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+/* Copyright 2003-2014 Joaquin M Lopez Munoz.
+ * 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)
+ *
+ * See http://www.boost.org/libs/multi_index for library home page.
+ */
+
+#ifndef BOOST_MULTI_INDEX_DETAIL_PROMOTES_ARG_HPP
+#define BOOST_MULTI_INDEX_DETAIL_PROMOTES_ARG_HPP
+
+#if defined(_MSC_VER)
+#pragma once
+#endif
+
+#include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */
+#include <boost/mpl/bool.hpp>
+#include <boost/type_traits/intrinsics.hpp>
+
+/* Metafunctions to check if f(arg1,arg2) promotes either arg1 to the type of
+ * arg2 or viceversa. By default, (i.e. if it cannot be determined), no
+ * promotion is assumed.
+ */
+
+#if !defined(BOOST_IS_CONVERTIBLE)
+
+namespace boost{
+
+namespace multi_index{
+
+namespace detail{
+
+template<typename F,typename Arg1,typename Arg2>
+struct promotes_1st_arg:mpl::false_{};
+
+template<typename F,typename Arg1,typename Arg2>
+struct promotes_2nd_arg:mpl::false_{};
+
+} /* namespace multi_index::detail */
+
+} /* namespace multi_index */
+
+} /* namespace boost */
+
+#else
+
+#include <boost/mpl/and.hpp>
+#include <boost/mpl/not.hpp>
+#include <boost/multi_index/detail/is_transparent.hpp>
+#include <boost/type_traits/is_convertible.hpp>
+
+namespace boost{
+
+namespace multi_index{
+
+namespace detail{
+  
+template<typename F,typename Arg1,typename Arg2>
+struct promotes_1st_arg:
+  mpl::and_<
+    mpl::not_<is_transparent<F,Arg1,Arg2> >,
+    is_convertible<const Arg1,Arg2>,
+    is_transparent<F,Arg2,Arg2>
+  >
+{};
+
+template<typename F,typename Arg1,typename Arg2>
+struct promotes_2nd_arg:
+  mpl::and_<
+    mpl::not_<is_transparent<F,Arg1,Arg2> >,
+    is_convertible<const Arg2,Arg1>,
+    is_transparent<F,Arg1,Arg1>
+  >
+{};
+
+} /* namespace multi_index::detail */
+
+} /* namespace multi_index */
+
+} /* namespace boost */
+
+#endif /* defined(BOOST_IS_CONVERTIBLE) */
+#endif