/****************************************************************************
**
** Copyright (C) 2020 The Qt Company Ltd.
** Copyright (C) 2019 Intel Corporation.
** Copyright (C) 2019 Mail.ru Group.
** Copyright (C) 2020 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Marc Mutz <marc.mutz@kdab.com>
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
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** $QT_END_LICENSE$
**
****************************************************************************/

#ifndef QSTRING_H
#define QSTRING_H

#if defined(QT_NO_CAST_FROM_ASCII) && defined(QT_RESTRICTED_CAST_FROM_ASCII)
#error QT_NO_CAST_FROM_ASCII and QT_RESTRICTED_CAST_FROM_ASCII must not be defined at the same time
#endif

#include <QtCore/qchar.h>
#include <QtCore/qbytearray.h>
#include <QtCore/qarraydata.h>
#include <QtCore/qnamespace.h>
#include <QtCore/qstringliteral.h>
#include <QtCore/qstringalgorithms.h>
#include <QtCore/qanystringview.h>
#include <QtCore/qstringtokenizer.h>

#include <string>
#include <iterator>

#include <stdarg.h>

#ifdef truncate
#error qstring.h must be included before any header file that defines truncate
#endif

#if defined(Q_OS_DARWIN) || defined(Q_QDOC)
Q_FORWARD_DECLARE_CF_TYPE(CFString);
Q_FORWARD_DECLARE_OBJC_CLASS(NSString);
#endif

QT_BEGIN_NAMESPACE

class QRegularExpression;
class QRegularExpressionMatch;
class QString;

namespace QtPrivate {
template <bool...B> class BoolList;
}

// QStringAlgorithms inline functions:

int QtPrivate::compareStringsUtf8(const char *lhs, qsizetype lhss, QStringView rhs, Qt::CaseSensitivity cs) noexcept
{ return compareStrings(QUtf8StringView(lhs, lhss), rhs, cs); }


class QLatin1String
{
public:
    constexpr inline QLatin1String() noexcept : m_size(0), m_data(nullptr) {}
    constexpr inline explicit QLatin1String(const char *s) noexcept : m_size(s ? qsizetype(strlen(s)) : 0), m_data(s) {}
    constexpr explicit QLatin1String(const char *f, const char *l)
        : QLatin1String(f, qsizetype(l - f)) {}
    constexpr inline explicit QLatin1String(const char *s, qsizetype sz) noexcept : m_size(sz), m_data(s) {}
    explicit QLatin1String(const QByteArray &s) noexcept : m_size(qsizetype(qstrnlen(s.constData(), s.size()))), m_data(s.constData()) {}

    inline QString toString() const;

    constexpr const char *latin1() const noexcept { return m_data; }
    constexpr qsizetype size() const noexcept { return m_size; }
    constexpr const char *data() const noexcept { return m_data; }

    constexpr bool isNull() const noexcept { return !data(); }
    constexpr bool isEmpty() const noexcept { return !size(); }

    template <typename...Args>
    Q_REQUIRED_RESULT inline QString arg(Args &&...args) const;

    [[nodiscard]] constexpr QLatin1Char at(qsizetype i) const
    { return Q_ASSERT(i >= 0), Q_ASSERT(i < size()), QLatin1Char(m_data[i]); }
    [[nodiscard]] constexpr QLatin1Char operator[](qsizetype i) const { return at(i); }

    Q_REQUIRED_RESULT constexpr QLatin1Char front() const { return at(0); }
    Q_REQUIRED_RESULT constexpr QLatin1Char back() const { return at(size() - 1); }

    Q_REQUIRED_RESULT int compare(QStringView other, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return QtPrivate::compareStrings(*this, other, cs); }
    Q_REQUIRED_RESULT int compare(QLatin1String other, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return QtPrivate::compareStrings(*this, other, cs); }
    Q_REQUIRED_RESULT constexpr int compare(QChar c) const noexcept
    { return isEmpty() || front() == c ? size() - 1 : uchar(m_data[0]) - c.unicode() ; }
    Q_REQUIRED_RESULT int compare(QChar c, Qt::CaseSensitivity cs) const noexcept
    { return QtPrivate::compareStrings(*this, QStringView(&c, 1), cs); }

    Q_REQUIRED_RESULT bool startsWith(QStringView s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return QtPrivate::startsWith(*this, s, cs); }
    Q_REQUIRED_RESULT bool startsWith(QLatin1String s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return QtPrivate::startsWith(*this, s, cs); }
    Q_REQUIRED_RESULT constexpr bool startsWith(QChar c) const noexcept
    { return !isEmpty() && front() == c; }
    Q_REQUIRED_RESULT inline bool startsWith(QChar c, Qt::CaseSensitivity cs) const noexcept
    { return QtPrivate::startsWith(*this, QStringView(&c, 1), cs); }

    Q_REQUIRED_RESULT bool endsWith(QStringView s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return QtPrivate::endsWith(*this, s, cs); }
    Q_REQUIRED_RESULT bool endsWith(QLatin1String s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return QtPrivate::endsWith(*this, s, cs); }
    Q_REQUIRED_RESULT constexpr bool endsWith(QChar c) const noexcept
    { return !isEmpty() && back() == c; }
    Q_REQUIRED_RESULT inline bool endsWith(QChar c, Qt::CaseSensitivity cs) const noexcept
    { return QtPrivate::endsWith(*this, QStringView(&c, 1), cs); }

    [[nodiscard]] qsizetype indexOf(QStringView s, qsizetype from = 0, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return QtPrivate::findString(*this, from, s, cs); }
    [[nodiscard]] qsizetype indexOf(QLatin1String s, qsizetype from = 0, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return QtPrivate::findString(*this, from, s, cs); }
    [[nodiscard]] qsizetype indexOf(QChar c, qsizetype from = 0, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return QtPrivate::findString(*this, from, QStringView(&c, 1), cs); }

    Q_REQUIRED_RESULT bool contains(QStringView s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return indexOf(s, 0, cs) != -1; }
    Q_REQUIRED_RESULT bool contains(QLatin1String s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return indexOf(s, 0, cs) != -1; }
    Q_REQUIRED_RESULT inline bool contains(QChar c, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return indexOf(QStringView(&c, 1), 0, cs) != -1; }

    [[nodiscard]] qsizetype lastIndexOf(QStringView s, qsizetype from = -1, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return QtPrivate::lastIndexOf(*this, from, s, cs); }
    [[nodiscard]] qsizetype lastIndexOf(QLatin1String s, qsizetype from = -1, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return QtPrivate::lastIndexOf(*this, from, s, cs); }
    [[nodiscard]] qsizetype lastIndexOf(QChar c, qsizetype from = -1, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return QtPrivate::lastIndexOf(*this, from, QStringView(&c, 1), cs); }

    using value_type = const char;
    using reference = value_type&;
    using const_reference = reference;
    using iterator = value_type*;
    using const_iterator = iterator;
    using difference_type = qsizetype; // violates Container concept requirements
    using size_type = qsizetype;       // violates Container concept requirements

    constexpr const_iterator begin() const noexcept { return data(); }
    constexpr const_iterator cbegin() const noexcept { return data(); }
    constexpr const_iterator end() const noexcept { return data() + size(); }
    constexpr const_iterator cend() const noexcept { return data() + size(); }

    using reverse_iterator = std::reverse_iterator<iterator>;
    using const_reverse_iterator = reverse_iterator;

    const_reverse_iterator rbegin() const noexcept { return const_reverse_iterator(end()); }
    const_reverse_iterator crbegin() const noexcept { return const_reverse_iterator(end()); }
    const_reverse_iterator rend() const noexcept { return const_reverse_iterator(begin()); }
    const_reverse_iterator crend() const noexcept { return const_reverse_iterator(begin()); }

    [[nodiscard]] constexpr QLatin1String mid(qsizetype pos, qsizetype n = -1) const
    {
        using namespace QtPrivate;
        auto result = QContainerImplHelper::mid(size(), &pos, &n);
        return result == QContainerImplHelper::Null ? QLatin1String() : QLatin1String(m_data + pos, n);
    }
    [[nodiscard]] constexpr QLatin1String left(qsizetype n) const
    {
        if (size_t(n) >= size_t(size()))
            n = size();
        return QLatin1String(m_data, n);
    }
    [[nodiscard]] constexpr QLatin1String right(qsizetype n) const
    {
        if (size_t(n) >= size_t(size()))
            n = size();
        return QLatin1String(m_data + m_size - n, n);
    }

    [[nodiscard]] constexpr QLatin1String sliced(qsizetype pos) const
    { verify(pos); return QLatin1String(m_data + pos, m_size - pos); }
    [[nodiscard]] constexpr QLatin1String sliced(qsizetype pos, qsizetype n) const
    { verify(pos, n); return QLatin1String(m_data + pos, n); }
    [[nodiscard]] constexpr QLatin1String first(qsizetype n) const
    { verify(n); return QLatin1String(m_data, n); }
    [[nodiscard]] constexpr QLatin1String last(qsizetype n) const
    { verify(n); return QLatin1String(m_data + size() - n, n); }
    [[nodiscard]] constexpr QLatin1String chopped(qsizetype n) const
    { verify(n); return QLatin1String(m_data, size() - n); }

    constexpr void chop(qsizetype n)
    { verify(n); m_size -= n; }
    constexpr void truncate(qsizetype n)
    { verify(n); m_size = n; }

    Q_REQUIRED_RESULT QLatin1String trimmed() const noexcept { return QtPrivate::trimmed(*this); }

    template <typename Needle, typename...Flags>
    Q_REQUIRED_RESULT inline constexpr auto tokenize(Needle &&needle, Flags...flags) const
        noexcept(noexcept(qTokenize(std::declval<const QLatin1String &>(), std::forward<Needle>(needle), flags...)))
            -> decltype(qTokenize(*this, std::forward<Needle>(needle), flags...))
    { return qTokenize(*this, std::forward<Needle>(needle), flags...); }

    inline bool operator==(const QString &s) const noexcept;
    inline bool operator!=(const QString &s) const noexcept;
    inline bool operator>(const QString &s) const noexcept;
    inline bool operator<(const QString &s) const noexcept;
    inline bool operator>=(const QString &s) const noexcept;
    inline bool operator<=(const QString &s) const noexcept;

