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/*
* Copyright (C) 2006-2019 Apple Inc. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
*/
#pragma once
#include <memory>
#include <type_traits>
#include <utility>
#include <wtf/RefPtr.h>
#include <wtf/UniqueRef.h>
namespace WTF {
class AtomString;
template<bool isPod, typename T>
struct VectorTraitsBase;
template<typename T>
struct VectorTraitsBase<false, T>
{
static constexpr bool needsInitialization = true;
static constexpr bool canInitializeWithMemset = false;
static constexpr bool canMoveWithMemcpy = false;
static constexpr bool canCopyWithMemcpy = false;
static constexpr bool canFillWithMemset = false;
static constexpr bool canCompareWithMemcmp = false;
};
template<typename T>
struct VectorTraitsBase<true, T>
{
static constexpr bool needsInitialization = false;
static constexpr bool canInitializeWithMemset = true;
static constexpr bool canMoveWithMemcpy = true;
static constexpr bool canCopyWithMemcpy = true;
static constexpr bool canFillWithMemset = sizeof(T) == sizeof(char) && std::is_integral<T>::value;
static constexpr bool canCompareWithMemcmp = true;
};
// Requiring std::has_unique_object_representations_v<T> to make sure the type doesn't have padding and can
// be used with memcmp().
template<typename T>
struct VectorTraits : VectorTraitsBase<std::is_standard_layout_v<T> && std::is_trivial_v<T> && std::has_unique_object_representations_v<T>, T> { };
struct SimpleClassVectorTraits : VectorTraitsBase<false, void>
{
static constexpr bool canInitializeWithMemset = true;
static constexpr bool canMoveWithMemcpy = true;
static constexpr bool canCompareWithMemcmp = true;
};
// We know smart pointers are simple enough that initializing to 0 and moving with memcpy
// (and then not destructing the original) will work.
template<typename P> struct VectorTraits<RefPtr<P>> : SimpleClassVectorTraits { };
template<typename P> struct VectorTraits<std::unique_ptr<P>> : SimpleClassVectorTraits { };
template<typename P> struct VectorTraits<UniqueRef<P>> : SimpleClassVectorTraits { };
template<typename P> struct VectorTraits<std::reference_wrapper<P>> : SimpleClassVectorTraits { };
template<typename P> struct VectorTraits<Ref<P>> : SimpleClassVectorTraits { };
template<> struct VectorTraits<AtomString> : SimpleClassVectorTraits { };
template<> struct VectorTraits<ASCIILiteral> : VectorTraitsBase<false, void> {
static constexpr bool canInitializeWithMemset = true;
static constexpr bool canMoveWithMemcpy = true;
static constexpr bool canCompareWithMemcmp = false;
};
template<typename First, typename Second>
struct VectorTraits<std::pair<First, Second>>
{
typedef VectorTraits<First> FirstTraits;
typedef VectorTraits<Second> SecondTraits;
static constexpr bool needsInitialization = FirstTraits::needsInitialization || SecondTraits::needsInitialization;
static constexpr bool canInitializeWithMemset = FirstTraits::canInitializeWithMemset && SecondTraits::canInitializeWithMemset;
static constexpr bool canMoveWithMemcpy = FirstTraits::canMoveWithMemcpy && SecondTraits::canMoveWithMemcpy;
static constexpr bool canCopyWithMemcpy = FirstTraits::canCopyWithMemcpy && SecondTraits::canCopyWithMemcpy;
static constexpr bool canFillWithMemset = false;
static constexpr bool canCompareWithMemcmp = FirstTraits::canCompareWithMemcmp && SecondTraits::canCompareWithMemcmp;
};
} // namespace WTF
using WTF::VectorTraits;
using WTF::SimpleClassVectorTraits;
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