Chris@16: 
Chris@16: #ifndef BOOST_MPL_IF_HPP_INCLUDED
Chris@16: #define BOOST_MPL_IF_HPP_INCLUDED
Chris@16: 
Chris@16: // Copyright Aleksey Gurtovoy 2000-2004
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. 
Chris@16: // (See accompanying file LICENSE_1_0.txt or copy at 
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: //
Chris@16: // See http://www.boost.org/libs/mpl for documentation.
Chris@16: 
Chris@101: // $Id$
Chris@101: // $Date$
Chris@101: // $Revision$
Chris@16: 
Chris@16: #include <boost/mpl/aux_/value_wknd.hpp>
Chris@16: #include <boost/mpl/aux_/static_cast.hpp>
Chris@16: #include <boost/mpl/aux_/na_spec.hpp>
Chris@16: #include <boost/mpl/aux_/lambda_support.hpp>
Chris@16: #include <boost/mpl/aux_/config/integral.hpp>
Chris@16: #include <boost/mpl/aux_/config/ctps.hpp>
Chris@16: #include <boost/mpl/aux_/config/workaround.hpp>
Chris@16: 
Chris@16: namespace boost { namespace mpl {
Chris@16: 
Chris@16: #if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
Chris@16: 
Chris@16: template<
Chris@16:       bool C
Chris@16:     , typename T1
Chris@16:     , typename T2
Chris@16:     >
Chris@16: struct if_c
Chris@16: {
Chris@16:     typedef T1 type;
Chris@16: };
Chris@16: 
Chris@16: template<
Chris@16:       typename T1
Chris@16:     , typename T2
Chris@16:     >
Chris@16: struct if_c<false,T1,T2>
Chris@16: {
Chris@16:     typedef T2 type;
Chris@16: };
Chris@16: 
Chris@16: // agurt, 05/sep/04: nondescriptive parameter names for the sake of DigitalMars
Chris@16: // (and possibly MWCW < 8.0); see http://article.gmane.org/gmane.comp.lib.boost.devel/108959
Chris@16: template<
Chris@16:       typename BOOST_MPL_AUX_NA_PARAM(T1)
Chris@16:     , typename BOOST_MPL_AUX_NA_PARAM(T2)
Chris@16:     , typename BOOST_MPL_AUX_NA_PARAM(T3)
Chris@16:     >
Chris@16: struct if_
Chris@16: {
Chris@16:  private:
Chris@16:     // agurt, 02/jan/03: two-step 'type' definition for the sake of aCC 
Chris@16:     typedef if_c<
Chris@16: #if defined(BOOST_MPL_CFG_BCC_INTEGRAL_CONSTANTS)
Chris@16:           BOOST_MPL_AUX_VALUE_WKND(T1)::value
Chris@16: #else
Chris@16:           BOOST_MPL_AUX_STATIC_CAST(bool, BOOST_MPL_AUX_VALUE_WKND(T1)::value)
Chris@16: #endif
Chris@16:         , T2
Chris@16:         , T3
Chris@16:         > almost_type_;
Chris@16:  
Chris@16:  public:
Chris@16:     typedef typename almost_type_::type type;
Chris@16:     
Chris@16:     BOOST_MPL_AUX_LAMBDA_SUPPORT(3,if_,(T1,T2,T3))
Chris@16: };
Chris@16: 
Chris@16: #else
Chris@16: 
Chris@16: // no partial class template specialization
Chris@16: 
Chris@16: namespace aux {
Chris@16: 
Chris@16: template< bool C >
Chris@16: struct if_impl
Chris@16: {
Chris@16:     template< typename T1, typename T2 > struct result_
Chris@16:     {
Chris@16:         typedef T1 type;
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: template<>
Chris@16: struct if_impl<false>
Chris@16: {
Chris@16:     template< typename T1, typename T2 > struct result_
Chris@16:     { 
Chris@16:         typedef T2 type;
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: } // namespace aux
Chris@16: 
Chris@16: template<
Chris@16:       bool C_
Chris@16:     , typename T1
Chris@16:     , typename T2
Chris@16:     >
Chris@16: struct if_c
Chris@16: {
Chris@16:     typedef typename aux::if_impl< C_ >
Chris@16:         ::template result_<T1,T2>::type type;
Chris@16: };
Chris@16: 
Chris@16: // (almost) copy & paste in order to save one more 
Chris@16: // recursively nested template instantiation to user
Chris@16: template<
Chris@16:       typename BOOST_MPL_AUX_NA_PARAM(C_)
Chris@16:     , typename BOOST_MPL_AUX_NA_PARAM(T1)
Chris@16:     , typename BOOST_MPL_AUX_NA_PARAM(T2)
Chris@16:     >
Chris@16: struct if_
Chris@16: {
Chris@16:     enum { msvc_wknd_ = BOOST_MPL_AUX_MSVC_VALUE_WKND(C_)::value };
Chris@16: 
Chris@16:     typedef typename aux::if_impl< BOOST_MPL_AUX_STATIC_CAST(bool, msvc_wknd_) >
Chris@16:         ::template result_<T1,T2>::type type;
Chris@16: 
Chris@16:     BOOST_MPL_AUX_LAMBDA_SUPPORT(3,if_,(C_,T1,T2))
Chris@16: };
Chris@16: 
Chris@16: #endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
Chris@16: 
Chris@16: BOOST_MPL_AUX_NA_SPEC(3, if_)
Chris@16: 
Chris@16: }}
Chris@16: 
Chris@16: #endif // BOOST_MPL_IF_HPP_INCLUDED