williamr@2: //  © Copyright Fernando Luis Cacciola Carballal 2000-2004
williamr@2: //  Use, modification, and distribution is subject to the Boost Software
williamr@2: //  License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
williamr@2: //  http://www.boost.org/LICENSE_1_0.txt)
williamr@2: 
williamr@2: //  See library home page at http://www.boost.org/libs/numeric/conversion
williamr@2: //
williamr@2: // Contact the author at: fernando_cacciola@hotmail.com
williamr@2: // 
williamr@2: #ifndef BOOST_NUMERIC_CONVERSION_DETAIL_META_FLC_12NOV2002_HPP
williamr@2: #define BOOST_NUMERIC_CONVERSION_DETAIL_META_FLC_12NOV2002_HPP
williamr@2: 
williamr@2: #include "boost/type_traits/remove_cv.hpp"
williamr@2: 
williamr@2: #include "boost/mpl/if.hpp"
williamr@2: #include "boost/mpl/eval_if.hpp"
williamr@2: #include "boost/mpl/equal_to.hpp"
williamr@2: #include "boost/mpl/not.hpp"
williamr@2: #include "boost/mpl/and.hpp"
williamr@2: #include "boost/mpl/bool.hpp"
williamr@2: #include "boost/mpl/identity.hpp"
williamr@2: 
williamr@2: namespace boost { namespace numeric { namespace convdetail
williamr@2: {
williamr@2:    template< class T1, class T2>
williamr@2:    struct equal_to
williamr@2:    {
williamr@2:    #if !defined(__BORLANDC__)
williamr@2:    
williamr@2:        enum { x = ( BOOST_MPL_AUX_VALUE_WKND(T1)::value == BOOST_MPL_AUX_VALUE_WKND(T2)::value ) };
williamr@2:            
williamr@2:        BOOST_STATIC_CONSTANT(bool, value = x);
williamr@2:            
williamr@2:        typedef mpl::bool_<value> type;
williamr@2:        
williamr@2:    #else
williamr@2:    
williamr@2:        BOOST_STATIC_CONSTANT(bool, value = (
williamr@2:              BOOST_MPL_AUX_VALUE_WKND(T1)::value 
williamr@2:                == BOOST_MPL_AUX_VALUE_WKND(T2)::value
williamr@2:            ));
williamr@2:            
williamr@2:        typedef mpl::bool_<(
williamr@2:              BOOST_MPL_AUX_VALUE_WKND(T1)::value 
williamr@2:                == BOOST_MPL_AUX_VALUE_WKND(T2)::value
williamr@2:            )> type;
williamr@2:    #endif
williamr@2:    };
williamr@2:     
williamr@2: // Metafunction:
williamr@2:   //
williamr@2:   //   ct_switch4<Value,Case0Val,Case1Val,Case2Val,Case0Type,Case1Type,Case2Type,DefaultType>::type
williamr@2:   //
williamr@2:   // {Value,Case(X)Val} are Integral Constants (such as: mpl::int_<>)
williamr@2:   // {Case(X)Type,DefaultType} are arbitrary types. (not metafunctions)
williamr@2:   //
williamr@2:   // Returns Case(X)Type if Val==Case(X)Val; DefaultType otherwise.
williamr@2:   //
williamr@2:   template<class Value,
williamr@2:            class Case0Val,
williamr@2:            class Case1Val,
williamr@2:            class Case2Val,
williamr@2:            class Case0Type,
williamr@2:            class Case1Type,
williamr@2:            class Case2Type,
williamr@2:            class DefaultType
williamr@2:           >
williamr@2:   struct ct_switch4
williamr@2:   {
williamr@2:     typedef mpl::identity<Case0Type> Case0TypeQ ;
williamr@2:     typedef mpl::identity<Case1Type> Case1TypeQ ;
williamr@2: 
williamr@2:     typedef equal_to<Value,Case0Val> is_case0 ;
williamr@2:     typedef equal_to<Value,Case1Val> is_case1 ;
williamr@2:     typedef equal_to<Value,Case2Val> is_case2 ;
williamr@2: 
williamr@2:     typedef mpl::if_<is_case2,Case2Type,DefaultType> choose_2_3Q ;
williamr@2:     typedef mpl::eval_if<is_case1,Case1TypeQ,choose_2_3Q> choose_1_2_3Q ;
williamr@2: 
williamr@2:     typedef typename
williamr@2:       mpl::eval_if<is_case0,Case0TypeQ,choose_1_2_3Q>::type
williamr@2:         type ;
williamr@2:   } ;
williamr@2: 
williamr@2: 
williamr@2: 
williamr@2: 
williamr@2:   // Metafunction:
williamr@2:   //
williamr@2:   //   for_both<expr0,expr1,TT,TF,FT,FF>::type
williamr@2:   //
williamr@2:   // {exp0,expr1} are Boolean Integral Constants
williamr@2:   // {TT,TF,FT,FF} are aribtrary types. (not metafunctions)
williamr@2:   //
williamr@2:   // According to the combined boolean value of 'expr0 && expr1', selects the corresponding type.
williamr@2:   //
williamr@2:   template<class expr0, class expr1, class TT, class TF, class FT, class FF>
williamr@2:   struct for_both
williamr@2:   {
williamr@2:     typedef mpl::identity<TF> TF_Q ;
williamr@2:     typedef mpl::identity<TT> TT_Q ;
williamr@2: 
williamr@2:     typedef typename mpl::not_<expr0>::type not_expr0 ;
williamr@2:     typedef typename mpl::not_<expr1>::type not_expr1 ;
williamr@2: 
williamr@2:     typedef typename mpl::and_<expr0,expr1>::type     caseTT ;
williamr@2:     typedef typename mpl::and_<expr0,not_expr1>::type caseTF ;
williamr@2:     typedef typename mpl::and_<not_expr0,expr1>::type caseFT ;
williamr@2: 
williamr@2:     typedef mpl::if_<caseFT,FT,FF>                    choose_FT_FF_Q ;
williamr@2:     typedef mpl::eval_if<caseTF,TF_Q,choose_FT_FF_Q> choose_TF_FT_FF_Q ;
williamr@2: 
williamr@2:     typedef typename mpl::eval_if<caseTT,TT_Q,choose_TF_FT_FF_Q>::type type ;
williamr@2:   } ;
williamr@2: 
williamr@2: } } } // namespace boost::numeric::convdetail
williamr@2: 
williamr@2: #endif
williamr@2: 
williamr@2: