// Copyright (C) 2022 The Qt Company Ltd.
// Copyright (C) 2021 Intel Corporation.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
// Qt-Security score:critical reason:data-parser

#include "qglobal.h"

#if defined(Q_CC_GNU_ONLY) && Q_CC_GNU >= 1000
/* gcc has complained about storing a pointer to a static QLocalePrivate in a
   QSharedDataPointer, whose destructor would free the non-heap object if the
   refcount ever got down to zero. The static instances this happens to are
   instantiated with a refcount of 1 that never gets decremented so as long as
   QSharedDataPointer keeps its incref()s and decref()s balanced it'll never get
   down to zero - but the clever compiler isn't quite smart enough to figure
   that out.
*/
QT_WARNING_DISABLE_GCC("-Wfree-nonheap-object") // false positive tracking
#endif

#if defined(Q_OS_MACOS)
#   include "private/qcore_mac_p.h"
#   include <CoreFoundation/CoreFoundation.h>
#endif

#include "qplatformdefs.h"

#include "qcalendar.h"
#include "qdatastream.h"
#include "qdebug.h"
#include "private/qduplicatetracker_p.h"
#include "qhashfunctions.h"
#include "qstring.h"
#include "qstringiterator_p.h"
#include "qlocale.h"
#include "qlocale_p.h"
#include "qlocale_tools_p.h"
#include <private/qtools_p.h>
#if QT_CONFIG(datetimeparser)
#include "private/qdatetimeparser_p.h"
#endif
#include "qnamespace.h"
#include "qdatetime.h"
#include "qstringlist.h"
#include "qvariant.h"
#include "qvarlengtharray.h"
#include "qstringbuilder.h"
#if QT_CONFIG(timezone)
#   include "qtimezone.h"
#endif
#include "private/qnumeric_p.h"
#include "private/qtools_p.h"
#include <cmath>
#ifndef QT_NO_SYSTEMLOCALE
#   include "qmutex.h"
#endif
#ifdef Q_OS_WIN
#   include <qt_windows.h>
#   include <time.h>
#endif

#include "private/qcalendarbackend_p.h"
#include "private/qgregoriancalendar_p.h"
#if QT_CONFIG(timezone) && QT_CONFIG(timezone_locale) && !QT_CONFIG(icu)
#   include "private/qtimezonelocale_p.h"
#endif
#if QT_CONFIG(datestring)
#   include "private/qttemporalpattern_p.h"
#endif

#include <q20iterator.h>

QT_BEGIN_NAMESPACE

constexpr int QLocale::DefaultTwoDigitBaseYear;

QT_IMPL_METATYPE_EXTERN_TAGGED(QList<Qt::DayOfWeek>, QList_Qt__DayOfWeek)
#ifndef QT_NO_SYSTEMLOCALE
QT_IMPL_METATYPE_EXTERN_TAGGED(QSystemLocale::CurrencyToStringArgument,
                               QSystemLocale__CurrencyToStringArgument)
#endif

using namespace Qt::StringLiterals;
using namespace QtMiscUtils;

#ifndef QT_NO_SYSTEMLOCALE
Q_CONSTINIT static QSystemLocale *_systemLocale = nullptr;
Q_CONSTINIT static QLocaleData systemLocaleData = {};
#endif

static_assert(ascii_isspace(' '));
static_assert(ascii_isspace('\t'));
static_assert(ascii_isspace('\n'));
static_assert(ascii_isspace('\v'));
static_assert(ascii_isspace('\f'));
static_assert(ascii_isspace('\r'));
static_assert(!ascii_isspace('\0'));
static_assert(!ascii_isspace('\a'));
static_assert(!ascii_isspace('a'));
static_assert(!ascii_isspace('\177'));
static_assert(!ascii_isspace(uchar('\200')));
static_assert(!ascii_isspace(uchar('\xA0')));   // NBSP (is a space but Latin 1, not ASCII)
static_assert(!ascii_isspace(uchar('\377')));

/******************************************************************************
** Helpers for accessing Qt locale database
*/

QT_BEGIN_INCLUDE_NAMESPACE
#include "qlocale_data_p.h"
QT_END_INCLUDE_NAMESPACE

QLocale::Language QLocalePrivate::codeToLanguage(QStringView code,
                                                 QLocale::LanguageCodeTypes codeTypes) noexcept
{
    const auto len = code.size();
    if (len != 2 && len != 3)
        return QLocale::AnyLanguage;

    const char16_t uc1 = code[0].toLower().unicode();
    const char16_t uc2 = code[1].toLower().unicode();
    const char16_t uc3 = len > 2 ? code[2].toLower().unicode() : 0;

    // All language codes are ASCII.
    if (uc1 > 0x7F || uc2 > 0x7F || uc3 > 0x7F)
        return QLocale::AnyLanguage;

    const AlphaCode codeBuf = { char(uc1), char(uc2), char(uc3) };

    auto searchCode = [codeBuf](auto f) {
        return std::find_if(languageCodeList.begin(), languageCodeList.end(),
                            [=](LanguageCodeEntry i) { return f(i) == codeBuf; });
    };

    if (codeTypes.testFlag(QLocale::ISO639Part1) && uc3 == 0) {
        auto i = searchCode([](LanguageCodeEntry i) { return i.part1; });
        if (i != languageCodeList.end())
            return QLocale::Language(std::distance(languageCodeList.begin(), i));
    }

    if (uc3 != 0) {
        if (codeTypes.testFlag(QLocale::ISO639Part2B)) {
            auto i = searchCode([](LanguageCodeEntry i) { return i.part2B; });
            if (i != languageCodeList.end())
                return QLocale::Language(std::distance(languageCodeList.begin(), i));
        }

        // Optimization: Part 2T code if present is always the same as Part 3 code.
        // This is asserted in iso639_3.LanguageCodeData.
        if (codeTypes.testFlag(QLocale::ISO639Part2T)
            && !codeTypes.testFlag(QLocale::ISO639Part3)) {
            auto i = searchCode([](LanguageCodeEntry i) { return i.part2T; });
            if (i != languageCodeList.end())
                return QLocale::Language(std::distance(languageCodeList.begin(), i));
        }

        if (codeTypes.testFlag(QLocale::ISO639Part3)) {
            auto i = searchCode([](LanguageCodeEntry i) { return i.part3; });
            if (i != languageCodeList.end())
                return QLocale::Language(std::distance(languageCodeList.begin(), i));
        }
    }

    if (codeTypes.testFlag(QLocale::LegacyLanguageCode) && uc3 == 0) {
        constexpr struct LegacyCodes {
            AlphaCode code;
            QLocale::Language language;
        } legacyCodes[] = {
            { {'n', 'o'}, QLocale::NorwegianBokmal }, // no -> nb
            { {'t', 'l'}, QLocale::Filipino },        // tl -> fil
            { {'s', 'h'}, QLocale::Serbian },         // sh -> sr[_Latn]
            { {'m', 'o'}, QLocale::Romanian },        // mo -> ro
            // Android uses the following deprecated codes:
            { {'i', 'w'}, QLocale::Hebrew },          // iw -> he
            { {'i', 'n'}, QLocale::Indonesian },      // in -> id
            { {'j', 'i'}, QLocale::Yiddish },         // ji -> yi
        };
        // We don't need binary search for seven entries (and they're not
        // sorted), so search linearly:
        for (const auto &e : legacyCodes) {
            if (codeBuf == e.code)
                return e.language;
        }
    }
    return QLocale::AnyLanguage;
}

static qsizetype scriptIndex(QStringView code, Qt::CaseSensitivity cs) noexcept
{
    if (code.size() != 4)
        return -1;

    // Scripts are titlecased in script_code_list.
    const bool fixCase = cs == Qt::CaseInsensitive;
    const unsigned char c0 = (fixCase ? code[0].toUpper() : code[0]).toLatin1();
    const unsigned char c1 = (fixCase ? code[1].toLower() : code[1]).toLatin1();
    const unsigned char c2 = (fixCase ? code[2].toLower() : code[2]).toLatin1();
    const unsigned char c3 = (fixCase ? code[3].toLower() : code[3]).toLatin1();
    // Any outside the Latin1 repertoire aren't ASCII => will not match.
    if (!c0 || !c1 || !c2 || !c3)
        return -1;

    constexpr qsizetype NumScripts = QLocale::LastScript + 1;
    static_assert(sizeof(script_code_list) == 4 * NumScripts + 1); // +1 for an extra NUL
    const unsigned char *c = script_code_list;
    for (qsizetype i = 0; i < NumScripts; ++i, c += 4) {
        if (c0 == c[0] && c1 == c[1] && c2 == c[2] && c3 == c[3])
            return i;
    }
    return -1;
}

QLocale::Script QLocalePrivate::codeToScript(QStringView code) noexcept
{
    qsizetype index = scriptIndex(code, Qt::CaseInsensitive);
    return index < 0 ? QLocale::AnyScript : QLocale::Script(index);
}

QLocale::Territory QLocalePrivate::codeToTerritory(QStringView code) noexcept
{
    const auto len = code.size();
    if (len != 2 && len != 3)
        return QLocale::AnyTerritory;

    char16_t uc1 = code[0].toUpper().unicode();
    char16_t uc2 = code[1].toUpper().unicode();
    char16_t uc3 = len > 2 ? code[2].toUpper().unicode() : 0;

    const unsigned char *c = territory_code_list;
    for (; *c != 0; c += 3) {
        if (uc1 == c[0] && uc2 == c[1] && uc3 == c[2])
            return QLocale::Territory((c - territory_code_list)/3);
    }

    return QLocale::AnyTerritory;
}

std::array<char, 4> QLocalePrivate::languageToCode(QLocale::Language language,
                                                   QLocale::LanguageCodeTypes codeTypes)
{
    if (language == QLocale::AnyLanguage || language > QLocale::LastLanguage)
        return {};
    if (language == QLocale::C)
        return {'C'};

    const LanguageCodeEntry &i = languageCodeList[language];

    if (codeTypes.testFlag(QLocale::ISO639Part1) && i.part1.isValid())
        return i.part1.decode();

    if (codeTypes.testFlag(QLocale::ISO639Part2B) && i.part2B.isValid())
        return i.part2B.decode();

    if (codeTypes.testFlag(QLocale::ISO639Part2T) && i.part2T.isValid())
        return i.part2T.decode();

    if (codeTypes.testFlag(QLocale::ISO639Part3))
        return i.part3.decode();

    return {};
}

QLatin1StringView QLocalePrivate::scriptToCode(QLocale::Script script)
{
    if (script == QLocale::AnyScript || script > QLocale::LastScript)
        return {};
    const unsigned char *c = script_code_list + 4 * script;
    return {reinterpret_cast<const char *>(c), 4};
}

QLatin1StringView QLocalePrivate::territoryToCode(QLocale::Territory territory)
{
    if (territory == QLocale::AnyTerritory || territory > QLocale::LastTerritory)
        return {};

    const unsigned char *c = territory_code_list + 3 * territory;
    return {reinterpret_cast<const char*>(c), c[2] == 0 ? 2 : 3};
}

namespace {
struct LikelyPair
{
    QLocaleId key; // Search key.
    QLocaleId value = QLocaleId { 0, 0, 0 };
};

bool operator<(LikelyPair lhs, LikelyPair rhs)
{
    // Must match the comparison LocaleDataWriter.likelySubtags() uses when
    // sorting, see qtbase/util/locale_database.qlocalexml2cpp.py
    const auto compare = [](int lhs, int rhs) {
        // 0 sorts after all other values; lhs and rhs are passed ushort values.
        const int huge = 0x10000;
        return (lhs ? lhs : huge) - (rhs ? rhs : huge);
    };
    const auto &left = lhs.key;
    const auto &right = rhs.key;
    // Comparison order: language, region, script:
    if (int cmp = compare(left.language_id, right.language_id))
        return cmp < 0;
    if (int cmp = compare(left.territory_id, right.territory_id))
        return cmp < 0;
    return compare(left.script_id, right.script_id) < 0;
}
} // anonymous namespace

/*!
    \internal
    Fill in blank fields of a locale ID.

    An ID in which some fields are zero stands for any locale that agrees with
    it in its non-zero fields.  CLDR's likely-subtag data is meant to help us
    chose which candidate to prefer.  (Note, however, that CLDR does have some
    cases where it maps an ID to a "best match" for which CLDR does not provide
    data, even though there are locales for which CLDR does provide data that do
    match the given ID.  It's telling us, unhelpfully but truthfully, what
    locale would (most likely) be meant by (someone using) the combination
    requested, even when that locale isn't yet supported.)  It may also map an
    obsolete or generic tag to a modern or more specific replacement, possibly
    filling in some of the other fields in the process (presently only for
    countries).  Note that some fields of the result may remain blank, but there
    is no more specific recommendation available.

    For the formal specification, see
    https://www.unicode.org/reports/tr35/#Likely_Subtags

    \note We also search und_script_region and und_region; they're not mentioned
    in the spec, but the examples clearly presume them and CLDR does provide
    such likely matches.
*/
QLocaleId QLocaleId::withLikelySubtagsAdded() const noexcept
{
    /* Each pattern that appears in a comments below, language_script_region and
       similar, indicates which of this's fields (even if blank) are being
       attended to in a given search; for fields left out of the pattern, the
       search uses 0 regardless of whether this has specified the field.

       If a key matches what we're searching for (possibly with a wildcard in
       the key matching a non-wildcard in our search), the tags from this that
       are specified in the key are replaced by the match (even if different);
       but the other tags of this replace what's in the match (even when the
       match does specify a value).

       Keep QLocaleXmlReader.__fillLikely() in sync with this, to ensure
       locale-appropriate time-zone naming works correctly.
    */
    static_assert(std::size(likely_subtags) % 2 == 0);
    auto *pairs = reinterpret_cast<const LikelyPair *>(likely_subtags);
    auto *const afterPairs = pairs + std::size(likely_subtags) / 2;
    LikelyPair sought { *this };
    // Our array is sorted in the order that puts all candidate matches in the
    // order we would want them; ones we should prefer appear before the others.
    if (language_id) {
        // language_script_region, language_region, language_script, language:
        pairs = std::lower_bound(pairs, afterPairs, sought);
        // Single language's block isn't long enough to warrant more binary
        // chopping within it - just traverse it all:
        for (; pairs < afterPairs && pairs->key.language_id == language_id; ++pairs) {
            const QLocaleId &key = pairs->key;
            if (key.territory_id && key.territory_id != territory_id)
                continue;
            if (key.script_id && key.script_id != script_id)
                continue;
            QLocaleId value = pairs->value;
            if (territory_id && !key.territory_id)
                value.territory_id = territory_id;
            if (script_id && !key.script_id)
                value.script_id = script_id;
            return value;
        }
    }
    // und_script_region or und_region (in that order):
    if (territory_id) {
        sought.key = QLocaleId { 0, script_id, territory_id };
        pairs = std::lower_bound(pairs, afterPairs, sought);
        // Again, individual und_?_region block isn't long enough to make binary
        // chop a win:
        for (; pairs < afterPairs && pairs->key.territory_id == territory_id; ++pairs) {
            const QLocaleId &key = pairs->key;
            Q_ASSERT(!key.language_id);
            if (key.script_id && key.script_id != script_id)
                continue;
            QLocaleId value = pairs->value;
            if (language_id)
                value.language_id = language_id;
            if (script_id && !key.script_id)
                value.script_id = script_id;
            return value;
        }
    }
    // und_script:
    if (script_id) {
        sought.key = QLocaleId { 0, script_id, 0 };
        pairs = std::lower_bound(pairs, afterPairs, sought);
        if (pairs < afterPairs && pairs->key.script_id == script_id) {
            Q_ASSERT(!pairs->key.language_id && !pairs->key.territory_id);
            QLocaleId value = pairs->value;
            if (language_id)
                value.language_id = language_id;
            if (territory_id)
                value.territory_id = territory_id;
            return value;
        }
    }
    // Finally, fall back to the match-all rule (if there is one):
    pairs = afterPairs - 1; // All other keys are < match-all.
    if (pairs->key.matchesAll()) {
        QLocaleId value = pairs->value;
        if (language_id)
            value.language_id = language_id;
        if (territory_id)
            value.territory_id = territory_id;
        if (script_id)
            value.script_id = script_id;
        return value;
    }
    return *this;
}

QLocaleId QLocaleId::withLikelySubtagsRemoved() const noexcept
{
    QLocaleId max = withLikelySubtagsAdded();
    // language
    {
        QLocaleId id { language_id, 0, 0 };
        if (id.withLikelySubtagsAdded() == max)
            return id;
    }
    // language_region
    if (territory_id) {
        QLocaleId id { language_id, 0, territory_id };
        if (id.withLikelySubtagsAdded() == max)
            return id;
    }
    // language_script
    if (script_id) {
        QLocaleId id { language_id, script_id, 0 };
        if (id.withLikelySubtagsAdded() == max)
            return id;
    }
    return max;
}

