From f830221c561bd9e84d4916189273f367f83b558e Mon Sep 17 00:00:00 2001
From: bolero-MURAKAMI <bolero.murakami@gmail.com>
Date: Sun, 13 Jul 2014 00:28:34 +0900
Subject: [PATCH] add tuple_traits

---
 sprout/tuple/tuple.hpp              |  2 +-
 sprout/tuple/tuple/get.hpp          |  9 +--
 sprout/tuple/tuple/traits.hpp       | 15 +++++
 sprout/tuple/tuple/tuple_traits.hpp | 85 +++++++++++++++++++++++++++++
 4 files changed, 106 insertions(+), 5 deletions(-)
 create mode 100644 sprout/tuple/tuple/traits.hpp
 create mode 100644 sprout/tuple/tuple/tuple_traits.hpp

diff --git a/sprout/tuple/tuple.hpp b/sprout/tuple/tuple.hpp
index 8933d66a..e21225dc 100644
--- a/sprout/tuple/tuple.hpp
+++ b/sprout/tuple/tuple.hpp
@@ -20,7 +20,7 @@
 #include <sprout/tuple/tuple/ignore.hpp>
 #include <sprout/tuple/tuple/make_tuple.hpp>
 #include <sprout/tuple/tuple/type_traits.hpp>
-#include <sprout/tuple/tuple/tuple_access_traits.hpp>
+#include <sprout/tuple/tuple/traits.hpp>
 #include <sprout/tuple/flexibly_construct.hpp>
 
 #endif	// #ifndef SPROUT_TUPLE_TUPLE_HPP
diff --git a/sprout/tuple/tuple/get.hpp b/sprout/tuple/tuple/get.hpp
index 53d26c8a..6398c2bd 100644
--- a/sprout/tuple/tuple/get.hpp
+++ b/sprout/tuple/tuple/get.hpp
@@ -16,6 +16,7 @@
 #include <sprout/tuple/tuple/tuple.hpp>
 #include <sprout/tuple/tuple/tuple_size.hpp>
 #include <sprout/tuple/tuple/tuple_element.hpp>
+#include <sprout/tuple/tuple/tuple_traits.hpp>
 #include <sprout/tuple/tuple/tuple_access_traits.hpp>
 #include <sprout/adl/not_found.hpp>
 
@@ -66,7 +67,7 @@ namespace sprout_tuple_detail {
 	using sprout_adl::tuple_get;
 
