ClickHouse/contrib/libboost/boost_1_62_0/boost/mpl/if.hpp

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#ifndef BOOST_MPL_IF_HPP_INCLUDED
#define BOOST_MPL_IF_HPP_INCLUDED
// Copyright Aleksey Gurtovoy 2000-2004
//
// 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/mpl for documentation.
// $Id$
// $Date$
// $Revision$
#include <boost/mpl/aux_/value_wknd.hpp>
#include <boost/mpl/aux_/static_cast.hpp>
#include <boost/mpl/aux_/na_spec.hpp>
#include <boost/mpl/aux_/lambda_support.hpp>
#include <boost/mpl/aux_/config/integral.hpp>
#include <boost/mpl/aux_/config/ctps.hpp>
#include <boost/mpl/aux_/config/workaround.hpp>
namespace boost { namespace mpl {
#if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
template<
bool C
, typename T1
, typename T2
>
struct if_c
{
typedef T1 type;
};
template<
typename T1
, typename T2
>
struct if_c<false,T1,T2>
{
typedef T2 type;
};
// agurt, 05/sep/04: nondescriptive parameter names for the sake of DigitalMars
// (and possibly MWCW < 8.0); see http://article.gmane.org/gmane.comp.lib.boost.devel/108959
template<
typename BOOST_MPL_AUX_NA_PARAM(T1)
, typename BOOST_MPL_AUX_NA_PARAM(T2)
, typename BOOST_MPL_AUX_NA_PARAM(T3)
>
struct if_
{
private:
// agurt, 02/jan/03: two-step 'type' definition for the sake of aCC
typedef if_c<
#if defined(BOOST_MPL_CFG_BCC_INTEGRAL_CONSTANTS)
BOOST_MPL_AUX_VALUE_WKND(T1)::value
#else
BOOST_MPL_AUX_STATIC_CAST(bool, BOOST_MPL_AUX_VALUE_WKND(T1)::value)
#endif
, T2
, T3
> almost_type_;
public:
typedef typename almost_type_::type type;
BOOST_MPL_AUX_LAMBDA_SUPPORT(3,if_,(T1,T2,T3))
};
#else
// no partial class template specialization
namespace aux {
template< bool C >
struct if_impl
{
template< typename T1, typename T2 > struct result_
{
typedef T1 type;
};
};
template<>
struct if_impl<false>
{
template< typename T1, typename T2 > struct result_
{
typedef T2 type;
};
};
} // namespace aux
template<
bool C_
, typename T1
, typename T2
>
struct if_c
{
typedef typename aux::if_impl< C_ >
::template result_<T1,T2>::type type;
};
// (almost) copy & paste in order to save one more
// recursively nested template instantiation to user
template<
typename BOOST_MPL_AUX_NA_PARAM(C_)
, typename BOOST_MPL_AUX_NA_PARAM(T1)
, typename BOOST_MPL_AUX_NA_PARAM(T2)
>
struct if_
{
enum { msvc_wknd_ = BOOST_MPL_AUX_MSVC_VALUE_WKND(C_)::value };
typedef typename aux::if_impl< BOOST_MPL_AUX_STATIC_CAST(bool, msvc_wknd_) >
::template result_<T1,T2>::type type;
BOOST_MPL_AUX_LAMBDA_SUPPORT(3,if_,(C_,T1,T2))
};
#endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
BOOST_MPL_AUX_NA_SPEC(3, if_)
}}
#endif // BOOST_MPL_IF_HPP_INCLUDED