quniquehandle_p.h

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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 QUNIQUEHANDLE_P_H
#define QUNIQUEHANDLE_P_H
 
//
//  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.
//
 
#include <QtCore/qtconfigmacros.h>
#include <QtCore/qassert.h>
 
#include <memory>
 
QT_BEGIN_NAMESPACE
 
// clang-format off
 
template <typename HandleTraits>
class QUniqueHandle
{
public:
    using Type = typename HandleTraits::Type;
 
    QUniqueHandle() = default;
 
    explicit QUniqueHandle(const Type &handle) noexcept
        : m_handle{ handle }
    {}
 
    QUniqueHandle(QUniqueHandle &&other) noexcept
        : m_handle{ other.release() }
    {}
 
    ~QUniqueHandle() noexcept
    {
        close();
    }
 
    QUniqueHandle& operator=(QUniqueHandle &&rhs) noexcept
    {
        if (this != std::addressof(rhs))
            reset(rhs.release());
 
        return *this;
    }
 
    QUniqueHandle(const QUniqueHandle &) = delete;
    QUniqueHandle &operator=(const QUniqueHandle &) = delete;
 
 
    [[nodiscard]] bool isValid() const noexcept
    {
        return m_handle != HandleTraits::invalidValue();
    }
 
    [[nodiscard]] explicit operator bool() const noexcept
    {
        return isValid();
    }
 
    [[nodiscard]] Type get() const noexcept
    {
        return m_handle;
    }
 
    void reset(const Type& handle) noexcept
    {
        if (handle == m_handle)
            return;
 
        close();
        m_handle = handle;
    }
 
    [[nodiscard]] Type release() noexcept
    {
        Type handle = m_handle;
        m_handle = HandleTraits::invalidValue();
        return handle;
    }
 
    [[nodiscard]] Type *operator&() noexcept  // NOLINT(google-runtime-operator)
    {
        Q_ASSERT(!isValid());
        return &m_handle;
    }
 
    void close() noexcept
    {
        if (!isValid())
            return;
 
        const bool success = HandleTraits::close(m_handle);
        Q_ASSERT(success);
 
        m_handle = HandleTraits::invalidValue();
    }
 
    [[nodiscard]] friend bool operator==(const QUniqueHandle &lhs, const QUniqueHandle &rhs) noexcept
    {
        return lhs.get() == rhs.get();
    }
 
    [[nodiscard]] friend bool operator!=(const QUniqueHandle &lhs, const QUniqueHandle &rhs) noexcept
    {
        return lhs.get() != rhs.get();
    }
 
    [[nodiscard]] friend bool operator<(const QUniqueHandle &lhs, const QUniqueHandle &rhs) noexcept
    {
        return lhs.get() < rhs.get();
    }
 
    [[nodiscard]] friend bool operator<=(const QUniqueHandle &lhs, const QUniqueHandle &rhs) noexcept
    {
        return lhs.get() <= rhs.get();
    }
 
    [[nodiscard]] friend bool operator>(const QUniqueHandle &lhs, const QUniqueHandle &rhs) noexcept
    {
        return lhs.get() > rhs.get();
    }
 
    [[nodiscard]] friend bool operator>=(const QUniqueHandle &lhs, const QUniqueHandle &rhs) noexcept
    {
        return lhs.get() >= rhs.get();
    }
 
private:
    Type m_handle{ HandleTraits::invalidValue() };
};
 
// clang-format on
 
QT_END_NAMESPACE
 
#endif