Imported Upstream version 1.67.0upstream/1.67.0

1 files changed, 98 insertions, 0 deletions

diff --git a/boost/hof/detail/unpack_tuple.hpp b/boost/hof/detail/unpack_tuple.hpp
new file mode 100644
index 0000000000..19b0e853f8
--- /dev/null
+++ b/boost/hof/detail/unpack_tuple.hpp
@@ -0,0 +1,98 @@
+/*=============================================================================
+    Copyright (c) 2016 Paul Fultz II
+    unpack_tuple.hpp
+    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_HOF_GUARD_UNPACK_TUPLE_HPP
+#define BOOST_HOF_GUARD_UNPACK_TUPLE_HPP
+
+#include <boost/hof/unpack_sequence.hpp>
+#include <boost/hof/returns.hpp>
+#include <boost/hof/detail/forward.hpp>
+#include <boost/hof/detail/seq.hpp>
+#include <tuple>
+#include <array>
+
+namespace boost { namespace hof {
+
+namespace detail {
+
+template<class Sequence>
+constexpr typename gens<std::tuple_size<Sequence>::value>::type 
+make_tuple_gens(const Sequence&)
+{
+    return {};
+}
+
+#if (defined(__GNUC__) && !defined (__clang__) && __GNUC__ == 4 && __GNUC_MINOR__ < 7)
+
+template<std::size_t I, class Tuple>
+struct tuple_element_return
+: std::tuple_element<I, Tuple>
+{};
+
+template<std::size_t I, class Tuple>
+struct tuple_element_return<I, Tuple&>
+: std::add_lvalue_reference<typename tuple_element_return<I, Tuple>::type>
+{};
+
+template<std::size_t I, class Tuple>
+struct tuple_element_return<I, Tuple&&>
+: std::add_rvalue_reference<typename tuple_element_return<I, Tuple>::type>
+{};
+
+template<std::size_t I, class Tuple>
+struct tuple_element_return<I, const Tuple>
+: std::add_const<typename tuple_element_return<I, Tuple>::type>
+{};
+
+template< std::size_t I, class Tuple, class R = typename tuple_element_return<I, Tuple&&>::type >
+R tuple_get( Tuple&& t ) 
+{ 
+    return (R&&)(std::get<I>(boost::hof::forward<Tuple>(t))); 
+}
+#define BOOST_HOF_UNPACK_TUPLE_GET boost::hof::detail::tuple_get
+#else
+#define BOOST_HOF_UNPACK_TUPLE_GET std::get
+
+#endif
+
+template<class F, class T, std::size_t ...N>
+constexpr auto unpack_tuple(F&& f, T&& t, seq<N...>) BOOST_HOF_RETURNS
+(
+    f(
+        BOOST_HOF_AUTO_FORWARD(BOOST_HOF_UNPACK_TUPLE_GET<N>(BOOST_HOF_AUTO_FORWARD(t)))...
+    )
+);
+
+struct unpack_tuple_apply
+{
+    template<class F, class S>
+    constexpr static auto apply(F&& f, S&& t) BOOST_HOF_RETURNS
+    (
+        boost::hof::detail::unpack_tuple(BOOST_HOF_FORWARD(F)(f), BOOST_HOF_FORWARD(S)(t), boost::hof::detail::make_tuple_gens(t))
+    );
+};
+
+}
+
+template<class... Ts>
+struct unpack_sequence<std::tuple<Ts...>>
+: detail::unpack_tuple_apply
+{};
+
+template<class T, class U>
+struct unpack_sequence<std::pair<T, U>>
+: detail::unpack_tuple_apply
+{};
+
+template<class T, std::size_t N>
+struct unpack_sequence<std::array<T, N>>
+: detail::unpack_tuple_apply
+{};
+
+}} // namespace boost::hof
+
+#endif