#if !defined(QT_NO_CAST_FROM_ASCII) && !defined(QT_RESTRICTED_CAST_FROM_ASCII)
    inline QT_ASCII_CAST_WARN bool operator==(const char *s) const;
    inline QT_ASCII_CAST_WARN bool operator!=(const char *s) const;
    inline QT_ASCII_CAST_WARN bool operator<(const char *s) const;
    inline QT_ASCII_CAST_WARN bool operator>(const char *s) const;
    inline QT_ASCII_CAST_WARN bool operator<=(const char *s) const;
    inline QT_ASCII_CAST_WARN bool operator>=(const char *s) const;

    inline QT_ASCII_CAST_WARN bool operator==(const QByteArray &s) const;
    inline QT_ASCII_CAST_WARN bool operator!=(const QByteArray &s) const;
    inline QT_ASCII_CAST_WARN bool operator<(const QByteArray &s) const;
    inline QT_ASCII_CAST_WARN bool operator>(const QByteArray &s) const;
    inline QT_ASCII_CAST_WARN bool operator<=(const QByteArray &s) const;
    inline QT_ASCII_CAST_WARN bool operator>=(const QByteArray &s) const;
#endif // !defined(QT_NO_CAST_FROM_ASCII) && !defined(QT_RESTRICTED_CAST_FROM_ASCII)

private:
    Q_ALWAYS_INLINE constexpr void verify(qsizetype pos, qsizetype n = 0) const
    {
        Q_ASSERT(pos >= 0);
        Q_ASSERT(pos <= size());
        Q_ASSERT(n >= 0);
        Q_ASSERT(n <= size() - pos);
    }
    qsizetype m_size;
    const char *m_data;
};
Q_DECLARE_TYPEINFO(QLatin1String, Q_MOVABLE_TYPE);

// Qt 4.x compatibility

//
// QLatin1String inline implementations
//
constexpr bool QtPrivate::isLatin1(QLatin1String) noexcept
{ return true; }

//
// QStringView members that require QLatin1String:
//
int QStringView::compare(QLatin1String s, Qt::CaseSensitivity cs) const noexcept
{ return QtPrivate::compareStrings(*this, s, cs); }
bool QStringView::startsWith(QLatin1String s, Qt::CaseSensitivity cs) const noexcept
{ return QtPrivate::startsWith(*this, s, cs); }
bool QStringView::endsWith(QLatin1String s, Qt::CaseSensitivity cs) const noexcept
{ return QtPrivate::endsWith(*this, s, cs); }
qsizetype QStringView::indexOf(QLatin1String s, qsizetype from, Qt::CaseSensitivity cs) const noexcept
{ return QtPrivate::findString(*this, from, s, cs); }
bool QStringView::contains(QLatin1String s, Qt::CaseSensitivity cs) const noexcept
{ return indexOf(s, 0, cs) != qsizetype(-1); }
qsizetype QStringView::lastIndexOf(QLatin1String s, qsizetype from, Qt::CaseSensitivity cs) const noexcept
{ return QtPrivate::lastIndexOf(*this, from, s, cs); }

//
// QAnyStringView members that require QLatin1String
//

constexpr QAnyStringView::QAnyStringView(QLatin1String str) noexcept
    : m_data{str.data()}, m_size{size_t(str.size()) | Tag::Latin1} {}

constexpr QLatin1String QAnyStringView::asLatin1StringView() const
{
    Q_ASSERT(isLatin1());
    return QLatin1String{m_data_utf8, int(size())};
}

template <typename Visitor>
constexpr decltype(auto) QAnyStringView::visit(Visitor &&v) const
{
    if (isUtf16())
        return std::forward<Visitor>(v)(asStringView());
    else if (isLatin1())
        return std::forward<Visitor>(v)(asLatin1StringView());
    else
        return std::forward<Visitor>(v)(asUtf8StringView());
}

//
// QAnyStringView members that require QAnyStringView::visit()
//

constexpr QChar QAnyStringView::front() const
{
    return visit([] (auto that) { return QAnyStringView::toQChar(that.front()); });
}
constexpr QChar QAnyStringView::back() const
{
    return visit([] (auto that) { return QAnyStringView::toQChar(that.back()); });
}


class Q_CORE_EXPORT QString
{
    typedef QTypedArrayData<char16_t> Data;
public:
    typedef QStringPrivate DataPointer;

    inline constexpr QString() noexcept;
    explicit QString(const QChar *unicode, qsizetype size = -1);
    QString(QChar c);
    QString(qsizetype size, QChar c);
    inline QString(QLatin1String latin1);
    inline QString(const QString &) noexcept;
    inline ~QString();
    QString &operator=(QChar c);
    QString &operator=(const QString &) noexcept;
    QString &operator=(QLatin1String latin1);
    inline QString(QString &&other) noexcept
    { qSwap(d, other.d); }
    inline QString &operator=(QString &&other) noexcept
    { qSwap(d, other.d); return *this; }
    inline void swap(QString &other) noexcept { qSwap(d, other.d); }
    inline qsizetype size() const { return d.size; }
    inline qsizetype count() const { return d.size; }
    inline qsizetype length() const { return d.size; }
    inline bool isEmpty() const;
    void resize(qsizetype size);
    void resize(qsizetype size, QChar fillChar);

    QString &fill(QChar c, qsizetype size = -1);
    void truncate(qsizetype pos);
    void chop(qsizetype n);

    inline qsizetype capacity() const;
    inline void reserve(qsizetype size);
    inline void squeeze();

    inline const QChar *unicode() const;
    inline QChar *data();
    inline const QChar *data() const;
    inline const QChar *constData() const;

    inline void detach();
    inline bool isDetached() const;
    inline bool isSharedWith(const QString &other) const { return d.isSharedWith(other.d); }
    void clear();

    inline const QChar at(qsizetype i) const;
    const QChar operator[](qsizetype i) const;
    Q_REQUIRED_RESULT QChar &operator[](qsizetype i);

    Q_REQUIRED_RESULT inline QChar front() const { return at(0); }
    Q_REQUIRED_RESULT inline QChar &front();
    Q_REQUIRED_RESULT inline QChar back() const { return at(size() - 1); }
    Q_REQUIRED_RESULT inline QChar &back();

    Q_REQUIRED_RESULT QString arg(qlonglong a, int fieldwidth=0, int base=10,
                QChar fillChar = QLatin1Char(' ')) const;
    Q_REQUIRED_RESULT QString arg(qulonglong a, int fieldwidth=0, int base=10,
                QChar fillChar = QLatin1Char(' ')) const;
    Q_REQUIRED_RESULT QString arg(long a, int fieldwidth=0, int base=10,
                QChar fillChar = QLatin1Char(' ')) const;
    Q_REQUIRED_RESULT QString arg(ulong a, int fieldwidth=0, int base=10,
                QChar fillChar = QLatin1Char(' ')) const;
    Q_REQUIRED_RESULT QString arg(int a, int fieldWidth = 0, int base = 10,
                QChar fillChar = QLatin1Char(' ')) const;
    Q_REQUIRED_RESULT QString arg(uint a, int fieldWidth = 0, int base = 10,
                QChar fillChar = QLatin1Char(' ')) const;
    Q_REQUIRED_RESULT QString arg(short a, int fieldWidth = 0, int base = 10,
                QChar fillChar = QLatin1Char(' ')) const;
    Q_REQUIRED_RESULT QString arg(ushort a, int fieldWidth = 0, int base = 10,
                QChar fillChar = QLatin1Char(' ')) const;
    Q_REQUIRED_RESULT QString arg(double a, int fieldWidth = 0, char fmt = 'g', int prec = -1,
                QChar fillChar = QLatin1Char(' ')) const;
    Q_REQUIRED_RESULT QString arg(char a, int fieldWidth = 0,
                QChar fillChar = QLatin1Char(' ')) const;
    Q_REQUIRED_RESULT QString arg(QChar a, int fieldWidth = 0,
                QChar fillChar = QLatin1Char(' ')) const;
#if QT_STRINGVIEW_LEVEL < 2
    Q_REQUIRED_RESULT QString arg(const QString &a, int fieldWidth = 0,
                QChar fillChar = QLatin1Char(' ')) const;
#endif
    Q_REQUIRED_RESULT QString arg(QStringView a, int fieldWidth = 0,
                QChar fillChar = QLatin1Char(' ')) const;
    Q_REQUIRED_RESULT QString arg(QLatin1String a, int fieldWidth = 0,
                QChar fillChar = QLatin1Char(' ')) const;
private:
    template <typename T>
    struct is_convertible_to_view_or_qstring_helper
        : std::integral_constant<bool,
            std::is_convertible<T, QString>::value ||
            std::is_convertible<T, QStringView>::value ||
            std::is_convertible<T, QLatin1String>::value> {};
    template <typename T>
    struct is_convertible_to_view_or_qstring
        : is_convertible_to_view_or_qstring_helper<typename std::decay<T>::type> {};
public:
    template <typename...Args>
    Q_REQUIRED_RESULT
#ifdef Q_CLANG_QDOC
    QString
#else
    typename std::enable_if<
        sizeof...(Args) >= 2 && std::is_same<
            QtPrivate::BoolList<is_convertible_to_view_or_qstring<Args>::value..., true>,
            QtPrivate::BoolList<true, is_convertible_to_view_or_qstring<Args>::value...>
        >::value,
        QString
    >::type
#endif
    arg(Args &&...args) const
    { return qToStringViewIgnoringNull(*this).arg(std::forward<Args>(args)...); }

    static QString vasprintf(const char *format, va_list ap) Q_ATTRIBUTE_FORMAT_PRINTF(1, 0);
    static QString asprintf(const char *format, ...) Q_ATTRIBUTE_FORMAT_PRINTF(1, 2);

    qsizetype indexOf(QChar c, qsizetype from = 0, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
    qsizetype indexOf(QLatin1String s, qsizetype from = 0, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
#if QT_STRINGVIEW_LEVEL < 2
    qsizetype indexOf(const QString &s, qsizetype from = 0, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
#endif
    Q_REQUIRED_RESULT qsizetype indexOf(QStringView s, qsizetype from = 0, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return QtPrivate::findString(*this, from, s, cs); }
    qsizetype lastIndexOf(QChar c, qsizetype from = -1, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
    qsizetype lastIndexOf(QLatin1String s, qsizetype from = -1, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
#if QT_STRINGVIEW_LEVEL < 2
    qsizetype lastIndexOf(const QString &s, qsizetype from = -1, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
#endif

