86 lines
2.6 KiB
C++
86 lines
2.6 KiB
C++
/*
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* Copyright (C) 2013-2014 Max Kellermann <max.kellermann@gmail.com>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef CAST_HXX
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#define CAST_HXX
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#include "OffsetPointer.hxx"
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#include <cstddef>
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template<typename T, typename U>
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constexpr T *
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OffsetCast(U *p, std::ptrdiff_t offset)
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{
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return reinterpret_cast<T *>(OffsetPointer(p, offset));
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}
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template<typename T, typename U>
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constexpr T *
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OffsetCast(const U *p, std::ptrdiff_t offset)
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{
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return reinterpret_cast<const T *>(OffsetPointer(p, offset));
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}
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template<class C, class A>
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constexpr std::ptrdiff_t
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ContainerAttributeOffset(const C *null_c, const A C::*p)
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{
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return std::ptrdiff_t((const char *)&(null_c->*p) - (const char *)null_c);
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}
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template<class C, class A>
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constexpr std::ptrdiff_t
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ContainerAttributeOffset(const A C::*p)
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{
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return ContainerAttributeOffset<C, A>(nullptr, p);
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}
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/**
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* Cast the given pointer to a struct member to its parent structure.
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*/
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template<class C, class A>
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constexpr C &
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ContainerCast(A &a, const A C::*member)
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{
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return *OffsetCast<C, A>(&a, -ContainerAttributeOffset<C, A>(member));
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}
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/**
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* Cast the given pointer to a struct member to its parent structure.
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*/
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template<class C, class A>
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constexpr const C &
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ContainerCast(const A &a, const A C::*member)
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{
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return *OffsetCast<const C, const A>(&a, -ContainerAttributeOffset<C, A>(member));
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}
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#endif
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