/* * 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/Vector.h> namespace WTF { template<bool isTriviallyDestructible, typename T> struct UniqueArrayMaker; template<typename T> struct UniqueArrayMaker<true, T> { using ResultType = typename std::unique_ptr<T[], FastFree<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. T* storage = static_cast<T*>(fastMalloc((Checked<size_t>(sizeof(T)) * size).unsafeGet())); VectorTypeOperations<T>::initialize(storage, storage + size); return ResultType(storage); } }; 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; public: struct Deleter { void operator()(T* pointer) { delete [] bitwise_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(bitwise_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;