From eec9c8692057794be759503f8974829a3c77396f Mon Sep 17 00:00:00 2001
From: bolero-MURAKAMI <bolero.murakami@gmail.com>
Date: Wed, 11 Oct 2017 17:18:48 +0900
Subject: [PATCH] add C++17 invoke function

---
 sprout/functional.hpp                       |  1 +
 sprout/functional/invoke.hpp                | 31 +++++++++++++++++++++
 sprout/type_traits/detail/invoke.hpp        | 24 +++++++++++-----
 sprout/type_traits/is_nothrow_invocable.hpp |  1 +
 4 files changed, 50 insertions(+), 7 deletions(-)
 create mode 100644 sprout/functional/invoke.hpp

diff --git a/sprout/functional.hpp b/sprout/functional.hpp
index 62b8ee79..7bc4772c 100644
--- a/sprout/functional.hpp
+++ b/sprout/functional.hpp
@@ -12,6 +12,7 @@
 #include <sprout/functional/base.hpp>
 #include <sprout/functional/functor.hpp>
 #include <sprout/functional/adaptor.hpp>
+#include <sprout/functional/invoke.hpp>
 #include <sprout/functional/ref.hpp>
 #include <sprout/functional/mem_fn.hpp>
 #include <sprout/functional/bind.hpp>
diff --git a/sprout/functional/invoke.hpp b/sprout/functional/invoke.hpp
new file mode 100644
index 00000000..d39a2310
--- /dev/null
+++ b/sprout/functional/invoke.hpp
@@ -0,0 +1,31 @@
+/*=============================================================================
+  Copyright (c) 2011 RiSK (sscrisk)
+  https://github.com/sscrisk/CEL---ConstExpr-Library
+
+  Copyright (c) 2011-2017 Bolero MURAKAMI
+  https://github.com/bolero-MURAKAMI/Sprout
+
+  Distributed under the Boost Software License, Version 1.0. (See accompanying
+  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+=============================================================================*/
+#ifndef SPROUT_FUNCTIONAL_INVOKE_HPP
+#define SPROUT_FUNCTIONAL_INVOKE_HPP
+
+#include <sprout/config.hpp>
+#include <sprout/utility/forward.hpp>
+#include <sprout/type_traits/invoke_result.hpp>
+#include <sprout/type_traits/is_nothrow_invocable.hpp>
+#include <sprout/type_traits/detail/invoke.hpp>
+
+namespace sprout {
+	//
+	// invoke
+	//
+	template<typename F, typename... Args>
+	inline SPROUT_CONSTEXPR typename sprout::invoke_result<F, Args...>::type
+	invoke(F&& f, Args&&... args) SPROUT_NOEXCEPT_IF((sprout::is_nothrow_invocable<F, Args...>::value)) {
+		return sprout::detail::invoke(sprout::forward<F>(f), sprout::forward<Args>(args)...);
+	}
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_FUNCTIONAL_INVOKE_HPP
diff --git a/sprout/type_traits/detail/invoke.hpp b/sprout/type_traits/detail/invoke.hpp
index 45267ffb..e6b0af6d 100644
--- a/sprout/type_traits/detail/invoke.hpp
+++ b/sprout/type_traits/detail/invoke.hpp
@@ -13,29 +13,39 @@
 #include <sprout/type_traits/identity.hpp>
 #include <sprout/type_traits/voider.hpp>
 #include <sprout/detail/nil_base.hpp>
-#include <sprout/utility/implicit_cast.hpp>
+#include <sprout/utility/forward.hpp>
 
 namespace sprout {
 	namespace detail {
 		template<typename F, typename... Args>
 		inline SPROUT_CONSTEXPR decltype(std::declval<F>()(std::declval<Args>()...))
-		invoke(F&&, Args&&...) SPROUT_NOEXCEPT_IF_EXPR(std::declval<F>()(std::declval<Args>()...));
+		invoke(F&& f, Args&&... args) SPROUT_NOEXCEPT_IF_EXPR(std::declval<F>()(std::declval<Args>()...)) {
+			return sprout::forward<F>(f)(sprout::forward<Args>(args)...);
+		}
 
