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// Copyright (C) 2020 The Qt Company Ltd.
// Copyright (C) 2019 Intel Corporation.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#ifndef QARRAYDATA_H
#define QARRAYDATA_H
#include <QtCore/qpair.h>
#include <QtCore/qatomic.h>
#include <QtCore/qflags.h>
#include <QtCore/qcontainerfwd.h>
#include <string.h>
QT_BEGIN_NAMESPACE
#if __has_cpp_attribute(gnu::malloc)
# define Q_DECL_MALLOCLIKE [[nodiscard, gnu::malloc]]
#else
# define Q_DECL_MALLOCLIKE [[nodiscard]]
#endif
template <class T> struct QTypedArrayData;
struct QArrayData
{
enum AllocationOption {
Grow,
KeepSize
};
enum GrowthPosition {
GrowsAtEnd,
GrowsAtBeginning
};
enum ArrayOption {
ArrayOptionDefault = 0,
CapacityReserved = 0x1 //!< the capacity was reserved by the user, try to keep it
};
Q_DECLARE_FLAGS(ArrayOptions, ArrayOption)
QBasicAtomicInt ref_;
ArrayOptions flags;
qsizetype alloc;
qsizetype allocatedCapacity() noexcept
{
return alloc;
}
qsizetype constAllocatedCapacity() const noexcept
{
return alloc;
}
/// Returns true if sharing took place
bool ref() noexcept
{
ref_.ref();
return true;
}
/// Returns false if deallocation is necessary
bool deref() noexcept
{
return ref_.deref();
}
bool isShared() const noexcept
{
return ref_.loadRelaxed() != 1;
}
// Returns true if a detach is necessary before modifying the data
// This method is intentionally not const: if you want to know whether
// detaching is necessary, you should be in a non-const function already
bool needsDetach() noexcept
{
return ref_.loadRelaxed() > 1;
}
qsizetype detachCapacity(qsizetype newSize) const noexcept
{
if (flags & CapacityReserved && newSize < constAllocatedCapacity())
return constAllocatedCapacity();
return newSize;
}
Q_DECL_MALLOCLIKE
static Q_CORE_EXPORT void *allocate(QArrayData **pdata, qsizetype objectSize, qsizetype alignment,
qsizetype capacity, AllocationOption option = QArrayData::KeepSize) noexcept;
Q_DECL_MALLOCLIKE
static Q_CORE_EXPORT void *allocate1(QArrayData **pdata, qsizetype capacity,
AllocationOption option = QArrayData::KeepSize) noexcept;
Q_DECL_MALLOCLIKE
static Q_CORE_EXPORT void *allocate2(QArrayData **pdata, qsizetype capacity,
AllocationOption option = QArrayData::KeepSize) noexcept;
[[nodiscard]] static Q_CORE_EXPORT std::pair<QArrayData *, void *> reallocateUnaligned(QArrayData *data, void *dataPointer,
qsizetype objectSize, qsizetype newCapacity, AllocationOption option) noexcept;
static Q_CORE_EXPORT void deallocate(QArrayData *data, qsizetype objectSize,
qsizetype alignment) noexcept;
};
Q_DECLARE_OPERATORS_FOR_FLAGS(QArrayData::ArrayOptions)
namespace QtPrivate {
// QArrayData with strictest alignment requirements supported by malloc()
#if defined(Q_PROCESSOR_X86_32) && defined(Q_CC_GNU)
// GCC's definition is incorrect since GCC 8 (commit r240248 in SVN; commit
// 63012d9a57edc950c5f30242d1e19318b5708060 in Git). This is applied to all
// GCC-like compilers in case they decide to follow GCC's lead in being wrong.
constexpr size_t MaxPrimitiveAlignment = 2 * sizeof(void *);
#else
constexpr size_t MaxPrimitiveAlignment = alignof(std::max_align_t);
#endif
struct alignas(MaxPrimitiveAlignment) AlignedQArrayData : QArrayData
{
};
}
template <class T>
struct QTypedArrayData
: QArrayData
{
struct AlignmentDummy { QtPrivate::AlignedQArrayData header; T data; };
[[nodiscard]] static std::pair<QTypedArrayData *, T *> allocate(qsizetype capacity, AllocationOption option = QArrayData::KeepSize)
{
static_assert(sizeof(QTypedArrayData) == sizeof(QArrayData));
QArrayData *d;
void *result;
if constexpr (sizeof(T) == 1) {
// necessarily, alignof(T) == 1
result = allocate1(&d, capacity, option);
} else if constexpr (sizeof(T) == 2) {
// alignof(T) may be 1, but that makes no difference
result = allocate2(&d, capacity, option);
} else {
result = QArrayData::allocate(&d, sizeof(T), alignof(AlignmentDummy), capacity, option);
}
#if __has_builtin(__builtin_assume_aligned)
// and yet we do offer results that have stricter alignment
result = __builtin_assume_aligned(result, Q_ALIGNOF(AlignmentDummy));
#endif
return {static_cast<QTypedArrayData *>(d), static_cast<T *>(result)};
}
static std::pair<QTypedArrayData *, T *>
reallocateUnaligned(QTypedArrayData *data, T *dataPointer, qsizetype capacity, AllocationOption option)
{
static_assert(sizeof(QTypedArrayData) == sizeof(QArrayData));
std::pair<QArrayData *, void *> pair =
QArrayData::reallocateUnaligned(data, dataPointer, sizeof(T), capacity, option);
return {static_cast<QTypedArrayData *>(pair.first), static_cast<T *>(pair.second)};
}
static void deallocate(QArrayData *data) noexcept
{
static_assert(sizeof(QTypedArrayData) == sizeof(QArrayData));
QArrayData::deallocate(data, sizeof(T), alignof(AlignmentDummy));
}
static T *dataStart(QArrayData *data, qsizetype alignment) noexcept
{
// Alignment is a power of two
Q_ASSERT(alignment >= qsizetype(alignof(QArrayData)) && !(alignment & (alignment - 1)));
void *start = reinterpret_cast<void *>(
(quintptr(data) + sizeof(QArrayData) + alignment - 1) & ~(alignment - 1));
return static_cast<T *>(start);
}
constexpr static qsizetype max_size() noexcept
{
// -1 to deal with the pointer one-past-the-end
return (QtPrivate::MaxAllocSize - sizeof(QtPrivate::AlignedQArrayData) - 1) / sizeof(T);
}
};
namespace QtPrivate {
struct Q_CORE_EXPORT QContainerImplHelper
{
enum CutResult { Null, Empty, Full, Subset };
static constexpr CutResult mid(qsizetype originalLength, qsizetype *_position, qsizetype *_length)
{
qsizetype &position = *_position;
qsizetype &length = *_length;
if (position > originalLength) {
position = 0;
length = 0;
return Null;
}
if (position < 0) {
if (length < 0 || length + position >= originalLength) {
position = 0;
length = originalLength;
return Full;
}
if (length + position <= 0) {
position = length = 0;
return Null;
}
length += position;
position = 0;
} else if (size_t(length) > size_t(originalLength - position)) {
length = originalLength - position;
}
if (position == 0 && length == originalLength)
return Full;
return length > 0 ? Subset : Empty;
}
};
}
#undef Q_DECL_MALLOCLIKE
QT_END_NAMESPACE
#endif // include guard
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