110 lines
3.1 KiB
C++
110 lines
3.1 KiB
C++
/*
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* Copyright (C) 2013-2014 Max Kellermann <max@duempel.org>
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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 "Compiler.h"
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#include <stddef.h>
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/**
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* Offset the given pointer by the specified number of bytes.
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*/
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static inline constexpr void *
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OffsetPointer(void *p, ptrdiff_t offset)
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{
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return (char *)p + offset;
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}
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/**
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* Offset the given pointer by the specified number of bytes.
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*/
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static inline constexpr const void *
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OffsetPointer(const void *p, ptrdiff_t offset)
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{
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return (const char *)p + offset;
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}
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template<typename T, typename U>
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static inline constexpr T *
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OffsetCast(U *p, 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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static inline constexpr T *
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OffsetCast(const U *p, 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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static constexpr inline ptrdiff_t
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ContainerAttributeOffset(const C *null_c, const A C::*p)
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{
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return ptrdiff_t((const char *)null_c - (const char *)&(null_c->*p));
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}
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template<class C, class A>
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static constexpr inline 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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#if defined(__clang__) || GCC_CHECK_VERSION(4,7)
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constexpr
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#endif
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static inline C &
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ContainerCast(A &a, 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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#if defined(__clang__) || GCC_CHECK_VERSION(4,7)
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constexpr
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#endif
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static inline const C &
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ContainerCast(const A &a, 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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