QByteArray QLocaleId::name(char separator) const
{
    if (language_id == QLocale::AnyLanguage)
        return QByteArray();
    if (language_id == QLocale::C)
        return QByteArrayLiteral("C");
    Q_ASSERT(language_id <= QLocale::LastLanguage);
    Q_ASSERT(script_id <= QLocale::LastScript);
    Q_ASSERT(territory_id <= QLocale::LastTerritory);

    const LanguageCodeEntry &language = languageCodeList[language_id];
    AlphaCode lang;
    qsizetype langLen;

    if (language.part1.isValid()) {
        lang = language.part1;
        langLen = 2;
    } else {
        lang = language.part2B.isValid() ? language.part2B : language.part3;
        langLen = 3;
    }

    const unsigned char *script =
            (script_id != QLocale::AnyScript ? script_code_list + 4 * script_id : nullptr);
    const unsigned char *country =
            (territory_id != QLocale::AnyTerritory
             ? territory_code_list + 3 * territory_id : nullptr);
    qsizetype len = langLen + (script ? 4 + 1 : 0) + (country ? (country[2] != 0 ? 3 : 2) + 1 : 0);
    QByteArray name(len, Qt::Uninitialized);
    char *uc = name.data();

    auto langArray = lang.decode();

    *uc++ = langArray[0];
    *uc++ = langArray[1];
    if (langLen > 2)
        *uc++ = langArray[2];

    if (script) {
        *uc++ = separator;
        *uc++ = script[0];
        *uc++ = script[1];
        *uc++ = script[2];
        *uc++ = script[3];
    }
    if (country) {
        *uc++ = separator;
        *uc++ = country[0];
        *uc++ = country[1];
        if (country[2] != 0)
            *uc++ = country[2];
    }
    return name;
}

QByteArray QLocalePrivate::bcp47Name(char separator) const
{
    if (m_data->m_language_id == QLocale::AnyLanguage)
        return QByteArray();
    if (m_data->m_language_id == QLocale::C)
        return QByteArrayView("en") % separator % QByteArrayView("POSIX");

    return m_data->id().withLikelySubtagsRemoved().name(separator);
}

static qsizetype findLocaleIndexById(QLocaleId localeId) noexcept
{
    qsizetype idx = locale_index[localeId.language_id];
    // If there are no locales for specified language (so we we've got the
    // default language, which has no associated script or country), give up:
    if (localeId.language_id && idx == 0)
        return idx;

    Q_ASSERT(localeId.acceptLanguage(locale_data[idx].m_language_id));

    do {
        if (localeId.acceptScriptTerritory(locale_data[idx].id()))
            return idx;
        ++idx;
    } while (localeId.acceptLanguage(locale_data[idx].m_language_id));

    return -1;
}

static constexpr qsizetype locale_data_size = q20::ssize(locale_data) - 1; // trailing guard
bool QLocaleData::allLocaleDataRows(bool (*check)(qsizetype, const QLocaleData &))
{
    for (qsizetype index = 0; index < locale_data_size; ++index) {
        if (!(*check)(index, locale_data[index]))
            return false;
    }
    return true;
}

// Internal: to enable tst_qlocaledata to access locales
const QLocaleData *QLocaleData::dataForLocaleIndex(qsizetype index)
{
    Q_PRE(index >= 0);
    Q_PRE(index < locale_data_size);
    return locale_data + index;
}

#if QT_CONFIG(timezone) && QT_CONFIG(timezone_locale) && !QT_CONFIG(icu)
namespace QtTimeZoneLocale {

// Indices of locales obtained from the given by likely subtag fall-backs.
QList<qsizetype> fallbackLocalesFor(qsizetype index)
{
    // Should match QLocaleXmlReader.pruneZoneNaming()'s fallbacks() helper,
    // aside from the special-case kludge for C -> en_US.
    Q_ASSERT(index < locale_data_size);
    QList<qsizetype> result = {index};
    QLocaleId id = locale_data[index].id();
    if (id.language_id == QLocale::C) {
        id = { QLocale::English, QLocale::LatinScript, QLocale::UnitedStates };
        qsizetype it = findLocaleIndexById(id);
        Q_ASSERT_X(it != -1, Q_FUNC_INFO, "Missing en_Latn_US from locale data");
        Q_ASSERT_X(it != index, // equivalent to !result.contains(it)
                   Q_FUNC_INFO, "en_Latn_US != C");
        result << it;
    }

    const QLocaleId base = id;
    QLocaleId likely = id.withLikelySubtagsAdded();
    if (likely != base) {
        qsizetype it = findLocaleIndexById(likely);
        if (it != -1 && !result.contains(it))
            result << it;
    }
    if (id.territory_id) {
        id.territory_id = 0;
        likely = id.withLikelySubtagsAdded();
        if (likely != base) {
            qsizetype it = findLocaleIndexById(likely);
            if (it != -1 && !result.contains(it))
                result << it;
        }
    }
    if (id.script_id) {
        id.script_id = 0;
        likely = id.withLikelySubtagsAdded();
        if (likely != base) {
            qsizetype it = findLocaleIndexById(likely);
            if (it != -1 && !result.contains(it))
                result << it;
        }
    }
    return result;
}

} // QtTimeZoneLocale
#endif // timezone_locale && !icu

qsizetype QLocaleData::findLocaleIndex(QLocaleId lid) noexcept
{
    QLocaleId localeId = lid;
    QLocaleId likelyId = localeId.withLikelySubtagsAdded();
    const ushort fallback = likelyId.language_id;

    // Try a straight match with the likely data:
    qsizetype index = findLocaleIndexById(likelyId);
    if (index >= 0)
        return index;
    QVarLengthArray<QLocaleId, 6> tried;
    tried.push_back(likelyId);

#define CheckCandidate(id) do { \
        if (!tried.contains(id)) { \
            index = findLocaleIndexById(id); \
            if (index >= 0) \
                return index; \
            tried.push_back(id); \
        } \
    } while (false) // end CheckCandidate

    // No match; try again with raw data:
    CheckCandidate(localeId);

    // No match; try again with likely country for language_script
    if (lid.territory_id && (lid.language_id || lid.script_id)) {
        localeId.territory_id = 0;
        likelyId = localeId.withLikelySubtagsAdded();
        CheckCandidate(likelyId);

        // No match; try again with any country
        CheckCandidate(localeId);
    }

    // No match; try again with likely script for language_region
    if (lid.script_id && (lid.language_id || lid.territory_id)) {
        localeId = QLocaleId { lid.language_id, 0, lid.territory_id };
        likelyId = localeId.withLikelySubtagsAdded();
        CheckCandidate(likelyId);

        // No match; try again with any script
        CheckCandidate(localeId);
    }
#undef CheckCandidate

    // No match; return base index for initial likely language:
    return locale_index[fallback];
}

static QStringView findTag(QStringView name) noexcept
{
    const std::u16string_view v(name.utf16(), size_t(name.size()));
    const auto i = v.find_first_of(u"_-.@");
    if (i == std::string_view::npos)
        return name;
    return name.first(qsizetype(i));
}

static bool validTag(QStringView tag)
{
    // Is tag is a non-empty sequence of ASCII letters and/or digits ?
    for (QChar uc : tag) {
        const char16_t ch = uc.unicode();
        if (!isAsciiLetterOrNumber(ch))
            return false;
    }
    return tag.size() > 0;
}

bool qt_splitLocaleName(QStringView name,
                        QStringView *lang, QStringView *script, QStringView *land) noexcept
{
    // Assume each of lang, script and land is nullptr or points to an empty QStringView.
    enum ParserState { NoState, LangState, ScriptState, CountryState };
    ParserState state = LangState;
    while (name.size() && state != NoState) {
        const QStringView tag = findTag(name);
        if (!validTag(tag))
            break;
        name = name.sliced(tag.size());
        const bool sep = name.size() > 0;
        if (sep) // tag wasn't all that remained; there was a separator
            name = name.sliced(1);

        switch (state) {
        case LangState:
            if (tag.size() != 2 && tag.size() != 3)
                return false;
            if (lang)
                *lang = tag;
            state = sep ? ScriptState : NoState;
            break;
        case ScriptState:
            if (scriptIndex(tag, Qt::CaseSensitive) >= 0) {
                if (script)
                    *script = tag;
                state = sep ? CountryState : NoState;
                break;
            }
            // It wasn't a script, assume it's a country.
            Q_FALLTHROUGH();
        case CountryState:
            if (land)
                *land = tag;
            state = NoState;
            break;
        case NoState: // Precluded by loop condition !
            Q_UNREACHABLE();
            break;
        }
    }
    return state != LangState;
}

QLocaleId QLocaleId::fromName(QStringView name) noexcept
{
    QStringView lang;
    QStringView script;
    QStringView land;
    if (!qt_splitLocaleName(name, &lang, &script, &land))
        return { QLocale::C, 0, 0 };

    // POSIX is a variant, but looks like a territory.
    if (land.compare("POSIX", Qt::CaseInsensitive) == 0)
        return { QLocale::C, 0, 0 };

    QLocale::Language langId = QLocalePrivate::codeToLanguage(lang);
    if (langId == QLocale::AnyLanguage)
        return { QLocale::C, 0, 0 };
    return { langId, QLocalePrivate::codeToScript(script), QLocalePrivate::codeToTerritory(land) };
}

QString qt_readEscapedFormatString(QStringView format, qsizetype *idx)
{
    qsizetype &i = *idx;

    Q_ASSERT(format.at(i) == u'\'');
    ++i;
    if (i == format.size())
        return QString();
    if (format.at(i).unicode() == '\'') { // "''" outside of a quoted string
        ++i;
        return "'"_L1;
    }

    QString result;

    while (i < format.size()) {
        if (format.at(i).unicode() == '\'') {
            if (format.mid(i + 1).startsWith(u'\'')) {
                // "''" inside a quoted string
                result.append(u'\'');
                i += 2;
            } else {
                break;
            }
        } else {
            result.append(format.at(i++));
        }
    }
    if (i < format.size())
        ++i;

    return result;
}

/*!
    \internal

    Counts the number of identical leading characters in \a s.

    If \a s is empty, returns 0.

    Otherwise, returns the number of consecutive \c{s.front()}
    characters at the start of \a s.

    \code
    qt_repeatCount(u"a");   // == 1
    qt_repeatCount(u"ab");  // == 1
    qt_repeatCount(u"aab"); // == 2
    \endcode
*/
qsizetype qt_repeatCount(QStringView s) noexcept
{
    if (s.isEmpty())
        return 0;
    const QChar c = s.front();
    qsizetype j = 1;
    while (j < s.size() && s.at(j) == c)
        ++j;
    return j;
}

Q_CONSTINIT static const QLocaleData *default_data = nullptr;
Q_CONSTINIT QBasicAtomicInt QLocalePrivate::s_generation = Q_BASIC_ATOMIC_INITIALIZER(0);

static QLocalePrivate *c_private() noexcept
{
    Q_CONSTINIT static QLocalePrivate c_locale(locale_data, 0, QLocale::OmitGroupSeparator, 1);
    return &c_locale;
}

static constexpr QLocale::NumberOptions defaultNumberOptions(QLocale::Language forLanguage)
{
    return forLanguage == QLocale::C ? QLocale::OmitGroupSeparator : QLocale::DefaultNumberOptions;
}

static constexpr QLocale::NumberOptions defaultNumberOptions(quint16 forLanguage)
{
    return defaultNumberOptions(QLocale::Language(forLanguage));
}

#ifndef QT_NO_SYSTEMLOCALE
/******************************************************************************
** Default system locale behavior
*/

/*!
    \internal
    Constructs a QSystemLocale object.

    The constructor will automatically install this object as the system locale.
    It and the destructor maintain a stack of system locales, with the
    most-recently-created instance (that hasn't yet been deleted) used as the
    system locale. This is only intended as a way to let a platform plugin
    install its own system locale, overriding what might otherwise be provided
    for its class of platform (as Android does, differing from Linux), and to
    let tests transiently override the system or plugin-supplied one. As such,
    there should not be diverse threads creating and destroying QSystemLocale
    instances concurrently, so no attempt is made at thread-safety in managing
    the stack.

    This constructor also resets the flag that'll prompt QLocale::system() to
    re-initialize its data, so that instantiating a QSystemLocale (even
    transiently) triggers a refresh of the system locale's data. This is
    exploited by some test code.
*/
QSystemLocale::QSystemLocale() : next(_systemLocale)
{
    _systemLocale = this;

    systemLocaleData.m_language_id = 0;
}

/*!
    \internal
    Deletes the object.
*/
QSystemLocale::~QSystemLocale()
{
    if (_systemLocale == this) {
        _systemLocale = next;

        // Change to system locale => force refresh.
        systemLocaleData.m_language_id = 0;
    } else {
        for (QSystemLocale *p = _systemLocale; p; p = p->next) {
            if (p->next == this)
                p->next = next;
        }
    }
}

static const QSystemLocale *systemLocale()
{
    if (_systemLocale)
        return _systemLocale;

    // As this is only ever instantiated with _systemLocale null, it is
    // necessarily the ->next-most in any chain that may subsequently develop;
    // and it won't be destructed until exit()-time.
    static QSystemLocale globalInstance;
    return &globalInstance;
}

static void updateSystemPrivate()
{
    // This function is NOT thread-safe!
    // It *should not* be called by anything but systemData()
    // It *is* called before {system,default}LocalePrivate exist.
    const QSystemLocale *sys_locale = systemLocale();

    // tell the object that the system locale has changed.
    sys_locale->query(QSystemLocale::LocaleChanged);

    // Populate system locale with fallback as basis
    systemLocaleData = locale_data[sys_locale->fallbackLocaleIndex()];

    QVariant res = sys_locale->query(QSystemLocale::LanguageId);
    if (!res.isNull()) {
        systemLocaleData.m_language_id = res.toInt();
        systemLocaleData.m_script_id = QLocale::AnyScript; // default for compatibility
    }
    res = sys_locale->query(QSystemLocale::TerritoryId);
    if (!res.isNull()) {
        systemLocaleData.m_territory_id = res.toInt();
        systemLocaleData.m_script_id = QLocale::AnyScript; // default for compatibility
    }
    res = sys_locale->query(QSystemLocale::ScriptId);
    if (!res.isNull())
        systemLocaleData.m_script_id = res.toInt();

    // Should we replace Any values based on likely sub-tags ?

    // If system locale is default locale, update the default collator's generation:
    if (default_data == &systemLocaleData)
        QLocalePrivate::s_generation.fetchAndAddRelaxed(1);
}
#endif // !QT_NO_SYSTEMLOCALE

static const QLocaleData *systemData(qsizetype *sysIndex = nullptr)
{
#ifndef QT_NO_SYSTEMLOCALE
    /*
      Copy over the information from the fallback locale and modify.

      If sysIndex is passed, it should be the m_index of the system locale's
      QLocalePrivate, which we'll update if it needs it.

