From 8b40dfd184f43a6da2933b7258a178137ec2d648 Mon Sep 17 00:00:00 2001
From: bolero-MURAKAMI <bolero.murakami@gmail.com>
Date: Mon, 6 Jan 2014 22:45:41 +0900
Subject: [PATCH] add type_traits/std_value_variables.hpp

---
 sprout/config/auto_config.hpp              |   9 ++
 sprout/config/compiler/borland.hpp         |   1 +
 sprout/config/compiler/clang.hpp           |   2 +
 sprout/config/compiler/codegear.hpp        |   1 +
 sprout/config/compiler/common_edg.hpp      |   1 +
 sprout/config/compiler/digitalmars.hpp     |   1 +
 sprout/config/compiler/gcc.hpp             |   1 +
 sprout/config/compiler/gcc_xml.hpp         |   1 +
 sprout/config/compiler/has_future.hpp      |   4 +
 sprout/config/compiler/metrowerks.hpp      |   1 +
 sprout/config/compiler/mpw.hpp             |   1 +
 sprout/config/compiler/no_future.hpp       |   4 +
 sprout/config/compiler/pathscale.hpp       |   1 +
 sprout/config/compiler/pgi.hpp             |   1 +
 sprout/config/compiler/sunpro_cc.hpp       |   1 +
 sprout/config/compiler/vacpp.hpp           |   1 +
 sprout/config/compiler/visualc.hpp         |   1 +
 sprout/config/suffix.hpp                   |   9 ++
 sprout/type_traits/std.hpp                 |   1 +
 sprout/type_traits/std_value_variables.hpp | 164 +++++++++++++++++++++
 20 files changed, 206 insertions(+)
 create mode 100644 sprout/type_traits/std_value_variables.hpp

diff --git a/sprout/config/auto_config.hpp b/sprout/config/auto_config.hpp
index 6bc8b47f..73ea597a 100644
--- a/sprout/config/auto_config.hpp
+++ b/sprout/config/auto_config.hpp
@@ -101,6 +101,15 @@
 #	endif	// #ifdef SPROUT_NO_CXX11_UNICODE_LITERALS
 #endif	// #ifndef SPROUT_CONFIG_DISABLE_UNICODE_LITERALS
 
+//
+// SPROUT_CONFIG_DISABLE_VARIABLE_TEMPLATES
+//
+#ifndef SPROUT_CONFIG_DISABLE_VARIABLE_TEMPLATES
+#	ifdef SPROUT_NO_CXX14_VARIABLE_TEMPLATES
+#		define SPROUT_CONFIG_DISABLE_VARIABLE_TEMPLATES
+#	endif	// #ifdef SPROUT_NO_CXX14_VARIABLE_TEMPLATES
+#endif	// #ifndef SPROUT_CONFIG_DISABLE_VARIABLE_TEMPLATES
+
 //
 // SPROUT_CONFIG_USE_SSCRISK_CEL
 //
diff --git a/sprout/config/compiler/borland.hpp b/sprout/config/compiler/borland.hpp
index 5e291d69..eef7673d 100644
--- a/sprout/config/compiler/borland.hpp
+++ b/sprout/config/compiler/borland.hpp
@@ -21,5 +21,6 @@
 #define SPROUT_NO_CXX11_UNICODE_LITERALS
 
 #define SPROUT_NO_CXX14_CONSTEXPR
+#define SPROUT_NO_CXX14_VARIABLE_TEMPLATES
 
 #endif	// #ifndef SPROUT_CONFIG_COMPILER_BORLAND_HPP
diff --git a/sprout/config/compiler/clang.hpp b/sprout/config/compiler/clang.hpp
index b5d0fc0b..cae16281 100644
--- a/sprout/config/compiler/clang.hpp
+++ b/sprout/config/compiler/clang.hpp
@@ -48,6 +48,8 @@
 #	define SPROUT_NO_CXX14_CONSTEXPR
 #endif
 
+#define SPROUT_NO_CXX14_VARIABLE_TEMPLATES
+
 #if !defined(SPROUT_NO_CXX11_CONSTEXPR)
 #	define SPROUT_WORKAROUND_NOT_TERMINATE_RECURSIVE_CONSTEXPR_FUNCTION_TEMPLATE
 #endif
diff --git a/sprout/config/compiler/codegear.hpp b/sprout/config/compiler/codegear.hpp
index b939a339..c601cbc5 100644
--- a/sprout/config/compiler/codegear.hpp
+++ b/sprout/config/compiler/codegear.hpp
@@ -19,5 +19,6 @@
 #define SPROUT_NO_CXX11_UNICODE_LITERALS
 
 #define SPROUT_NO_CXX14_CONSTEXPR
+#define SPROUT_NO_CXX14_VARIABLE_TEMPLATES
 
 #endif	// #ifndef SPROUT_CONFIG_COMPILER_CODEGEAR_HPP
diff --git a/sprout/config/compiler/common_edg.hpp b/sprout/config/compiler/common_edg.hpp
index 45f810c7..c7d7ec55 100644
--- a/sprout/config/compiler/common_edg.hpp
+++ b/sprout/config/compiler/common_edg.hpp
@@ -19,5 +19,6 @@
 #define SPROUT_NO_CXX11_UNICODE_LITERALS
 
 #define SPROUT_NO_CXX14_CONSTEXPR
+#define SPROUT_NO_CXX14_VARIABLE_TEMPLATES
 
 #endif	// #ifndef SPROUT_CONFIG_COMPILER_COMMON_EDG_HPP
diff --git a/sprout/config/compiler/digitalmars.hpp b/sprout/config/compiler/digitalmars.hpp
index 57cdcd6e..200f5c7b 100644
--- a/sprout/config/compiler/digitalmars.hpp
+++ b/sprout/config/compiler/digitalmars.hpp
@@ -19,5 +19,6 @@
 #define SPROUT_NO_CXX11_UNICODE_LITERALS
 
 #define SPROUT_NO_CXX14_CONSTEXPR
+#define SPROUT_NO_CXX14_VARIABLE_TEMPLATES
 
 #endif	// #ifndef SPROUT_CONFIG_COMPILER_DIGITALMARS_HPP
diff --git a/sprout/config/compiler/gcc.hpp b/sprout/config/compiler/gcc.hpp
index 3c744e55..597c94e3 100644
--- a/sprout/config/compiler/gcc.hpp
+++ b/sprout/config/compiler/gcc.hpp
@@ -53,5 +53,6 @@
 #endif
 
 #define SPROUT_NO_CXX14_CONSTEXPR
+#define SPROUT_NO_CXX14_VARIABLE_TEMPLATES
 
 #endif	// #ifndef SPROUT_CONFIG_COMPILER_GCC_HPP
diff --git a/sprout/config/compiler/gcc_xml.hpp b/sprout/config/compiler/gcc_xml.hpp
index f7674a96..106c2c33 100644
--- a/sprout/config/compiler/gcc_xml.hpp
+++ b/sprout/config/compiler/gcc_xml.hpp
@@ -19,5 +19,6 @@
 #define SPROUT_NO_CXX11_UNICODE_LITERALS
 
 #define SPROUT_NO_CXX14_CONSTEXPR
+#define SPROUT_NO_CXX14_VARIABLE_TEMPLATES
 
 #endif	// #ifndef SPROUT_CONFIG_COMPILER_GCC_XML_HPP
diff --git a/sprout/config/compiler/has_future.hpp b/sprout/config/compiler/has_future.hpp
index 6ae5d554..195205c5 100644
--- a/sprout/config/compiler/has_future.hpp
+++ b/sprout/config/compiler/has_future.hpp
@@ -36,4 +36,8 @@
 #	define SPROUT_HAS_UNICODE_LITERALS
 #endif
 
+#ifndef SPROUT_NO_CXX14_VARIABLE_TEMPLATES
+#	define SPROUT_HAS_VARIABLE_TEMPLATES
+#endif
+
 #endif	// #ifndef SPROUT_CONFIG_COMPILER_HAS_FUTURE_HPP
diff --git a/sprout/config/compiler/metrowerks.hpp b/sprout/config/compiler/metrowerks.hpp
index ea4bb16f..968f4b29 100644
--- a/sprout/config/compiler/metrowerks.hpp
+++ b/sprout/config/compiler/metrowerks.hpp
@@ -19,5 +19,6 @@
 #define SPROUT_NO_CXX11_UNICODE_LITERALS
 
 #define SPROUT_NO_CXX14_CONSTEXPR
+#define SPROUT_NO_CXX14_VARIABLE_TEMPLATES
 
 #endif	// #ifndef SPROUT_CONFIG_COMPILER_METROWERKS_HPP
diff --git a/sprout/config/compiler/mpw.hpp b/sprout/config/compiler/mpw.hpp
index 7e3f5b6a..ad0a7736 100644
--- a/sprout/config/compiler/mpw.hpp
+++ b/sprout/config/compiler/mpw.hpp
@@ -19,5 +19,6 @@
 #define SPROUT_NO_CXX11_UNICODE_LITERALS
 
 #define SPROUT_NO_CXX14_CONSTEXPR
+#define SPROUT_NO_CXX14_VARIABLE_TEMPLATES
 
 #endif	// #ifndef SPROUT_CONFIG_COMPILER_MPW_HPP
diff --git a/sprout/config/compiler/no_future.hpp b/sprout/config/compiler/no_future.hpp
index e17167b1..1f415e23 100644
--- a/sprout/config/compiler/no_future.hpp
+++ b/sprout/config/compiler/no_future.hpp
@@ -36,4 +36,8 @@
 #	define SPROUT_NO_UNICODE_LITERALS
 #endif
 
+#ifdef SPROUT_NO_CXX14_VARIABLE_TEMPLATES
+#	define SPROUT_NO_VARIABLE_TEMPLATES
+#endif
+
 #endif	// #ifndef SPROUT_CONFIG_COMPILER_NO_FUTURE_HPP
diff --git a/sprout/config/compiler/pathscale.hpp b/sprout/config/compiler/pathscale.hpp
index 6051be64..c249e508 100644
--- a/sprout/config/compiler/pathscale.hpp
+++ b/sprout/config/compiler/pathscale.hpp
@@ -20,6 +20,7 @@
 #	define SPROUT_NO_CXX11_UNICODE_LITERALS
 
 #	define SPROUT_NO_CXX14_CONSTEXPR
+#	define SPROUT_NO_CXX14_VARIABLE_TEMPLATES
 #endif
 
 #endif	// #ifndef SPROUT_CONFIG_COMPILER_PATHSCALE_HPP
diff --git a/sprout/config/compiler/pgi.hpp b/sprout/config/compiler/pgi.hpp
index 7053a1c9..1499ebf2 100644
--- a/sprout/config/compiler/pgi.hpp
+++ b/sprout/config/compiler/pgi.hpp
@@ -19,5 +19,6 @@
 #define SPROUT_NO_CXX11_UNICODE_LITERALS
 
 #define SPROUT_NO_CXX14_CONSTEXPR
+#define SPROUT_NO_CXX14_VARIABLE_TEMPLATES
 
 #endif	// #ifndef SPROUT_CONFIG_COMPILER_PGI_HPP
diff --git a/sprout/config/compiler/sunpro_cc.hpp b/sprout/config/compiler/sunpro_cc.hpp
index bee3cde0..f6d6b0a4 100644
--- a/sprout/config/compiler/sunpro_cc.hpp
+++ b/sprout/config/compiler/sunpro_cc.hpp
@@ -19,5 +19,6 @@
 #define SPROUT_NO_CXX11_UNICODE_LITERALS
 
 #define SPROUT_NO_CXX14_CONSTEXPR
+#define SPROUT_NO_CXX14_VARIABLE_TEMPLATES
 
 #endif	// #ifndef SPROUT_CONFIG_COMPILER_SUNPRO_CC_HPP
diff --git a/sprout/config/compiler/vacpp.hpp b/sprout/config/compiler/vacpp.hpp
index 69d2b00a..3bffbdcc 100644
--- a/sprout/config/compiler/vacpp.hpp
+++ b/sprout/config/compiler/vacpp.hpp
@@ -23,5 +23,6 @@
 #define SPROUT_NO_CXX11_UNICODE_LITERALS
 
 #define SPROUT_NO_CXX14_CONSTEXPR
+#define SPROUT_NO_CXX14_VARIABLE_TEMPLATES
 
 #endif	// #ifndef SPROUT_CONFIG_COMPILER_VACPP_HPP
diff --git a/sprout/config/compiler/visualc.hpp b/sprout/config/compiler/visualc.hpp
index 22e43159..7b99b1c4 100644
--- a/sprout/config/compiler/visualc.hpp
+++ b/sprout/config/compiler/visualc.hpp
@@ -21,5 +21,6 @@
 #define SPROUT_NO_CXX11_UNICODE_LITERALS
 
 #define SPROUT_NO_CXX14_CONSTEXPR
+#define SPROUT_NO_CXX14_VARIABLE_TEMPLATES
 
 #endif	// #ifndef SPROUT_CONFIG_COMPILER_VISUALC_HPP
diff --git a/sprout/config/suffix.hpp b/sprout/config/suffix.hpp
index c2b78487..909979d9 100644
--- a/sprout/config/suffix.hpp
+++ b/sprout/config/suffix.hpp
@@ -138,6 +138,15 @@
 #	define SPROUT_USE_UNICODE_LITERALS 0
 #endif	// #ifndef SPROUT_CONFIG_DISABLE_UNICODE_LITERALS
 
+//
+// SPROUT_USE_VARIABLE_TEMPLATES
+//
+#ifndef SPROUT_CONFIG_DISABLE_VARIABLE_TEMPLATES
+#	define SPROUT_USE_VARIABLE_TEMPLATES 1
+#else	// #ifndef SPROUT_CONFIG_DISABLE_VARIABLE_TEMPLATES
+#	define SPROUT_USE_VARIABLE_TEMPLATES 0
+#endif	// #ifndef SPROUT_CONFIG_DISABLE_VARIABLE_TEMPLATES
+
 //
 // SPROUT_USE_BUILTIN_CMATH_FUNCTION
 //
diff --git a/sprout/type_traits/std.hpp b/sprout/type_traits/std.hpp
index d52e17a0..197fc999 100644
--- a/sprout/type_traits/std.hpp
+++ b/sprout/type_traits/std.hpp
@@ -12,5 +12,6 @@
 #include <sprout/type_traits/integral_constant.hpp>
 #include <sprout/type_traits/std_type_traits.hpp>
 #include <sprout/type_traits/std_type_aliases.hpp>
+#include <sprout/type_traits/std_value_variables.hpp>
 
 #endif	// #ifndef SPROUT_TYPE_TRAITS_STD_HPP
diff --git a/sprout/type_traits/std_value_variables.hpp b/sprout/type_traits/std_value_variables.hpp
new file mode 100644
index 00000000..b198d0a2
--- /dev/null
+++ b/sprout/type_traits/std_value_variables.hpp
@@ -0,0 +1,164 @@
+/*=============================================================================
+  Copyright (c) 2011-2013 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_TYPE_TRAITS_STD_VALUE_VARIABLES_HPP
+#define SPROUT_TYPE_TRAITS_STD_VALUE_VARIABLES_HPP
+
+#include <sprout/config.hpp>
+#if SPROUT_USE_VARIABLE_TEMPLATES
+#	include <cstddef>
+#	include <sprout/type_traits/std_type_traits.hpp>
+#endif	// #if SPROUT_USE_VARIABLE_TEMPLATES
+
+namespace sprout {
+#if SPROUT_USE_VARIABLE_TEMPLATES
+	// 20.10.4.1 Primary type categories
+
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_void_v = sprout::is_void<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_null_pointer_v = sprout::is_null_pointer<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_integral_v = sprout::is_integral<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_floating_point_v = sprout::is_floating_point<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_array_v = sprout::is_array<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_pointer_v = sprout::is_pointer<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_lvalue_reference_v = sprout::is_lvalue_reference<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_rvalue_reference_v = sprout::is_rvalue_reference<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_member_object_pointer_v = sprout::is_member_object_pointer<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_member_function_pointer_v = sprout::is_member_function_pointer<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_enum_v = sprout::is_enum<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_union_v = sprout::is_union<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_class_v = sprout::is_class<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_function_v = sprout::is_function<T>::value;
+
+	// 20.10.4.2 Composite type traits
+
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_reference_v = sprout::is_reference<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_arithmetic_v = sprout::is_arithmetic<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_fundamental_v = sprout::is_fundamental<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_object_v = sprout::is_object<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_scalar_v = sprout::is_scalar<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_compound_v = sprout::is_compound<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_member_pointer_v = sprout::is_member_pointer<T>::value;
+
+	// 20.10.4.3 Type properties
+
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_const_v = sprout::is_const<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_volatile_v = sprout::is_volatile<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_trivial_v = sprout::is_trivial<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_trivially_copyable_v = sprout::is_trivially_copyable<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_standard_layout_v = sprout::is_standard_layout<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_pod_v = sprout::is_pod<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_literal_type_v = sprout::is_literal_type<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_empty_v = sprout::is_empty<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_polymorphic_v = sprout::is_polymorphic<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_abstract_v = sprout::is_abstract<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_signed_v = sprout::is_signed<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_unsigned_v = sprout::is_unsigned<T>::value;
+	template<typename T, typename... Args>
+	SPROUT_STATIC_CONSTEXPR bool is_constructible_v = sprout::is_constructible<T, Args...>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_default_constructible_v = sprout::is_default_constructible<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_copy_constructible_v = sprout::is_copy_constructible<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_move_constructible_v = sprout::is_move_constructible<T>::value;
+	template<typename T, typename U>
+	SPROUT_STATIC_CONSTEXPR bool is_assignable_v = sprout::is_assignable<T, U>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_copy_assignable_v = sprout::is_copy_assignable<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_move_assignable_v = sprout::is_move_assignable<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_destructible_v = sprout::is_destructible<T>::value;
+	template<typename T, typename... Args>
+	SPROUT_STATIC_CONSTEXPR bool is_trivially_constructible_v = sprout::is_trivially_constructible<T, Args...>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_trivially_default_constructible_v = sprout::is_trivially_default_constructible<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_trivially_copy_constructible_v = sprout::is_trivially_copy_constructible<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_trivially_move_constructible_v = sprout::is_trivially_move_constructible<T>::value;
+	template<typename T, typename U>
+	SPROUT_STATIC_CONSTEXPR bool is_trivially_assignable_v = sprout::is_trivially_assignable<T, U>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_trivially_copy_assignable_v = sprout::is_trivially_copy_assignable<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_trivially_move_assignable_v = sprout::is_trivially_move_assignable<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_trivially_destructible_v = sprout::is_trivially_destructible<T>::value;
+	template<typename T, typename... Args>
+	SPROUT_STATIC_CONSTEXPR bool is_nothrow_constructible_v = sprout::is_nothrow_constructible<T, Args...>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_nothrow_default_constructible_v = sprout::is_nothrow_default_constructible<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_nothrow_copy_constructible_v = sprout::is_nothrow_copy_constructible<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_nothrow_move_constructible_v = sprout::is_nothrow_move_constructible<T>::value;
+	template<typename T, typename U>
+	SPROUT_STATIC_CONSTEXPR bool is_nothrow_assignable_v = sprout::is_nothrow_assignable<T, U>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_nothrow_copy_assignable_v = sprout::is_nothrow_copy_assignable<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_nothrow_move_assignable_v = sprout::is_nothrow_move_assignable<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool is_nothrow_destructible_v = sprout::is_nothrow_destructible<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR bool has_virtual_destructor_v = sprout::has_virtual_destructor<T>::value;
+
+	// 20.10.5 Type property queries
+
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR std::size_t alignment_of_v = sprout::alignment_of<T>::value;
+	template<typename T>
+	SPROUT_STATIC_CONSTEXPR std::size_t rank_v = sprout::rank<T>::value;
+	template<typename T, unsigned I = 0>
+	SPROUT_STATIC_CONSTEXPR std::size_t extent_v = sprout::extent<T, I>::value;
+
+	// 20.10.6 Relationships between types
+
+	template<typename T, typename U>
+	SPROUT_STATIC_CONSTEXPR bool is_same_v = sprout::is_same<T, U>::value;
+	template<typename From, typename To>
+	SPROUT_STATIC_CONSTEXPR bool is_base_of_v = sprout::is_base_of<From, To>::value;
+	template<typename From, typename To>
+	SPROUT_STATIC_CONSTEXPR bool is_convertible_v = sprout::is_convertible<From, To>>::value;
+#endif	// #if SPROUT_USE_VARIABLE_TEMPLATES
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_TYPE_TRAITS_STD_VALUE_VARIABLES_HPP