 	template<std::size_t I, typename T>
-	inline SPROUT_CONSTEXPR typename sprout::tuples::tuple_element<I, T>::type&
+	inline SPROUT_CONSTEXPR typename sprout::tuples::tuple_traits<T>::template lvalue_reference<I>::type
 	tuple_get(T& t)
 	SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(sprout::tuples::tuple_access_traits<T>::template tuple_get<I>(std::declval<T&>())))
 	{
@@ -75,15 +76,15 @@ namespace sprout_tuple_detail {
 	template<std::size_t I, typename T>
 	inline SPROUT_CONSTEXPR typename std::enable_if<
 		!std::is_const<T>::value && !std::is_volatile<T>::value && !std::is_reference<T>::value,
-		typename sprout::tuples::tuple_element<I, typename std::remove_reference<T>::type>::type&&
+		typename sprout::tuples::tuple_traits<typename std::remove_reference<T>::type>::template rvalue_reference<I>::type
 	>::type
 	tuple_get(T&& t)
-	SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(sprout::tuples::tuple_access_traits<T>::template tuple_get<I>(std::declval<T&&>())))
+	SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(sprout::tuples::tuple_access_traits<typename std::remove_reference<T>::type>::template tuple_get<I>(std::declval<T&&>())))
 	{
 		return sprout::tuples::tuple_access_traits<T>::template tuple_get<I>(t);
 	}
 	template<std::size_t I, typename T>
-	inline SPROUT_CONSTEXPR typename sprout::tuples::tuple_element<I, T>::type const&
+	inline SPROUT_CONSTEXPR typename sprout::tuples::tuple_traits<T const>::template lvalue_reference<I>::type
 	tuple_get(T const& t)
 	SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(sprout::tuples::tuple_access_traits<T const>::template tuple_get<I>(std::declval<T const&>())))
 	{
diff --git a/sprout/tuple/tuple/traits.hpp b/sprout/tuple/tuple/traits.hpp
new file mode 100644
index 00000000..e96dd8ad
--- /dev/null
+++ b/sprout/tuple/tuple/traits.hpp
@@ -0,0 +1,15 @@
+/*=============================================================================
+  Copyright (c) 2011-2014 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_TUPLE_TUPLE_TRAITS_HPP
+#define SPROUT_TUPLE_TUPLE_TRAITS_HPP
+
+#include <sprout/config.hpp>
+#include <sprout/tuple/tuple/tuple_traits.hpp>
+#include <sprout/tuple/tuple/tuple_access_traits.hpp>
+
+#endif	// #ifndef SPROUT_TUPLE_TUPLE_TRAITS_HPP
diff --git a/sprout/tuple/tuple/tuple_traits.hpp b/sprout/tuple/tuple/tuple_traits.hpp
new file mode 100644
index 00000000..6bd44234
--- /dev/null
+++ b/sprout/tuple/tuple/tuple_traits.hpp
@@ -0,0 +1,85 @@
+/*=============================================================================
+  Copyright (c) 2011-2014 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_TUPLE_TUPLE_TUPLE_TRAITS_HPP
+#define SPROUT_TUPLE_TUPLE_TUPLE_TRAITS_HPP
+
+#include <tuple>
+#include <type_traits>
+#include <sprout/config.hpp>
+#include <sprout/workaround/std/cstddef.hpp>
+#include <sprout/tuple/tuple/tuple_size.hpp>
+#include <sprout/tuple/tuple/tuple_element.hpp>
+
+namespace sprout {
+	namespace tuples {
+		//
+		// tuple_traits
+		//
+		template<typename Tuple>
+		struct tuple_traits {
+		public:
+			SPROUT_STATIC_CONSTEXPR std::size_t size = sprout::tuples::tuple_size<Tuple>::value;
+		public:
+			template<std::size_t I>
+			struct element
+				: public sprout::tuples::tuple_element<I, Tuple>
+			{};
+			template<std::size_t I>
+			struct lvalue_reference
+				: public std::add_lvalue_reference<typename element<I>::type>
+			{};
+			template<std::size_t I>
+			struct const_lvalue_reference
+				: public std::add_lvalue_reference<typename element<I>::type const>
+			{};
+			template<std::size_t I>
+			struct rvalue_reference
+				: public std::add_rvalue_reference<typename element<I>::type>
+			{};
+			template<std::size_t I>
+			struct const_rvalue_reference
+				: public std::add_rvalue_reference<typename element<I>::type const>
+			{};
+		};
+		template<typename Tuple>
+		SPROUT_CONSTEXPR_OR_CONST std::size_t sprout::tuples::tuple_traits<Tuple>::size;
+
+		template<typename Tuple>
+		struct tuple_traits<Tuple const> {
+		public:
+			SPROUT_STATIC_CONSTEXPR std::size_t size = sprout::tuples::tuple_traits<Tuple>::size;
+		public:
+			template<std::size_t I>
+			struct element
+				: public sprout::tuples::tuple_traits<Tuple>::template element<I>
+			{};
+			template<std::size_t I>
+			struct lvalue_reference
+				: public sprout::tuples::tuple_traits<Tuple>::template const_lvalue_reference<I>
+			{};
+			template<std::size_t I>
+			struct const_lvalue_reference
+				: public sprout::tuples::tuple_traits<Tuple>::template const_lvalue_reference<I>
+			{};
+			template<std::size_t I>
+			struct rvalue_reference
+				: public sprout::tuples::tuple_traits<Tuple>::template const_rvalue_reference<I>
+			{};
+			template<std::size_t I>
+			struct const_rvalue_reference
+				: public sprout::tuples::tuple_traits<Tuple>::template const_rvalue_reference<I>
+			{};
+		};
+		template<typename Tuple>
+		SPROUT_CONSTEXPR_OR_CONST std::size_t sprout::tuples::tuple_traits<Tuple const>::size;
+	}	// namespace tuples
+
+	using sprout::tuples::tuple_traits;
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_TUPLE_TUPLE_TUPLE_TRAITS_HPP