      This modifies (cross-thread) global state, so is mutex-protected.
    */
    {
        Q_CONSTINIT static QLocaleId sysId;
        bool updated = false;

        Q_CONSTINIT static QBasicMutex systemDataMutex;
        systemDataMutex.lock();
        if (systemLocaleData.m_language_id == 0) {
            updateSystemPrivate();
            updated = true;
        }
        // Initialization of system private has *sysIndex == -1 to hit this.
        if (sysIndex && (updated || *sysIndex < 0)) {
            const QLocaleId nowId = systemLocaleData.id();
            if (sysId != nowId || *sysIndex < 0) {
                // This look-up may be expensive:
                *sysIndex = QLocaleData::findLocaleIndex(nowId);
                sysId = nowId;
            }
        }
        systemDataMutex.unlock();
    }

    return &systemLocaleData;
#else
    Q_UNUSED(sysIndex);
    return locale_data;
#endif
}

static const QLocaleData *defaultData()
{
    if (!default_data)
        default_data = systemData();
    return default_data;
}

static qsizetype defaultIndex()
{
    const QLocaleData *const data = defaultData();
#ifndef QT_NO_SYSTEMLOCALE
    if (data == &systemLocaleData) {
        // Work out a suitable index matching the system data, for use when
        // accessing calendar data, when not fetched from system.
        return QLocaleData::findLocaleIndex(data->id());
    }
#endif

    using QtPrivate::q_points_into_range;
    Q_ASSERT(q_points_into_range(data, locale_data));
    return data - locale_data;
}

const QLocaleData *QLocaleData::c() noexcept
{
    Q_ASSERT(locale_index[QLocale::C] == 0);
    return locale_data;
}

#ifndef QT_NO_DATASTREAM
QDataStream &operator<<(QDataStream &ds, const QLocale &l)
{
    ds << l.name();
    return ds;
}

QDataStream &operator>>(QDataStream &ds, QLocale &l)
{
    QString s;
    ds >> s;
    l = QLocale(s);
    return ds;
}
#endif // QT_NO_DATASTREAM

Q_GLOBAL_STATIC(QSharedDataPointer<QLocalePrivate>, defaultLocalePrivate,
                new QLocalePrivate(defaultData(), defaultIndex(),
                                   defaultNumberOptions(defaultData()->m_language_id)))

static QLocalePrivate *localePrivateByName(QStringView name)
{
    if (name == u"C")
        return c_private();
    const qsizetype index = QLocaleData::findLocaleIndex(QLocaleId::fromName(name));
    return new QLocalePrivate(QLocaleData::dataForLocaleIndex(index), index,
                              defaultNumberOptions(locale_data[index].m_language_id));
}

static QLocalePrivate *findLocalePrivate(QLocale::Language language, QLocale::Script script,
                                         QLocale::Territory territory)
{
    if (language == QLocale::C)
        return c_private();

    qsizetype index = QLocaleData::findLocaleIndex(QLocaleId { language, script, territory });
    const QLocaleData *data = QLocaleData::dataForLocaleIndex(index);

    QLocale::NumberOptions numberOptions = QLocale::DefaultNumberOptions;

    // If not found, should use default locale:
    if (data->m_language_id == QLocale::C) {
        if (defaultLocalePrivate.exists())
            numberOptions = defaultLocalePrivate->data()->m_numberOptions;
        data = defaultData();
        index = defaultIndex();
    }
    return new QLocalePrivate(data, index, numberOptions);
}

bool comparesEqual(const QLocale &loc, QLocale::Language lang)
{
    // Keep in sync with findLocalePrivate()!
    auto compareWithPrivate = [&loc](const QLocaleData *data, QLocale::NumberOptions opts)
    {
        return loc.d->m_data == data && loc.d->m_numberOptions == opts;
    };

    if (lang == QLocale::C)
        return compareWithPrivate(c_private()->m_data, c_private()->m_numberOptions);

    qsizetype index = QLocaleData::findLocaleIndex(QLocaleId { lang });
    const QLocaleData *data = QLocaleData::dataForLocaleIndex(index);

    QLocale::NumberOptions numberOptions = QLocale::DefaultNumberOptions;

    // If not found, should use default locale:
    if (data->m_language_id == QLocale::C) {
        if (defaultLocalePrivate.exists())
            numberOptions = defaultLocalePrivate->data()->m_numberOptions;
        data = defaultData();
    }
    return compareWithPrivate(data, numberOptions);
}

static std::optional<QString>
systemLocaleString(const QLocaleData *that, QSystemLocale::QueryType type)
{
#ifndef QT_NO_SYSTEMLOCALE
    if (that != &systemLocaleData)
        return std::nullopt;

    QVariant v = systemLocale()->query(type);
    if (v.metaType() != QMetaType::fromType<QString>())
        return std::nullopt;

    return v.toString();
#else
    Q_UNUSED(that)
    Q_UNUSED(type)
    return std::nullopt;
#endif
}

static QString localeString(const QLocaleData *that, QSystemLocale::QueryType type,
                            QLocaleData::DataRange range)
{
    if (auto opt = systemLocaleString(that, type))
        return *opt;
    return range.getData(single_character_data);
}

QString QLocaleData::decimalPoint() const
{
    return localeString(this, QSystemLocale::DecimalPoint, decimalSeparator());
}

QString QLocaleData::groupSeparator() const
{
    return localeString(this, QSystemLocale::GroupSeparator, groupDelim());
}

QString QLocaleData::percentSign() const
{
    return percent().getData(single_character_data);
}

QString QLocaleData::listSeparator() const
{
    return listDelimit().getData(single_character_data);
}

QString QLocaleData::zeroDigit() const
{
    return localeString(this, QSystemLocale::ZeroDigit, zero());
}

char32_t QLocaleData::zeroUcs() const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (this == &systemLocaleData) {
        const auto text = systemLocale()->query(QSystemLocale::ZeroDigit).toString();
        if (!text.isEmpty()) {
            if (text.size() == 1 && !text.at(0).isSurrogate())
                return text.at(0).unicode();
            if (text.size() == 2 && text.at(0).isHighSurrogate())
                return QChar::surrogateToUcs4(text.at(0), text.at(1));
        }
    }
#endif
    return zero().ucsFirst(single_character_data);
}

QString QLocaleData::negativeSign() const
{
    return localeString(this, QSystemLocale::NegativeSign, minus());
}

QString QLocaleData::positiveSign() const
{
    return localeString(this, QSystemLocale::PositiveSign, plus());
}

QString QLocaleData::exponentSeparator() const
{
    return exponential().getData(single_character_data);
}

QLocaleData::GroupSizes QLocaleData::groupSizes() const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (this == &systemLocaleData) {
        QVariant queryResult = systemLocale()->query(QSystemLocale::Grouping);
        if (!queryResult.isNull()) {
            QLocaleData::GroupSizes sysGroupSizes =
                    queryResult.value<QLocaleData::GroupSizes>();
            if (sysGroupSizes.first <= 0)
                sysGroupSizes.first = m_grouping_first;
            if (sysGroupSizes.higher <= 0)
                sysGroupSizes.higher = m_grouping_higher;
            if (sysGroupSizes.least <= 0)
                sysGroupSizes.least = m_grouping_least;
            return sysGroupSizes;
        }
    }
#endif
    return { m_grouping_first,
             m_grouping_higher,
             m_grouping_least };
}

/*!
 \internal
*/
QLocale::QLocale(QLocalePrivate &dd)
    // If this ever becomes explicitly noexcept(false),
    // adjust QLocale::c() to not use this ctor anymore.
    : d(&dd)
{}

/*!
    \variable QLocale::DefaultTwoDigitBaseYear
    \since 6.7

    \brief The default start year of the century within which a format taking
    a two-digit year will select. The value of the constant is \c {1900}.

    Some locales use, particularly for ShortFormat, only the last two digits of
    the year. Proir to 6.7 the year 1900 was always used as a base year for
    such cases. Now various QLocale and QDate functions have the overloads that
    allow callers to specify the base year, and this constant is used as its
    default value.

    \sa toDate(), toDateTime(), QDate::fromString(), QDateTime::fromString()
*/

/*!
    \since 6.3

    Constructs a QLocale object with the specified \a name.

    The name has the format "language[_script][_territory][.codeset][@modifier]"
    or "C", where:

    \list
    \li language is a lowercase, two-letter, ISO 639 language code (some
        three-letter codes are also recognized),
    \li script is a capitalized, four-letter, ISO 15924 script code,
    \li territory is an uppercase, two-letter, ISO 3166 territory code
        (some numeric codes are also recognized), and
    \li codeset and modifier are ignored.
    \endlist

    The separator can be either underscore \c{'_'} (U+005F, "low line") or a
    dash \c{'-'} (U+002D, "hyphen-minus"). If QLocale has no data for the
    specified combination of language, script, and territory, then it uses the
    most suitable match it can find instead. If the string violates the locale
    format, or no suitable data can be found for the specified keys, the "C"
    locale is used instead.

    This constructor is much slower than QLocale(Language, Script, Territory) or
    QLocale(Language, Territory).

    \sa bcp47Name(), {Matching combinations of language, script and territory}
*/
QLocale::QLocale(QStringView name)
    : d(localePrivateByName(name))
{
}

/*!
    \fn QLocale::QLocale(const QString &name)
    \overload
*/

/*!
    Constructs a QLocale object initialized with the default locale.

    If no default locale was set using setDefault(), this locale will be the
    same as the one returned by system().

    \sa setDefault(), system()
*/

QLocale::QLocale()
    : d(c_private())
{
    if (!defaultLocalePrivate.isDestroyed()) {
        // Make sure system data is up to date:
        systemData();
        d = *defaultLocalePrivate;
    }
}

/*!
    Constructs a QLocale object for the specified \a language and \a territory.

    If there is more than one script in use for this combination, a likely
    script will be selected. If QLocale has no data for the specified \a
    language, the default locale is used. If QLocale has no data for the
    specified combination of \a language and \a territory, an alternative
    territory may be used instead.

    \sa setDefault(), {Matching combinations of language, script and territory}
*/

QLocale::QLocale(Language language, Territory territory)
    : d(findLocalePrivate(language, AnyScript, territory))
{
}

/*!
    \since 4.8

    Constructs a QLocale object for the specified \a language, \a script and \a
    territory.

    If QLocale does not have data for the given combination, it will find data
    for as good a match as it can. It falls back on the default locale if

    \list
    \li \a language is \c AnyLanguage and no language can be inferred from \a
        script and \a territory
    \li QLocale has no data for the language, either given as \a language or
        inferred as above.
    \endlist

    \sa setDefault(), {Matching combinations of language, script and territory}
*/

QLocale::QLocale(Language language, Script script, Territory territory)
    : d(findLocalePrivate(language, script, territory))
{
}

/*!
    Constructs a QLocale object as a copy of \a other.
*/

QLocale::QLocale(const QLocale &other) noexcept = default;

/*!
    Destructor
*/

QLocale::~QLocale()
{
}

/*!
    Assigns \a other to this QLocale object and returns a reference
    to this QLocale object.
*/

QLocale &QLocale::operator=(const QLocale &other) noexcept = default;

/*!
    \internal
    Equality comparison.
*/

bool QLocale::equals(const QLocale &other) const noexcept
{
    return d->m_data == other.d->m_data && d->m_numberOptions == other.d->m_numberOptions;
}

/*!
    \fn void QLocale::swap(QLocale &other)
    \since 5.6
    \memberswap{locale}
*/

/*!
    \since 5.6
    \qhashold{QLocale}
*/
size_t qHash(const QLocale &key, size_t seed) noexcept
{
    return qHashMulti(seed, key.d->m_data, key.d->m_numberOptions);
}

/*!
    \since 4.2

    Sets the \a options related to number conversions for this QLocale instance.

    \sa numberOptions(), FloatingPointPrecisionOption
*/
void QLocale::setNumberOptions(NumberOptions options)
{
    d->m_numberOptions = options;
}

/*!
    \since 4.2

    Returns the options related to number conversions for this QLocale instance.

    By default, no options are set for the standard locales, except for the "C"
    locale, which has OmitGroupSeparator set by default.

    \sa setNumberOptions(), toString(), groupSeparator(), FloatingPointPrecisionOption
*/
QLocale::NumberOptions QLocale::numberOptions() const
{
    return d->m_numberOptions;
}

/*!
  \fn QString QLocale::quoteString(const QString &str, QuotationStyle style) const

    \since 4.8

    Returns \a str quoted according to the current locale using the given
    quotation \a style.
*/

/*!
    \since 6.0

    \overload
*/
QString QLocale::quoteString(QStringView str, QuotationStyle style) const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        QVariant res;
        if (style == AlternateQuotation)
            res = systemLocale()->query(QSystemLocale::StringToAlternateQuotation,
                                        QVariant::fromValue(str));
        if (res.isNull() || style == StandardQuotation)
            res = systemLocale()->query(QSystemLocale::StringToStandardQuotation,
                                        QVariant::fromValue(str));
        if (!res.isNull())
            return res.toString();
    }
#endif

    QLocaleData::DataRange start, end;
    if (style == StandardQuotation) {
        start = d->m_data->quoteStart();
        end = d->m_data->quoteEnd();
    } else {
        start = d->m_data->quoteStartAlternate();
        end = d->m_data->quoteEndAlternate();
    }

    return start.viewData(single_character_data) % str % end.viewData(single_character_data);
}

/*!
    \since 4.8

    Returns a string that represents a join of a given \a list of strings with
    a separator defined by the locale.
*/
QString QLocale::createSeparatedList(const QStringList &list) const
{
    // May be empty if list is empty or sole entry is empty.
#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        QVariant res =
            systemLocale()->query(QSystemLocale::ListToSeparatedString, QVariant::fromValue(list));

        if (!res.isNull())
            return res.toString();
    }
#endif

    const qsizetype size = list.size();
    if (size < 1)
        return QString();

    if (size == 1)
        return list.at(0);

    if (size == 2)
        return d->m_data->pairListPattern().getData(
            list_pattern_part_data).arg(list.at(0), list.at(1));

    QStringView formatStart = d->m_data->startListPattern().viewData(list_pattern_part_data);
    QStringView formatMid = d->m_data->midListPattern().viewData(list_pattern_part_data);
    QStringView formatEnd = d->m_data->endListPattern().viewData(list_pattern_part_data);
    QString result = formatStart.arg(list.at(0), list.at(1));
    for (qsizetype i = 2; i < size - 1; ++i)
        result = formatMid.arg(result, list.at(i));
    result = formatEnd.arg(result, list.at(size - 1));
    return result;
}

/*!
    \nonreentrant

    Sets the global default locale to \a locale.

    This locale is used when a QLocale object is constructed with no
    arguments. If this function is not called, the system's locale is used.

    \warning In a multithreaded application, the default locale should be set at
    application startup, before any non-GUI threads are created.

    \sa system(), c()
*/

void QLocale::setDefault(const QLocale &locale)
{
    default_data = locale.d->m_data;

    if (defaultLocalePrivate.isDestroyed())
        return; // avoid crash on exit
    if (!defaultLocalePrivate.exists()) {
        // Force it to exist; see QTBUG-83016
        [[maybe_unused]] QLocale ignoreme;
        Q_ASSERT(defaultLocalePrivate.exists());
    }

    // update the cached private
    *defaultLocalePrivate = locale.d;
    QLocalePrivate::s_generation.fetchAndAddRelaxed(1);
}

/*!
    Returns the language of this locale.

    \sa script(), territory(), languageToString(), bcp47Name()
*/
QLocale::Language QLocale::language() const
{
    return Language(d->languageId());
}

/*!
    \since 4.8

    Returns the script of this locale.

    \sa language(), territory(), languageToString(), scriptToString(), bcp47Name()
*/
QLocale::Script QLocale::script() const
{
    return Script(d->m_data->m_script_id);
}

/*!
    \since 6.2

    Returns the territory of this locale.

    \sa language(), script(), territoryToString(), bcp47Name()
*/
QLocale::Territory QLocale::territory() const
{
    return Territory(d->territoryId());
}

#if QT_DEPRECATED_SINCE(6, 6)
/*!
    \deprecated [6.6] Use \l territory() instead.

    Returns the territory of this locale.

    \sa language(), script(), territoryToString(), bcp47Name()
*/
QLocale::Country QLocale::country() const
{
    return territory();
}
#endif

/*!
    \since 6.7
    \enum QLocale::TagSeparator

    Indicate how to combine the parts that make up a locale identifier.

    A locale identifier may be made up of several tags, indicating language,
    script and territory (plus, potentially, other details), joined together to
    form the identifier. Various standards and conventional forms use either a
    dash (the Unicode HYPHEN-MINUS, U+002D) or an underscore (LOW LINE, U+005F).
    Different clients of QLocale may thus need one or the other.

    \value Dash Use \c{'-'}, the dash or hyphen character.
    \value Underscore Use \c{'_'}, the underscore character.

    \note Although dash and underscore are the only separators used in public
    standards (as at 2023), it is possible to cast any \l
    {https://en.cppreference.com/w/cpp/language/ascii} {ASCII} character to this
    type if a non-standard ASCII separator is needed. Casting a non-ASCII
    character (with decimal value above 127) is not supported: such values are
    reserved for future use as enum members if some public standard ever uses a
    non-ASCII separator. It is, of course, possible to use QString::replace() to
    replace the separator used by a function taking a parameter of this type
    with an arbitrary Unicode character or string.
*/

Q_DECL_COLD_FUNCTION static void badSeparatorWarning(const char *method, char sep)
{
    qWarning("QLocale::%s(): Using non-ASCII separator '%c' (%02x) is unsupported",
             method, sep, uint(uchar(sep)));
}

/*!
    \brief The short name of this locale.

    Returns the language and territory of this locale as a string of the form
    "language_territory", where language is a lowercase, two-letter ISO 639
    language code, and territory is an uppercase, two- or three-letter ISO 3166
    territory code. If the locale has no specified territory, only the language
    name is returned. Since Qt 6.7 an optional \a separator parameter can be
    supplied to override the default underscore character separating the two
    tags.

    Even if the QLocale object was constructed with an explicit script, name()
    will not contain it for compatibility reasons. Use \l bcp47Name() instead if
    you need a full locale name, or construct the string you want to identify a
    locale by from those returned by passing its \l language() to \l
    languageToCode() and similar for the script and territory.

    \sa QLocale(), language(), script(), territory(), bcp47Name(), uiLanguages()
*/

QString QLocale::name(TagSeparator separator) const
{
    const char sep = char(separator);
    if (uchar(sep) > 0x7f) {
        badSeparatorWarning("name", sep);
        return {};
    }
    const auto code = d->languageCode();
    QLatin1StringView view{code.data()};

    Language l = language();
    if (l == C)
        return view;

    Territory c = territory();
    if (c == AnyTerritory)
        return view;

    return view + QLatin1Char(sep) + d->territoryCode();
}

template <typename T> static inline
T toIntegral_helper(const QLocalePrivate *d, QStringView str, bool *ok)
{
    constexpr bool isUnsigned = std::is_unsigned_v<T>;
    using Int64 = typename std::conditional_t<isUnsigned, quint64, qint64>;

    QSimpleParsedNumber<Int64> r{};
    if constexpr (isUnsigned)
        r = d->m_data->stringToUnsLongLong(str, 10, d->m_numberOptions);
    else
        r = d->m_data->stringToLongLong(str, 10, d->m_numberOptions);

    if (ok)
        *ok = r.ok();

    Int64 val = r.result;
    if (T(val) != val) {
        if (ok != nullptr)
            *ok = false;
        val = 0;
    }
    return T(val);
}


/*!
    \since 4.8

    \brief Returns the BCP47 field names joined with dashes.

    This combines as many of language, script and territory (and possibly other
    BCP47 fields) for this locale as are needed to uniquely specify it. Note
    that fields may be omitted if the Unicode consortium's \l {Matching
    combinations of language, script and territory}{Likely Subtag Rules} imply
    the omitted fields when given those retained. See \l name() for how to
    construct a string from individual fields, if some other format is needed.

    Unlike uiLanguages(), the value returned by bcp47Name() represents the
    locale name of the QLocale data; this need not be the language the
    user-interface should be in.

    This function tries to conform the locale name to the IETF Best Common
    Practice 47, defined by RFC 5646. Since Qt 6.7, it supports an optional \a
    separator parameter which can be used to override the BCP47-specified use of
    a hyphen to separate the tags. For use in IETF-defined protocols, however,
    the default, QLocale::TagSeparator::Dash, should be retained.

    \sa name(), language(), territory(), script(), uiLanguages()
*/
QString QLocale::bcp47Name(TagSeparator separator) const
{
    const char sep = char(separator);
    if (uchar(sep) > 0x7f) {
        badSeparatorWarning("bcp47Name", sep);
        return {};
    }
    return QString::fromLatin1(d->bcp47Name(sep));
}

/*!
    Returns the two- or three-letter language code for \a language, as defined
    in the ISO 639 standards.

    If specified, \a codeTypes selects which set of codes to consider. The first
    code from the set that is defined for \a language is returned. Otherwise,
    all ISO-639 codes are considered. The codes are considered in the following
    order: \c ISO639Part1, \c ISO639Part2B, \c ISO639Part2T, \c ISO639Part3.
    \c LegacyLanguageCode is ignored by this function.

    \note For \c{QLocale::C} the function returns \c{"C"}.
    For \c QLocale::AnyLanguage an empty string is returned.
    If the language has no code in any selected code set, an empty string
    is returned.

    \since 6.3
    \sa codeToLanguage(), language(), name(), bcp47Name(), territoryToCode(), scriptToCode()
*/
QString QLocale::languageToCode(Language language, LanguageCodeTypes codeTypes)
{
    const auto code = QLocalePrivate::languageToCode(language, codeTypes);
    return QLatin1StringView{code.data()};
}

/*!
    Returns the QLocale::Language enum corresponding to the two- or three-letter
    \a languageCode, as defined in the ISO 639 standards.

    If specified, \a codeTypes selects which set of codes to consider for
    conversion. By default all codes known to Qt are considered. The codes are
    matched in the following order: \c ISO639Part1, \c ISO639Part2B,
    \c ISO639Part2T, \c ISO639Part3, \c LegacyLanguageCode.

    If the code is invalid or not known \c QLocale::AnyLanguage is returned.

    \since 6.3
    \sa languageToCode(), codeToTerritory(), codeToScript()
*/
QLocale::Language QLocale::codeToLanguage(QStringView languageCode,
                                          LanguageCodeTypes codeTypes) noexcept
{
    return QLocalePrivate::codeToLanguage(languageCode, codeTypes);
}

/*!
    \since 6.2

    Returns the two-letter territory code for \a territory, as defined
    in the ISO 3166 standard.

    \note For \c{QLocale::AnyTerritory} an empty string is returned.

    \sa codeToTerritory(), territory(), name(), bcp47Name(), languageToCode(), scriptToCode()
*/
QString QLocale::territoryToCode(QLocale::Territory territory)
{
    return QLocalePrivate::territoryToCode(territory);
}

/*!
    \since 6.2

    Returns the QLocale::Territory enum corresponding to the two-letter or
    three-digit \a territoryCode, as defined in the ISO 3166 standard.

    If the code is invalid or not known QLocale::AnyTerritory is returned.

    \sa territoryToCode(), codeToLanguage(), codeToScript()
*/
QLocale::Territory QLocale::codeToTerritory(QStringView territoryCode) noexcept
{
    return QLocalePrivate::codeToTerritory(territoryCode);
}

#if QT_DEPRECATED_SINCE(6, 6)
/*!
    \deprecated [6.6] Use \l territoryToCode() instead.

    Returns the two-letter territory code for \a country, as defined
    in the ISO 3166 standard.

    \note For \c{QLocale::AnyTerritory} or \c{QLocale::AnyCountry} an empty string is returned.

    \sa codeToTerritory(), territory(), name(), bcp47Name(), languageToCode(), scriptToCode()
*/
QString QLocale::countryToCode(Country country)
{
    return territoryToCode(country);
}

/*!
    Returns the QLocale::Territory enum corresponding to the two-letter or
    three-digit \a countryCode, as defined in the ISO 3166 standard.

    If the code is invalid or not known QLocale::AnyTerritory is returned.

    \deprecated [6.6] Use codeToTerritory(QStringView) instead.
    \since 6.1
    \sa territoryToCode(), codeToLanguage(), codeToScript()
*/
QLocale::Country QLocale::codeToCountry(QStringView countryCode) noexcept
{
    return QLocalePrivate::codeToTerritory(countryCode);
}
#endif

/*!
    Returns the four-letter script code for \a script, as defined in the
    ISO 15924 standard.

    \note For \c{QLocale::AnyScript} an empty string is returned.

    \since 6.1
    \sa script(), name(), bcp47Name(), languageToCode(), territoryToCode()
*/
QString QLocale::scriptToCode(Script script)
{
    return QLocalePrivate::scriptToCode(script);
}

/*!
    Returns the QLocale::Script enum corresponding to the four-letter script
    \a scriptCode, as defined in the ISO 15924 standard.

    If the code is invalid or not known QLocale::AnyScript is returned.

    \since 6.1
    \sa scriptToCode(), codeToLanguage(), codeToTerritory()
*/
QLocale::Script QLocale::codeToScript(QStringView scriptCode) noexcept
{
    return QLocalePrivate::codeToScript(scriptCode);
}

/*!
    Returns a QString containing the name of \a language.

    \sa territoryToString(), scriptToString(), bcp47Name()
*/

QString QLocale::languageToString(Language language)
{
    if (language > LastLanguage)
        return "Unknown"_L1;
    return QString::fromUtf8(language_name_list + language_name_index[language]);
}

/*!
    \since 6.2

    Returns a QString containing the name of \a territory.

    \sa languageToString(), scriptToString(), territory(), bcp47Name()
*/
QString QLocale::territoryToString(Territory territory)
{
    if (territory > LastTerritory)
        return "Unknown"_L1;
    return QString::fromUtf8(territory_name_list + territory_name_index[territory]);
}

#if QT_DEPRECATED_SINCE(6, 6)
/*!
    \deprecated [6.6] Use \l territoryToString() instead.

    Returns a QString containing the name of \a country.

    \sa languageToString(), scriptToString(), territory(), bcp47Name()
*/
QString QLocale::countryToString(Country country)
{
    return territoryToString(country);
}
#endif

/*!
    \since 4.8

    Returns a QString containing the name of \a script.

    \sa languageToString(), territoryToString(), script(), bcp47Name()
*/
QString QLocale::scriptToString(Script script)
{
    if (script > LastScript)
        return "Unknown"_L1;
    return QString::fromUtf8(script_name_list + script_name_index[script]);
}

/*!
    \fn short QLocale::toShort(const QString &s, bool *ok) const

    Returns the short int represented by the localized string \a s.

    If the conversion fails the function returns 0.

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    This function ignores leading and trailing whitespace.

    \sa toUShort(), toString()
*/

/*!
    \fn ushort QLocale::toUShort(const QString &s, bool *ok) const

    Returns the unsigned short int represented by the localized string \a s.

    If the conversion fails the function returns 0.

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    This function ignores leading and trailing whitespace.

    \sa toShort(), toString()
*/

/*!
    \fn int QLocale::toInt(const QString &s, bool *ok) const
    Returns the int represented by the localized string \a s.

    If the conversion fails the function returns 0.

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    This function ignores leading and trailing whitespace.

    \sa toUInt(), toString()
*/

/*!
    \fn uint QLocale::toUInt(const QString &s, bool *ok) const
    Returns the unsigned int represented by the localized string \a s.

    If the conversion fails the function returns 0.

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    This function ignores leading and trailing whitespace.

    \sa toInt(), toString()
*/

/*!
    \since 5.13
    \fn long QLocale::toLong(const QString &s, bool *ok) const

    Returns the long int represented by the localized string \a s.

    If the conversion fails the function returns 0.

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    This function ignores leading and trailing whitespace.

    \sa toInt(), toULong(), toDouble(), toString()
*/

/*!
    \since 5.13
    \fn ulong QLocale::toULong(const QString &s, bool *ok) const

    Returns the unsigned long int represented by the localized
    string \a s.

    If the conversion fails the function returns 0.

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    This function ignores leading and trailing whitespace.

    \sa toLong(), toInt(), toDouble(), toString()
*/

/*!
    \fn qlonglong QLocale::toLongLong(const QString &s, bool *ok) const
    Returns the long long int represented by the localized string \a s.

    If the conversion fails the function returns 0.

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    This function ignores leading and trailing whitespace.

    \sa toInt(), toULongLong(), toDouble(), toString()
*/

/*!
    \fn qulonglong QLocale::toULongLong(const QString &s, bool *ok) const

    Returns the unsigned long long int represented by the localized
    string \a s.

    If the conversion fails the function returns 0.

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    This function ignores leading and trailing whitespace.

    \sa toLongLong(), toInt(), toDouble(), toString()
*/

/*!
    \fn float QLocale::toFloat(const QString &s, bool *ok) const

    Returns the float represented by the localized string \a s.

    Returns an infinity if the conversion overflows or 0.0 if the
    conversion fails for any other reason (e.g. underflow).

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    This function ignores leading and trailing whitespace.

    \sa toDouble(), toInt(), toString()
*/

/*!
    \fn double QLocale::toDouble(const QString &s, bool *ok) const
    Returns the double represented by the localized string \a s.

    Returns an infinity if the conversion overflows or 0.0 if the
    conversion fails for any other reason (e.g. underflow).

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    \snippet code/src_corelib_text_qlocale.cpp 3

    Notice that the last conversion returns 1234.0, because '.' is the
    thousands group separator in the German locale.

    This function ignores leading and trailing whitespace.

    \sa toFloat(), toInt(), toString()
*/

/*!
    Returns the short int represented by the localized string \a s.

    If the conversion fails, the function returns 0.

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    This function ignores leading and trailing whitespace.

    \sa toUShort(), toString()

    \since 5.10
*/

short QLocale::toShort(QStringView s, bool *ok) const
{
    return toIntegral_helper<short>(d, s, ok);
}

/*!
    Returns the unsigned short int represented by the localized string \a s.

    If the conversion fails, the function returns 0.

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    This function ignores leading and trailing whitespace.

    \sa toShort(), toString()

    \since 5.10
*/

ushort QLocale::toUShort(QStringView s, bool *ok) const
{
    return toIntegral_helper<ushort>(d, s, ok);
}

/*!
    Returns the int represented by the localized string \a s.

    If the conversion fails, the function returns 0.

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    This function ignores leading and trailing whitespace.

    \sa toUInt(), toString()

    \since 5.10
*/

int QLocale::toInt(QStringView s, bool *ok) const
{
    return toIntegral_helper<int>(d, s, ok);
}

/*!
    Returns the unsigned int represented by the localized string \a s.

    If the conversion fails, the function returns 0.

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    This function ignores leading and trailing whitespace.

    \sa toInt(), toString()

    \since 5.10
*/

uint QLocale::toUInt(QStringView s, bool *ok) const
{
    return toIntegral_helper<uint>(d, s, ok);
}

/*!
    \since 5.13
    Returns the long int represented by the localized string \a s.

    If the conversion fails the function returns 0.

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    This function ignores leading and trailing whitespace.

    \sa toInt(), toULong(), toDouble(), toString()
*/

long QLocale::toLong(QStringView s, bool *ok) const
{
    return toIntegral_helper<long>(d, s, ok);
}

/*!
    \since 5.13
    Returns the unsigned long int represented by the localized
    string \a s.

    If the conversion fails the function returns 0.

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    This function ignores leading and trailing whitespace.

    \sa toLong(), toInt(), toDouble(), toString()
*/

ulong QLocale::toULong(QStringView s, bool *ok) const
{
    return toIntegral_helper<ulong>(d, s, ok);
}

/*!
    Returns the long long int represented by the localized string \a s.

    If the conversion fails, the function returns 0.

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    This function ignores leading and trailing whitespace.

    \sa toInt(), toULongLong(), toDouble(), toString()

    \since 5.10
*/


qlonglong QLocale::toLongLong(QStringView s, bool *ok) const
{
    return toIntegral_helper<qlonglong>(d, s, ok);
}

/*!
    Returns the unsigned long long int represented by the localized
    string \a s.

    If the conversion fails, the function returns 0.

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    This function ignores leading and trailing whitespace.

    \sa toLongLong(), toInt(), toDouble(), toString()

    \since 5.10
*/

qulonglong QLocale::toULongLong(QStringView s, bool *ok) const
{
    return toIntegral_helper<qulonglong>(d, s, ok);
}

/*!
    Returns the float represented by the localized string \a s.

    Returns an infinity if the conversion overflows or 0.0 if the
    conversion fails for any other reason (e.g. underflow).

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    This function ignores leading and trailing whitespace.

    \sa toDouble(), toInt(), toString()

    \since 5.10
*/

float QLocale::toFloat(QStringView s, bool *ok) const
{
    return QLocaleData::convertDoubleToFloat(toDouble(s, ok), ok);
}

/*!
    Returns the double represented by the localized string \a s.

    Returns an infinity if the conversion overflows or 0.0 if the
    conversion fails for any other reason (e.g. underflow).

    If \a ok is not \nullptr, failure is reported by setting *\a{ok}
    to \c false, and success by setting *\a{ok} to \c true.

    \snippet code/src_corelib_text_qlocale.cpp 3-qstringview

    Notice that the last conversion returns 1234.0, because '.' is the
    thousands group separator in the German locale.

    This function ignores leading and trailing whitespace.

    \sa toFloat(), toInt(), toString()

    \since 5.10
*/

double QLocale::toDouble(QStringView s, bool *ok) const
{
    return d->m_data->stringToDouble(s, ok, d->m_numberOptions);
}

/*!
    Returns a localized string representation of \a i.

    \sa toLongLong(), numberOptions(), zeroDigit(), positiveSign()
*/

QString QLocale::toString(qlonglong i) const
{
    int flags = (d->m_numberOptions & OmitGroupSeparator
                 ? 0 : QLocaleData::GroupDigits);

    return d->m_data->longLongToString(i, -1, 10, -1, flags);
}

/*!
    \overload

    \sa toULongLong(), numberOptions(), zeroDigit(), positiveSign()
*/

QString QLocale::toString(qulonglong i) const
{
    int flags = (d->m_numberOptions & OmitGroupSeparator
                 ? 0 : QLocaleData::GroupDigits);

    return d->m_data->unsLongLongToString(i, -1, 10, -1, flags);
}
// ### Incorrect way of calculating the width, will be fixed soon.
static qsizetype stringWidth(QStringView text)
{
    QStringIterator counter(text);
    qsizetype count = 0;
    while (counter.hasNext()) {
        ++count;
        [[maybe_unused]] auto ch = counter.next();
    }
    return count;
}

static unsigned calculateFlags(int fieldWidth, char32_t fillChar,
                               const QLocale &locale)
{
    unsigned flags = QLocaleData::NoFlags;
    if (!(locale.numberOptions() & QLocale::OmitGroupSeparator))
        flags |= QLocaleData::GroupDigits;
    if (fieldWidth < 0)
        flags |= QLocaleData::LeftAdjusted;
    else if (fillChar == U'0')
        flags |= QLocaleData::ZeroPadded;

    return flags;
}

static QString calculateFiller(qsizetype padding,
                               char32_t fillChar,
                               [[maybe_unused]] qsizetype fieldWidth,
                               const QLocaleData *localeData)
{
    QString filler;
    if (fillChar == U'0') {
        Q_ASSERT(fieldWidth < 0);
        filler = localeData->zeroDigit();
    } else {
        filler = QString(QChar::fromUcs4(fillChar));
    }
    // ### size is not width
    if (padding > 1)
        filler = filler.repeated(padding);
    return filler;
}

/*!
    \fn QString QLocale::toString(short number, int fieldWidth, char32_t fillChar) const
    \fn QString QLocale::toString(int number, int fieldWidth, char32_t fillChar) const
    \fn QString QLocale::toString(long number, int fieldWidth, char32_t fillChar) const
    \include qlocale.cpp tostring-with-padding
    \include qlocale.cpp tostring-signed-padding
*/
/*!
//! [tostring-with-padding]
    Returns a string representation of the given \a number.

    The string's length shall be at least the absolute value of \a fieldWidth,
    using \a fillChar as padding if the \a number has fewer digits. If
    \a fillChar is \c{'0'} the zero digit of this locale is used as padding.
    If \a fieldWidth is negative the string starts with its representation
    of \a number and, if shorter, is padded to length \c{-fieldWidth} with
    the given \a fillChar. For positive fieldWidth, the padding appears before
    the representation of \a number.
//! [tostring-with-padding]
//! [tostring-signed-padding]
    When the \a number is negative and \a fieldWidth is positive, if
    \a fillChar is a \c{'0'} the padding is inserted between this locale's
    minus sign and the start of the number's digits.
    \overload toString()
//! [tostring-signed-padding]
 */
QString QLocale::toString(qlonglong number, int fieldWidth, char32_t fillChar) const
{
    int absFieldWidth = qAbs(fieldWidth);
    int width = (fillChar == U'0') ? absFieldWidth : -1;
    unsigned flags = calculateFlags(fieldWidth, fillChar, *this);

    QString result = d->m_data->longLongToString(number, -1, 10, width, flags);
    qsizetype padding = absFieldWidth - stringWidth(result);

    if (padding > 0) {
        QString filler = calculateFiller(padding, fillChar, fieldWidth, d->m_data);
        if (fieldWidth < 0)
            result.append(filler);
        else
            result.prepend(filler);
    }
    return result;
}

/*!
    \fn QString QLocale::toString(ushort number, int fieldWidth, char32_t fillChar) const
    \fn QString QLocale::toString(uint number, int fieldWidth, char32_t fillChar) const
    \fn QString QLocale::toString(ulong number, int fieldWidth, char32_t fillChar) const
    \include qlocale.cpp tostring-with-padding
    \overload toString()
 */
/*!
    \include qlocale.cpp tostring-with-padding
    \overload toString()
 */
QString QLocale::toString(qulonglong number, int fieldWidth, char32_t fillChar) const
{
    int absFieldWidth = qAbs(fieldWidth);
    int width = (fillChar == U'0') ? absFieldWidth : -1;
    unsigned flags = calculateFlags(fieldWidth, fillChar, *this);

    QString result = d->m_data->unsLongLongToString(number, -1, 10, width, flags);
    qsizetype padding = absFieldWidth - stringWidth(result);

    if (padding > 0) {
        QString filler = calculateFiller(padding, fillChar, fieldWidth, d->m_data);
        if (fieldWidth < 0)
            result.append(filler);
        else
            result.prepend(filler);
    }
    return result;
}

/*!
    Returns a localized string representation of the given \a date in the
    specified \a format.
    If \a format is an empty string, an empty string is returned.

    \sa QDate::toString()
*/

QString QLocale::toString(QDate date, const QString &format) const
{
    return toString(date, qToStringViewIgnoringNull(format));
}

/*!
    Returns a localized string representation of the given \a time according
    to the specified \a format.
    If \a format is an empty string, an empty string is returned.

    \sa QTime::toString()
*/

QString QLocale::toString(QTime time, const QString &format) const
{
    return toString(time, qToStringViewIgnoringNull(format));
}

/*!
    \since 4.4
    \fn QString QLocale::toString(const QDateTime &dateTime, const QString &format) const

    Returns a localized string representation of the given \a dateTime according
    to the specified \a format.
    If \a format is an empty string, an empty string is returned.

    \sa QDateTime::toString(), QDate::toString(), QTime::toString()
*/

/*!
    \since 5.14

    Returns a localized string representation of the given \a date in the
    specified \a format, optionally for a specified calendar \a cal.
    If \a format is an empty string, an empty string is returned.

    \sa QDate::toString()
*/
QString QLocale::toString(QDate date, QStringView format, QCalendar cal) const
{
    return cal.dateTimeToString(format, QDateTime(), date, QTime(), *this);
}

/*!
    \since 5.10
    \overload
*/
QString QLocale::toString(QDate date, QStringView format) const
{
    return QCalendar().dateTimeToString(format, QDateTime(), date, QTime(), *this);
}

/*!
    \since 5.14

    Returns a localized string representation of the given \a date according
    to the specified \a format (see dateFormat()), optionally for a specified
    calendar \a cal.

    \note Some locales may use formats that limit the range of years they can
    represent.
*/
QString QLocale::toString(QDate date, FormatType format, QCalendar cal) const
{
    if (!date.isValid())
        return QString();

#ifndef QT_NO_SYSTEMLOCALE
    if (cal.isGregorian() && d->m_data == &systemLocaleData) {
        QVariant res = systemLocale()->query(format == LongFormat
                                             ? QSystemLocale::DateToStringLong
                                             : QSystemLocale::DateToStringShort,
                                             date);
        if (!res.isNull())
            return res.toString();
    }
#endif

    QString format_str = dateFormat(format);
    return toString(date, format_str, cal);
}

/*!
    \since 4.5
    \overload
*/
QString QLocale::toString(QDate date, FormatType format) const
{
    if (!date.isValid())
        return QString();

#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        QVariant res = systemLocale()->query(format == LongFormat
                                             ? QSystemLocale::DateToStringLong
                                             : QSystemLocale::DateToStringShort,
                                             date);
        if (!res.isNull())
            return res.toString();
    }
#endif

    QString format_str = dateFormat(format);
    return toString(date, format_str);
}

static bool timeFormatContainsAP(QStringView format)
{
    qsizetype i = 0;
    while (i < format.size()) {
        if (format.at(i).unicode() == '\'') {
            qt_readEscapedFormatString(format, &i);
            continue;
        }

        if (format.at(i).toLower().unicode() == 'a')
            return true;

        ++i;
    }
    return false;
}

/*!
    \since 4.5

    Returns a localized string representation of the given \a time according
    to the specified \a format.
    If \a format is an empty string, an empty string is returned.

    \sa QTime::toString()
*/
QString QLocale::toString(QTime time, QStringView format) const
{
    return QCalendar().dateTimeToString(format, QDateTime(), QDate(), time, *this);
}

/*!
    \since 5.14

    Returns a localized string representation of the given \a dateTime according
    to the specified \a format, optionally for a specified calendar \a cal.
    If \a format is an empty string, an empty string is returned.

    \sa QDateTime::toString(), QDate::toString(), QTime::toString()
*/
QString QLocale::toString(const QDateTime &dateTime, QStringView format, QCalendar cal) const
{
    return cal.dateTimeToString(format, dateTime, QDate(), QTime(), *this);
}

/*!
    \since 5.10
    \overload
*/
QString QLocale::toString(const QDateTime &dateTime, QStringView format) const
{
    return QCalendar().dateTimeToString(format, dateTime, QDate(), QTime(), *this);
}

/*!
    \since 5.14

    Returns a localized string representation of the given \a dateTime according
    to the specified \a format (see dateTimeFormat()), optionally for a
    specified calendar \a cal.

    \note Some locales may use formats that limit the range of years they can
    represent.
*/
QString QLocale::toString(const QDateTime &dateTime, FormatType format, QCalendar cal) const
{
    if (!dateTime.isValid())
        return QString();

#ifndef QT_NO_SYSTEMLOCALE
    if (cal.isGregorian() && d->m_data == &systemLocaleData) {
        QVariant res = systemLocale()->query(format == LongFormat
                                             ? QSystemLocale::DateTimeToStringLong
                                             : QSystemLocale::DateTimeToStringShort,
                                             dateTime);
        if (!res.isNull())
            return res.toString();
    }
#endif

    const QString format_str = dateTimeFormat(format);
    return toString(dateTime, format_str, cal);
}

/*!
    \since 4.4
    \overload
*/
QString QLocale::toString(const QDateTime &dateTime, FormatType format) const
{
    if (!dateTime.isValid())
        return QString();

#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        QVariant res = systemLocale()->query(format == LongFormat
                                             ? QSystemLocale::DateTimeToStringLong
                                             : QSystemLocale::DateTimeToStringShort,
                                             dateTime);
        if (!res.isNull())
            return res.toString();
    }
#endif

    const QString format_str = dateTimeFormat(format);
    return toString(dateTime, format_str);
}


/*!
    Returns a localized string representation of the given \a time in the
    specified \a format (see timeFormat()).
*/

QString QLocale::toString(QTime time, FormatType format) const
{
    if (!time.isValid())
        return QString();

#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        QVariant res = systemLocale()->query(format == LongFormat
                                             ? QSystemLocale::TimeToStringLong
                                             : QSystemLocale::TimeToStringShort,
                                             time);
        if (!res.isNull())
            return res.toString();
    }
#endif

    QString format_str = timeFormat(format);
    return toString(time, format_str);
}

/*!
    \since 4.1

    Returns the date format used for the current locale.

    If \a format is LongFormat, the format will be elaborate, otherwise it will be short.
    For example, LongFormat for the \c{en_US} locale is \c{dddd, MMMM d, yyyy},
    ShortFormat is \c{M/d/yy}.

    \sa QDate::toString(), QDate::fromString()
*/

QString QLocale::dateFormat(FormatType format) const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        QVariant res = systemLocale()->query(format == LongFormat
                                             ? QSystemLocale::DateFormatLong
                                             : QSystemLocale::DateFormatShort,
                                             QVariant());
        if (!res.isNull())
            return res.toString();
    }
#endif

    return (format == LongFormat
            ? d->m_data->longDateFormat()
            : d->m_data->shortDateFormat()
           ).getData(date_format_data);
}

/*!
    \since 4.1

    Returns the time format used for the current locale.

    If \a format is LongFormat, the format will be elaborate, otherwise it will be short.
    For example, LongFormat for the \c{en_US} locale is \c{h:mm:ss AP t},
    ShortFormat is \c{h:mm AP}.

    \sa QTime::toString(), QTime::fromString()
*/

QString QLocale::timeFormat(FormatType format) const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        QVariant res = systemLocale()->query(format == LongFormat
                                             ? QSystemLocale::TimeFormatLong
                                             : QSystemLocale::TimeFormatShort,
                                             QVariant());
        if (!res.isNull())
            return res.toString();
    }
#endif

    return (format == LongFormat
            ? d->m_data->longTimeFormat()
            : d->m_data->shortTimeFormat()
           ).getData(time_format_data);
}

/*!
    \since 4.4

    Returns the date time format used for the current locale.

    If \a format is LongFormat, the format will be elaborate, otherwise it will be short.
    For example, LongFormat for the \c{en_US} locale is \c{dddd, MMMM d, yyyy h:mm:ss AP t},
    ShortFormat is \c{M/d/yy h:mm AP}.

    \sa QDateTime::toString(), QDateTime::fromString()
*/

QString QLocale::dateTimeFormat(FormatType format) const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        QVariant res = systemLocale()->query(format == LongFormat
                                             ? QSystemLocale::DateTimeFormatLong
                                             : QSystemLocale::DateTimeFormatShort,
                                             QVariant());
        if (!res.isNull()) {
            return res.toString();
        }
    }
#endif
    return dateFormat(format) + u' ' + timeFormat(format);
}

#if QT_CONFIG(datestring)
/*!
    \since 4.4

    Reads \a string as a time in a locale-specific \a format.

    Parses \a string and returns the time it represents. The format of the time
    string is chosen according to the \a format parameter (see timeFormat()).

    \note Any am/pm indicators used must match \l amText() or \l pmText(),
    ignoring case.

    If the time could not be parsed, returns an invalid time.

    \sa timeFormat(), toDate(), toDateTime(), QTime::fromString()
*/
QTime QLocale::toTime(const QString &string, FormatType format) const
{
    return toTime(string, timeFormat(format));
}

/*!
    \since 4.4

    Reads \a string as a date in a locale-specific \a format.

    Parses \a string and returns the date it represents. The format of the date
    string is chosen according to the \a format parameter (see dateFormat()).

//! [base-year-for-short]
    Some locales use, particularly for ShortFormat, only the last two digits of
    the year. In such a case, the 100 years starting at \a baseYear are the
    candidates first considered. Prior to 6.7 there was no \a baseYear parameter
    and 1900 was always used. This is the default for \a baseYear, selecting a
    year from then to 1999. In some cases, other fields may lead to the next or
    previous century being selected, to get a result consistent with all fields
    given. See \l QDate::fromString() for details.
//! [base-year-for-short]

    \note Month and day names, where used, must be given in the locale's
    language.

    If the date could not be parsed, returns an invalid date.

    \sa dateFormat(), toTime(), toDateTime(), QDate::fromString()
*/
QDate QLocale::toDate(const QString &string, FormatType format, int baseYear) const
{
    return toDate(string, dateFormat(format), baseYear);
}

/*!
    \since 5.14
    \overload
*/
QDate QLocale::toDate(const QString &string, FormatType format, QCalendar cal, int baseYear) const
{
    return toDate(string, dateFormat(format), cal, baseYear);
}

/*!
    \since 4.4

    Reads \a string as a date-time in a locale-specific \a format.

    Parses \a string and returns the date-time it represents. The format of the
    date string is chosen according to the \a format parameter (see
    dateFormat()).

    \include qlocale.cpp base-year-for-short

    \note Month and day names, where used, must be given in the locale's
    language. Any am/pm indicators used must match \l amText() or \l pmText(),
    ignoring case.

    If the string could not be parsed, returns an invalid QDateTime.

    \sa dateTimeFormat(), toTime(), toDate(), QDateTime::fromString()
*/
QDateTime QLocale::toDateTime(const QString &string, FormatType format, int baseYear) const
{
    return toDateTime(string, dateTimeFormat(format), baseYear);
}

/*!
    \since 5.14
    \overload
*/
QDateTime QLocale::toDateTime(const QString &string, FormatType format, QCalendar cal,
                              int baseYear) const
{
    return toDateTime(string, dateTimeFormat(format), cal, baseYear);
}

/*!
    \since 4.4

    Reads \a string as a time in the given \a format.

    Parses \a string and returns the time it represents. See QTime::fromString()
    for the interpretation of \a format.

    \note Any am/pm indicators used must match \l amText() or \l pmText(),
    ignoring case.

    If the time could not be parsed, returns an invalid time.

    \sa timeFormat(), toDate(), toDateTime(), QTime::fromString()
*/
QTime QLocale::toTime(const QString &string, const QString &format) const
{
#if QT_CONFIG(datetimeparser)
    QTimePattern pattern = QTimePattern::fromQtFormat(format);
    pattern.setLocale(*this);
    if (auto match = pattern.parse(string, QTime(0, 0)); match.size == string.size())
        return std::move(match.payload);
#else
    Q_UNUSED(string);
    Q_UNUSED(format);
#endif
    return {};
}

/*!
    \since 4.4

    Reads \a string as a date in the given \a format.

    Parses \a string and returns the date it represents. See QDate::fromString()
    for the interpretation of \a format.

//! [base-year-for-two-digit]
    When \a format only specifies the last two digits of a year, the 100 years
    starting at \a baseYear are the candidates first considered. Prior to 6.7
    there was no \a baseYear parameter and 1900 was always used. This is the
    default for \a baseYear, selecting a year from then to 1999. In some cases,
    other fields may lead to the next or previous century being selected, to get
    a result consistent with all fields given. See \l QDate::fromString() for
    details.
//! [base-year-for-two-digit]

    \note Month and day names, where used, must be given in the locale's
    language.

    If the date could not be parsed, returns an invalid date.

    \sa dateFormat(), toTime(), toDateTime(), QDate::fromString()
*/
QDate QLocale::toDate(const QString &string, const QString &format, int baseYear) const
{
    return toDate(string, format, QCalendar(), baseYear);
}

/*!
    \since 5.14
    \overload
*/
QDate QLocale::toDate(const QString &string, const QString &format, QCalendar cal, int baseYear) const
{
#if QT_CONFIG(datetimeparser)
    QDatePattern pattern = QDatePattern::fromQtFormat(format);
    pattern.setLocale(*this);
    pattern.setCalendar(cal);
    pattern.setBaseYear(baseYear);
    if (auto match = pattern.parse(string, QDate(baseYear, 1, 1, cal));
             match.size == string.size()) {
        return std::move(match.payload);
    }
#else
    Q_UNUSED(string);
    Q_UNUSED(format);
    Q_UNUSED(cal);
    Q_UNUSED(baseYear);
#endif
    return {};
}

/*!
    \since 4.4

    Reads \a string as a date-time in the given \a format.

    Parses \a string and returns the date-time it represents.  See
    QDateTime::fromString() for the interpretation of \a format.

    \include qlocale.cpp base-year-for-two-digit

    \note Month and day names, where used, must be given in the locale's
    language. Any am/pm indicators used must match \l amText() or \l pmText(),
    ignoring case.

    If the string could not be parsed, returns an invalid QDateTime.  If the
    string can be parsed and represents an invalid date-time (e.g. in a gap
    skipped by a time-zone transition), the returned QDateTime represents a
    near-by datetime that is valid (typically differing from it by the width of
    the gap in valid datetimes, e.g. the hour skipped by a transition). Passing
    that to fromMSecsSinceEpoch() will produce a valid date-time that isn't
    faithfully represented by the string parsed.

    \sa dateTimeFormat(), toTime(), toDate(), QDateTime::fromString()
*/
QDateTime QLocale::toDateTime(const QString &string, const QString &format, int baseYear) const
{
    return toDateTime(string, format, QCalendar(), baseYear);
}

/*!
    \since 5.14
    \overload
*/
QDateTime QLocale::toDateTime(const QString &string, const QString &format, QCalendar cal,
                              int baseYear) const
{
#if QT_CONFIG(datetimeparser)
    QDateTimePattern pattern = QDateTimePattern::fromQtFormat(format);
    pattern.setLocale(*this);
    pattern.setCalendar(cal);
    pattern.setBaseYear(baseYear);
    if (auto match = pattern.parse(string, QDate(baseYear, 1, 1, cal).startOfDay());
             match.size == string.size()) {
        return std::move(match.payload);
    }
#else
    Q_UNUSED(string);
    Q_UNUSED(format);
    Q_UNUSED(cal);
    Q_UNUSED(baseYear);
#endif
    return {};
}
#endif // datestring

/*!
    \since 4.1

    Returns the fractional part separator for this locale.

    This is the token that separates the whole number part from the fracional
    part in the representation of a number which has a fractional part. This is
    commonly called the "decimal point character" - even though, in many
    locales, it is not a "point" (or similar dot). It is (since Qt 6.0) returned
    as a string in case some locale needs more than one UTF-16 code-point to
    represent its separator.

    \sa groupSeparator(), toString()
*/
QString QLocale::decimalPoint() const
{
    return d->m_data->decimalPoint();
}

/*!
    \since 4.1

    Returns the digit-grouping separator for this locale.

    This is a token used to break up long sequences of digits, in the
    representation of a number, to make it easier to read. In some locales it
    may be empty, indicating that digits should not be broken up into groups in
    this way. In others it may be a spacing character. It is (since Qt 6.0)
    returned as a string in case some locale needs more than one UTF-16
    code-point to represent its separator.

    \sa decimalPoint(), toString()
*/
QString QLocale::groupSeparator() const
{
    return d->m_data->groupSeparator();
}

/*!
    \since 4.1

    Returns the percent marker of this locale.

    This is a token presumed to be appended to a number to indicate a
    percentage. It is (since Qt 6.0) returned as a string because, in some
    locales, it is not a single character - for example, because it includes a
    text-direction-control character.

    \sa toString()
*/
QString QLocale::percent() const
{
    return d->m_data->percentSign();
}

/*!
    \since 4.1

    Returns the zero digit character of this locale.

    This is a single Unicode character but may be encoded as a surrogate pair,
    so is (since Qt 6.0) returned as a string. In most locales, other digits
    follow it in Unicode ordering - however, some number systems, notably those
    using U+3007 as zero, do not have contiguous digits. Use toString() to
    obtain suitable representations of numbers, rather than trying to construct
    them from this zero digit.

    \sa toString()
*/
QString QLocale::zeroDigit() const
{
    return d->m_data->zeroDigit();
}

/*!
    \since 4.1

    Returns the negative sign indicator of this locale.

    This is a token presumed to be used as a prefix to a number to indicate that
    it is negative. It is (since Qt 6.0) returned as a string because, in some
    locales, it is not a single character - for example, because it includes a
    text-direction-control character.

    \sa positiveSign(), toString()
*/
QString QLocale::negativeSign() const
{
    return d->m_data->negativeSign();
}

/*!
    \since 4.5

    Returns the positive sign indicator of this locale.

    This is a token presumed to be used as a prefix to a number to indicate that
    it is positive. It is (since Qt 6.0) returned as a string because, in some
    locales, it is not a single character - for example, because it includes a
    text-direction-control character.

    \sa negativeSign(), toString()
*/
QString QLocale::positiveSign() const
{
    return d->m_data->positiveSign();
}

/*!
    \since 4.1

    Returns the exponent separator for this locale.

    This is a token used to separate mantissa from exponent in some
    floating-point numeric representations. It is (since Qt 6.0) returned as a
    string because, in some locales, it is not a single character - for example,
    it may consist of a multiplication sign and a representation of the "ten to
    the power" operator.

    \sa toString(double, char, int)
*/
QString QLocale::exponential() const
{
    return d->m_data->exponentSeparator();
}

/*!
    \overload
    Returns a string representing the floating-point number \a f.

    The form of the representation is controlled by the \a format and \a
    precision parameters.

    The \a format defaults to \c{'g'}. It can be any of the following:

    \table
    \header \li Format \li Meaning \li Meaning of \a precision
    \row \li \c 'e' \li format as [-]9.9e[+|-]999 \li number of digits \e after the decimal point
    \row \li \c 'E' \li format as [-]9.9E[+|-]999 \li "
    \row \li \c 'f' \li format as [-]9.9 \li "
    \row \li \c 'F' \li same as \c 'f' except for INF and NAN (see below) \li "
    \row \li \c 'g' \li use \c 'e' or \c 'f' format, whichever is more concise \li maximum number of significant digits (trailing zeroes are omitted)
    \row \li \c 'G' \li use \c 'E' or \c 'F' format, whichever is more concise \li "
    \endtable

    The special \a precision value QLocale::FloatingPointShortest selects the
    shortest representation that, when read as a number, gets back the original floating-point
    value. Aside from that, any negative \a precision is ignored in favor of the
    default, 6.

    For the \c 'e', \c 'f' and \c 'g' formats, positive infinity is represented
    as "inf", negative infinity as "-inf" and floating-point NaN (not-a-number)
    values are represented as "nan". For the \c 'E', \c 'F' and \c 'G' formats,
    "INF" and "NAN" are used instead. This does not vary with locale.

    \sa toDouble(), numberOptions(), exponential(), decimalPoint(), zeroDigit(),
        positiveSign(), percent(), toCurrencyString(), formattedDataSize(),
        QLocale::FloatingPointPrecisionOption
*/

QString QLocale::toString(double f, char format, int precision) const
{
    QLocaleData::DoubleForm form = QLocaleData::DFDecimal;
    uint flags = isAsciiUpper(format) ? QLocaleData::CapitalEorX : 0;

    switch (QtMiscUtils::toAsciiLower(format)) {
    case 'f':
        form = QLocaleData::DFDecimal;
        break;
    case 'e':
        form = QLocaleData::DFExponent;
        break;
    case 'g':
        form = QLocaleData::DFSignificantDigits;
        break;
    default:
        break;
    }

    if (!(d->m_numberOptions & OmitGroupSeparator))
        flags |= QLocaleData::GroupDigits;
    if (!(d->m_numberOptions & OmitLeadingZeroInExponent))
        flags |= QLocaleData::ZeroPadExponent;
    if (d->m_numberOptions & IncludeTrailingZeroesAfterDot)
        flags |= QLocaleData::AddTrailingZeroes;
    return d->m_data->doubleToString(f, precision, form, -1, flags);
}

/*!
    Returns a QLocale object initialized to the "C" locale.

    This locale is based on en_US but with various quirks of its own, such as
    simplified number formatting and its own date formatting. It implements the
    POSIX standards that describe the behavior of standard library functions of
    the "C" programming language.

    Among other things, this means its collation order is based on the ASCII
    values of letters, so that (for case-sensitive sorting) all upper-case
    letters sort before any lower-case one (rather than each letter's upper- and
    lower-case forms sorting adjacent to one another, before the next letter's
    two forms).

    \sa system()
*/
QLocale QLocale::c() noexcept
{
    return QLocale(*c_private());
}

/*!
    Returns a QLocale object initialized to the system locale.

    The system locale may use system-specific sources for locale data, where
    available, otherwise falling back on QLocale's built-in database entry for
    the language, script and territory the system reports.

    For example, on Windows and Mac, this locale will use the decimal/grouping
    characters and date/time formats specified in the system configuration
    panel.

    \sa c()
*/

QLocale QLocale::system()
{
    constexpr auto sysData = []() {
        // Same return as systemData(), but leave the setup to the actual call to it.
#ifdef QT_NO_SYSTEMLOCALE
        return locale_data;
#else
        return &systemLocaleData;
#endif
    };
    Q_CONSTINIT static QLocalePrivate locale(sysData(), -1, DefaultNumberOptions, 1);
    // Calling systemData() ensures system data is up to date; we also need it
    // to ensure that locale's index stays up to date:
    systemData(&locale.m_index);
    Q_ASSERT(locale.m_index >= 0 && locale.m_index < locale_data_size);
    locale.m_numberOptions = defaultNumberOptions(locale.m_data->m_language_id);

    return QLocale(locale);
}

/*!
    Returns a list of valid locale objects that match the given \a language, \a
    script and \a territory.

    Getting a list of all locales:
    QList<QLocale> allLocales = QLocale::matchingLocales(QLocale::AnyLanguage, QLocale::AnyScript,
                                                         QLocale::AnyTerritory);

    Getting a list of locales suitable for Russia:
    QList<QLocale> locales = QLocale::matchingLocales(QLocale::AnyLanguage, QLocale::AnyScript,
                                                      QLocale::Russia);
*/
QList<QLocale> QLocale::matchingLocales(Language language, Script script, Territory territory)
{
    QList<QLocale> result;

    const QLocaleId filter { language, script, territory };
    if (!filter.isValid())
        return result;

    if (language == C) {
        result.emplace_back(C);
        return result;
    }

    if (filter.matchesAll())
        result.reserve(locale_data_size);

    quint16 index = locale_index[language];
    // There may be no matches, for some languages (e.g. Abkhazian at CLDR v39).
    while (index < locale_data_size
           && filter.acceptLanguage(locale_data[index].m_language_id)) {
        const QLocaleId id = locale_data[index].id();
        if (filter.acceptScriptTerritory(id)) {
            result.append(QLocale(*(id.language_id == C ? c_private()
                                    : new QLocalePrivate(locale_data + index, index))));
        }
        ++index;
    }

    // Add current system locale, if it matches
    const auto syslocaledata = systemData();

    if (filter.acceptLanguage(syslocaledata->m_language_id)) {
        const QLocaleId id = syslocaledata->id();
        if (filter.acceptScriptTerritory(id))
            result.append(system());
    }

    return result;
}

#if QT_DEPRECATED_SINCE(6, 6)
/*!
    \deprecated [6.6] Use \l matchingLocales() instead and consult the \l territory() of each.
    \since 4.3

    Returns the list of countries that have entries for \a language in Qt's locale
    database. If the result is an empty list, then \a language is not represented in
    Qt's locale database.

    \sa matchingLocales()
*/
QList<QLocale::Country> QLocale::countriesForLanguage(Language language)
{
    const auto locales = matchingLocales(language, AnyScript, AnyCountry);
    QList<Country> result;
    result.reserve(locales.size());
    for (const auto &locale : locales)
        result.append(locale.territory());
    return result;
}
#endif

/*!
    \since 4.2

    Returns the localized name of \a month, in the format specified
    by \a type.

    For example, if the locale is \c en_US and \a month is 1,
    \l LongFormat will return \c January. \l ShortFormat \c Jan,
    and \l NarrowFormat \c J.

    \sa dayName(), standaloneMonthName()
*/
QString QLocale::monthName(int month, FormatType type) const
{
    return QCalendar().monthName(*this, month, QCalendar::Unspecified, type);
}

/*!
    \since 4.5

    Returns the localized name of \a month that is used as a
    standalone text, in the format specified by \a type.

    If the locale information doesn't specify the standalone month
    name then return value is the same as in monthName().

    \sa monthName(), standaloneDayName()
*/
QString QLocale::standaloneMonthName(int month, FormatType type) const
{
    return QCalendar().standaloneMonthName(*this, month, QCalendar::Unspecified, type);
}

/*!
    \since 4.2

    Returns the localized name of the \a day (where 1 represents
    Monday, 2 represents Tuesday and so on), in the format specified
    by \a type.

    For example, if the locale is \c en_US and \a day is 1,
    \l LongFormat will return \c Monday, \l ShortFormat \c Mon,
    and \l NarrowFormat \c M.

    \sa monthName(), standaloneDayName()
*/
QString QLocale::dayName(int day, FormatType type) const
{
    return QCalendar().weekDayName(*this, day, type);
}

/*!
    \since 4.5

    Returns the localized name of the \a day (where 1 represents
    Monday, 2 represents Tuesday and so on) that is used as a
    standalone text, in the format specified by \a type.

    If the locale information does not specify the standalone day
    name then return value is the same as in dayName().

    \sa dayName(), standaloneMonthName()
*/
QString QLocale::standaloneDayName(int day, FormatType type) const
{
    return QCalendar().standaloneWeekDayName(*this, day, type);
}

// Calendar look-up of month and day names:

// Get locale-specific month name data:
static const QCalendarLocale &getMonthDataFor(const QLocalePrivate *loc,
                                              const QCalendarLocale *table)
{
    // Only used in assertions
    [[maybe_unused]] const auto sameLocale = [](const QLocaleData &locale,
                                                const QCalendarLocale &cal) {
        return locale.m_language_id == cal.m_language_id
            && locale.m_script_id == cal.m_script_id
            && locale.m_territory_id == cal.m_territory_id;
    };
    const QCalendarLocale &monthly = table[loc->m_index];
#ifdef QT_NO_SYSTEMLOCALE
    [[maybe_unused]] constexpr bool isSys = false;
#else // Can't have preprocessor directives in a macro's parameter list, so use local.
    [[maybe_unused]] const bool isSys = loc->m_data == &systemLocaleData;
#endif
    Q_ASSERT(loc->m_data == &locale_data[loc->m_index] || isSys);
    // Compare monthly to locale_data[] entry, as the m_index used with
    // systemLocaleData is a best fit, not necessarily an exact match.
    Q_ASSERT(sameLocale(locale_data[loc->m_index], monthly));
    return monthly;
}

/*!
  \internal
 */

static QString rawMonthName(const QCalendarLocale &localeData,
                            const char16_t *monthsData, int month,
                            QLocale::FormatType type)
{
    const QLocaleData::DataRange range = localeData.monthName(type);
    return range.getListEntry(monthsData, month - 1);
}

/*!
  \internal
 */

static QString rawStandaloneMonthName(const QCalendarLocale &localeData,
                                      const char16_t *monthsData, int month,
                                      QLocale::FormatType type)
{
    const QLocaleData::DataRange range = localeData.standaloneMonthName(type);
    if (QString name = range.getListEntry(monthsData, month - 1); !name.isEmpty())
        return name;
    return rawMonthName(localeData, monthsData, month, type);
}

/*!
  \internal
 */

static QString rawWeekDayName(const QLocaleData *data, const int day,
                              QLocale::FormatType type)
{
    QLocaleData::DataRange range;
    switch (type) {
    case QLocale::LongFormat:
        range = data->longDayNames();
        break;
    case QLocale::ShortFormat:
        range = data->shortDayNames();
        break;
    case QLocale::NarrowFormat:
        range = data->narrowDayNames();
        break;
    default:
        return QString();
    }
    return range.getListEntry(days_data, day == 7 ? 0 : day);
}

/*!
  \internal
 */

static QString rawStandaloneWeekDayName(const QLocaleData *data, const int day,
                                        QLocale::FormatType type)
{
    QLocaleData::DataRange range;
    switch (type) {
    case QLocale::LongFormat:
        range =data->longDayNamesStandalone();
        break;
    case QLocale::ShortFormat:
        range = data->shortDayNamesStandalone();
        break;
    case QLocale::NarrowFormat:
        range = data->narrowDayNamesStandalone();
        break;
    default:
        return QString();
    }
    QString name = range.getListEntry(days_data, day == 7 ? 0 : day);
    if (name.isEmpty())
        return rawWeekDayName(data, day, type);
    return name;
}

// Refugees from qcalendar.cpp that need functions above:

QString QCalendarBackend::monthName(const QLocale &locale, int month, int,
                                    QLocale::FormatType format) const
{
    Q_ASSERT(month >= 1 && month <= maximumMonthsInYear());
    return rawMonthName(getMonthDataFor(locale.d, localeMonthIndexData()),
                        localeMonthData(), month, format);
}

QString QRomanCalendar::monthName(const QLocale &locale, int month, int year,
                                  QLocale::FormatType format) const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (locale.d->m_data == &systemLocaleData) {
        Q_ASSERT(month >= 1 && month <= 12);
        QSystemLocale::QueryType queryType = QSystemLocale::MonthNameLong;
        switch (format) {
        case QLocale::LongFormat:
            queryType = QSystemLocale::MonthNameLong;
            break;
        case QLocale::ShortFormat:
            queryType = QSystemLocale::MonthNameShort;
            break;
        case QLocale::NarrowFormat:
            queryType = QSystemLocale::MonthNameNarrow;
            break;
        }
        QVariant res = systemLocale()->query(queryType, month);
        if (!res.isNull())
            return res.toString();
    }
#endif

    return QCalendarBackend::monthName(locale, month, year, format);
}

QString QCalendarBackend::standaloneMonthName(const QLocale &locale, int month, int,
                                              QLocale::FormatType format) const
{
    Q_ASSERT(month >= 1 && month <= maximumMonthsInYear());
    return rawStandaloneMonthName(getMonthDataFor(locale.d, localeMonthIndexData()),
                                  localeMonthData(), month, format);
}

QString QRomanCalendar::standaloneMonthName(const QLocale &locale, int month, int year,
                                            QLocale::FormatType format) const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (locale.d->m_data == &systemLocaleData) {
        Q_ASSERT(month >= 1 && month <= 12);
        QSystemLocale::QueryType queryType = QSystemLocale::StandaloneMonthNameLong;
        switch (format) {
        case QLocale::LongFormat:
            queryType = QSystemLocale::StandaloneMonthNameLong;
            break;
        case QLocale::ShortFormat:
            queryType = QSystemLocale::StandaloneMonthNameShort;
            break;
        case QLocale::NarrowFormat:
            queryType = QSystemLocale::StandaloneMonthNameNarrow;
            break;
        }
        QVariant res = systemLocale()->query(queryType, month);
        if (!res.isNull())
            return res.toString();
    }
#endif

    return QCalendarBackend::standaloneMonthName(locale, month, year, format);
}

// Most calendars share the common week-day naming, modulo locale.
// Calendars that don't must override these methods.
QString QCalendarBackend::weekDayName(const QLocale &locale, int day,
                                      QLocale::FormatType format) const
{
    if (day < 1 || day > 7)
        return QString();

#ifndef QT_NO_SYSTEMLOCALE
    if (locale.d->m_data == &systemLocaleData) {
        QSystemLocale::QueryType queryType = QSystemLocale::DayNameLong;
        switch (format) {
        case QLocale::LongFormat:
            queryType = QSystemLocale::DayNameLong;
            break;
        case QLocale::ShortFormat:
            queryType = QSystemLocale::DayNameShort;
            break;
        case QLocale::NarrowFormat:
            queryType = QSystemLocale::DayNameNarrow;
            break;
        }
        QVariant res = systemLocale()->query(queryType, day);
        if (!res.isNull())
            return res.toString();
    }
#endif

    return rawWeekDayName(locale.d->m_data, day, format);
}

QString QCalendarBackend::standaloneWeekDayName(const QLocale &locale, int day,
                                                QLocale::FormatType format) const
{
    if (day < 1 || day > 7)
        return QString();

#ifndef QT_NO_SYSTEMLOCALE
    if (locale.d->m_data == &systemLocaleData) {
        QSystemLocale::QueryType queryType = QSystemLocale::StandaloneDayNameLong;
        switch (format) {
        case QLocale::LongFormat:
            queryType = QSystemLocale::StandaloneDayNameLong;
            break;
        case QLocale::ShortFormat:
            queryType = QSystemLocale::StandaloneDayNameShort;
            break;
        case QLocale::NarrowFormat:
            queryType = QSystemLocale::StandaloneDayNameNarrow;
            break;
        }
        QVariant res = systemLocale()->query(queryType, day);
        if (!res.isNull())
            return res.toString();
    }
#endif

    return rawStandaloneWeekDayName(locale.d->m_data, day, format);
}

// End of this block of qcalendar.cpp refugees.  (One more follows.)

/*!
    \since 4.8

    Returns the first day of the week according to the current locale.
*/
Qt::DayOfWeek QLocale::firstDayOfWeek() const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        const auto res = systemLocale()->query(QSystemLocale::FirstDayOfWeek);
        if (!res.isNull())
            return static_cast<Qt::DayOfWeek>(res.toUInt());
    }
#endif
    return static_cast<Qt::DayOfWeek>(d->m_data->m_first_day_of_week);
}

QLocale::MeasurementSystem QLocalePrivate::measurementSystem() const
{
    /* Unicode CLDR's information about measurement systems doesn't say which to
       use by default in each locale. Even if it did, adding another entry in
       every locale's row of locale_data[] would take up much more memory than
       the small table below.
    */
    struct TerritoryLanguage
    {
        quint16 languageId;
        quint16 territoryId;
        QLocale::MeasurementSystem system;
    };
    // TODO: research how realistic and/or complete this is:
    constexpr TerritoryLanguage ImperialMeasurementSystems[] = {
        { QLocale::English, QLocale::UnitedStates, QLocale::ImperialUSSystem },
        { QLocale::English, QLocale::UnitedStatesMinorOutlyingIslands, QLocale::ImperialUSSystem },
        { QLocale::Spanish, QLocale::UnitedStates, QLocale::ImperialUSSystem },
        { QLocale::Hawaiian, QLocale::UnitedStates, QLocale::ImperialUSSystem },
        { QLocale::English, QLocale::UnitedKingdom, QLocale::ImperialUKSystem }
    };

    for (const auto &system : ImperialMeasurementSystems) {
        if (system.languageId == m_data->m_language_id
            && system.territoryId == m_data->m_territory_id) {
            return system.system;
        }
    }
    return QLocale::MetricSystem;
}

/*!
    \since 4.8

    Returns a list of days that are considered weekdays according to the current locale.
*/
QList<Qt::DayOfWeek> QLocale::weekdays() const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        auto res
            = qvariant_cast<QList<Qt::DayOfWeek> >(systemLocale()->query(QSystemLocale::Weekdays));
        if (!res.isEmpty())
            return res;
    }
#endif
    QList<Qt::DayOfWeek> weekdays;
    quint16 weekendStart = d->m_data->m_weekend_start;
    quint16 weekendEnd = d->m_data->m_weekend_end;
    for (int day = Qt::Monday; day <= Qt::Sunday; day++) {
        if ((weekendEnd >= weekendStart && (day < weekendStart || day > weekendEnd)) ||
            (weekendEnd < weekendStart && (day > weekendEnd && day < weekendStart)))
                weekdays << static_cast<Qt::DayOfWeek>(day);
    }
    return weekdays;
}

/*!
    \since 4.4

    Returns the measurement system for the locale.
*/
QLocale::MeasurementSystem QLocale::measurementSystem() const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        const auto res = systemLocale()->query(QSystemLocale::MeasurementSystem);
        if (!res.isNull())
            return MeasurementSystem(res.toInt());
    }
#endif

    return d->measurementSystem();
}

/*!
  \since 4.7

  Returns the text direction of the language.
*/
Qt::LayoutDirection QLocale::textDirection() const
{
    switch (script()) {
    case AdlamScript:
    case ArabicScript:
    case AvestanScript:
    case CypriotScript:
    case HatranScript:
    case HebrewScript:
    case ImperialAramaicScript:
    case InscriptionalPahlaviScript:
    case InscriptionalParthianScript:
    case KharoshthiScript:
    case LydianScript:
    case MandaeanScript:
    case ManichaeanScript:
    case MendeKikakuiScript:
    case MeroiticCursiveScript:
    case MeroiticScript:
    case NabataeanScript:
    case NkoScript:
    case OldHungarianScript:
    case OldNorthArabianScript:
    case OldSouthArabianScript:
    case OrkhonScript:
    case PalmyreneScript:
    case PhoenicianScript:
    case PsalterPahlaviScript:
    case SamaritanScript:
    case SyriacScript:
    case ThaanaScript:
        return Qt::RightToLeft;
    default:
        break;
    }
    return Qt::LeftToRight;
}

/*!
  \since 4.8

  Returns an uppercase copy of \a str.

  If Qt Core is using the ICU libraries, they will be used to perform
  the transformation according to the rules of the current locale.
  Otherwise the conversion may be done in a platform-dependent manner,
  with QString::toUpper() as a generic fallback.

  \note In some cases the uppercase form of a string may be longer than the
  original.

  \sa QString::toUpper()
*/
QString QLocale::toUpper(const QString &str) const
{
#if !defined(QT_BOOTSTRAPPED) && (QT_CONFIG(icu) || defined(Q_OS_WIN) || defined(Q_OS_APPLE))
    bool ok = true;
    QString result = d->toUpper(str, &ok);
    if (ok)
        return result;
    // else fall through and use Qt's toUpper
#endif
    return str.toUpper();
}

/*!
  \since 4.8

  Returns a lowercase copy of \a str.

  If Qt Core is using the ICU libraries, they will be used to perform
  the transformation according to the rules of the current locale.
  Otherwise the conversion may be done in a platform-dependent manner,
  with QString::toLower() as a generic fallback.

  \sa QString::toLower()
*/
QString QLocale::toLower(const QString &str) const
{
#if !defined(QT_BOOTSTRAPPED) && (QT_CONFIG(icu) || defined(Q_OS_WIN) || defined(Q_OS_APPLE))
    bool ok = true;
    const QString result = d->toLower(str, &ok);
    if (ok)
        return result;
    // else fall through and use Qt's toLower
#endif
    return str.toLower();
}


/*!
    \since 4.5

    Returns the localized name of the "AM" suffix for times specified using
    the conventions of the 12-hour clock.

    \sa pmText()
*/
QString QLocale::amText() const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        auto res = systemLocale()->query(QSystemLocale::AMText).toString();
        if (!res.isEmpty())
            return res;
    }
#endif
    return d->m_data->anteMeridiem().getData(am_data);
}

/*!
    \since 4.5

    Returns the localized name of the "PM" suffix for times specified using
    the conventions of the 12-hour clock.

    \sa amText()
*/
QString QLocale::pmText() const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        auto res = systemLocale()->query(QSystemLocale::PMText).toString();
        if (!res.isEmpty())
            return res;
    }
#endif
    return d->m_data->postMeridiem().getData(pm_data);
}

// For the benefit of QCalendar, below.
static QString offsetFromAbbreviation(QString &&text)
{
    QStringView tail{text};
    // May need to strip a prefix:
    if (tail.startsWith("UTC"_L1) || tail.startsWith("GMT"_L1))
        tail = tail.sliced(3);
    // TODO: there may be a locale-specific alternative prefix.
    // Hard to know without zone-name L10n details, though.
    return (tail.isEmpty() // The Qt::UTC case omits the zero offset:
            ? u"+00:00"_s
            // Whole-hour offsets may lack the zero minutes:
            : (tail.size() <= 3
               ? tail + ":00"_L1
               : std::move(text).right(tail.size())));
}

// For the benefit of QCalendar, below, when not provided by QTZL.
#if !QT_CONFIG(datestring)
// No need for temporal data serialization and parsing code.
#elif QT_CONFIG(icu) || !(QT_CONFIG(timezone) && QT_CONFIG(timezone_locale))
namespace QtTimeZoneLocale {

// TODO: is there a way to get this non-kludgily from ICU ?
// If so, that version goes in QTZL.cpp's relevant #if-ery branch.
QString zoneOffsetFormat([[maybe_unused]] const QLocale &locale,
                         qsizetype,
                         QtTemporalPattern::TemporalFieldFlags,
                         const QDateTime &when,
                         int offsetSeconds)
{
    // Only the non-ICU TZ-locale code uses the prefix forms, so this tacitly
    // assumes flags: Numeric | Abbreviated | NeedNoUtcPrefix | ZeroPad.
    QString text =
#if QT_CONFIG(timezone)
        locale != QLocale::system()
        ? when.timeRepresentation().displayName(when, QTimeZone::OffsetName, locale)
        :
#endif
        when.toOffsetFromUtc(offsetSeconds).timeZoneAbbreviation();

    if (!text.isEmpty())
        text = offsetFromAbbreviation(std::move(text));
    // else: no suitable representation of the zone.
    return text;
}

} // QtTimeZoneLocale
#endif // ICU or no TZ L10n

// Another intrusion from QCalendar, using some of the tools above:
QString QCalendarBackend::dateTimeToString(QStringView format, const QDateTime &datetime,
                                           QDate dateOnly, QTime timeOnly,
                                           const QLocale &locale) const
{
    QDate date;
    QTime time;
    bool formatDate = false;
    bool formatTime = false;
    if (datetime.isValid()) {
        date = datetime.date();
        time = datetime.time();
        formatDate = true;
        formatTime = true;
    } else if (dateOnly.isValid()) {
        date = dateOnly;
        formatDate = true;
    } else if (timeOnly.isValid()) {
        time = timeOnly;
        formatTime = true;
    } else {
        return QString();
    }

    QString result;
    int year = 0, month = 0, day = 0;
    if (formatDate) {
        const auto parts = julianDayToDate(date.toJulianDay());
        if (!parts.isValid())
            return QString();
        year = parts.year;
        month = parts.month;
        day = parts.day;
    }

    auto appendToResult = [&](int t, int repeat) {
        auto data = locale.d->m_data;
        if (repeat > 1)
            result.append(data->longLongToString(t, -1, 10, repeat, QLocaleData::ZeroPadded));
        else
            result.append(data->longLongToString(t));
    };

    auto formatType = [](int repeat) {
        return repeat == 3 ? QLocale::ShortFormat : QLocale::LongFormat;
    };

    qsizetype i = 0;
    while (i < format.size()) {
        if (format.at(i).unicode() == '\'') {
            result.append(qt_readEscapedFormatString(format, &i));
            continue;
        }

        const QChar c = format.at(i);
        qsizetype rep = qt_repeatCount(format.mid(i));
        Q_ASSERT(rep < std::numeric_limits<int>::max());
        int repeat = int(rep);
        bool used = false;
        if (formatDate) {
            switch (c.unicode()) {
            case 'y':
                used = true;
                if (repeat >= 4)
                    repeat = 4;
                else if (repeat >= 2)
                    repeat = 2;

                switch (repeat) {
                case 4:
                    appendToResult(year, (year < 0) ? 5 : 4);
                    break;
                case 2:
                    appendToResult(year % 100, 2);
                    break;
                default:
                    repeat = 1;
                    result.append(c);
                    break;
                }
                break;

            case 'M':
                used = true;
                repeat = qMin(repeat, 4);
                if (repeat <= 2)
                    appendToResult(month, repeat);
                else
                    result.append(monthName(locale, month, year, formatType(repeat)));
                break;

            case 'd':
                used = true;
                repeat = qMin(repeat, 4);
                if (repeat <= 2)
                    appendToResult(day, repeat);
                else
                    result.append(
                            locale.dayName(dayOfWeek(date.toJulianDay()), formatType(repeat)));
                break;

            default:
                break;
            }
        }
        if (!used && formatTime) {
            switch (c.unicode()) {
            case 'h': {
                used = true;
                repeat = qMin(repeat, 2);
                int hour = time.hour();
                if (timeFormatContainsAP(format)) {
                    if (hour > 12)
                        hour -= 12;
                    else if (hour == 0)
                        hour = 12;
                }
                appendToResult(hour, repeat);
                break;
            }
            case 'H':
                used = true;
                repeat = qMin(repeat, 2);
                appendToResult(time.hour(), repeat);
                break;

            case 'm':
                used = true;
                repeat = qMin(repeat, 2);
                appendToResult(time.minute(), repeat);
                break;

            case 's':
                used = true;
                repeat = qMin(repeat, 2);
                appendToResult(time.second(), repeat);
                break;

            case 'A':
            case 'a': {
                QString text = time.hour() < 12 ? locale.amText() : locale.pmText();
                used = true;
                repeat = 1;
                if (format.mid(i + 1).startsWith(u'p', Qt::CaseInsensitive))
                    ++repeat;
                if (c.unicode() == 'A' && (repeat == 1 || format.at(i + 1).unicode() == 'P'))
                    text = std::move(text).toUpper();
                else if (c.unicode() == 'a' && (repeat == 1 || format.at(i + 1).unicode() == 'p'))
                    text = std::move(text).toLower();
                // else 'Ap' or 'aP' => use CLDR text verbatim, preserving case
                result.append(text);
                break;
            }

            case 'z':
                used = true;
                repeat = qMin(repeat, 3);