    Q_REQUIRED_RESULT qsizetype lastIndexOf(QStringView s, qsizetype from = -1, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return QtPrivate::lastIndexOf(*this, from, s, cs); }

    inline bool contains(QChar c, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
#if QT_STRINGVIEW_LEVEL < 2
    inline bool contains(const QString &s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
#endif
    inline bool contains(QLatin1String s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
    inline bool contains(QStringView s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept;
    qsizetype count(QChar c, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
    qsizetype count(const QString &s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
    qsizetype count(QStringView s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;

#if QT_CONFIG(regularexpression)
    qsizetype indexOf(const QRegularExpression &re, qsizetype from = 0,
                      QRegularExpressionMatch *rmatch = nullptr) const;
    qsizetype lastIndexOf(const QRegularExpression &re, qsizetype from = -1,
                          QRegularExpressionMatch *rmatch = nullptr) const;
    bool contains(const QRegularExpression &re, QRegularExpressionMatch *rmatch = nullptr) const;
    qsizetype count(const QRegularExpression &re) const;
#endif

    enum SectionFlag {
        SectionDefault             = 0x00,
        SectionSkipEmpty           = 0x01,
        SectionIncludeLeadingSep   = 0x02,
        SectionIncludeTrailingSep  = 0x04,
        SectionCaseInsensitiveSeps = 0x08
    };
    Q_DECLARE_FLAGS(SectionFlags, SectionFlag)

    QString section(QChar sep, qsizetype start, qsizetype end = -1, SectionFlags flags = SectionDefault) const;
    QString section(const QString &in_sep, qsizetype start, qsizetype end = -1, SectionFlags flags = SectionDefault) const;
#if QT_CONFIG(regularexpression)
    QString section(const QRegularExpression &re, qsizetype start, qsizetype end = -1, SectionFlags flags = SectionDefault) const;
#endif
    Q_REQUIRED_RESULT QString left(qsizetype n) const;
    Q_REQUIRED_RESULT QString right(qsizetype n) const;
    Q_REQUIRED_RESULT QString mid(qsizetype position, qsizetype n = -1) const;

    Q_REQUIRED_RESULT QString first(qsizetype n) const
    { Q_ASSERT(n >= 0); Q_ASSERT(n <= size()); return QString(data(), n); }
    Q_REQUIRED_RESULT QString last(qsizetype n) const
    { Q_ASSERT(n >= 0); Q_ASSERT(n <= size()); return QString(data() + size() - n, n); }
    Q_REQUIRED_RESULT QString sliced(qsizetype pos) const
    { Q_ASSERT(pos >= 0); Q_ASSERT(pos <= size()); return QString(data() + pos, size() - pos); }
    Q_REQUIRED_RESULT QString sliced(qsizetype pos, qsizetype n) const
    { Q_ASSERT(pos >= 0); Q_ASSERT(n >= 0); Q_ASSERT(size_t(pos) + size_t(n) <= size_t(size())); return QString(data() + pos, n); }
    Q_REQUIRED_RESULT QString chopped(qsizetype n) const
    { Q_ASSERT(n >= 0); Q_ASSERT(n <= size()); return first(size() - n); }


#if QT_STRINGVIEW_LEVEL < 2
    bool startsWith(const QString &s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
#endif
    Q_REQUIRED_RESULT bool startsWith(QStringView s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return QtPrivate::startsWith(*this, s, cs); }
    bool startsWith(QLatin1String s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
    bool startsWith(QChar c, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;

#if QT_STRINGVIEW_LEVEL < 2
    bool endsWith(const QString &s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
#endif
    Q_REQUIRED_RESULT bool endsWith(QStringView s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return QtPrivate::endsWith(*this, s, cs); }
    bool endsWith(QLatin1String s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
    bool endsWith(QChar c, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;

    bool isUpper() const;
    bool isLower() const;

    Q_REQUIRED_RESULT QString leftJustified(qsizetype width, QChar fill = QLatin1Char(' '), bool trunc = false) const;
    Q_REQUIRED_RESULT QString rightJustified(qsizetype width, QChar fill = QLatin1Char(' '), bool trunc = false) const;

#if !defined(Q_CLANG_QDOC)
    Q_REQUIRED_RESULT QString toLower() const &
    { return toLower_helper(*this); }
    Q_REQUIRED_RESULT QString toLower() &&
    { return toLower_helper(*this); }
    Q_REQUIRED_RESULT QString toUpper() const &
    { return toUpper_helper(*this); }
    Q_REQUIRED_RESULT QString toUpper() &&
    { return toUpper_helper(*this); }
    Q_REQUIRED_RESULT QString toCaseFolded() const &
    { return toCaseFolded_helper(*this); }
    Q_REQUIRED_RESULT QString toCaseFolded() &&
    { return toCaseFolded_helper(*this); }
    Q_REQUIRED_RESULT QString trimmed() const &
    { return trimmed_helper(*this); }
    Q_REQUIRED_RESULT QString trimmed() &&
    { return trimmed_helper(*this); }
    Q_REQUIRED_RESULT QString simplified() const &
    { return simplified_helper(*this); }
    Q_REQUIRED_RESULT QString simplified() &&
    { return simplified_helper(*this); }
#else
    Q_REQUIRED_RESULT QString toLower() const;
    Q_REQUIRED_RESULT QString toUpper() const;
    Q_REQUIRED_RESULT QString toCaseFolded() const;
    Q_REQUIRED_RESULT QString trimmed() const;
    Q_REQUIRED_RESULT QString simplified() const;
#endif
    Q_REQUIRED_RESULT QString toHtmlEscaped() const;

    QString &insert(qsizetype i, QChar c);
    QString &insert(qsizetype i, const QChar *uc, qsizetype len);
#if QT_STRINGVIEW_LEVEL < 2
    inline QString &insert(qsizetype i, const QString &s) { return insert(i, s.constData(), s.length()); }
#endif
    inline QString &insert(qsizetype i, QStringView v) { return insert(i, v.data(), v.length()); }
    QString &insert(qsizetype i, QLatin1String s);

    QString &append(QChar c);
    QString &append(const QChar *uc, qsizetype len);
#if QT_STRINGVIEW_LEVEL < 2
    QString &append(const QString &s);
#endif
    inline QString &append(QStringView v) { return append(v.data(), v.length()); }
    QString &append(QLatin1String s);

    inline QString &prepend(QChar c) { return insert(0, c); }
    inline QString &prepend(const QChar *uc, qsizetype len) { return insert(0, uc, len); }
#if QT_STRINGVIEW_LEVEL < 2
    inline QString &prepend(const QString &s) { return insert(0, s); }
#endif
    inline QString &prepend(QStringView v) { return prepend(v.data(), v.length()); }
    inline QString &prepend(QLatin1String s) { return insert(0, s); }

    inline QString &operator+=(QChar c) { return append(c); }

#if QT_STRINGVIEW_LEVEL < 2
    inline QString &operator+=(const QString &s) { return append(s); }
#endif
    inline QString &operator+=(QStringView v) { return append(v); }
    inline QString &operator+=(QLatin1String s) { return append(s); }

    QString &remove(qsizetype i, qsizetype len);
    QString &remove(QChar c, Qt::CaseSensitivity cs = Qt::CaseSensitive);
    QString &remove(QLatin1String s, Qt::CaseSensitivity cs = Qt::CaseSensitive);
    QString &remove(const QString &s, Qt::CaseSensitivity cs = Qt::CaseSensitive);
    QString &replace(qsizetype i, qsizetype len, QChar after);
    QString &replace(qsizetype i, qsizetype len, const QChar *s, qsizetype slen);
    QString &replace(qsizetype i, qsizetype len, const QString &after);
    QString &replace(QChar before, QChar after, Qt::CaseSensitivity cs = Qt::CaseSensitive);
    QString &replace(const QChar *before, qsizetype blen, const QChar *after, qsizetype alen, Qt::CaseSensitivity cs = Qt::CaseSensitive);
    QString &replace(QLatin1String before, QLatin1String after, Qt::CaseSensitivity cs = Qt::CaseSensitive);
    QString &replace(QLatin1String before, const QString &after, Qt::CaseSensitivity cs = Qt::CaseSensitive);
    QString &replace(const QString &before, QLatin1String after, Qt::CaseSensitivity cs = Qt::CaseSensitive);
    QString &replace(const QString &before, const QString &after,
                     Qt::CaseSensitivity cs = Qt::CaseSensitive);
    QString &replace(QChar c, const QString &after, Qt::CaseSensitivity cs = Qt::CaseSensitive);
    QString &replace(QChar c, QLatin1String after, Qt::CaseSensitivity cs = Qt::CaseSensitive);
#if QT_CONFIG(regularexpression)
    QString &replace(const QRegularExpression &re, const QString  &after);
    inline QString &remove(const QRegularExpression &re)
    { return replace(re, QString()); }
#endif

public:
    Q_REQUIRED_RESULT
    QStringList split(const QString &sep, Qt::SplitBehavior behavior = Qt::KeepEmptyParts,
                      Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
    Q_REQUIRED_RESULT
    QStringList split(QChar sep, Qt::SplitBehavior behavior = Qt::KeepEmptyParts,
                      Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
#ifndef QT_NO_REGULAREXPRESSION
    Q_REQUIRED_RESULT
    QStringList split(const QRegularExpression &sep,
                      Qt::SplitBehavior behavior = Qt::KeepEmptyParts) const;
#endif

