95 lines
3.2 KiB
C++
95 lines
3.2 KiB
C++
// =====================================================================================================================
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// fennec, a free and open source game engine
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// Copyright (C) 2025 Medusa Slockbower
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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 General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (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 General Public License for more details.
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//2
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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// =====================================================================================================================
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#ifndef FENNEC_MEMORY_DETAIL_PTR_TRAITS_H
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#define FENNEC_MEMORY_DETAIL_PTR_TRAITS_H
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#include <fennec/lang/conditional_types.h>
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#include <fennec/lang/types.h>
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#include <fennec/lang/type_traits.h>
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#include <fennec/lang/type_sequences.h>
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namespace fennec
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{
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namespace detail
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{
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// helper to get the element type of the pointer class
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template<typename ClassT, typename = void>
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struct _ptr_get_element : first_element<ClassT> { }; // Default case, return the first template parameter
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// overload for types that have a member `ClassT::element_t`
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template<typename ClassT> requires requires { typename ClassT::element_t; }
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struct _ptr_get_element<ClassT, ClassT> { using type = typename ClassT::element_t; };
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// helper for generating `pointer_to`
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template<typename PtrT, typename ElemT, bool_t = is_void_v<ElemT>>
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struct _ptr_traits_ptr_to
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{
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using pointer_t = PtrT;
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using element_t = ElemT;
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static constexpr pointer_t pointer_to(element_t& obj) {
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return pointer_t::pointer_to(obj);
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}
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};
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// overload for C style pointers
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template<typename ElemT>
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struct _ptr_traits_ptr_to<ElemT*, ElemT, false>
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{
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using pointer_t = ElemT*;
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using element_t = ElemT;
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static constexpr pointer_t pointer_to(element_t& obj) {
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return addressof(obj);
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}
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};
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// underlying implementation for classes that behave like pointers
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template<typename ClassT, typename ElemT, bool_t = is_void_v<ElemT>>
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struct _ptr_traits_impl : _ptr_traits_ptr_to<ClassT, ElemT>
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{
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private:
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template<typename TypeT>
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using _diff_t = typename TypeT::diff_t; // Helper to prevent substitution issues with detecting the difference type
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template<typename BaseT, typename OElemT> // Helper to prevent substitution issues with detecting a defined rebind
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using _rebind_helper = type_identity<typename BaseT::template rebind<OElemT>>;
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public:
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using pointer_t = ClassT;
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using element_t = _ptr_get_element<ClassT>;
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using diff_t = _diff_t<ClassT>;
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template<class U> using rebind = detect_t<replace_first_element<ClassT, U>, _rebind_helper, ClassT, ElemT>;
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};
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// overload for an undefined type
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template<typename ClassT> struct _ptr_traits_impl<ClassT, undefined_t> {};
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// overload for void element
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template<typename PtrT, typename ElemT> struct _ptr_traits_ptr_to<PtrT, ElemT, true> { };
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}
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}
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#endif // FENNEC_MEMORY_DETAIL_PTR_TRAITS_H
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