 
 //
@@ -72,7 +72,7 @@ namespace invoke_hpp
         template
         <
             typename Base, typename F, typename Derived,
-            typename std::enable_if_t<std::is_base_of<Base, std::decay_t<Derived>>::value, int> = 0
+            typename std::enable_if<std::is_base_of<Base, typename std::decay<Derived>::type>::value, int>::type = 0
         >
         constexpr auto invoke_member_object_impl(F Base::* f, Derived&& ref)
         INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
@@ -81,7 +81,7 @@ namespace invoke_hpp
         template
         <
             typename Base, typename F, typename RefWrap,
-            typename std::enable_if_t<is_reference_wrapper<std::decay_t<RefWrap>>::value, int> = 0
+            typename std::enable_if<is_reference_wrapper<typename std::decay<RefWrap>::type>::value, int>::type = 0
         >
         constexpr auto invoke_member_object_impl(F Base::* f, RefWrap&& ref)
         INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
@@ -90,10 +90,10 @@ namespace invoke_hpp
         template
         <
             typename Base, typename F, typename Pointer,
-            typename std::enable_if_t<
-                !std::is_base_of<Base, std::decay_t<Pointer>>::value &&
-                !is_reference_wrapper<std::decay_t<Pointer>>::value
-            , int> = 0
+            typename std::enable_if<
+                !std::is_base_of<Base, typename std::decay<Pointer>::type>::value &&
+                !is_reference_wrapper<typename std::decay<Pointer>::type>::value
+            , int>::type = 0
         >
         constexpr auto invoke_member_object_impl(F Base::* f, Pointer&& ptr)
         INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
@@ -106,7 +106,7 @@ namespace invoke_hpp
         template
         <
             typename Base, typename F, typename Derived, typename... Args,
-            typename std::enable_if_t<std::is_base_of<Base, std::decay_t<Derived>>::value, int> = 0
+            typename std::enable_if<std::is_base_of<Base, typename std::decay<Derived>::type>::value, int>::type = 0
         >
         constexpr auto invoke_member_function_impl(F Base::* f, Derived&& ref, Args&&... args)
         INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
@@ -115,7 +115,7 @@ namespace invoke_hpp
         template
         <
             typename Base, typename F, typename RefWrap, typename... Args,
-            typename std::enable_if_t<is_reference_wrapper<std::decay_t<RefWrap>>::value, int> = 0
+            typename std::enable_if<is_reference_wrapper<typename std::decay<RefWrap>::type>::value, int>::type = 0
         >
         constexpr auto invoke_member_function_impl(F Base::* f, RefWrap&& ref, Args&&... args)
         INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
@@ -124,10 +124,10 @@ namespace invoke_hpp
         template
         <
             typename Base, typename F, typename Pointer, typename... Args,
-            typename std::enable_if_t<
-                !std::is_base_of<Base, std::decay_t<Pointer>>::value &&
-                !is_reference_wrapper<std::decay_t<Pointer>>::value
-            , int> = 0
+            typename std::enable_if<
+                !std::is_base_of<Base, typename std::decay<Pointer>::type>::value &&
+                !is_reference_wrapper<typename std::decay<Pointer>::type>::value
+            , int>::type = 0
         >
         constexpr auto invoke_member_function_impl(F Base::* f, Pointer&& ptr, Args&&... args)
         INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
@@ -137,7 +137,7 @@ namespace invoke_hpp
     template
     <
         typename F, typename... Args,
-        typename std::enable_if_t<!std::is_member_pointer<std::decay_t<F>>::value, int> = 0
+        typename std::enable_if<!std::is_member_pointer<typename std::decay<F>::type>::value, int>::type = 0
     >
     constexpr auto invoke(F&& f, Args&&... args)
     INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
@@ -146,7 +146,7 @@ namespace invoke_hpp
     template
     <
         typename F, typename T,
-        typename std::enable_if_t<std::is_member_object_pointer<std::decay_t<F>>::value, int> = 0
+        typename std::enable_if<std::is_member_object_pointer<typename std::decay<F>::type>::value, int>::type = 0
     >
     constexpr auto invoke(F&& f, T&& t)
     INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
@@ -155,7 +155,7 @@ namespace invoke_hpp
     template
     <
         typename F, typename... Args,
-        typename std::enable_if_t<std::is_member_function_pointer<std::decay_t<F>>::value, int> = 0
+        typename std::enable_if<std::is_member_function_pointer<typename std::decay<F>::type>::value, int>::type = 0
     >
     constexpr auto invoke(F&& f, Args&&... args)
     INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
@@ -205,10 +205,10 @@ namespace invoke_hpp
 