    template <typename Needle, typename...Flags>
    Q_REQUIRED_RESULT inline auto tokenize(Needle &&needle, Flags...flags) const &
        noexcept(noexcept(qTokenize(std::declval<const QString &>(), std::forward<Needle>(needle), flags...)))
            -> decltype(qTokenize(*this, std::forward<Needle>(needle), flags...))
    { return qTokenize(qToStringViewIgnoringNull(*this), std::forward<Needle>(needle), flags...); }

    template <typename Needle, typename...Flags>
    Q_REQUIRED_RESULT inline auto tokenize(Needle &&needle, Flags...flags) const &&
        noexcept(noexcept(qTokenize(std::declval<const QString>(), std::forward<Needle>(needle), flags...)))
            -> decltype(qTokenize(std::move(*this), std::forward<Needle>(needle), flags...))
    { return qTokenize(std::move(*this), std::forward<Needle>(needle), flags...); }

    template <typename Needle, typename...Flags>
    Q_REQUIRED_RESULT inline auto tokenize(Needle &&needle, Flags...flags) &&
        noexcept(noexcept(qTokenize(std::declval<QString>(), std::forward<Needle>(needle), flags...)))
            -> decltype(qTokenize(std::move(*this), std::forward<Needle>(needle), flags...))
    { return qTokenize(std::move(*this), std::forward<Needle>(needle), flags...); }


    enum NormalizationForm {
        NormalizationForm_D,
        NormalizationForm_C,
        NormalizationForm_KD,
        NormalizationForm_KC
    };
    Q_REQUIRED_RESULT QString normalized(NormalizationForm mode, QChar::UnicodeVersion version = QChar::Unicode_Unassigned) const;

    Q_REQUIRED_RESULT QString repeated(qsizetype times) const;

    const ushort *utf16() const;

#if defined(Q_COMPILER_REF_QUALIFIERS) && !defined(QT_COMPILING_QSTRING_COMPAT_CPP) && !defined(Q_CLANG_QDOC)
    Q_REQUIRED_RESULT QByteArray toLatin1() const &
    { return toLatin1_helper(*this); }
    Q_REQUIRED_RESULT QByteArray toLatin1() &&
    { return toLatin1_helper_inplace(*this); }
    Q_REQUIRED_RESULT QByteArray toUtf8() const &
    { return toUtf8_helper(*this); }
    Q_REQUIRED_RESULT QByteArray toUtf8() &&
    { return toUtf8_helper(*this); }
    Q_REQUIRED_RESULT QByteArray toLocal8Bit() const &
    { return toLocal8Bit_helper(isNull() ? nullptr : constData(), size()); }
    Q_REQUIRED_RESULT QByteArray toLocal8Bit() &&
    { return toLocal8Bit_helper(isNull() ? nullptr : constData(), size()); }
#else
    Q_REQUIRED_RESULT QByteArray toLatin1() const;
    Q_REQUIRED_RESULT QByteArray toUtf8() const;
    Q_REQUIRED_RESULT QByteArray toLocal8Bit() const;
#endif
    Q_REQUIRED_RESULT QList<uint> toUcs4() const;

    // note - this are all inline so we can benefit from strlen() compile time optimizations
    static inline QString fromLatin1(const char *str, qsizetype size = -1)
    {
        return QString(fromLatin1_helper(str, (str && size == -1)  ? qsizetype(strlen(str)) : size));
    }
    static inline QString fromUtf8(const char *str, qsizetype size = -1)
    {
        return fromUtf8_helper(str, (str && size == -1) ? qsizetype(strlen(str)) : size);
    }
#ifdef __cpp_char8_t
    Q_WEAK_OVERLOAD
    static inline QString fromUtf8(const char8_t *str, qsizetype size = -1)
    { return fromUtf8(reinterpret_cast<const char *>(str), int(size)); }
#endif
    static inline QString fromLocal8Bit(const char *str, qsizetype size = -1)
    {
        return fromLocal8Bit_helper(str, (str && size == -1) ? qsizetype(strlen(str)) : size);
    }
    static inline QString fromLatin1(const QByteArray &str)
    { return str.isNull() ? QString() : fromLatin1(str.data(), qstrnlen(str.constData(), str.size())); }
    static inline QString fromUtf8(const QByteArray &str)
    { return str.isNull() ? QString() : fromUtf8(str.data(), qstrnlen(str.constData(), str.size())); }
    static inline QString fromLocal8Bit(const QByteArray &str)
    { return str.isNull() ? QString() : fromLocal8Bit(str.data(), qstrnlen(str.constData(), str.size())); }
    static QString fromUtf16(const char16_t *, qsizetype size = -1);
    static QString fromUcs4(const char32_t *, qsizetype size = -1);
    static QString fromRawData(const QChar *, qsizetype size);

#if QT_DEPRECATED_SINCE(6, 0)
    QT_DEPRECATED_VERSION_X_6_0("Use char16_t* overload.")
    static QString fromUtf16(const ushort *str, qsizetype size = -1)
    { return fromUtf16(reinterpret_cast<const char16_t *>(str), size); }
    QT_DEPRECATED_VERSION_X_6_0("Use char32_t* overload.")
    static QString fromUcs4(const uint *str, qsizetype size = -1)
    { return fromUcs4(reinterpret_cast<const char32_t *>(str), size); }
#endif

    inline qsizetype toWCharArray(wchar_t *array) const;
    Q_REQUIRED_RESULT static inline QString fromWCharArray(const wchar_t *string, qsizetype size = -1);

    QString &setRawData(const QChar *unicode, qsizetype size);
    QString &setUnicode(const QChar *unicode, qsizetype size);
    inline QString &setUtf16(const ushort *utf16, qsizetype size);

#if QT_STRINGVIEW_LEVEL < 2
    int compare(const QString &s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept;
#endif
    int compare(QLatin1String other, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept;
    inline int compare(QStringView s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept;
    int compare(QChar ch, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
    { return compare(QStringView{&ch, 1}, cs); }

    static inline int compare(const QString &s1, const QString &s2,
                              Qt::CaseSensitivity cs = Qt::CaseSensitive) noexcept
    { return s1.compare(s2, cs); }

    static inline int compare(const QString &s1, QLatin1String s2,
                              Qt::CaseSensitivity cs = Qt::CaseSensitive) noexcept
    { return s1.compare(s2, cs); }
    static inline int compare(QLatin1String s1, const QString &s2,
                              Qt::CaseSensitivity cs = Qt::CaseSensitive) noexcept
    { return -s2.compare(s1, cs); }
    static int compare(const QString &s1, QStringView s2, Qt::CaseSensitivity cs = Qt::CaseSensitive) noexcept
    { return s1.compare(s2, cs); }
    static int compare(QStringView s1, const QString &s2, Qt::CaseSensitivity cs = Qt::CaseSensitive) noexcept
    { return -s2.compare(s1, cs); }

    int localeAwareCompare(const QString& s) const;
    int localeAwareCompare(QStringView s) const;
    static int localeAwareCompare(const QString& s1, const QString& s2)
    { return s1.localeAwareCompare(s2); }

    static int localeAwareCompare(QStringView s1, QStringView s2);

    short toShort(bool *ok=nullptr, int base=10) const
    { return toIntegral_helper<short>(*this, ok, base); }
    ushort toUShort(bool *ok=nullptr, int base=10) const
    { return toIntegral_helper<ushort>(*this, ok, base); }
    int toInt(bool *ok=nullptr, int base=10) const
    { return toIntegral_helper<int>(*this, ok, base); }
    uint toUInt(bool *ok=nullptr, int base=10) const
    { return toIntegral_helper<uint>(*this, ok, base); }
    long toLong(bool *ok=nullptr, int base=10) const
    { return toIntegral_helper<long>(*this, ok, base); }
    ulong toULong(bool *ok=nullptr, int base=10) const
    { return toIntegral_helper<ulong>(*this, ok, base); }
    qlonglong toLongLong(bool *ok=nullptr, int base=10) const;
    qulonglong toULongLong(bool *ok=nullptr, int base=10) const;
    float toFloat(bool *ok=nullptr) const;
    double toDouble(bool *ok=nullptr) const;

    QString &setNum(short, int base=10);
    QString &setNum(ushort, int base=10);
    QString &setNum(int, int base=10);
    QString &setNum(uint, int base=10);
    QString &setNum(long, int base=10);
    QString &setNum(ulong, int base=10);
    QString &setNum(qlonglong, int base=10);
    QString &setNum(qulonglong, int base=10);
    QString &setNum(float, char f='g', int prec=6);
    QString &setNum(double, char f='g', int prec=6);

    static QString number(int, int base=10);
    static QString number(uint, int base=10);
    static QString number(long, int base=10);
    static QString number(ulong, int base=10);
    static QString number(qlonglong, int base=10);
    static QString number(qulonglong, int base=10);
    static QString number(double, char f='g', int prec=6);

    friend Q_CORE_EXPORT bool operator==(const QString &s1, const QString &s2) noexcept;
    friend Q_CORE_EXPORT bool operator<(const QString &s1, const QString &s2) noexcept;
    friend inline bool operator>(const QString &s1, const QString &s2) noexcept { return s2 < s1; }
    friend inline bool operator!=(const QString &s1, const QString &s2) noexcept { return !(s1 == s2); }
    friend inline bool operator<=(const QString &s1, const QString &s2) noexcept { return !(s1 > s2); }
    friend inline bool operator>=(const QString &s1, const QString &s2) noexcept { return !(s1 < s2); }

    bool operator==(QLatin1String s) const noexcept;
    bool operator<(QLatin1String s) const noexcept;
    bool operator>(QLatin1String s) const noexcept;
    inline bool operator!=(QLatin1String s) const noexcept { return !operator==(s); }
    inline bool operator<=(QLatin1String s) const noexcept { return !operator>(s); }
    inline bool operator>=(QLatin1String s) const noexcept { return !operator<(s); }

