68 lines
1.8 KiB
C++
68 lines
1.8 KiB
C++
/*!
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* \file if.h
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* \brief Template meta-programming conditional helpers
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*
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* Copyright (C) 2018 Christos Choutouridis
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation, either version 3
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __utl_meta_if_h__
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#define __utl_meta_if_h__
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#include <utl/impl/version.h>
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/*!
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* \ingroup meta
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* \defgroup if
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* conditional type support header
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*/
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//! @{
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namespace utl {
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//! select _T1 or _T2 based on _C
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//! @{
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template <bool _C, typename _T1, typename _T2>
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struct select_ {
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typedef _T1 type;
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};
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template <typename _T1, typename _T2>
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struct select_ <false, _T1, _T2> {
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typedef _T2 type;
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};
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//! @}
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//! select _Tp if _C is true, else SFINAE
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//! @{
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template <bool _C, typename _Tp = void>
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struct if_ {
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typedef _Tp type;
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};
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template<typename _Tp> // Partial specialization for false.
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struct if_ <false, _Tp> { };
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//! Alias template for if_
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template<bool _C, typename _Tp = void>
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using if_t = typename if_<_C, _Tp>::type;
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//! Publicly recognized alias template for if_
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template<bool _C, typename _Tp = void>
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using enable_if_t = typename if_<_C, _Tp>::type;
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//! @}
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}
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//! @}
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#endif /* __utl_meta_if_h__ */
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