#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.

// $Source: /cvsroot/boost/boost/boost/mpl/if.hpp,v $

// $Date: 2004/09/07 08:51:31 $

// $Revision: 1.25 $

#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