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62 lines
1.5 KiB
C++
62 lines
1.5 KiB
C++
//-----------------------------------------------------------------------------
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// boost empty.hpp header file
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// See http://www.boost.org for updates, documentation, and revision history.
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//-----------------------------------------------------------------------------
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//
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// Copyright (c) 2003
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// Eric Friedman
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//
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// Permission to use, copy, modify, distribute and sell this software
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// and its documentation for any purpose is hereby granted without fee,
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// provided that the above copyright notice appears in all copies and
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// that both the copyright notice and this permission notice appear in
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// supporting documentation. No representations are made about the
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// suitability of this software for any purpose. It is provided "as is"
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// without express or implied warranty.
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#ifndef BOOST_EMPTY_HPP
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#define BOOST_EMPTY_HPP
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#include <iosfwd> // for std::basic_ostream forward declare
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#include "boost/config.hpp"
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#include "boost/mpl/bool.hpp"
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#include "boost/type_traits/is_pod.hpp"
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namespace boost {
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struct empty
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{
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};
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template <>
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struct is_pod<empty>
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{
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BOOST_STATIC_CONSTANT(bool, value = true);
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typedef mpl::bool_<value> type;
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};
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bool operator==(const empty&, const empty&)
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{
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return true;
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}
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bool operator<(const empty&, const empty&)
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{
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return false;
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}
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template <typename E, typename T>
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inline std::basic_ostream<E,T>& operator<<(
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std::basic_ostream<E,T>& out
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, const empty&
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)
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{
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// (output nothing)
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return out;
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}
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} // namespace boost
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#endif // BOOST_EMPTY_HPP
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