    // ASCII compatibility
#if defined(QT_RESTRICTED_CAST_FROM_ASCII)
    template <qsizetype N>
    inline QString(const char (&ch)[N])
        : QString(fromUtf8(ch))
    {}
    template <qsizetype N>
    QString(char (&)[N]) = delete;
    template <qsizetype N>
    inline QString &operator=(const char (&ch)[N])
    { return (*this = fromUtf8(ch, N - 1)); }
    template <qsizetype N>
    QString &operator=(char (&)[N]) = delete;
#endif
#if !defined(QT_NO_CAST_FROM_ASCII) && !defined(QT_RESTRICTED_CAST_FROM_ASCII)
    inline QT_ASCII_CAST_WARN QString(const char *ch)
        : QString(fromUtf8(ch))
    {}
    inline QT_ASCII_CAST_WARN QString(const QByteArray &a)
        : QString(fromUtf8(a))
    {}
    inline QT_ASCII_CAST_WARN QString &operator=(const char *ch)
    { return (*this = fromUtf8(ch)); }
    inline QT_ASCII_CAST_WARN QString &operator=(const QByteArray &a)
    { return (*this = fromUtf8(a)); }

    // these are needed, so it compiles with STL support enabled
    inline QT_ASCII_CAST_WARN QString &prepend(const char *s)
    { return prepend(QString::fromUtf8(s)); }
    inline QT_ASCII_CAST_WARN QString &prepend(const QByteArray &s)
    { return prepend(QString::fromUtf8(s)); }
    inline QT_ASCII_CAST_WARN QString &append(const char *s)
    { return append(QString::fromUtf8(s)); }
    inline QT_ASCII_CAST_WARN QString &append(const QByteArray &s)
    { return append(QString::fromUtf8(s)); }
    inline QT_ASCII_CAST_WARN QString &insert(qsizetype i, const char *s)
    { return insert(i, QString::fromUtf8(s)); }
    inline QT_ASCII_CAST_WARN QString &insert(qsizetype i, const QByteArray &s)
    { return insert(i, QString::fromUtf8(s)); }
    inline QT_ASCII_CAST_WARN QString &operator+=(const char *s)
    { return append(QString::fromUtf8(s)); }
    inline QT_ASCII_CAST_WARN QString &operator+=(const QByteArray &s)
    { return append(QString::fromUtf8(s)); }

    inline QT_ASCII_CAST_WARN bool operator==(const char *s) const;
    inline QT_ASCII_CAST_WARN bool operator!=(const char *s) const;
    inline QT_ASCII_CAST_WARN bool operator<(const char *s) const;
    inline QT_ASCII_CAST_WARN bool operator<=(const char *s) const;
    inline QT_ASCII_CAST_WARN bool operator>(const char *s) const;
    inline QT_ASCII_CAST_WARN bool operator>=(const char *s) const;

    inline QT_ASCII_CAST_WARN bool operator==(const QByteArray &s) const;
    inline QT_ASCII_CAST_WARN bool operator!=(const QByteArray &s) const;
    inline QT_ASCII_CAST_WARN bool operator<(const QByteArray &s) const;
    inline QT_ASCII_CAST_WARN bool operator>(const QByteArray &s) const;
    inline QT_ASCII_CAST_WARN bool operator<=(const QByteArray &s) const;
    inline QT_ASCII_CAST_WARN bool operator>=(const QByteArray &s) const;

    friend inline QT_ASCII_CAST_WARN bool operator==(const char *s1, const QString &s2);
    friend inline QT_ASCII_CAST_WARN bool operator!=(const char *s1, const QString &s2);
    friend inline QT_ASCII_CAST_WARN bool operator<(const char *s1, const QString &s2);
    friend inline QT_ASCII_CAST_WARN bool operator>(const char *s1, const QString &s2);
    friend inline QT_ASCII_CAST_WARN bool operator<=(const char *s1, const QString &s2);
    friend inline QT_ASCII_CAST_WARN bool operator>=(const char *s1, const QString &s2);
#endif

    typedef QChar *iterator;
    typedef const QChar *const_iterator;
    typedef iterator Iterator;
    typedef const_iterator ConstIterator;
    typedef std::reverse_iterator<iterator> reverse_iterator;
    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
    inline iterator begin();
    inline const_iterator begin() const;
    inline const_iterator cbegin() const;
    inline const_iterator constBegin() const;
    inline iterator end();
    inline const_iterator end() const;
    inline const_iterator cend() const;
    inline const_iterator constEnd() const;
    reverse_iterator rbegin() { return reverse_iterator(end()); }
    reverse_iterator rend() { return reverse_iterator(begin()); }
    const_reverse_iterator rbegin() const { return const_reverse_iterator(end()); }
    const_reverse_iterator rend() const { return const_reverse_iterator(begin()); }
    const_reverse_iterator crbegin() const { return const_reverse_iterator(end()); }
    const_reverse_iterator crend() const { return const_reverse_iterator(begin()); }

    // STL compatibility
    typedef qsizetype size_type;
    typedef qptrdiff difference_type;
    typedef const QChar & const_reference;
    typedef QChar & reference;
    typedef QChar *pointer;
    typedef const QChar *const_pointer;
    typedef QChar value_type;
    inline void push_back(QChar c) { append(c); }
    inline void push_back(const QString &s) { append(s); }
    inline void push_front(QChar c) { prepend(c); }
    inline void push_front(const QString &s) { prepend(s); }
    void shrink_to_fit() { squeeze(); }

    static inline QString fromStdString(const std::string &s);
    inline std::string toStdString() const;
    static inline QString fromStdWString(const std::wstring &s);
    inline std::wstring toStdWString() const;

    static inline QString fromStdU16String(const std::u16string &s);
    inline std::u16string toStdU16String() const;
    static inline QString fromStdU32String(const std::u32string &s);
    inline std::u32string toStdU32String() const;

#if defined(Q_OS_DARWIN) || defined(Q_QDOC)
    static QString fromCFString(CFStringRef string);
    CFStringRef toCFString() const Q_DECL_CF_RETURNS_RETAINED;
    static QString fromNSString(const NSString *string);
    NSString *toNSString() const Q_DECL_NS_RETURNS_AUTORELEASED;
#endif

    inline bool isNull() const { return d->isNull(); }


    bool isSimpleText() const;
    bool isRightToLeft() const;
    Q_REQUIRED_RESULT bool isValidUtf16() const noexcept
    { return QStringView(*this).isValidUtf16(); }

    QString(qsizetype size, Qt::Initialization);
    explicit QString(DataPointer &&dd) : d(std::move(dd)) {}

private:
#if defined(QT_NO_CAST_FROM_ASCII)
    QString &operator+=(const char *s);
    QString &operator+=(const QByteArray &s);
    QString(const char *ch);
    QString(const QByteArray &a);
    QString &operator=(const char  *ch);
    QString &operator=(const QByteArray &a);
#endif

    DataPointer d;
    static const char16_t _empty;

    friend inline bool operator==(QChar, const QString &) noexcept;
    friend inline bool operator< (QChar, const QString &) noexcept;
    friend inline bool operator> (QChar, const QString &) noexcept;
    friend inline bool operator==(QChar, QLatin1String) noexcept;
    friend inline bool operator< (QChar, QLatin1String) noexcept;
    friend inline bool operator> (QChar, QLatin1String) noexcept;

    void reallocData(qsizetype alloc, Data::ArrayOptions options);
    void reallocGrowData(qsizetype alloc, Data::ArrayOptions options);
    static int compare_helper(const QChar *data1, qsizetype length1,
                              const QChar *data2, qsizetype length2,
                              Qt::CaseSensitivity cs = Qt::CaseSensitive) noexcept;
    static int compare_helper(const QChar *data1, qsizetype length1,
                              const char *data2, qsizetype length2,
                              Qt::CaseSensitivity cs = Qt::CaseSensitive);
    static int compare_helper(const QChar *data1, qsizetype length1,
                              QLatin1String s2,
                              Qt::CaseSensitivity cs = Qt::CaseSensitive) noexcept;
    static int localeAwareCompare_helper(const QChar *data1, qsizetype length1,
                                         const QChar *data2, qsizetype length2);
    static QString toLower_helper(const QString &str);
    static QString toLower_helper(QString &str);
    static QString toUpper_helper(const QString &str);
    static QString toUpper_helper(QString &str);
    static QString toCaseFolded_helper(const QString &str);
    static QString toCaseFolded_helper(QString &str);
    static QString trimmed_helper(const QString &str);
    static QString trimmed_helper(QString &str);
    static QString simplified_helper(const QString &str);
    static QString simplified_helper(QString &str);
    static DataPointer fromLatin1_helper(const char *str, qsizetype size = -1);
    static QString fromUtf8_helper(const char *str, qsizetype size);
    static QString fromLocal8Bit_helper(const char *, qsizetype size);
    static QByteArray toLatin1_helper(const QString &);
    static QByteArray toLatin1_helper_inplace(QString &);
    static QByteArray toUtf8_helper(const QString &);
    static QByteArray toLocal8Bit_helper(const QChar *data, qsizetype size);
    static qsizetype toUcs4_helper(const ushort *uc, qsizetype length, uint *out);
    static qlonglong toIntegral_helper(QStringView string, bool *ok, int base);
    static qulonglong toIntegral_helper(QStringView string, bool *ok, uint base);
    void replace_helper(size_t *indices, qsizetype nIndices, qsizetype blen, const QChar *after, qsizetype alen);
    friend class QStringView;
    friend class QByteArray;
    friend class QCollator;
    friend struct QAbstractConcatenable;

    template <typename T> static
    T toIntegral_helper(QStringView string, bool *ok, int base)
    {
        using Int64 = typename std::conditional<std::is_unsigned<T>::value, qulonglong, qlonglong>::type;
        using Int32 = typename std::conditional<std::is_unsigned<T>::value, uint, int>::type;

        // we select the right overload by casting base to int or uint
        Int64 val = toIntegral_helper(string, ok, Int32(base));
        if (T(val) != val) {
            if (ok)
                *ok = false;
            val = 0;
        }
        return T(val);
    }

public:
    inline DataPointer &data_ptr() { return d; }
    inline const DataPointer &data_ptr() const { return d; }
};

