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