143 lines
4.5 KiB
C++
143 lines
4.5 KiB
C++
/*!
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* \file integralconstant.h
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* \brief Template meta-programming integral constant
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*
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* Copyright (C) 2018-2019 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_integralconstant_h__
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#define __utl_meta_integralconstant_h__
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#include <utl/core/impl.h>
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/*!
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* \ingroup meta
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* \defgroup integral
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* integral constant support header
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*/
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//! @{
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namespace utl {
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namespace meta {
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/*!
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* Empty type
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* utl::meta's nil type is not pure nil. It's a recursive "de-referencable nil.
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* Each time someone applies ::type to it, he gets back nil_. This way we can prevent
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* a lot of compilation errors in a wrong meta:: handling.
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*/
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struct nil_ {
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using type = nil_;
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};
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//! Type alias for \p _Tp::type. Used to evaluate/extract return type of metafunctions
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template <typename _Tp>
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using eval = typename _Tp::type;
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//! integral_
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//! Integral Constant is a holder class for a compile-time value of an integral type.
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//! Every Integral Constant is also a null-ary Metafunction, returning itself.
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//! An integral constant object is implicitly convertible to the corresponding
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//! run-time value of the wrapped integral type
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//! @{
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template <typename _Tp, _Tp _v>
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struct integral_ {
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using value_type = _Tp;
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using type = integral_<_Tp, _v>;
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constexpr operator value_type() const noexcept {
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return value;
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}
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constexpr value_type operator()() const noexcept {
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return value;
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}
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static constexpr _Tp value = _v;
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};
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template<typename _Tp, _Tp _v>
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constexpr _Tp integral_<_Tp, _v>::value;
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//! @}
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//! Wrappers for basic types
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//! @{
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//! bool_ type: integral constant wrapper for bool
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template<bool _v>
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using bool_ = integral_<bool, _v>;
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using true_ = bool_<true>; //!< The type used as a compile-time boolean with true value.
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using false_ = bool_<false>; //!< The type used as a compile-time boolean with false value.
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//! int8_ type: integral constant wrapper for \c int8_t
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template<int8_t _v>
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using int8_ = integral_<int8_t, _v>;
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//! uint8_ type: integral constant wrapper for \c uint8_t
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template<uint8_t _v>
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using uint8_ = integral_<uint8_t, _v>;
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//! int16_ type: integral constant wrapper for \c int16_t
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template<int16_t _v>
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using int16_ = integral_<int16_t, _v>;
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//! uint16_ type: integral constant wrapper for \c uint16_t
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template<uint16_t _v>
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using uint16_ = integral_<uint16_t, _v>;
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//! int32_ type: integral constant wrapper for \c int32_t
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template<int32_t _v>
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using int32_ = integral_<int32_t, _v>;
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//! uint32_ type: integral constant wrapper for \c uint32_t
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template<uint32_t _v>
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using uint32_ = integral_<uint32_t, _v>;
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//! char_ type: integral constant wrapper for \c char
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template<char _v>
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using char_ = integral_<char, _v>;
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//! int_ type: integral constant wrapper for \c int
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template<int _v>
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using int_ = integral_<int, _v>;
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//! long_ type: integral constant wrapper for \c long
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template<long _v>
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using long_ = integral_<long, _v>;
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//! index_ type: integral constant wrapper for \c index_t a.k.a std::size_t
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template<index_t _v>
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using index_ = integral_<index_t, _v>;
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//! size_ type: integral constant wrapper for \c size_t a.k.a std::size_t
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template<size_t _v>
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using size_ = integral_<size_t, _v>;
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//! Computes the size of the type \p _Tp.
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//! Complexity \f$ O(1) \f$.
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template <typename _Tp>
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using sizeof_ = size_<sizeof(_Tp)>;
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//! Computes the alignment required for any instance of the type \p _Tp.
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//! Complexity \f$ O(1) \f$.
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template <typename _Tp>
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using alignof_ = size_<alignof(_Tp)>;
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//! @}
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//! The last position we can express for indexing
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using Npos = size_<index_t(-1)>;
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}}
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//!@}
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#endif /* __utl_meta_integralconstant_h__ */
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