//
// QLatin1String inline members that require QString:
//

QString QLatin1String::toString() const { return *this; }

//
// QStringView inline members that require QString:
//

QString QStringView::toString() const
{ return Q_ASSERT(size() == length()), QString(data(), length()); }

qint64 QStringView::toLongLong(bool *ok, int base) const
{ return QString::toIntegral_helper<qint64>(*this, ok, base); }
quint64 QStringView::toULongLong(bool *ok, int base) const
{ return QString::toIntegral_helper<quint64>(*this, ok, base); }
long QStringView::toLong(bool *ok, int base) const
{ return QString::toIntegral_helper<long>(*this, ok, base); }
ulong QStringView::toULong(bool *ok, int base) const
{ return QString::toIntegral_helper<ulong>(*this, ok, base); }
int QStringView::toInt(bool *ok, int base) const
{ return QString::toIntegral_helper<int>(*this, ok, base); }
uint QStringView::toUInt(bool *ok, int base) const
{ return QString::toIntegral_helper<uint>(*this, ok, base); }
short QStringView::toShort(bool *ok, int base) const
{ return QString::toIntegral_helper<short>(*this, ok, base); }
ushort QStringView::toUShort(bool *ok, int base) const
{ return QString::toIntegral_helper<ushort>(*this, ok, base); }

//
// QUtf8StringView inline members that require QString:
//

template <bool UseChar8T>
QString QBasicUtf8StringView<UseChar8T>::toString() const
{
    Q_ASSERT(size() == int(size()));
    return QString::fromUtf8(data(), int(size()));
}

//
// QAnyStringView inline members that require QString:
//

QAnyStringView::QAnyStringView(const QByteArray &str) noexcept
    : QAnyStringView{str.isNull() ? nullptr : str.data(), str.size()} {}
QAnyStringView::QAnyStringView(const QString &str) noexcept
    : QAnyStringView{str.isNull() ? nullptr : str.data(), str.size()} {}

QString QAnyStringView::toString() const
{ return QtPrivate::convertToQString(*this); }

//
// QString inline members
//
inline QString::QString(QLatin1String aLatin1) : d(fromLatin1_helper(aLatin1.latin1(), aLatin1.size()))
{ }
inline const QChar QString::at(qsizetype i) const
{ Q_ASSERT(size_t(i) < size_t(size())); return QChar(d.data()[i]); }
inline const QChar QString::operator[](qsizetype i) const
{ Q_ASSERT(size_t(i) < size_t(size())); return QChar(d.data()[i]); }
inline bool QString::isEmpty() const
{ return d.size == 0; }
inline const QChar *QString::unicode() const
{ return data(); }
inline const QChar *QString::data() const
{
#if QT5_NULL_STRINGS == 1
    return reinterpret_cast<const QChar *>(d.data() ? d.data() : &_empty);
#else
    return reinterpret_cast<const QChar *>(d.data());
#endif
}
inline QChar *QString::data()
{
    detach();
    Q_ASSERT(d.data());
    return reinterpret_cast<QChar *>(d.data());
}
inline const QChar *QString::constData() const
{ return data(); }
inline void QString::detach()
{ if (d->needsDetach()) reallocData(d.size, d->detachFlags()); }
inline bool QString::isDetached() const
{ return !d->isShared(); }
inline void QString::clear()
{ if (!isNull()) *this = QString(); }
inline QString::QString(const QString &other) noexcept : d(other.d)
{ }
inline qsizetype QString::capacity() const { return qsizetype(d->constAllocatedCapacity()); }
inline QString &QString::setNum(short n, int base)
{ return setNum(qlonglong(n), base); }
inline QString &QString::setNum(ushort n, int base)
{ return setNum(qulonglong(n), base); }
inline QString &QString::setNum(int n, int base)
{ return setNum(qlonglong(n), base); }
inline QString &QString::setNum(uint n, int base)
{ return setNum(qulonglong(n), base); }
inline QString &QString::setNum(long n, int base)
{ return setNum(qlonglong(n), base); }
inline QString &QString::setNum(ulong n, int base)
{ return setNum(qulonglong(n), base); }
inline QString &QString::setNum(float n, char f, int prec)
{ return setNum(double(n),f,prec); }
inline QString QString::arg(int a, int fieldWidth, int base, QChar fillChar) const
{ return arg(qlonglong(a), fieldWidth, base, fillChar); }
inline QString QString::arg(uint a, int fieldWidth, int base, QChar fillChar) const
{ return arg(qulonglong(a), fieldWidth, base, fillChar); }
inline QString QString::arg(long a, int fieldWidth, int base, QChar fillChar) const
{ return arg(qlonglong(a), fieldWidth, base, fillChar); }
inline QString QString::arg(ulong a, int fieldWidth, int base, QChar fillChar) const
{ return arg(qulonglong(a), fieldWidth, base, fillChar); }
inline QString QString::arg(short a, int fieldWidth, int base, QChar fillChar) const
{ return arg(qlonglong(a), fieldWidth, base, fillChar); }
inline QString QString::arg(ushort a, int fieldWidth, int base, QChar fillChar) const
{ return arg(qulonglong(a), fieldWidth, base, fillChar); }

inline QString QString::section(QChar asep, qsizetype astart, qsizetype aend, SectionFlags aflags) const
{ return section(QString(asep), astart, aend, aflags); }

QT_WARNING_PUSH
QT_WARNING_DISABLE_MSVC(4127)   // "conditional expression is constant"
QT_WARNING_DISABLE_INTEL(111)   // "statement is unreachable"

inline qsizetype QString::toWCharArray(wchar_t *array) const
{
    return qToStringViewIgnoringNull(*this).toWCharArray(array);
}

qsizetype QStringView::toWCharArray(wchar_t *array) const
{
    if (sizeof(wchar_t) == sizeof(QChar)) {
        if (auto src = data())
            memcpy(array, src, sizeof(QChar) * size());
        return size();
    } else {
        return QString::toUcs4_helper(reinterpret_cast<const ushort *>(data()), size(),
                                      reinterpret_cast<uint *>(array));
    }
}

QT_WARNING_POP

inline QString QString::fromWCharArray(const wchar_t *string, qsizetype size)
{
    return sizeof(wchar_t) == sizeof(QChar) ? fromUtf16(reinterpret_cast<const char16_t *>(string), size)
                                            : fromUcs4(reinterpret_cast<const char32_t *>(string), size);
}

inline constexpr QString::QString() noexcept {}
inline QString::~QString() {}

inline void QString::reserve(qsizetype asize)
{
    if (d->needsDetach() || asize >= capacity() - d.freeSpaceAtBegin()) {
        reallocData(qMax(asize, size()), d->detachFlags() | Data::CapacityReserved);
    } else {
        d->setFlag(Data::CapacityReserved);
    }
}

inline void QString::squeeze()
{
    if ((d->flags() & Data::CapacityReserved) == 0)
        return;
    if (d->needsDetach() || d.size < capacity()) {
        reallocData(d.size, d->detachFlags() & ~Data::CapacityReserved);
    } else {
        d->clearFlag(Data::CapacityReserved);
    }
}

inline QString &QString::setUtf16(const ushort *autf16, qsizetype asize)
{ return setUnicode(reinterpret_cast<const QChar *>(autf16), asize); }
inline QChar &QString::operator[](qsizetype i)
{ Q_ASSERT(i >= 0 && i < size()); return data()[i]; }
inline QChar &QString::front() { return operator[](0); }
inline QChar &QString::back() { return operator[](size() - 1); }
inline QString::iterator QString::begin()
{ detach(); return reinterpret_cast<QChar*>(d.data()); }
inline QString::const_iterator QString::begin() const
{ return reinterpret_cast<const QChar*>(d.data()); }
inline QString::const_iterator QString::cbegin() const
{ return reinterpret_cast<const QChar*>(d.data()); }
inline QString::const_iterator QString::constBegin() const
{ return reinterpret_cast<const QChar*>(d.data()); }
inline QString::iterator QString::end()
{ detach(); return reinterpret_cast<QChar*>(d.data() + d.size); }
inline QString::const_iterator QString::end() const
{ return reinterpret_cast<const QChar*>(d.data() + d.size); }
inline QString::const_iterator QString::cend() const
{ return reinterpret_cast<const QChar*>(d.data() + d.size); }
inline QString::const_iterator QString::constEnd() const
{ return reinterpret_cast<const QChar*>(d.data() + d.size); }
#if QT_STRINGVIEW_LEVEL < 2
inline bool QString::contains(const QString &s, Qt::CaseSensitivity cs) const
{ return indexOf(s, 0, cs) != -1; }
#endif
inline bool QString::contains(QLatin1String s, Qt::CaseSensitivity cs) const
{ return indexOf(s, 0, cs) != -1; }
inline bool QString::contains(QChar c, Qt::CaseSensitivity cs) const
{ return indexOf(c, 0, cs) != -1; }
inline bool QString::contains(QStringView s, Qt::CaseSensitivity cs) const noexcept
{ return indexOf(s, 0, cs) != -1; }

inline bool operator==(QLatin1String s1, QLatin1String s2) noexcept
{ return s1.size() == s2.size() && (!s1.size() || !memcmp(s1.latin1(), s2.latin1(), s1.size())); }
inline bool operator!=(QLatin1String s1, QLatin1String s2) noexcept
{ return !operator==(s1, s2); }
inline bool operator<(QLatin1String s1, QLatin1String s2) noexcept
{
    const qsizetype len = qMin(s1.size(), s2.size());
    const int r = len ? memcmp(s1.latin1(), s2.latin1(), len) : 0;
    return r < 0 || (r == 0 && s1.size() < s2.size());
}
inline bool operator>(QLatin1String s1, QLatin1String s2) noexcept
{ return operator<(s2, s1); }
inline bool operator<=(QLatin1String s1, QLatin1String s2) noexcept
{ return !operator>(s1, s2); }
inline bool operator>=(QLatin1String s1, QLatin1String s2) noexcept
{ return !operator<(s1, s2); }

inline bool QLatin1String::operator==(const QString &s) const noexcept
{ return s == *this; }
inline bool QLatin1String::operator!=(const QString &s) const noexcept
{ return s != *this; }
inline bool QLatin1String::operator>(const QString &s) const noexcept
{ return s < *this; }
inline bool QLatin1String::operator<(const QString &s) const noexcept
{ return s > *this; }
inline bool QLatin1String::operator>=(const QString &s) const noexcept
{ return s <= *this; }
inline bool QLatin1String::operator<=(const QString &s) const noexcept
{ return s >= *this; }

#if !defined(QT_NO_CAST_FROM_ASCII) && !defined(QT_RESTRICTED_CAST_FROM_ASCII)
inline bool QString::operator==(const char *s) const
{ return QString::compare_helper(constData(), size(), s, -1) == 0; }
inline bool QString::operator!=(const char *s) const
{ return QString::compare_helper(constData(), size(), s, -1) != 0; }
inline bool QString::operator<(const char *s) const
{ return QString::compare_helper(constData(), size(), s, -1) < 0; }
inline bool QString::operator>(const char *s) const
{ return QString::compare_helper(constData(), size(), s, -1) > 0; }
inline bool QString::operator<=(const char *s) const
{ return QString::compare_helper(constData(), size(), s, -1) <= 0; }
inline bool QString::operator>=(const char *s) const
{ return QString::compare_helper(constData(), size(), s, -1) >= 0; }

inline QT_ASCII_CAST_WARN bool operator==(const char *s1, const QString &s2)
{ return QString::compare_helper(s2.constData(), s2.size(), s1, -1) == 0; }
inline QT_ASCII_CAST_WARN bool operator!=(const char *s1, const QString &s2)
{ return QString::compare_helper(s2.constData(), s2.size(), s1, -1) != 0; }
inline QT_ASCII_CAST_WARN bool operator<(const char *s1, const QString &s2)
{ return QString::compare_helper(s2.constData(), s2.size(), s1, -1) > 0; }
inline QT_ASCII_CAST_WARN bool operator>(const char *s1, const QString &s2)
{ return QString::compare_helper(s2.constData(), s2.size(), s1, -1) < 0; }
inline QT_ASCII_CAST_WARN bool operator<=(const char *s1, const QString &s2)
{ return QString::compare_helper(s2.constData(), s2.size(), s1, -1) >= 0; }
inline QT_ASCII_CAST_WARN bool operator>=(const char *s1, const QString &s2)
{ return QString::compare_helper(s2.constData(), s2.size(), s1, -1) <= 0; }

inline QT_ASCII_CAST_WARN bool operator==(const char *s1, QLatin1String s2)
{ return QString::fromUtf8(s1) == s2; }
inline QT_ASCII_CAST_WARN bool operator!=(const char *s1, QLatin1String s2)
{ return QString::fromUtf8(s1) != s2; }
inline QT_ASCII_CAST_WARN bool operator<(const char *s1, QLatin1String s2)
{ return (QString::fromUtf8(s1) < s2); }
inline QT_ASCII_CAST_WARN bool operator>(const char *s1, QLatin1String s2)
{ return (QString::fromUtf8(s1) > s2); }
inline QT_ASCII_CAST_WARN bool operator<=(const char *s1, QLatin1String s2)
{ return (QString::fromUtf8(s1) <= s2); }
inline QT_ASCII_CAST_WARN bool operator>=(const char *s1, QLatin1String s2)
{ return (QString::fromUtf8(s1) >= s2); }

inline QT_ASCII_CAST_WARN bool QLatin1String::operator==(const char *s) const
{ return QString::fromUtf8(s) == *this; }
inline QT_ASCII_CAST_WARN bool QLatin1String::operator!=(const char *s) const
{ return QString::fromUtf8(s) != *this; }
inline QT_ASCII_CAST_WARN bool QLatin1String::operator<(const char *s) const
{ return QString::fromUtf8(s) > *this; }
inline QT_ASCII_CAST_WARN bool QLatin1String::operator>(const char *s) const
{ return QString::fromUtf8(s) < *this; }
inline QT_ASCII_CAST_WARN bool QLatin1String::operator<=(const char *s) const
{ return QString::fromUtf8(s) >= *this; }
inline QT_ASCII_CAST_WARN bool QLatin1String::operator>=(const char *s) const
{ return QString::fromUtf8(s) <= *this; }

inline QT_ASCII_CAST_WARN bool QLatin1String::operator==(const QByteArray &s) const
{ return QString::fromUtf8(s) == *this; }
inline QT_ASCII_CAST_WARN bool QLatin1String::operator!=(const QByteArray &s) const
{ return QString::fromUtf8(s) != *this; }
inline QT_ASCII_CAST_WARN bool QLatin1String::operator<(const QByteArray &s) const
{ return QString::fromUtf8(s) > *this; }
inline QT_ASCII_CAST_WARN bool QLatin1String::operator>(const QByteArray &s) const
{ return QString::fromUtf8(s) < *this; }
inline QT_ASCII_CAST_WARN bool QLatin1String::operator<=(const QByteArray &s) const
{ return QString::fromUtf8(s) >= *this; }
inline QT_ASCII_CAST_WARN bool QLatin1String::operator>=(const QByteArray &s) const
{ return QString::fromUtf8(s) <= *this; }

inline QT_ASCII_CAST_WARN bool QString::operator==(const QByteArray &s) const
{ return QString::compare_helper(constData(), size(), s.constData(), qstrnlen(s.constData(), s.size())) == 0; }
inline QT_ASCII_CAST_WARN bool QString::operator!=(const QByteArray &s) const
{ return QString::compare_helper(constData(), size(), s.constData(), qstrnlen(s.constData(), s.size())) != 0; }
inline QT_ASCII_CAST_WARN bool QString::operator<(const QByteArray &s) const
{ return QString::compare_helper(constData(), size(), s.constData(), s.size()) < 0; }
inline QT_ASCII_CAST_WARN bool QString::operator>(const QByteArray &s) const
{ return QString::compare_helper(constData(), size(), s.constData(), s.size()) > 0; }
inline QT_ASCII_CAST_WARN bool QString::operator<=(const QByteArray &s) const
{ return QString::compare_helper(constData(), size(), s.constData(), s.size()) <= 0; }
inline QT_ASCII_CAST_WARN bool QString::operator>=(const QByteArray &s) const
{ return QString::compare_helper(constData(), size(), s.constData(), s.size()) >= 0; }

inline bool QByteArray::operator==(const QString &s) const
{ return QString::compare_helper(s.constData(), s.size(), constData(), qstrnlen(constData(), size())) == 0; }
inline bool QByteArray::operator!=(const QString &s) const
{ return QString::compare_helper(s.constData(), s.size(), constData(), qstrnlen(constData(), size())) != 0; }
inline bool QByteArray::operator<(const QString &s) const
{ return QString::compare_helper(s.constData(), s.size(), constData(), size()) > 0; }
inline bool QByteArray::operator>(const QString &s) const
{ return QString::compare_helper(s.constData(), s.size(), constData(), size()) < 0; }
inline bool QByteArray::operator<=(const QString &s) const
{ return QString::compare_helper(s.constData(), s.size(), constData(), size()) >= 0; }
inline bool QByteArray::operator>=(const QString &s) const
{ return QString::compare_helper(s.constData(), s.size(), constData(), size()) <= 0; }
#endif // !defined(QT_NO_CAST_FROM_ASCII) && !defined(QT_RESTRICTED_CAST_FROM_ASCII)

#if !defined(QT_USE_FAST_OPERATOR_PLUS) && !defined(QT_USE_QSTRINGBUILDER)
inline const QString operator+(const QString &s1, const QString &s2)
{ QString t(s1); t += s2; return t; }
inline const QString operator+(const QString &s1, QChar s2)
{ QString t(s1); t += s2; return t; }
inline const QString operator+(QChar s1, const QString &s2)
{ QString t(s1); t += s2; return t; }
#  if !defined(QT_NO_CAST_FROM_ASCII) && !defined(QT_RESTRICTED_CAST_FROM_ASCII)
inline QT_ASCII_CAST_WARN const QString operator+(const QString &s1, const char *s2)
{ QString t(s1); t += QString::fromUtf8(s2); return t; }
inline QT_ASCII_CAST_WARN const QString operator+(const char *s1, const QString &s2)
{ QString t = QString::fromUtf8(s1); t += s2; return t; }
inline QT_ASCII_CAST_WARN const QString operator+(const QByteArray &ba, const QString &s)
{ QString t = QString::fromUtf8(ba); t += s; return t; }
inline QT_ASCII_CAST_WARN const QString operator+(const QString &s, const QByteArray &ba)
{ QString t(s); t += QString::fromUtf8(ba); return t; }
#  endif // QT_NO_CAST_FROM_ASCII
#endif // QT_USE_QSTRINGBUILDER

inline std::string QString::toStdString() const
{ return toUtf8().toStdString(); }

inline QString QString::fromStdString(const std::string &s)
{ return fromUtf8(s.data(), int(s.size())); }

inline std::wstring QString::toStdWString() const
{
    std::wstring str;
    str.resize(length());
#if __cplusplus >= 201703L
    str.resize(toWCharArray(str.data()));
#else
    if (length())
        str.resize(toWCharArray(&str.front()));
#endif
    return str;
}

inline QString QString::fromStdWString(const std::wstring &s)
{ return fromWCharArray(s.data(), int(s.size())); }

inline QString QString::fromStdU16String(const std::u16string &s)
{ return fromUtf16(s.data(), int(s.size())); }

inline std::u16string QString::toStdU16String() const
{ return std::u16string(reinterpret_cast<const char16_t*>(utf16()), length()); }

inline QString QString::fromStdU32String(const std::u32string &s)
{ return fromUcs4(s.data(), int(s.size())); }

inline std::u32string QString::toStdU32String() const
{
    std::u32string u32str(length(), char32_t(0));
    int len = toUcs4_helper(reinterpret_cast<const ushort *>(constData()), length(),
                            reinterpret_cast<uint*>(&u32str[0]));
    u32str.resize(len);
    return u32str;
}

#if !defined(QT_NO_DATASTREAM) || (defined(QT_BOOTSTRAPPED) && !defined(QT_BUILD_QMAKE))
Q_CORE_EXPORT QDataStream &operator<<(QDataStream &, const QString &);
Q_CORE_EXPORT QDataStream &operator>>(QDataStream &, QString &);
#endif

Q_DECLARE_SHARED(QString)
Q_DECLARE_OPERATORS_FOR_FLAGS(QString::SectionFlags)

inline int QString::compare(QStringView s, Qt::CaseSensitivity cs) const noexcept
{ return -s.compare(*this, cs); }

// QChar <> QString
inline bool operator==(QChar lhs, const QString &rhs) noexcept
{ return rhs.size() == 1 && lhs == rhs.front(); }
inline bool operator< (QChar lhs, const QString &rhs) noexcept
{ return QString::compare_helper(&lhs, 1, rhs.data(), rhs.size()) <  0; }
inline bool operator> (QChar lhs, const QString &rhs) noexcept
{ return QString::compare_helper(&lhs, 1, rhs.data(), rhs.size()) >  0; }

inline bool operator!=(QChar lhs, const QString &rhs) noexcept { return !(lhs == rhs); }
inline bool operator<=(QChar lhs, const QString &rhs) noexcept { return !(lhs >  rhs); }
inline bool operator>=(QChar lhs, const QString &rhs) noexcept { return !(lhs <  rhs); }

inline bool operator==(const QString &lhs, QChar rhs) noexcept { return   rhs == lhs; }
inline bool operator!=(const QString &lhs, QChar rhs) noexcept { return !(rhs == lhs); }
inline bool operator< (const QString &lhs, QChar rhs) noexcept { return   rhs >  lhs; }
inline bool operator> (const QString &lhs, QChar rhs) noexcept { return   rhs <  lhs; }
inline bool operator<=(const QString &lhs, QChar rhs) noexcept { return !(rhs <  lhs); }
inline bool operator>=(const QString &lhs, QChar rhs) noexcept { return !(rhs >  lhs); }

// QChar <> QLatin1String
inline bool operator==(QChar lhs, QLatin1String rhs) noexcept
{ return rhs.size() == 1 && lhs == rhs.front(); }
inline bool operator< (QChar lhs, QLatin1String rhs) noexcept
{ return QString::compare_helper(&lhs, 1, rhs) <  0; }
inline bool operator> (QChar lhs, QLatin1String rhs) noexcept
{ return QString::compare_helper(&lhs, 1, rhs) >  0; }

inline bool operator!=(QChar lhs, QLatin1String rhs) noexcept { return !(lhs == rhs); }
inline bool operator<=(QChar lhs, QLatin1String rhs) noexcept { return !(lhs >  rhs); }
inline bool operator>=(QChar lhs, QLatin1String rhs) noexcept { return !(lhs <  rhs); }

inline bool operator==(QLatin1String lhs, QChar rhs) noexcept { return   rhs == lhs; }
inline bool operator!=(QLatin1String lhs, QChar rhs) noexcept { return !(rhs == lhs); }
inline bool operator< (QLatin1String lhs, QChar rhs) noexcept { return   rhs >  lhs; }
inline bool operator> (QLatin1String lhs, QChar rhs) noexcept { return   rhs <  lhs; }
inline bool operator<=(QLatin1String lhs, QChar rhs) noexcept { return !(rhs <  lhs); }
inline bool operator>=(QLatin1String lhs, QChar rhs) noexcept { return !(rhs >  lhs); }

#if 0
// QStringView <> QStringView
inline bool operator==(QStringView lhs, QStringView rhs) noexcept { return lhs.size() == rhs.size() && QtPrivate::compareStrings(lhs, rhs) == 0; }
inline bool operator!=(QStringView lhs, QStringView rhs) noexcept { return !(lhs == rhs); }
inline bool operator< (QStringView lhs, QStringView rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) <  0; }
inline bool operator<=(QStringView lhs, QStringView rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) <= 0; }
inline bool operator> (QStringView lhs, QStringView rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) >  0; }
inline bool operator>=(QStringView lhs, QStringView rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) >= 0; }
#endif

// QStringView <> QChar
inline bool operator==(QStringView lhs, QChar rhs) noexcept { return lhs == QStringView(&rhs, 1); }
inline bool operator!=(QStringView lhs, QChar rhs) noexcept { return lhs != QStringView(&rhs, 1); }
inline bool operator< (QStringView lhs, QChar rhs) noexcept { return lhs <  QStringView(&rhs, 1); }
inline bool operator<=(QStringView lhs, QChar rhs) noexcept { return lhs <= QStringView(&rhs, 1); }
inline bool operator> (QStringView lhs, QChar rhs) noexcept { return lhs >  QStringView(&rhs, 1); }
inline bool operator>=(QStringView lhs, QChar rhs) noexcept { return lhs >= QStringView(&rhs, 1); }

inline bool operator==(QChar lhs, QStringView rhs) noexcept { return QStringView(&lhs, 1) == rhs; }
inline bool operator!=(QChar lhs, QStringView rhs) noexcept { return QStringView(&lhs, 1) != rhs; }
inline bool operator< (QChar lhs, QStringView rhs) noexcept { return QStringView(&lhs, 1) <  rhs; }
inline bool operator<=(QChar lhs, QStringView rhs) noexcept { return QStringView(&lhs, 1) <= rhs; }
inline bool operator> (QChar lhs, QStringView rhs) noexcept { return QStringView(&lhs, 1) >  rhs; }
inline bool operator>=(QChar lhs, QStringView rhs) noexcept { return QStringView(&lhs, 1) >= rhs; }

// QStringView <> QLatin1String
inline bool operator==(QStringView lhs, QLatin1String rhs) noexcept { return lhs.size() == rhs.size() && QtPrivate::compareStrings(lhs, rhs) == 0; }
inline bool operator!=(QStringView lhs, QLatin1String rhs) noexcept { return !(lhs == rhs); }
inline bool operator< (QStringView lhs, QLatin1String rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) <  0; }
inline bool operator<=(QStringView lhs, QLatin1String rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) <= 0; }
inline bool operator> (QStringView lhs, QLatin1String rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) >  0; }
inline bool operator>=(QStringView lhs, QLatin1String rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) >= 0; }

inline bool operator==(QLatin1String lhs, QStringView rhs) noexcept { return lhs.size() == rhs.size() && QtPrivate::compareStrings(lhs, rhs) == 0; }
inline bool operator!=(QLatin1String lhs, QStringView rhs) noexcept { return !(lhs == rhs); }
inline bool operator< (QLatin1String lhs, QStringView rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) <  0; }
inline bool operator<=(QLatin1String lhs, QStringView rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) <= 0; }
inline bool operator> (QLatin1String lhs, QStringView rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) >  0; }
inline bool operator>=(QLatin1String lhs, QStringView rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) >= 0; }

inline int QString::localeAwareCompare(QStringView s) const
{ return localeAwareCompare_helper(constData(), length(), s.constData(), s.length()); }
inline int QString::localeAwareCompare(QStringView s1, QStringView s2)
{ return localeAwareCompare_helper(s1.constData(), s1.length(), s2.constData(), s2.length()); }

namespace QtPrivate {
// used by qPrintable() and qUtf8Printable() macros
inline const QString &asString(const QString &s)    { return s; }
inline QString &&asString(QString &&s)              { return std::move(s); }
}

//
// QStringView::arg() implementation
//

namespace QtPrivate {

struct ArgBase {
    enum Tag : uchar { L1, U8, U16 } tag;
};

struct QStringViewArg : ArgBase {
    QStringView string;
    QStringViewArg() = default;
    constexpr explicit QStringViewArg(QStringView v) noexcept : ArgBase{U16}, string{v} {}
};

struct QLatin1StringArg : ArgBase {
    QLatin1String string;
    QLatin1StringArg() = default;
    constexpr explicit QLatin1StringArg(QLatin1String v) noexcept : ArgBase{L1}, string{v} {}
};

Q_REQUIRED_RESULT Q_CORE_EXPORT QString argToQString(QStringView pattern, size_t n, const ArgBase **args);
Q_REQUIRED_RESULT Q_CORE_EXPORT QString argToQString(QLatin1String pattern, size_t n, const ArgBase **args);

template <typename StringView, typename...Args>
Q_REQUIRED_RESULT Q_ALWAYS_INLINE QString argToQStringDispatch(StringView pattern, const Args &...args)
{
    const ArgBase *argBases[] = {&args..., /* avoid zero-sized array */ nullptr};
    return QtPrivate::argToQString(pattern, sizeof...(Args), argBases);
}

          inline QStringViewArg   qStringLikeToArg(const QString &s) noexcept { return QStringViewArg{qToStringViewIgnoringNull(s)}; }
constexpr inline QStringViewArg   qStringLikeToArg(QStringView s) noexcept { return QStringViewArg{s}; }
          inline QStringViewArg   qStringLikeToArg(const QChar &c) noexcept { return QStringViewArg{QStringView{&c, 1}}; }
constexpr inline QLatin1StringArg qStringLikeToArg(QLatin1String s) noexcept { return QLatin1StringArg{s}; }

} // namespace QtPrivate

template <typename...Args>
Q_ALWAYS_INLINE
QString QStringView::arg(Args &&...args) const
{
    return QtPrivate::argToQStringDispatch(*this, QtPrivate::qStringLikeToArg(args)...);
}

template <typename...Args>
Q_ALWAYS_INLINE
QString QLatin1String::arg(Args &&...args) const
{
    return QtPrivate::argToQStringDispatch(*this, QtPrivate::qStringLikeToArg(args)...);
}

QT_END_NAMESPACE

#if defined(QT_USE_FAST_OPERATOR_PLUS) || defined(QT_USE_QSTRINGBUILDER)
#include <QtCore/qstringbuilder.h>
#endif

#endif // QSTRING_H