1 // (c) Copyright Fernando Luis Cacciola Carballal 2000-2004 2 // Use, modification, and distribution is subject to the Boost Software 3 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at 4 // http://www.boost.org/LICENSE_1_0.txt) 5 6 // See library home page at http://www.boost.org/libs/numeric/conversion 7 // 8 // Contact the author at: fernando_cacciola@hotmail.com 9 // 10 #ifndef BOOST_NUMERIC_CONVERSION_DETAIL_META_FLC_12NOV2002_HPP 11 #define BOOST_NUMERIC_CONVERSION_DETAIL_META_FLC_12NOV2002_HPP 12 13 #include "boost/type_traits/remove_cv.hpp" 14 15 #include "boost/mpl/if.hpp" 16 #include "boost/mpl/eval_if.hpp" 17 #include "boost/mpl/equal_to.hpp" 18 #include "boost/mpl/not.hpp" 19 #include "boost/mpl/and.hpp" 20 #include "boost/mpl/bool.hpp" 21 #include "boost/mpl/identity.hpp" 22 23 namespace boost { namespace numeric { namespace convdetail 24 { 25 template< class T1, class T2> 26 struct equal_to 27 { 28 #if !defined(__BORLANDC__) 29 30 enum { x = ( BOOST_MPL_AUX_VALUE_WKND(T1)::value == BOOST_MPL_AUX_VALUE_WKND(T2)::value ) }; 31 32 BOOST_STATIC_CONSTANT(bool, value = x); 33 34 typedef mpl::bool_<value> type; 35 36 #else 37 38 BOOST_STATIC_CONSTANT(bool, value = ( 39 BOOST_MPL_AUX_VALUE_WKND(T1)::value 40 == BOOST_MPL_AUX_VALUE_WKND(T2)::value 41 )); 42 43 typedef mpl::bool_<( 44 BOOST_MPL_AUX_VALUE_WKND(T1)::value 45 == BOOST_MPL_AUX_VALUE_WKND(T2)::value 46 )> type; 47 #endif 48 }; 49 50 // Metafunction: 51 // 52 // ct_switch4<Value,Case0Val,Case1Val,Case2Val,Case0Type,Case1Type,Case2Type,DefaultType>::type 53 // 54 // {Value,Case(X)Val} are Integral Constants (such as: mpl::int_<>) 55 // {Case(X)Type,DefaultType} are arbitrary types. (not metafunctions) 56 // 57 // Returns Case(X)Type if Val==Case(X)Val; DefaultType otherwise. 58 // 59 template<class Value, 60 class Case0Val, 61 class Case1Val, 62 class Case2Val, 63 class Case0Type, 64 class Case1Type, 65 class Case2Type, 66 class DefaultType 67 > 68 struct ct_switch4 69 { 70 typedef mpl::identity<Case0Type> Case0TypeQ ; 71 typedef mpl::identity<Case1Type> Case1TypeQ ; 72 73 typedef equal_to<Value,Case0Val> is_case0 ; 74 typedef equal_to<Value,Case1Val> is_case1 ; 75 typedef equal_to<Value,Case2Val> is_case2 ; 76 77 typedef mpl::if_<is_case2,Case2Type,DefaultType> choose_2_3Q ; 78 typedef mpl::eval_if<is_case1,Case1TypeQ,choose_2_3Q> choose_1_2_3Q ; 79 80 typedef typename 81 mpl::eval_if<is_case0,Case0TypeQ,choose_1_2_3Q>::type 82 type ; 83 } ; 84 85 86 87 88 // Metafunction: 89 // 90 // for_both<expr0,expr1,TT,TF,FT,FF>::type 91 // 92 // {exp0,expr1} are Boolean Integral Constants 93 // {TT,TF,FT,FF} are aribtrary types. (not metafunctions) 94 // 95 // According to the combined boolean value of 'expr0 && expr1', selects the corresponding type. 96 // 97 template<class expr0, class expr1, class TT, class TF, class FT, class FF> 98 struct for_both 99 { 100 typedef mpl::identity<TF> TF_Q ; 101 typedef mpl::identity<TT> TT_Q ; 102 103 typedef typename mpl::not_<expr0>::type not_expr0 ; 104 typedef typename mpl::not_<expr1>::type not_expr1 ; 105 106 typedef typename mpl::and_<expr0,expr1>::type caseTT ; 107 typedef typename mpl::and_<expr0,not_expr1>::type caseTF ; 108 typedef typename mpl::and_<not_expr0,expr1>::type caseFT ; 109 110 typedef mpl::if_<caseFT,FT,FF> choose_FT_FF_Q ; 111 typedef mpl::eval_if<caseTF,TF_Q,choose_FT_FF_Q> choose_TF_FT_FF_Q ; 112 113 typedef typename mpl::eval_if<caseTT,TT_Q,choose_TF_FT_FF_Q>::type type ; 114 } ; 115 116 } } } // namespace boost::numeric::convdetail 117 118 #endif 119 120 121