sl@0: 
sl@0: #ifndef BOOST_MPL_IF_HPP_INCLUDED
sl@0: #define BOOST_MPL_IF_HPP_INCLUDED
sl@0: 
sl@0: // Copyright Aleksey Gurtovoy 2000-2004
sl@0: //
sl@0: // Distributed under the Boost Software License, Version 1.0. 
sl@0: // (See accompanying file LICENSE_1_0.txt or copy at 
sl@0: // http://www.boost.org/LICENSE_1_0.txt)
sl@0: //
sl@0: // See http://www.boost.org/libs/mpl for documentation.
sl@0: 
sl@0: // $Source: /cvsroot/boost/boost/boost/mpl/if.hpp,v $
sl@0: // $Date: 2004/09/07 08:51:31 $
sl@0: // $Revision: 1.25 $
sl@0: 
sl@0: #include <boost/mpl/aux_/value_wknd.hpp>
sl@0: #include <boost/mpl/aux_/static_cast.hpp>
sl@0: #include <boost/mpl/aux_/na_spec.hpp>
sl@0: #include <boost/mpl/aux_/lambda_support.hpp>
sl@0: #include <boost/mpl/aux_/config/integral.hpp>
sl@0: #include <boost/mpl/aux_/config/ctps.hpp>
sl@0: #include <boost/mpl/aux_/config/workaround.hpp>
sl@0: 
sl@0: namespace boost { namespace mpl {
sl@0: 
sl@0: #if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
sl@0: 
sl@0: template<
sl@0:       bool C
sl@0:     , typename T1
sl@0:     , typename T2
sl@0:     >
sl@0: struct if_c
sl@0: {
sl@0:     typedef T1 type;
sl@0: };
sl@0: 
sl@0: template<
sl@0:       typename T1
sl@0:     , typename T2
sl@0:     >
sl@0: struct if_c<false,T1,T2>
sl@0: {
sl@0:     typedef T2 type;
sl@0: };
sl@0: 
sl@0: // agurt, 05/sep/04: nondescriptive parameter names for the sake of DigitalMars
sl@0: // (and possibly MWCW < 8.0); see http://article.gmane.org/gmane.comp.lib.boost.devel/108959
sl@0: template<
sl@0:       typename BOOST_MPL_AUX_NA_PARAM(T1)
sl@0:     , typename BOOST_MPL_AUX_NA_PARAM(T2)
sl@0:     , typename BOOST_MPL_AUX_NA_PARAM(T3)
sl@0:     >
sl@0: struct if_
sl@0: {
sl@0:  private:
sl@0:     // agurt, 02/jan/03: two-step 'type' definition for the sake of aCC 
sl@0:     typedef if_c<
sl@0: #if defined(BOOST_MPL_CFG_BCC_INTEGRAL_CONSTANTS)
sl@0:           BOOST_MPL_AUX_VALUE_WKND(T1)::value
sl@0: #else
sl@0:           BOOST_MPL_AUX_STATIC_CAST(bool, BOOST_MPL_AUX_VALUE_WKND(T1)::value)
sl@0: #endif
sl@0:         , T2
sl@0:         , T3
sl@0:         > almost_type_;
sl@0:  
sl@0:  public:
sl@0:     typedef typename almost_type_::type type;
sl@0:     
sl@0:     BOOST_MPL_AUX_LAMBDA_SUPPORT(3,if_,(T1,T2,T3))
sl@0: };
sl@0: 
sl@0: #else
sl@0: 
sl@0: // no partial class template specialization
sl@0: 
sl@0: namespace aux {
sl@0: 
sl@0: template< bool C >
sl@0: struct if_impl
sl@0: {
sl@0:     template< typename T1, typename T2 > struct result_
sl@0:     {
sl@0:         typedef T1 type;
sl@0:     };
sl@0: };
sl@0: 
sl@0: template<>
sl@0: struct if_impl<false>
sl@0: {
sl@0:     template< typename T1, typename T2 > struct result_
sl@0:     { 
sl@0:         typedef T2 type;
sl@0:     };
sl@0: };
sl@0: 
sl@0: } // namespace aux
sl@0: 
sl@0: template<
sl@0:       bool C_
sl@0:     , typename T1
sl@0:     , typename T2
sl@0:     >
sl@0: struct if_c
sl@0: {
sl@0:     typedef typename aux::if_impl< C_ >
sl@0:         ::template result_<T1,T2>::type type;
sl@0: };
sl@0: 
sl@0: // (almost) copy & paste in order to save one more 
sl@0: // recursively nested template instantiation to user
sl@0: template<
sl@0:       typename BOOST_MPL_AUX_NA_PARAM(C_)
sl@0:     , typename BOOST_MPL_AUX_NA_PARAM(T1)
sl@0:     , typename BOOST_MPL_AUX_NA_PARAM(T2)
sl@0:     >
sl@0: struct if_
sl@0: {
sl@0:     enum { msvc_wknd_ = BOOST_MPL_AUX_MSVC_VALUE_WKND(C_)::value };
sl@0: 
sl@0:     typedef typename aux::if_impl< BOOST_MPL_AUX_STATIC_CAST(bool, msvc_wknd_) >
sl@0:         ::template result_<T1,T2>::type type;
sl@0: 
sl@0:     BOOST_MPL_AUX_LAMBDA_SUPPORT(3,if_,(C_,T1,T2))
sl@0: };
sl@0: 
sl@0: #endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
sl@0: 
sl@0: BOOST_MPL_AUX_NA_SPEC(3, if_)
sl@0: 
sl@0: }}
sl@0: 
sl@0: #endif // BOOST_MPL_IF_HPP_INCLUDED