         template < typename R, typename F, typename... Args >
         struct is_invocable_r_impl<void_t<is_invocable_r_impl_tag, invoke_result_t<F, Args...>>, R, F, Args...>
-        : std::conditional_t<
+        : std::conditional<
             std::is_void<R>::value,
             std::true_type,
-            std::is_convertible<invoke_result_t<F, Args...>, R>> {};
+            std::is_convertible<invoke_result_t<F, Args...>, R>>::type {};
     }
 
     template < typename R, typename F, typename... Args >
@@ -223,26 +223,51 @@ namespace invoke_hpp
 // apply
 //
 
+namespace invoke_hpp
+{
+    namespace impl
+    {
+        template<typename T, T... Ints>
+        struct integer_sequence
+        {
+            typedef T value_type;
+            static constexpr std::size_t size() { return sizeof...(Ints); }
+        };
+
+        template<std::size_t... Ints>
+        using index_sequence = integer_sequence<std::size_t, Ints...>;
+
+        template<typename T, std::size_t N, T... Is>
+        struct make_integer_sequence : make_integer_sequence<T, N-1, N-1, Is...> {};
+
+        template<typename T, T... Is>
+        struct make_integer_sequence<T, 0, Is...> : integer_sequence<T, Is...> {};
+
+        template<std::size_t N>
+        using make_index_sequence = make_integer_sequence<std::size_t, N>;
+
+        template<typename... T>
+        using index_sequence_for = make_index_sequence<sizeof...(T)>;
+    }
+}
+
 namespace invoke_hpp
 {
     namespace impl
     {
         template < typename F, typename Tuple, std::size_t... I >
-        constexpr decltype(auto) apply_impl(F&& f, Tuple&& args, std::index_sequence<I...>)
-        INVOKE_HPP_NOEXCEPT_RETURN(
+        constexpr auto apply_impl(F&& f, Tuple&& args, impl::index_sequence<I...>)
+        INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
             invoke_hpp::invoke(
                 std::forward<F>(f),
                 std::get<I>(std::forward<Tuple>(args))...))
     }
 
     template < typename F, typename Tuple >
-    constexpr decltype(auto) apply(F&& f, Tuple&& args)
-    INVOKE_HPP_NOEXCEPT_RETURN(
+    constexpr auto apply(F&& f, Tuple&& args)
+    INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
         impl::apply_impl(
             std::forward<F>(f),
             std::forward<Tuple>(args),
-            std::make_index_sequence<std::tuple_size<std::decay_t<Tuple>>::value>()))
+            impl::make_index_sequence<std::tuple_size<typename std::decay<Tuple>::type>::value>()))
 }
-
-#undef INVOKE_HPP_NOEXCEPT_RETURN
-#undef INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN

From 4ca21a07a61f1de4a5c579a2b2c58b2a0515a6a0 Mon Sep 17 00:00:00 2001
From: Dmytro <33125344+smay1613@users.noreply.github.com>
Date: Tue, 19 May 2020 16:25:25 +0300
Subject: [PATCH 2/2] Update invoke.hpp

---
 headers/invoke.hpp/invoke.hpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/headers/invoke.hpp/invoke.hpp b/headers/invoke.hpp/invoke.hpp
index 4c6a646..47c027b 100644
--- a/headers/invoke.hpp/invoke.hpp
+++ b/headers/invoke.hpp/invoke.hpp
@@ -271,3 +271,7 @@ namespace invoke_hpp
             std::forward<Tuple>(args),
             impl::make_index_sequence<std::tuple_size<typename std::decay<Tuple>::type>::value>()))
 }
+
+
+#undef INVOKE_HPP_NOEXCEPT_RETURN
+#undef INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN