Added thirdparty: boost library

thirdparty/include/boost/hof/is_unpackable.hpp

@@ -0,0 +1,115 @@
+/*=============================================================================
+    Copyright (c) 2016 Paul Fultz II
+    is_unpackable.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_IS_UNPACKABLE_HPP
+#define BOOST_HOF_GUARD_IS_UNPACKABLE_HPP
+
+/// is_unpackable
+/// =============
+/// 
+/// This is a trait that can be used to detect whether the type can be called
+/// with `unpack`.
+/// 
+/// Synopsis
+/// --------
+/// 
+///     template<class T>
+///     struct is_unpackable;
+/// 
+/// Example
+/// -------
+/// 
+///     #include <boost/hof.hpp>
+///     #include <cassert>
+/// 
+///     int main() {
+///         static_assert(boost::hof::is_unpackable<std::tuple<int>>::value, "Failed");
+///     }
+/// 
+
+#include <boost/hof/unpack_sequence.hpp>
+#include <boost/hof/is_invocable.hpp>
+#include <boost/hof/always.hpp>
+#include <boost/hof/detail/static_const_var.hpp>
+#include <boost/hof/detail/unpack_tuple.hpp>
+
+namespace boost { namespace hof {
+
+namespace detail {
+
+struct unpack_impl_f
+{
+    template<class F, class Sequence>
+    constexpr auto operator()(F&& f, Sequence&& s) const BOOST_HOF_RETURNS
+    (
+        boost::hof::unpack_sequence<typename std::remove_cv<typename std::remove_reference<Sequence>::type>::type>::
+                apply(BOOST_HOF_FORWARD(F)(f), BOOST_HOF_FORWARD(Sequence)(s))
+    );
+};
+
+BOOST_HOF_DECLARE_STATIC_VAR(unpack_impl, unpack_impl_f);
+
+#if BOOST_HOF_CHECK_UNPACK_SEQUENCE
+struct private_unpack_type {};
+template<class Sequence>
+struct unpack_impl_result
+{
+    static_assert(boost::hof::is_invocable<unpack_impl_f, decltype(boost::hof::always(private_unpack_type())), Sequence>::value,
+        "Unpack is invalid for this sequence. The function used to unpack this sequence is not callable."
+    );
+    typedef decltype(boost::hof::detail::unpack_impl(boost::hof::always(private_unpack_type()), std::declval<Sequence>())) type;
+};
+
+template<class Sequence>
+struct is_proper_sequence
+: std::is_same<
+    private_unpack_type, 
+    typename unpack_impl_result<Sequence>::type
+>
+{};
+#endif
+template<class Sequence, class=void>
+struct is_unpackable_impl
+: std::true_type
+{
+#if BOOST_HOF_CHECK_UNPACK_SEQUENCE
+    static_assert(is_proper_sequence<Sequence>::value,
+        "Unpack is invalid for this sequence. The function used to unpack this sequence does not invoke the function."
+    );
+#endif
+};
+
+template<class Sequence>
+struct is_unpackable_impl<Sequence, typename detail::holder<
+    typename unpack_sequence<Sequence>::not_unpackable
+>::type>
+: std::false_type
+{};
+
+}
+
+template<class Sequence>
+struct is_unpackable
+: detail::is_unpackable_impl<
+    typename std::remove_cv<typename std::remove_reference<Sequence>::type>::type
+>
+{
+#if BOOST_HOF_CHECK_UNPACK_SEQUENCE
+typedef detail::is_unpackable_impl<
+    typename std::remove_cv<typename std::remove_reference<Sequence>::type>::type
+> base;
+
+typedef std::conditional<base::value, detail::is_proper_sequence<Sequence>, std::true_type> check;
+static_assert(check::type::value,
+    "Unpack is invalid for this sequence. The function used to unpack this sequence does not invoke the function."
+);
+#endif
+};
+
+}} // namespace boost::hof
+
+#endif