 		template<typename Base, typename T, typename Derived>
 		inline SPROUT_CONSTEXPR decltype(std::declval<Derived>().*(std::declval<T Base::*>()))
-		invoke(T Base::*, Derived&&) SPROUT_NOEXCEPT_IF_EXPR(std::declval<Derived>().*(std::declval<T Base::*>()));
+		invoke(T Base::* pm, Derived&& d) SPROUT_NOEXCEPT_IF_EXPR(std::declval<Derived>().*(std::declval<T Base::*>())) {
+			return sprout::forward<Derived>(d).*(pm);
+		}
 
 		template<typename PMD, typename Pointer>
 		inline SPROUT_CONSTEXPR decltype((*std::declval<Pointer>()).*(std::declval<PMD>()))
-		invoke(PMD&&, Pointer&&) SPROUT_NOEXCEPT_IF_EXPR((*std::declval<Pointer>()).*(std::declval<PMD>()));
+		invoke(PMD&& pmd, Pointer&& ptr) SPROUT_NOEXCEPT_IF_EXPR((*std::declval<Pointer>()).*(std::declval<PMD>())) {
+			return sprout::forward<Pointer>(ptr).*(sprout::forward<PMD>(pmd));
+		}
 
 		template<typename Base, typename T, typename Derived, typename... Args>
 		inline SPROUT_CONSTEXPR decltype((std::declval<Derived>().*(std::declval<T Base::*>()))(std::declval<Args>()...))
-		invoke(T Base::*, Derived&&, Args&&...) SPROUT_NOEXCEPT_IF_EXPR((std::declval<Derived>().*(std::declval<T Base::*>()))(std::declval<Args>()...));
+		invoke(T Base::* pm, Derived&& d, Args&&... args) SPROUT_NOEXCEPT_IF_EXPR((std::declval<Derived>().*(std::declval<T Base::*>()))(std::declval<Args>()...)) {
+			return (sprout::forward<Derived>(d).*(pm))(sprout::forward<Args>(args)...);
+		}
 
 		template<typename PMF, typename Pointer, typename... Args>
 		inline SPROUT_CONSTEXPR decltype(((*std::declval<Pointer>()).*(std::declval<PMF>()))(std::declval<Args>()...))
-		invoke(PMF&& pmf, Pointer&& ptr, Args&&... args) SPROUT_NOEXCEPT_IF_EXPR(((*std::declval<Pointer>()).*(std::declval<PMF>()))(std::declval<Args>()...));
+		invoke(PMF&& pmf, Pointer&& ptr, Args&&... args) SPROUT_NOEXCEPT_IF_EXPR(((*std::declval<Pointer>()).*(std::declval<PMF>()))(std::declval<Args>()...)) {
+			return (sprout::forward<Pointer>(ptr).*(sprout::forward<PMF>(pmf)))(sprout::forward<Args>(args)...);
+		}
 
 		template<typename R, typename F, typename... Args>
 		inline SPROUT_CONSTEXPR R
@@ -55,7 +65,7 @@ namespace sprout {
 
 		template<typename R, typename PMF, typename Pointer, typename... Args>
 		inline SPROUT_CONSTEXPR decltype(R(((*std::declval<Pointer>()).*(std::declval<PMF>()))(std::declval<Args>()...)))
-		invoke(PMF&& pmf, Pointer&& ptr, Args&&... args) SPROUT_NOEXCEPT_IF_EXPR(R(((*std::declval<Pointer>()).*(std::declval<PMF>()))(std::declval<Args>()...)));
+		invoke(PMF&&, Pointer&&, Args&&...) SPROUT_NOEXCEPT_IF_EXPR(R(((*std::declval<Pointer>()).*(std::declval<PMF>()))(std::declval<Args>()...)));
 	}	// namespace detail
 
 	namespace detail {
diff --git a/sprout/type_traits/is_nothrow_invocable.hpp b/sprout/type_traits/is_nothrow_invocable.hpp
index 7521f0df..80e87507 100644
--- a/sprout/type_traits/is_nothrow_invocable.hpp
+++ b/sprout/type_traits/is_nothrow_invocable.hpp
@@ -11,6 +11,7 @@
 #include <sprout/config.hpp>
 #include <sprout/type_traits/integral_constant.hpp>
 #include <sprout/type_traits/invoke_result.hpp>
+#include <sprout/type_traits/is_invocable.hpp>
 #include <sprout/type_traits/detail/invoke.hpp>
 
 namespace sprout {