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// Copyright (C) 2023 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#ifndef QTCORE_QSMALLBYTEARRAY_P_H
#define QTCORE_QSMALLBYTEARRAY_P_H
#include <QtCore/qbytearrayview.h>
#include <QtCore/qtconfigmacros.h>
#include <QtCore/qtypes.h>
#include <array>
#include <limits>
//
// W A R N I N G
// -------------
//
// This file is not part of the Qt API. It exists purely as an
// implementation detail. This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
QT_BEGIN_NAMESPACE
//
// A fixed-max-size version of QByteArray. Since it's fixed-max-size, it's
// never going to the heap. Can contain a maximum of 256 octets. Never
// NUL-terminates on its own.
//
template <size_t N>
class QSmallByteArray
{
std::array<quint8, N> m_data;
static_assert(N <= (std::numeric_limits<std::uint8_t>::max)());
quint8 m_size = 0;
public:
QSmallByteArray() = default;
// all compiler-generated SMFs are ok!
template <std::size_t M, std::enable_if_t<M < N, bool> = true> // M == N is for copy ctor!
constexpr QSmallByteArray(const QSmallByteArray<M> &other) noexcept
{
assign(other);
}
template <std::size_t M, std::enable_if_t<M < N, bool> = true> // M == N is for copy-assignment op!
constexpr QSmallByteArray &operator=(const QSmallByteArray<M> &other) noexcept
{
assign(other);
return *this;
}
template <typename Container> // ### underconstrained
constexpr void assign(const Container &c)
{
const size_t otherSize = size_t(std::size(c));
Q_ASSERT(otherSize < N);
memcpy(data(), std::data(c), otherSize);
m_size = quint8(otherSize);
}
constexpr quint8 *data() noexcept { return m_data.data(); }
constexpr const quint8 *data() const noexcept { return m_data.data(); }
constexpr qsizetype size() const noexcept { return qsizetype{m_size}; }
constexpr quint8 &operator[](qsizetype n)
{
Q_ASSERT(n < size());
return data()[n];
}
constexpr const quint8 &operator[](qsizetype n) const
{
Q_ASSERT(n < size());
return data()[n];
}
constexpr bool isEmpty() const noexcept { return size() == 0; }
constexpr void clear() noexcept { m_size = 0; }
constexpr void resizeForOverwrite(qsizetype s)
{
Q_ASSERT(s >= 0);
Q_ASSERT(size_t(s) <= N);
m_size = std::uint8_t(s);
}
constexpr void resize(qsizetype s, quint8 v)
{
const auto oldSize = size();
resizeForOverwrite(s);
if (s > oldSize)
memset(data() + oldSize, v, size() - oldSize);
}
constexpr QByteArrayView toByteArrayView() const noexcept
{ return *this; }
constexpr auto begin() noexcept { return data(); }
constexpr auto begin() const noexcept { return data(); }
constexpr auto cbegin() const noexcept { return begin(); }
constexpr auto end() noexcept { return data() + size(); }
constexpr auto end() const noexcept { return data() + size(); }
constexpr auto cend() const noexcept { return end(); }
};
QT_END_NAMESPACE
#endif // QTCORE_QSMALLBYTEARRAY_P_H
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