From 24652d1f7d4fe69ff884c76457934c255651ad41 Mon Sep 17 00:00:00 2001
From: BlackMATov <blackmat@mail.ru>
Date: Tue, 19 May 2020 21:56:58 +0700
Subject: [PATCH] finalize C++11 impl

---
 CMakeLists.txt                |  4 +-
 README.md                     |  6 +--
 headers/invoke.hpp/invoke.hpp | 73 ++++++++++++++++++-----------------
 3 files changed, 43 insertions(+), 40 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5162735..328bcf3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-# 3.8 version is required for `cxx_std_14`
+# 3.8 version is required for `cxx_std_11`
 cmake_minimum_required(VERSION 3.8 FATAL_ERROR)
 
 if(NOT DEFINED PROJECT_NAME)
@@ -8,7 +8,7 @@ endif()
 project(invoke.hpp)
 
 add_library(${PROJECT_NAME} INTERFACE)
-target_compile_features(${PROJECT_NAME} INTERFACE cxx_std_14)
+target_compile_features(${PROJECT_NAME} INTERFACE cxx_std_11)
 target_include_directories(${PROJECT_NAME} INTERFACE headers)
 
 if(BUILD_AS_STANDALONE)
diff --git a/README.md b/README.md
index 94a7c03..ee5c829 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # invoke.hpp
 
-> std::invoke/std::apply analogs for C++14
+> std::invoke/std::apply analogs for C++11/14
 
 [![travis][badge.travis]][travis]
 [![appveyor][badge.appveyor]][appveyor]
@@ -12,14 +12,14 @@
 [badge.travis]: https://img.shields.io/travis/BlackMATov/invoke.hpp/master.svg?logo=travis
 [badge.appveyor]: https://img.shields.io/appveyor/ci/BlackMATov/invoke-hpp/master.svg?logo=appveyor
 [badge.codecov]: https://img.shields.io/codecov/c/github/BlackMATov/invoke.hpp/master.svg?logo=codecov
-[badge.language]: https://img.shields.io/badge/language-C%2B%2B14-red.svg
+[badge.language]: https://img.shields.io/badge/language-C%2B%2B11-red.svg
 [badge.license]: https://img.shields.io/badge/license-MIT-blue.svg
 [badge.paypal]: https://img.shields.io/badge/donate-PayPal-orange.svg?logo=paypal&colorA=00457C
 
 [travis]: https://travis-ci.org/BlackMATov/invoke.hpp
 [appveyor]: https://ci.appveyor.com/project/BlackMATov/invoke-hpp
 [codecov]: https://codecov.io/gh/BlackMATov/invoke.hpp
-[language]: https://en.wikipedia.org/wiki/C%2B%2B14
+[language]: https://en.wikipedia.org/wiki/C%2B%2B11
 [license]: https://en.wikipedia.org/wiki/MIT_License
 [paypal]: https://www.paypal.me/matov
 
diff --git a/headers/invoke.hpp/invoke.hpp b/headers/invoke.hpp/invoke.hpp
index 47c027b..5bd950e 100644
--- a/headers/invoke.hpp/invoke.hpp
+++ b/headers/invoke.hpp/invoke.hpp
@@ -11,9 +11,6 @@
 #include <functional>
 #include <type_traits>
 
-#define INVOKE_HPP_NOEXCEPT_RETURN(...) \
-    noexcept(noexcept(__VA_ARGS__)) { return __VA_ARGS__; }
-
 #define INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(...) \
     noexcept(noexcept(__VA_ARGS__)) -> decltype (__VA_ARGS__) { return __VA_ARGS__; }
 
@@ -35,6 +32,42 @@ namespace invoke_hpp
     using void_t = typename impl::make_void<Args...>::type;
 }
 
+//
+// integer_sequence
+//
+
+namespace invoke_hpp
+{
+    template < typename T, T... Ints >
+    struct integer_sequence {
+        using value_type = T;
+        static constexpr std::size_t size() noexcept { return sizeof...(Ints); }
+    };
+
+    template < std::size_t... Ints >
+    using index_sequence = integer_sequence<std::size_t, Ints...>;
+
+    namespace impl
+    {
+        template < typename T, std::size_t N, T... Ints >
+        struct make_integer_sequence_impl
+        : make_integer_sequence_impl<T, N - 1, N - 1, Ints...> {};
+
+        template < typename T, T... Ints >
+        struct make_integer_sequence_impl<T, 0, Ints...>
+        : integer_sequence<T, Ints...> {};
+    }
+
+    template < typename T, std::size_t N >
+    using make_integer_sequence = impl::make_integer_sequence_impl<T, N>;
+
+    template < std::size_t N >
+    using make_index_sequence = make_integer_sequence<std::size_t, N>;
+
+    template < typename... Ts >
+    using index_sequence_for = make_index_sequence<sizeof...(Ts)>;
+}
+
 //
 // is_reference_wrapper
 //
@@ -223,40 +256,12 @@ 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 auto apply_impl(F&& f, Tuple&& args, impl::index_sequence<I...>)
+        constexpr auto apply_impl(F&& f, Tuple&& args, index_sequence<I...>)
         INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
             invoke_hpp::invoke(
                 std::forward<F>(f),
@@ -269,9 +274,7 @@ namespace invoke_hpp
         impl::apply_impl(
             std::forward<F>(f),
             std::forward<Tuple>(args),
-            impl::make_index_sequence<std::tuple_size<typename std::decay<Tuple>::type>::value>()))
+            make_index_sequence<std::tuple_size<typename std::decay<Tuple>::type>::value>()))
 }
 
-
-#undef INVOKE_HPP_NOEXCEPT_RETURN
 #undef INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN