early-access version 3088

externals/vcpkg/packages/boost-context_x64-windows/include/boost/context/detail/apply.hpp

@@ -0,0 +1,74 @@
+
+//          Copyright Oliver Kowalke 2014.
+// 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 BOOST_CONTEXT_DETAIL_APPLY_H
+#define BOOST_CONTEXT_DETAIL_APPLY_H
+
+#include <functional>
+#include <tuple>
+#include <type_traits>
+#include <utility>
+
+#include <boost/config.hpp>
+
+#include <boost/context/detail/config.hpp>
+#if defined(BOOST_NO_CXX17_STD_INVOKE)
+#include <boost/context/detail/invoke.hpp>
+#endif
+#include <boost/context/detail/index_sequence.hpp>
+
+#ifdef BOOST_HAS_ABI_HEADERS
+# include BOOST_ABI_PREFIX
+#endif
+
+#if defined(BOOST_MSVC)
+# pragma warning(push)
+# pragma warning(disable: 4100)
+#endif
+
+namespace boost {
+namespace context {
+namespace detail {
+
+template< typename Fn, typename Tpl, std::size_t ... I >
+auto
+apply_impl( Fn && fn, Tpl && tpl, index_sequence< I ... >) 
+#if defined(BOOST_NO_CXX17_STD_INVOKE)
+    -> decltype( boost::context::detail::invoke( std::forward< Fn >( fn), std::get< I >( std::forward< Tpl >( tpl) ) ... ) )
+#else
+    -> decltype( std::invoke( std::forward< Fn >( fn), std::get< I >( std::forward< Tpl >( tpl) ) ... ) )
+#endif
+{
+#if defined(BOOST_NO_CXX17_STD_INVOKE)
+    return boost::context::detail::invoke( std::forward< Fn >( fn), std::get< I >( std::forward< Tpl >( tpl) ) ... );
+#else
+    return std::invoke( std::forward< Fn >( fn), std::get< I >( std::forward< Tpl >( tpl) ) ... );
+#endif
+}
+
+template< typename Fn, typename Tpl >
+auto
+apply( Fn && fn, Tpl && tpl) 
+    -> decltype( apply_impl( std::forward< Fn >( fn),
+                 std::forward< Tpl >( tpl),
+                 make_index_sequence< std::tuple_size< typename std::decay< Tpl >::type >::value >{}) )
+{
+    return apply_impl( std::forward< Fn >( fn),
+                       std::forward< Tpl >( tpl),
+                       make_index_sequence< std::tuple_size< typename std::decay< Tpl >::type >::value >{});
+}
+
+}}}
+
+#if defined(BOOST_MSVC)
+# pragma warning(pop)
+#endif
+
+#ifdef BOOST_HAS_ABI_HEADERS
+#include BOOST_ABI_SUFFIX
+#endif
+
+#endif // BOOST_CONTEXT_DETAIL_APPLY_H

externals/vcpkg/packages/boost-context_x64-windows/include/boost/context/detail/config.hpp

@@ -0,0 +1,136 @@
+
+//          Copyright Oliver Kowalke 2014.
+// 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 BOOST_CONTEXT_DETAIL_CONFIG_H
+#define BOOST_CONTEXT_DETAIL_CONFIG_H
+
+// required for SD-6 compile-time integer sequences
+#include <utility>
+
+#include <boost/config.hpp>
+#include <boost/detail/workaround.hpp>
+
+#ifdef BOOST_CONTEXT_DECL
+# undef BOOST_CONTEXT_DECL
+#endif
+
+#if (defined(BOOST_ALL_DYN_LINK) || defined(BOOST_CONTEXT_DYN_LINK) ) && ! defined(BOOST_CONTEXT_STATIC_LINK)
+# if defined(BOOST_CONTEXT_SOURCE)
+#  define BOOST_CONTEXT_DECL BOOST_SYMBOL_EXPORT
+#  define BOOST_CONTEXT_BUILD_DLL
+# else
+#  define BOOST_CONTEXT_DECL BOOST_SYMBOL_IMPORT
+# endif
+#endif
+
+#if ! defined(BOOST_CONTEXT_DECL)
+# define BOOST_CONTEXT_DECL
+#endif
+
+#if ! defined(BOOST_USE_UCONTEXT) && defined(__CYGWIN__)
+# define BOOST_USE_UCONTEXT
+#endif
+
+#if ! defined(BOOST_CONTEXT_SOURCE) && ! defined(BOOST_ALL_NO_LIB) && ! defined(BOOST_CONTEXT_NO_LIB)
+# define BOOST_LIB_NAME boost_context
+# if defined(BOOST_ALL_DYN_LINK) || defined(BOOST_CONTEXT_DYN_LINK)
+#  define BOOST_DYN_LINK
+# endif
+# include <boost/config/auto_link.hpp>
+#endif
+
+#undef BOOST_CONTEXT_CALLDECL
+#if (defined(i386) || defined(__i386__) || defined(__i386) \
+     || defined(__i486__) || defined(__i586__) || defined(__i686__) \
+     || defined(__X86__) || defined(_X86_) || defined(__THW_INTEL__) \
+     || defined(__I86__) || defined(__INTEL__) || defined(__IA32__) \
+     || defined(_M_IX86) || defined(_I86_)) && defined(BOOST_WINDOWS)
+# define BOOST_CONTEXT_CALLDECL __cdecl
+#else
+# define BOOST_CONTEXT_CALLDECL
+#endif
+
+#if defined(BOOST_USE_SEGMENTED_STACKS)
+# if ! ( (defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6) ) ) || \
+         (defined(__clang__) && (__clang_major__ > 2 || ( __clang_major__ == 2 && __clang_minor__ > 3) ) ) )
+#  error "compiler does not support segmented_stack stacks"
+# endif
+# define BOOST_CONTEXT_SEGMENTS 10
+#endif
+
+
+#define BOOST_CONTEXT_NO_CXX14_INTEGER_SEQUENCE
+// use rd6 macros for std::integer_sequence
+#if defined(__cpp_lib_integer_sequence) && __cpp_lib_integer_sequence >= 201304
+# undef BOOST_CONTEXT_NO_CXX14_INTEGER_SEQUENCE
+#endif
+// workaroud: MSVC 14 does not provide macros to test for compile-time integer sequence
+#if _MSC_VER > 1800 // _MSC_VER == 1800 -> MS Visual Studio 2013
+# undef BOOST_CONTEXT_NO_INDEX_SEQUENCE
+#endif
+// workaround: Xcode clang feature detection
+#if ! defined(__cpp_lib_integer_sequence) && __cpp_lib_integer_sequence >= 201304
+# if _LIBCPP_STD_VER > 11
+#  undef BOOST_CONTEXT_NO_CXX14_INTEGER_SEQUENCE
+# endif
+#endif
+
+// workaroud: MSVC 14 does support constexpr
+#if _MSC_VER > 1800 // _MSC_VER == 1800 -> MS Visual Studio 2013
+# undef BOOST_NO_CXX11_CONSTEXPR
+#endif
+
+#undef BOOST_CONTEXT_NO_CXX11
+#if defined(BOOST_NO_CXX11_AUTO_DECLARATIONS) || \
+    defined(BOOST_NO_CXX11_CONSTEXPR) || \
+    defined(BOOST_NO_CXX11_DEFAULTED_FUNCTIONS) || \
+    defined(BOOST_NO_CXX11_FINAL) || \
+    defined(BOOST_NO_CXX11_HDR_TUPLE) || \
+    defined(BOOST_NO_CXX11_NOEXCEPT) || \
+    defined(BOOST_NO_CXX11_NULLPTR) || \
+    defined(BOOST_NO_CXX11_RVALUE_REFERENCES) || \
+    defined(BOOST_NO_CXX11_TEMPLATE_ALIASES) || \
+    defined(BOOST_NO_CXX11_UNIFIED_INITIALISATION_SYNTAX) || \
+    defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) || \
+    defined(BOOST_NO_HDR_ATOMIC) || \
+    defined(BOOST_NO_HDR_TUPLE) 
+# define BOOST_CONTEXT_NO_CXX11
+#endif
+
+#if ! defined(BOOST_EXECUTION_CONTEXT)
+# if defined(BOOST_USE_SEGMENTED_STACKS)
+#  define BOOST_EXECUTION_CONTEXT 1
+# else
+#  define BOOST_EXECUTION_CONTEXT 2
+# endif
+#endif
+
+#if ! defined(BOOST_NO_CXX11_CONSTEXPR)
+// modern architectures have cachelines with 64byte length
+// ARM Cortex-A15 32/64byte, Cortex-A9 16/32/64bytes
+// MIPS 74K: 32byte, 4KEc: 16byte
+// ist should be safe to use 64byte for all
+static constexpr std::size_t cache_alignment{ 64 };
+static constexpr std::size_t cacheline_length{ 64 };
+// lookahead size for prefetching
+static constexpr std::size_t prefetch_stride{ 4 * cacheline_length };
+#endif
+
+#if defined(__GLIBCPP__) || defined(__GLIBCXX__)
+// GNU libstdc++ 3
+#  define BOOST_CONTEXT_HAS_CXXABI_H
+#endif
+
+#if defined( BOOST_CONTEXT_HAS_CXXABI_H )
+# include <cxxabi.h>
+#endif
+
+#if defined(__OpenBSD__)
+// stacks need mmap(2) with MAP_STACK
+# define BOOST_CONTEXT_USE_MAP_STACK
+#endif
+
+#endif // BOOST_CONTEXT_DETAIL_CONFIG_H

externals/vcpkg/packages/boost-context_x64-windows/include/boost/context/detail/disable_overload.hpp

@@ -0,0 +1,40 @@
+
+//          Copyright Oliver Kowalke 2014.
+// 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 BOOST_CONTEXT_DETAIL_DISABLE_OVERLOAD_H
+#define BOOST_CONTEXT_DETAIL_DISABLE_OVERLOAD_H
+
+#include <type_traits>
+
+#include <boost/config.hpp>
+
+#include <boost/context/detail/config.hpp>
+
+#ifdef BOOST_HAS_ABI_HEADERS
+# include BOOST_ABI_PREFIX
+#endif
+
+namespace boost {
+namespace context {
+namespace detail {
+
+// http://ericniebler.com/2013/08/07/universal-references-and-the-copy-constructo/
+template< typename X, typename Y >
+using disable_overload =
+    typename std::enable_if<
+        ! std::is_base_of<
+            X,
+            typename std::decay< Y >::type
+        >::value
+    >::type;
+
+}}}
+
+#ifdef BOOST_HAS_ABI_HEADERS
+#include BOOST_ABI_SUFFIX
+#endif
+
+#endif // BOOST_CONTEXT_DETAIL_DISABLE_OVERLOAD_H

externals/vcpkg/packages/boost-context_x64-windows/include/boost/context/detail/exception.hpp

@@ -0,0 +1,39 @@
+
+//          Copyright Oliver Kowalke 2014.
+// 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 BOOST_CONTEXT_DETAIL_EXCEPTION_H
+#define BOOST_CONTEXT_DETAIL_EXCEPTION_H
+
+#include <boost/assert.hpp>
+#include <boost/config.hpp>
+
+#include <boost/context/detail/fcontext.hpp>
+
+#ifdef BOOST_HAS_ABI_HEADERS
+# include BOOST_ABI_PREFIX
+#endif
+
+namespace boost {
+namespace context {
+namespace detail {
+
+struct forced_unwind {
+    fcontext_t  fctx{ nullptr };
+
+    forced_unwind() = default;
+
+    forced_unwind( fcontext_t fctx_) :
+        fctx( fctx_) {
+    }
+};
+
+}}}
+
+#ifdef BOOST_HAS_ABI_HEADERS
+#include BOOST_ABI_SUFFIX
+#endif
+
+#endif // BOOST_CONTEXT_DETAIL_EXCEPTION_H

externals/vcpkg/packages/boost-context_x64-windows/include/boost/context/detail/exchange.hpp

@@ -0,0 +1,36 @@
+
+//          Copyright Oliver Kowalke 2014.
+// 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 BOOST_CONTEXT_DETAIL_EXCHANGE_H
+#define BOOST_CONTEXT_DETAIL_EXCHANGE_H
+
+#include <algorithm>
+#include <utility>
+
+#include <boost/config.hpp>
+
+#ifdef BOOST_HAS_ABI_HEADERS
+# include BOOST_ABI_PREFIX
+#endif
+
+namespace boost {
+namespace context {
+namespace detail {
+
+template< typename T, typename U = T >
+T exchange( T & t, U && nv) {
+    T ov = std::move( t);
+    t = std::forward< U >( nv);
+    return ov;
+}
+
+}}}
+
+#ifdef BOOST_HAS_ABI_HEADERS
+#include BOOST_ABI_SUFFIX
+#endif
+
+#endif // BOOST_CONTEXT_DETAIL_EXCHANGE_H

externals/vcpkg/packages/boost-context_x64-windows/include/boost/context/detail/externc.hpp

@@ -0,0 +1,23 @@
+
+//          Copyright Oliver Kowalke 2014.
+// 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)
+//
+
+#include <boost/config.hpp>
+#include <boost/context/detail/config.hpp>
+
+#if defined(BOOST_USE_ASAN)
+extern "C" {
+void __sanitizer_start_switch_fiber( void **, const void *, size_t);
+void __sanitizer_finish_switch_fiber( void *, const void **, size_t *);
+}
+#endif
+
+#if defined(BOOST_USE_SEGMENTED_STACKS)
+extern "C" {
+void __splitstack_getcontext( void * [BOOST_CONTEXT_SEGMENTS]);
+void __splitstack_setcontext( void * [BOOST_CONTEXT_SEGMENTS]);
+}
+#endif

externals/vcpkg/packages/boost-context_x64-windows/include/boost/context/detail/fcontext.hpp

@@ -0,0 +1,46 @@
+
+//          Copyright Oliver Kowalke 2009.
+// 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 BOOST_CONTEXT_DETAIL_FCONTEXT_H
+#define BOOST_CONTEXT_DETAIL_FCONTEXT_H
+
+#include <boost/config.hpp>
+#include <boost/cstdint.hpp>
+
+#include <boost/context/detail/config.hpp>
+
+#ifdef BOOST_HAS_ABI_HEADERS
+# include BOOST_ABI_PREFIX
+#endif
+
+namespace boost {
+namespace context {
+namespace detail {
+
+typedef void*   fcontext_t;
+
+struct transfer_t {
+    fcontext_t  fctx;
+    void    *   data;
+};
+
+extern "C" BOOST_CONTEXT_DECL
+transfer_t BOOST_CONTEXT_CALLDECL jump_fcontext( fcontext_t const to, void * vp);
+extern "C" BOOST_CONTEXT_DECL
+fcontext_t BOOST_CONTEXT_CALLDECL make_fcontext( void * sp, std::size_t size, void (* fn)( transfer_t) );
+
+// based on an idea of Giovanni Derreta
+extern "C" BOOST_CONTEXT_DECL
+transfer_t BOOST_CONTEXT_CALLDECL ontop_fcontext( fcontext_t const to, void * vp, transfer_t (* fn)( transfer_t) );
+
+}}}
+
+#ifdef BOOST_HAS_ABI_HEADERS
+# include BOOST_ABI_SUFFIX
+#endif
+
+#endif // BOOST_CONTEXT_DETAIL_FCONTEXT_H
+

externals/vcpkg/packages/boost-context_x64-windows/include/boost/context/detail/index_sequence.hpp

@@ -0,0 +1,50 @@
+
+//          Copyright Oliver Kowalke 2014.
+// 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 BOOST_CONTEXT_DETAIL_INDEX_SEQUENCE_H
+#define BOOST_CONTEXT_DETAIL_INDEX_SEQUENCE_H
+
+#include <cstddef>
+
+#include <boost/config.hpp>
+
+#include <boost/context/detail/config.hpp>
+
+#if defined(BOOST_CONTEXT_NO_CXX14_INTEGER_SEQUENCE)
+#include <boost/mp11/integer_sequence.hpp>
+#endif
+
+#ifdef BOOST_HAS_ABI_HEADERS
+# include BOOST_ABI_PREFIX
+#endif
+
+namespace boost {
+namespace context {
+namespace detail {
+
+#if ! defined(BOOST_CONTEXT_NO_CXX14_INTEGER_SEQUENCE)
+template< std::size_t ... I >
+using index_sequence = std::index_sequence< I ... >;
+template< std::size_t I >
+using make_index_sequence = std::make_index_sequence< I >;
+template< typename ... T >
+using index_sequence_for = std::index_sequence_for< T ... >;
+#else
+template< std::size_t ... I >
+using index_sequence = mp11::index_sequence< I ... >;
+template< std::size_t I >
+using make_index_sequence = mp11::make_index_sequence< I >;
+template< typename ... T >
+using index_sequence_for = mp11::index_sequence_for< T ... >;
+#endif
+
+}}}
+
+#ifdef BOOST_HAS_ABI_HEADERS
+#include BOOST_ABI_SUFFIX
+#endif
+
+#endif // BOOST_CONTEXT_DETAIL_INDEX_SEQUENCE_H

externals/vcpkg/packages/boost-context_x64-windows/include/boost/context/detail/invoke.hpp

@@ -0,0 +1,50 @@
+
+//          Copyright Oliver Kowalke 2014.
+// 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 BOOST_CONTEXT_DETAIL_INVOKE_H
+#define BOOST_CONTEXT_DETAIL_INVOKE_H
+
+#include <functional>
+#include <type_traits>
+#include <utility>
+
+#include <boost/config.hpp>
+
+#include <boost/context/detail/config.hpp>
+
+#ifdef BOOST_HAS_ABI_HEADERS
+# include BOOST_ABI_PREFIX
+#endif
+
+namespace boost {
+namespace context {
+namespace detail {
+
+template< typename Fn, typename ... Args >
+typename std::enable_if<
+    std::is_member_pointer< typename std::decay< Fn >::type >::value,
+    typename std::result_of< Fn &&( Args && ... ) >::type
+>::type
+invoke( Fn && fn, Args && ... args) {
+    return std::mem_fn( fn)( std::forward< Args >( args) ... );   
+}
+
+template< typename Fn, typename ... Args >
+typename std::enable_if<
+    ! std::is_member_pointer< typename std::decay< Fn >::type >::value,
+    typename std::result_of< Fn &&( Args && ... ) >::type
+>::type
+invoke( Fn && fn, Args && ... args) {
+    return std::forward< Fn >( fn)( std::forward< Args >( args) ... );
+}
+
+}}}
+
+#ifdef BOOST_HAS_ABI_HEADERS
+#include BOOST_ABI_SUFFIX
+#endif
+
+#endif // BOOST_CONTEXT_DETAIL_INVOKE_H

externals/vcpkg/packages/boost-context_x64-windows/include/boost/context/detail/prefetch.hpp

@@ -0,0 +1,78 @@
+//          Copyright Oliver Kowalke 2017.
+// 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 BOOST_CONTEXT_DETAIL_PREFETCH_H
+#define BOOST_CONTEXT_DETAIL_PREFETCH_H
+
+#include <cstddef>
+#include <cstdint>
+
+#include <boost/config.hpp>
+#include <boost/predef.h>
+
+#include <boost/context/detail/config.hpp>
+
+#if BOOST_COMP_INTEL || BOOST_COMP_INTEL_EMULATED
+#include <immintrin.h>
+#endif
+
+#if BOOST_COMP_MSVC && !defined(_M_ARM) && !defined(_M_ARM64)
+#include <mmintrin.h>
+#endif
+
+#ifdef BOOST_HAS_ABI_HEADERS
+#  include BOOST_ABI_PREFIX
+#endif
+
+namespace boost {
+namespace context {
+namespace detail {
+
+#if BOOST_COMP_GNUC || BOOST_COMP_CLANG
+#define BOOST_HAS_PREFETCH 1
+BOOST_FORCEINLINE
+void prefetch( void * addr) {
+    // L1 cache : hint == 1
+    __builtin_prefetch( addr, 1, 1);
+}
+#elif BOOST_COMP_INTEL || BOOST_COMP_INTEL_EMULATED
+#define BOOST_HAS_PREFETCH 1
+BOOST_FORCEINLINE
+void prefetch( void * addr) {
+    // L1 cache : hint == _MM_HINT_T0
+    _mm_prefetch( (const char *)addr, _MM_HINT_T0);
+}
+#elif BOOST_COMP_MSVC && !defined(_M_ARM) && !defined(_M_ARM64)
+#define BOOST_HAS_PREFETCH 1
+BOOST_FORCEINLINE
+void prefetch( void * addr) {
+    // L1 cache : hint == _MM_HINT_T0
+    _mm_prefetch( (const char *)addr, _MM_HINT_T0);
+}
+#endif
+
+inline
+void prefetch_range( void * addr, std::size_t len) {
+#if defined(BOOST_HAS_PREFETCH)
+    void * vp = addr;
+    void * end = reinterpret_cast< void * >(
+        reinterpret_cast< uintptr_t >( addr) + static_cast< uintptr_t >( len) );
+    while ( vp < end) {
+        prefetch( vp);
+        vp = reinterpret_cast< void * >(
+            reinterpret_cast< uintptr_t >( vp) + static_cast< uintptr_t >( prefetch_stride) );
+    }
+#endif
+}
+
+#undef BOOST_HAS_PREFETCH
+
+}}}
+
+#ifdef BOOST_HAS_ABI_HEADERS
+#  include BOOST_ABI_SUFFIX
+#endif
+
+#endif // BOOST_CONTEXT_DETAIL_PREFETCH_H

externals/vcpkg/packages/boost-context_x64-windows/include/boost/context/detail/tuple.hpp

@@ -0,0 +1,129 @@
+
+//          Copyright Oliver Kowalke 2014.
+// 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 BOOST_CONTEXT_DETAIL_TUPLE_H
+#define BOOST_CONTEXT_DETAIL_TUPLE_H
+
+#include <tuple>
+#include <utility>
+
+#include <boost/config.hpp>
+
+#include <boost/context/detail/config.hpp>
+#include <boost/context/detail/index_sequence.hpp>
+
+#ifdef BOOST_HAS_ABI_HEADERS
+# include BOOST_ABI_PREFIX
+#endif
+
+namespace boost {
+namespace context {
+namespace detail {
+
+template< typename ... S, typename ... T, std::size_t ... I >
+void
+head_impl( std::tuple< S ... > & s,
+           std::tuple< T ... > & t, index_sequence< I ... >) {
+    t = std::tuple< T ... >{ std::get< I >( s) ... };
+}
+
+template< typename ... S, typename ... T, std::size_t ... I >
+void
+head_impl( std::tuple< S ... > && s,
+           std::tuple< T ... > & t, index_sequence< I ... >) {
+    t = std::tuple< T ... >{ std::get< I >( std::move( s) ) ... };
+}
+
+template< typename ... S, std::size_t ... I1, typename ... T, std::size_t ... I2 >
+void
+tail_impl( std::tuple< S ... > & s, index_sequence< I1 ... >,
+           std::tuple< T ... > & t, index_sequence< I2 ... >) {
+    constexpr std::size_t Idx = (sizeof...(I1)) - (sizeof...(I2));
+    t = std::tuple< T ... >{ std::get< (Idx + I2) >( s) ... };
+}
+
+template< typename ... S, std::size_t ... I1, typename ... T, std::size_t ... I2 >
+void
+tail_impl( std::tuple< S ... > && s, index_sequence< I1 ... >,
+           std::tuple< T ... > & t, index_sequence< I2 ... >) {
+    constexpr std::size_t Idx = (sizeof...(I1)) - (sizeof...(I2));
+    t = std::tuple< T ... >{ std::get< (Idx + I2) >( std::move( s) ) ... };
+}
+
+template< typename ... T >
+class tuple_head;
+
+template< typename ... T >
+class tuple_head< std::tuple< T ... > > {
+private:
+    std::tuple< T ... > &   t_;
+
+public:
+    tuple_head( std::tuple< T ... > & t) noexcept :
+        t_( t) {
+    }
+
+    template< typename ... S >
+    void operator=( std::tuple< S ... > & s) {
+        static_assert((sizeof...(T)) <= (sizeof...(S)), "invalid tuple size");
+        head_impl( s,
+                   t_, index_sequence_for< T ... >{} );
+    }
+    template< typename ... S >
+    void operator=( std::tuple< S ... > && s) {
+        static_assert((sizeof...(T)) <= (sizeof...(S)), "invalid tuple size");
+        head_impl( std::move( s),
+                   t_, index_sequence_for< T ... >{} );
+    }
+};
+
+template< typename ... T >
+class tuple_tail;
+
+template< typename ... T >
+class tuple_tail< std::tuple< T ... > > {
+private:
+    std::tuple< T ... > &   t_;
+
+public:
+    tuple_tail( std::tuple< T ... > & t) noexcept :
+        t_( t) {
+    }
+
+    template< typename ... S >
+    void operator=( std::tuple< S ... > & s) {
+        static_assert((sizeof...(T)) <= (sizeof...(S)), "invalid tuple size");
+        tail_impl( s, index_sequence_for< S ... >{},
+                   t_, index_sequence_for< T ... >{} );
+    }
+
+    template< typename ... S >
+    void operator=( std::tuple< S ... > && s) {
+        static_assert((sizeof...(T)) <= (sizeof...(S)), "invalid tuple size");
+        tail_impl( std::move( s), index_sequence_for< S ... >{},
+                   t_, index_sequence_for< T ... >{} );
+    }
+};
+
+template< typename ... T >
+detail::tuple_head< std::tuple< T ... > >
+head( std::tuple< T ... > & tpl) {
+    return tuple_head< std::tuple< T ... > >{ tpl };
+}
+
+template< typename ... T >
+detail::tuple_tail< std::tuple< T ... > >
+tail( std::tuple< T ... > & tpl) {
+    return tuple_tail< std::tuple< T ... > >{ tpl };
+}
+
+}}}
+
+#ifdef BOOST_HAS_ABI_HEADERS
+#include BOOST_ABI_SUFFIX
+#endif
+
+#endif // BOOST_CONTEXT_DETAIL_TUPLE_H