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-rw-r--r--boost/hof/detail/join.hpp43
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diff --git a/boost/hof/detail/join.hpp b/boost/hof/detail/join.hpp
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+/*=============================================================================
+ Copyright (c) 2012 Paul Fultz II
+ join.h
+ 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_FUNCTION_DETAIL_JOIN_H
+#define BOOST_HOF_GUARD_FUNCTION_DETAIL_JOIN_H
+
+#include <boost/hof/detail/holder.hpp>
+
+namespace boost { namespace hof { namespace detail {
+
+template<class... Ts>
+struct join_args
+{};
+
+template<template <class...> class T, class Args, class=void>
+struct join_impl
+{};
+
+template<template <class...> class T, class... Args>
+struct join_impl<T, join_args<Args...>, typename holder<
+ T<Args...>
+>::type>
+{ typedef T<Args...> type; };
+
+template<template <class...> class T, class... Args>
+struct join
+: join_impl<T, join_args<Args...>>
+{};
+
+}}} // namespace boost::hof
+
+#if defined(__GNUC__) && !defined (__clang__) && __GNUC__ == 4 && __GNUC_MINOR__ < 7
+#define BOOST_HOF_JOIN(c, ...) typename boost::hof::detail::join<c, __VA_ARGS__>::type
+#else
+#define BOOST_HOF_JOIN(c, ...) c<__VA_ARGS__>
+
+#endif
+
+#endif