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/*
* Copyright (C) 2018 Yusuke Suzuki <utatane.tea@gmail.com>. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <wtf/CheckedArithmetic.h>
#include <wtf/FastMalloc.h>
#include <wtf/MallocSpan.h>
#include <wtf/Vector.h>
namespace WTF {
DECLARE_ALLOCATOR_WITH_HEAP_IDENTIFIER(UniqueArray);
DECLARE_ALLOCATOR_WITH_HEAP_IDENTIFIER(UniqueArrayElement);
template<bool isTriviallyDestructible, typename T> struct UniqueArrayMaker;
template<typename T>
struct UniqueArrayFree {
static_assert(std::is_trivially_destructible<T>::value);
void operator()(T* pointer) const
{
UniqueArrayMalloc::free(const_cast<typename std::remove_cv<T>::type*>(pointer));
}
};
template<typename T>
struct UniqueArrayFree<T[]> {
static_assert(std::is_trivially_destructible<T>::value);
void operator()(T* pointer) const
{
UniqueArrayMalloc::free(const_cast<typename std::remove_cv<T>::type*>(pointer));
}
};
template<typename T>
struct UniqueArrayMaker<true, T> {
using ResultType = typename std::unique_ptr<T[], UniqueArrayFree<T[]>>;
static ResultType make(size_t size)
{
// C++ `new T[N]` stores its `N` to somewhere. Otherwise, `delete []` cannot destroy
// these N elements. But we do not want to increase the size of allocated memory.
// If it is acceptable, we can just use Vector<T> instead. So this UniqueArray<T> only
// accepts the type T which has a trivial destructor. This allows us to skip calling
// destructors for N elements. And this allows UniqueArray<T> not to store its N size.
static_assert(std::is_trivially_destructible<T>::value);
// Do not use placement new like `new (storage) T[size]()`. `new T[size]()` requires
// larger storage than the `sizeof(T) * size` storage since it want to store `size`
// to somewhere.
auto storage = MallocSpan<T, UniqueArrayMalloc>::malloc(Checked<size_t>(sizeof(T)) * size);
VectorTypeOperations<T>::initialize(storage.mutableSpan().data(), storage.mutableSpan().subspan(size).data());
return ResultType(storage.leakSpan().data());
}
};
template<typename T>
struct UniqueArrayMaker<false, T> {
// Since we do not know how to store/retrieve N size to/from allocated memory when calling new [] and delete [],
// we use new [] and delete [] operators simply. We create UniqueArrayElement container for the type T.
// UniqueArrayElement has new [] and delete [] operators for FastMalloc. We allocate UniqueArrayElement[] and cast
// it to T[]. When deleting, the custom deleter casts T[] to UniqueArrayElement[] and deletes it.
class UniqueArrayElement {
WTF_MAKE_FAST_ALLOCATED_WITH_HEAP_IDENTIFIER(UniqueArrayElement);
public:
struct Deleter {
void operator()(T* pointer)
{
delete [] std::bit_cast<UniqueArrayElement*>(pointer);
};
};
UniqueArrayElement() = default;
T value { };
};
static_assert(sizeof(T) == sizeof(UniqueArrayElement));
using ResultType = typename std::unique_ptr<T[], typename UniqueArrayElement::Deleter>;
static ResultType make(size_t size)
{
return ResultType(std::bit_cast<T*>(new UniqueArrayElement[size]()));
}
};
template<typename T>
using UniqueArray = typename UniqueArrayMaker<std::is_trivially_destructible<T>::value, T>::ResultType;
template<typename T>
UniqueArray<T> makeUniqueArray(size_t size)
{
static_assert(std::is_same<typename std::remove_extent<T>::type, T>::value);
return UniqueArrayMaker<std::is_trivially_destructible<T>::value, T>::make(size);
}
} // namespace WTF
using WTF::UniqueArray;
using WTF::makeUniqueArray;
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