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+// Boost.Units - A C++ library for zero-overhead dimensional analysis and
+// unit/quantity manipulation and conversion
+//
+// Copyright (C) 2003-2008 Matthias Christian Schabel
+// Copyright (C) 2007-2008 Steven Watanabe
+//
+// 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_UNITS_DETAIL_PREVENT_REDEFINITION_HPP
+#define BOOST_UNITS_DETAIL_PREVENT_REDEFINITION_HPP
+
+#include <boost/mpl/long.hpp>
+
+namespace boost {
+
+namespace units {
+
+namespace detail {
+
+struct no { no() {} char dummy; };
+struct yes { no dummy[2]; };
+
+template<bool> struct ordinal_has_already_been_defined;
+
+template<>
+struct ordinal_has_already_been_defined<true> { };
+
+template<>
+struct ordinal_has_already_been_defined<false> { typedef void type; };
+
+}
+
+/// This must be in namespace boost::units so that ADL
+/// will work. we need a mangled name because it must
+/// be found by ADL
+/// INTERNAL ONLY
+template<class T>
+detail::no
+boost_units_is_registered(const T&)
+{ detail::no result; return(result); }
+
+/// INTERNAL ONLY
+template<class T>
+detail::no
+boost_units_unit_is_registered(const T&)
+{ detail::no result; return(result); }
+
+} // namespace units
+
+} // namespace boost
+
+#endif // BOOST_UNITS_PREVENT_ORDINAL_REDEFINITION_IMPL_HPP