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/*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#ifndef __BLI_MEMORY_UTILS_HH__
#define __BLI_MEMORY_UTILS_HH__
/** \file
* \ingroup bli
* Some of the functions below have very similar alternatives in the standard library. However, it
* is rather annoying to use those when debugging. Therefore, some more specialized and easier to
* debug functions are provided here.
*/
#include <memory>
#include <new>
#include "BLI_utildefines.h"
namespace blender {
/**
* Call the destructor on n consecutive values. For trivially destructible types, this does
* nothing.
*
* Exception Safety: Destructors shouldn't throw exceptions.
*
* Before:
* ptr: initialized
* After:
* ptr: uninitialized
*/
template<typename T> void destruct_n(T *ptr, uint n)
{
static_assert(std::is_nothrow_destructible_v<T>,
"This should be true for all types. Destructors are noexcept by default.");
/* This is not strictly necessary, because the loop below will be optimized away anyway. It is
* nice to make behavior this explicitly, though. */
if (std::is_trivially_destructible<T>::value) {
return;
}
for (uint i = 0; i < n; i++) {
ptr[i].~T();
}
}
/**
* Call the default constructor on n consecutive elements. For trivially constructible types, this
* does nothing.
*
* Exception Safety: Strong.
*
* Before:
* ptr: uninitialized
* After:
* ptr: initialized
*/
template<typename T> void default_construct_n(T *ptr, uint n)
{
/* This is not strictly necessary, because the loop below will be optimized away anyway. It is
* nice to make behavior this explicitly, though. */
if (std::is_trivially_constructible<T>::value) {
return;
}
uint current = 0;
try {
for (; current < n; current++) {
new ((void *)(ptr + current)) T;
}
}
catch (...) {
destruct_n(ptr, current);
throw;
}
}
/**
* Copy n values from src to dst.
*
* Exception Safety: Basic.
*
* Before:
* src: initialized
* dst: initialized
* After:
* src: initialized
* dst: initialized
*/
template<typename T> void initialized_copy_n(const T *src, uint n, T *dst)
{
for (uint i = 0; i < n; i++) {
dst[i] = src[i];
}
}
/**
* Copy n values from src to dst.
*
* Exception Safety: Strong.
*
* Before:
* src: initialized
* dst: uninitialized
* After:
* src: initialized
* dst: initialized
*/
template<typename T> void uninitialized_copy_n(const T *src, uint n, T *dst)
{
uint current = 0;
try {
for (; current < n; current++) {
new ((void *)(dst + current)) T(src[current]);
}
}
catch (...) {
destruct_n(dst, current);
throw;
}
}
/**
* Move n values from src to dst.
*
* Exception Safety: Basic.
*
* Before:
* src: initialized
* dst: initialized
* After:
* src: initialized, moved-from
* dst: initialized
*/
template<typename T> void initialized_move_n(T *src, uint n, T *dst)
{
for (uint i = 0; i < n; i++) {
dst[i] = std::move(src[i]);
}
}
/**
* Move n values from src to dst.
*
* Exception Safety: Basic.
*
* Before:
* src: initialized
* dst: uninitialized
* After:
* src: initialized, moved-from
* dst: initialized
*/
template<typename T> void uninitialized_move_n(T *src, uint n, T *dst)
{
static_assert(std::is_nothrow_move_constructible_v<T>,
"Ideally, all types should have this property. We might have to remove this "
"limitation of a real reason comes up.");
uint current = 0;
try {
for (; current < n; current++) {
new ((void *)(dst + current)) T(std::move(src[current]));
}
}
catch (...) {
destruct_n(dst, current);
throw;
}
}
/**
* Relocate n values from src to dst. Relocation is a move followed by destruction of the src
* value.
*
* Exception Safety: Basic.
*
* Before:
* src: initialized
* dst: initialized
* After:
* src: uninitialized
* dst: initialized
*/
template<typename T> void initialized_relocate_n(T *src, uint n, T *dst)
{
initialized_move_n(src, n, dst);
destruct_n(src, n);
}
/**
* Relocate n values from src to dst. Relocation is a move followed by destruction of the src
* value.
*
* Exception Safety: Basic.
*
* Before:
* src: initialized
* dst: uninitialized
* After:
* src: uninitialized
* dst: initialized
*/
template<typename T> void uninitialized_relocate_n(T *src, uint n, T *dst)
{
uninitialized_move_n(src, n, dst);
destruct_n(src, n);
}
/**
* Copy the value to n consecutive elements.
*
* Exception Safety: Basic.
*
* Before:
* dst: initialized
* After:
* dst: initialized
*/
template<typename T> void initialized_fill_n(T *dst, uint n, const T &value)
{
for (uint i = 0; i < n; i++) {
dst[i] = value;
}
}
/**
* Copy the value to n consecutive elements.
*
* Exception Safety: Strong.
*
* Before:
* dst: uninitialized
* After:
* dst: initialized
*/
template<typename T> void uninitialized_fill_n(T *dst, uint n, const T &value)
{
uint current = 0;
try {
for (; current < n; current++) {
new ((void *)(dst + current)) T(value);
}
}
catch (...) {
destruct_n(dst, current);
throw;
}
}
template<typename T> struct DestructValueAtAddress {
void operator()(T *ptr)
{
ptr->~T();
}
};
/**
* A destruct_ptr is like unique_ptr, but it will only call the destructor and will not free the
* memory. This is useful when using custom allocators.
*/
template<typename T> using destruct_ptr = std::unique_ptr<T, DestructValueAtAddress<T>>;
/**
* An `AlignedBuffer` is a byte array with at least the given size and alignment. The buffer will
* not be initialized by the default constructor.
*/
template<size_t Size, size_t Alignment> class alignas(Alignment) AlignedBuffer {
private:
/* Don't create an empty array. This causes problems with some compilers. */
char buffer_[(Size > 0) ? Size : 1];
public:
operator void *()
{
return (void *)buffer_;
}
operator const void *() const
{
return (void *)buffer_;
}
void *ptr()
{
return (void *)buffer_;
}
const void *ptr() const
{
return (const void *)buffer_;
}
};
/**
* This can be used to reserve memory for C++ objects whose lifetime is different from the
* lifetime of the object they are embedded in. It's used by containers with small buffer
* optimization and hash table implementations.
*/
template<typename T, size_t Size = 1> class TypedBuffer {
private:
AlignedBuffer<sizeof(T) * Size, alignof(T)> buffer_;
public:
operator T *()
{
return (T *)&buffer_;
}
operator const T *() const
{
return (const T *)&buffer_;
}
T &operator*()
{
return *(T *)&buffer_;
}
const T &operator*() const
{
return *(const T *)&buffer_;
}
T *ptr()
{
return (T *)&buffer_;
}
const T *ptr() const
{
return (const T *)&buffer_;
}
T &ref()
{
return *(T *)&buffer_;
}
const T &ref() const
{
return *(const T *)&buffer_;
}
};
/**
* This can be used by container constructors. A parameter of this type should be used to indicate
* that the constructor does not construct the elements.
*/
class NoInitialization {
};
} // namespace blender
#endif /* __BLI_MEMORY_UTILS_HH__ */
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