                // note: the millisecond component is treated like the decimal part of the seconds
                // so ms == 2 is always printed as "002", but ms == 200 can be either "2" or "200"
                appendToResult(time.msec(), 3);
                if (repeat != 3) {
                    const QString zero = locale.zeroDigit();
                    if (result.endsWith(zero))
                        result.chop(zero.size());
                    if (result.endsWith(zero))
                        result.chop(zero.size());
                }
                break;

            case 't': {
#if QT_CONFIG(datestring)
                // Feature check should really apply to the whole function, but
                // this portion of it depends on internals entangled with the
                // feature.
                enum AbbrType { Long, Offset, Short };
                const auto tzAbbr = [locale](const QDateTime &when, AbbrType type) {
                    QString text;
                    if (type == Offset) {
                        using Flag = QtTemporalPattern::TemporalFieldFlag;
                        constexpr auto noPrefixOffset = Flag::Numeric | Flag::Abbreviated
                            | Flag::NeedNoUtcPrefix | Flag::ZeroPad;
                        text = QtTimeZoneLocale::zoneOffsetFormat(locale, locale.d->m_index,
                                                                  noPrefixOffset,
                                                                  when, when.offsetFromUtc());
                        // When using timezone_locale data, this should always succeed:
                        if (!text.isEmpty())
                            return text;
                    }
#   if QT_CONFIG(timezone)
                    if (type != Short || locale != QLocale::system()) {
                        QTimeZone::NameType mode =
                            type == Short ? QTimeZone::ShortName
                            : type == Long ? QTimeZone::LongName : QTimeZone::OffsetName;
                        text = when.timeRepresentation().displayName(when, mode, locale);
                        if (!text.isEmpty())
                            return text;
                        // else fall back to an unlocalized one if we can find one.
                    }
                    if (type == Long) {
                        // If no long name found, use IANA ID:
                        text = QString::fromLatin1(when.timeZone().id());
                        if (!text.isEmpty())
                            return text;
                    }
                    // else: prefer QDateTime's abbreviation, for backwards-compatibility.
#   endif // else, make do with non-localized abbreviation:
                    // Absent timezone_locale data, Offset might still reach here:
                    if (type == Offset) // Our prior failure might not have tried this:
                        text = when.toOffsetFromUtc(when.offsetFromUtc()).timeZoneAbbreviation();
                    if (text.isEmpty()) // Notably including type != Offset
                        text = when.timeZoneAbbreviation();
                    if (type == Offset)
                        text = offsetFromAbbreviation(std::move(text));
                    return text;
                };

                used = true;
                repeat = qMin(repeat, 4);
                // If we don't have a date-time, use the current system time:
                const QDateTime when = formatDate ? datetime : QDateTime::currentDateTime();
                QString text;
                switch (repeat) {
                case 4:
                    text = tzAbbr(when, Long);
                    break;
                case 3: // ±hh:mm
                case 2: // ±hhmm (we'll remove the ':' at the end)
                    text = tzAbbr(when, Offset);
                    if (repeat == 2)
                        text.remove(u':');
                    break;
                default:
                    text = tzAbbr(when, Short);
                    // UTC-offset zones only include minutes if non-zero.
                    if (text.startsWith("UTC"_L1) && text.size() == 6)
                        text += ":00"_L1;
                    break;
                }
                if (!text.isEmpty())
                    result.append(text);
#endif // datestring
                break;
            }

            default:
                break;
            }
        }
        if (!used)
            result.resize(result.size() + repeat, c);
        i += repeat;
    }

    return result;
}
// End of QCalendar intrustions

QString QLocaleData::doubleToString(double d, int precision, DoubleForm form,
                                    int width, unsigned flags) const
{
    // Although the special handling of F.P.Shortest below is limited to
    // DFSignificantDigits, the double-conversion library does treat it
    // specially for the other forms, shedding trailing zeros for DFDecimal and
    // using the shortest mantissa that faithfully represents the value for
    // DFExponent.
    if (precision != QLocale::FloatingPointShortest && precision < 0)
        precision = 6;
    if (width < 0)
        width = 0;

    int decpt;
    qsizetype bufSize = 1;
    if (precision == QLocale::FloatingPointShortest)
        bufSize += std::numeric_limits<double>::max_digits10;
    else if (form == DFDecimal && qt_is_finite(d))
        bufSize += wholePartSpace(qAbs(d)) + precision;
    else // Add extra digit due to different interpretations of precision.
        bufSize += qMax(2, precision) + 1; // Must also be big enough for "nan" or "inf"

    QVarLengthArray<char> buf(bufSize);
    int length;
    bool negative = false;
    qt_doubleToAscii(d, form, precision, buf.data(), bufSize, negative, length, decpt);

    const QString prefix = signPrefix(negative && !qIsNull(d), flags);
    QString numStr;

    if (length == 3
        && (qstrncmp(buf.data(), "inf", 3) == 0 || qstrncmp(buf.data(), "nan", 3) == 0)) {
        numStr = QString::fromLatin1(buf.data(), length);
    } else { // Handle finite values
        const QString zero = zeroDigit();
        QString digits = QString::fromLatin1(buf.data(), length);

        if (zero == u"0") {
            // No need to convert digits.
            Q_ASSERT(std::all_of(buf.cbegin(), buf.cbegin() + length, isAsciiDigit));
            // That check is taken care of in unicodeForDigits, below.
        } else if (zero.size() == 2 && zero.at(0).isHighSurrogate()) {
            const char32_t zeroUcs4 = QChar::surrogateToUcs4(zero.at(0), zero.at(1));
            QString converted;
            converted.reserve(2 * digits.size());
            for (QChar ch : std::as_const(digits)) {
                const char32_t digit = unicodeForDigit(ch.unicode() - '0', zeroUcs4);
                Q_ASSERT(QChar::requiresSurrogates(digit));
                converted.append(QChar::highSurrogate(digit));
                converted.append(QChar::lowSurrogate(digit));
            }
            digits = std::move(converted);
        } else {
            Q_ASSERT(zero.size() == 1);
            Q_ASSERT(!zero.at(0).isSurrogate());
            char16_t z = zero.at(0).unicode();
            char16_t *const value = reinterpret_cast<char16_t *>(digits.data());
            for (qsizetype i = 0; i < digits.size(); ++i)
                value[i] = unicodeForDigit(value[i] - '0', z);
        }

        const bool mustMarkDecimal = flags & ForcePoint;
        const bool groupDigits = flags & GroupDigits;
        const int minExponentDigits = flags & ZeroPadExponent ? 2 : 1;
        switch (form) {
        case DFExponent:
            numStr = exponentForm(std::move(digits), decpt, precision, PMDecimalDigits,
                                  mustMarkDecimal, minExponentDigits);
            break;
        case DFDecimal:
            numStr = decimalForm(std::move(digits), decpt, precision, PMDecimalDigits,
                                 mustMarkDecimal, groupDigits);
            break;
        case DFSignificantDigits: {
            PrecisionMode mode
                = (flags & AddTrailingZeroes) ? PMSignificantDigits : PMChopTrailingZeros;

            /* POSIX specifies sprintf() to follow fprintf(), whose 'g/G' format
               says; with P = 6 if precision unspecified else 1 if precision is
               0 else precision; when 'e/E' would have exponent X, use:
                 * 'f/F' if P > X >= -4, with precision P-1-X
                 * 'e/E' otherwise, with precision P-1
               Helpfully, we already have mapped precision < 0 to 6 - except for
               F.P.Shortest mode, which is its own story - and those of our
               callers with unspecified precision either used 6 or -1 for it.
            */
            bool useDecimal;
            if (precision == QLocale::FloatingPointShortest) {
                // Find out which representation is shorter.
                // Set bias to everything added to exponent form but not
                // decimal, minus the converse.

                const QLocaleData::GroupSizes grouping = groupSizes();
                // Exponent adds separator, sign and digits:
                int bias = 2 + minExponentDigits;
                // Decimal form may get grouping separators inserted:
                if (groupDigits && decpt >= grouping.first + grouping.least)
                    bias -= (decpt - grouping.least) / grouping.higher + 1;
                // X = decpt - 1 needs two digits if decpt > 10:
                if (decpt > 10 && minExponentDigits == 1)
                    ++bias;
                // Assume digitCount < 95, so we can ignore the 3-digit
                // exponent case (we'll set useDecimal false anyway).

                const qsizetype digitCount = digits.size() / zero.size();
                if (!mustMarkDecimal) {
                    // Decimal separator is skipped if at end; adjust if
                    // that happens for only one form:
                    if (digitCount <= decpt && digitCount > 1)
                        ++bias; // decimal but not exponent
                    else if (digitCount == 1 && decpt <= 0)
                        --bias; // exponent but not decimal
                }
                // When 0 < decpt <= digitCount, the forms have equal digit
                // counts, plus things bias has taken into account; otherwise
                // decimal form's digit count is right-padded with zeros to
                // decpt, when decpt is positive, otherwise it's left-padded
                // with 1 - decpt zeros.
                useDecimal = (decpt <= 0 ? 1 - decpt <= bias
                              : decpt <= digitCount ? 0 <= bias : decpt <= digitCount + bias);
            } else {
                // X == decpt - 1, POSIX's P; -4 <= X < P iff -4 < decpt <= P
                Q_ASSERT(precision >= 0);
                useDecimal = decpt > -4 && decpt <= (precision ? precision : 1);
            }

            numStr = useDecimal
                ? decimalForm(std::move(digits), decpt, precision, mode,
                              mustMarkDecimal, groupDigits)
                : exponentForm(std::move(digits), decpt, precision, mode,
                               mustMarkDecimal, minExponentDigits);
            break;
        }
        }

        // Pad with zeros. LeftAdjusted overrides ZeroPadded.
        if (flags & ZeroPadded && !(flags & LeftAdjusted)) {
            for (qsizetype i = numStr.size() / zero.size() + prefix.size(); i < width; ++i)
                numStr.prepend(zero);
        }
    }

    return prefix + (flags & CapitalEorX
                     ? std::move(numStr).toUpper()
                     : std::move(numStr).toLower());
}

QString QLocaleData::decimalForm(QString &&digits, int decpt, int precision,
                                 PrecisionMode pm, bool mustMarkDecimal,
                                 bool groupDigits) const
{
    const QString zero = zeroDigit();
    const auto digitWidth = zero.size();
    Q_ASSERT(digitWidth == 1 || digitWidth == 2);
    Q_ASSERT(digits.size() % digitWidth == 0);

    // Separator needs to go at index decpt: so add zeros before or after the
    // given digits, if they don't reach that position already:
    if (decpt < 0) {
        for (; decpt < 0; ++decpt)
            digits.prepend(zero);
    } else {
        for (qsizetype i = digits.size() / digitWidth; i < decpt; ++i)
            digits.append(zero);
    }

    switch (pm) {
    case PMDecimalDigits:
        for (qsizetype i = digits.size() / digitWidth - decpt; i < precision; ++i)
            digits.append(zero);
        break;
    case  PMSignificantDigits:
        for (qsizetype i = digits.size() / digitWidth; i < precision; ++i)
            digits.append(zero);
        break;
    case PMChopTrailingZeros:
        Q_ASSERT(digits.size() / digitWidth <= qMax(decpt, 1) || !digits.endsWith(zero));
        break;
    }

    if (mustMarkDecimal || decpt < digits.size() / digitWidth)
        digits.insert(decpt * digitWidth, decimalPoint());

    if (groupDigits) {
        const QLocaleData::GroupSizes grouping = groupSizes();
        const QString group = groupSeparator();
        qsizetype i = decpt - grouping.least;
        if (i >= grouping.first) {
            digits.insert(i * digitWidth, group);
            while ((i -= grouping.higher) > 0)
                digits.insert(i * digitWidth, group);
        }
    }

    if (decpt == 0)
        digits.prepend(zero);

    return std::move(digits);
}

QString QLocaleData::exponentForm(QString &&digits, int decpt, int precision,
                                  PrecisionMode pm, bool mustMarkDecimal,
                                  int minExponentDigits) const
{
    const QString zero = zeroDigit();
    const auto digitWidth = zero.size();
    Q_ASSERT(digitWidth == 1 || digitWidth == 2);
    Q_ASSERT(digits.size() % digitWidth == 0);

    switch (pm) {
    case PMDecimalDigits:
        for (qsizetype i = digits.size() / digitWidth; i < precision + 1; ++i)
            digits.append(zero);
        break;
    case PMSignificantDigits:
        for (qsizetype i = digits.size() / digitWidth; i < precision; ++i)
            digits.append(zero);
        break;
    case PMChopTrailingZeros:
        Q_ASSERT(digits.size() / digitWidth <= 1 || !digits.endsWith(zero));
        break;
    }

    if (mustMarkDecimal || digits.size() > digitWidth)
        digits.insert(digitWidth, decimalPoint());

    digits.append(exponentSeparator());
    digits.append(longLongToString(decpt - 1, minExponentDigits, 10, -1, AlwaysShowSign));

    return std::move(digits);
}

QString QLocaleData::signPrefix(bool negative, unsigned flags) const
{
    if (negative)
        return negativeSign();
    if (flags & AlwaysShowSign)
        return positiveSign();
    if (flags & BlankBeforePositive)
        return u" "_s;
    return {};
}

QString QLocaleData::longLongToString(qlonglong n, int precision,
                                      int base, int width, unsigned flags) const
{
    bool negative = n < 0;

    /*
      Negating std::numeric_limits<qlonglong>::min() hits undefined behavior, so
      taking an absolute value has to take a slight detour.
     */
    QString numStr = qulltoa(negative ? 1u + qulonglong(-(n + 1)) : qulonglong(n),
                             base, zeroDigit());

    return applyIntegerFormatting(std::move(numStr), negative, precision, base, width, flags);
}

QString QLocaleData::unsLongLongToString(qulonglong l, int precision,
                                         int base, int width, unsigned flags) const
{
    return applyIntegerFormatting(qulltoa(l, base, zeroDigit()),
                                  false, precision, base, width, flags);
}

QString QLocaleData::applyIntegerFormatting(QString &&numStr, bool negative, int precision,
                                            int base, int width, unsigned flags) const
{
    const QString zero = base == 10 ? zeroDigit() : QStringLiteral("0");
    const auto digitWidth = zero.size();
    const auto digitCount = numStr.size() / digitWidth;

    const auto basePrefix = [&] () -> QStringView {
        if (flags & ShowBase) {
            const bool upper = flags & UppercaseBase;
            if (base == 16)
                return upper ? u"0X" : u"0x";
            if (base == 2)
                return upper ? u"0B" : u"0b";
            if (base == 8 && !numStr.startsWith(zero))
                return zero;
        }
        return {};
    }();

    const QString prefix = signPrefix(negative, flags) + basePrefix;
    // Count how much of width we've used up.  Each digit counts as one
    qsizetype usedWidth = digitCount + prefix.size();

    if (base == 10 && flags & GroupDigits) {
        const QLocaleData::GroupSizes grouping = groupSizes();
        const QString group = groupSeparator();
        qsizetype i = digitCount - grouping.least;
        if (i >= grouping.first) {
            numStr.insert(i * digitWidth, group);
            ++usedWidth;
            while ((i -= grouping.higher) > 0) {
                numStr.insert(i * digitWidth, group);
                ++usedWidth;
            }
        }
        // TODO: should we group any zero-padding we add later ?
    }

    const bool noPrecision = precision == -1;
    if (noPrecision)
        precision = 1;

    for (qsizetype i = numStr.size(); i < precision; ++i) {
        numStr.prepend(zero);
        usedWidth++;
    }

    // LeftAdjusted overrides ZeroPadded; and sprintf() only pads when
    // precision is not specified in the format string.
    if (noPrecision && flags & ZeroPadded && !(flags & LeftAdjusted)) {
        for (qsizetype i = usedWidth; i < width; ++i)
            numStr.prepend(zero);
    }

    QString result(flags & CapitalEorX ? std::move(numStr).toUpper() : std::move(numStr));
    if (prefix.size())
        result.prepend(prefix);
    return result;
}

QLocaleData::NumericData::NumericData(const QLocaleData *data, QLocaleData::NumberMode mode)
    : grouping(data->groupSizes()), isC(data == c())
      // Note: actually test pointer equality to c(), not language == C, as
      // system locale might be configured as C with tweaks.
{
    if (isC)
        return;
    setZero(data->zero().viewData(single_character_data));
    group = data->groupDelim().viewData(single_character_data);
    // Note: minus, plus and exponent might not actually be single characters.
    minus = data->minus().viewData(single_character_data);
    plus = data->plus().viewData(single_character_data);
    if (mode != IntegerMode)
        decimal = data->decimalSeparator().viewData(single_character_data);
    if (mode == DoubleScientificMode) {
        exponent = data->exponential().viewData(single_character_data);
        // exponentCyrillic means "apply the Cyrrilic-specific exponent hack"
        exponentCyrillic = data->m_script_id == QLocale::CyrillicScript;
    }
#ifndef QT_NO_SYSTEMLOCALE
    if (data == &systemLocaleData) {
        const auto getString = [sys = systemLocale()](QSystemLocale::QueryType query) {
            return sys->query(query).toString();
        };
        if (mode != IntegerMode) {
            sysDecimal = getString(QSystemLocale::DecimalPoint);
            if (sysDecimal.size())
                decimal = QStringView{sysDecimal};
        }
        sysGroup = getString(QSystemLocale::GroupSeparator);
        if (sysGroup.size())
            group = QStringView{sysGroup};
        sysMinus = getString(QSystemLocale::NegativeSign);
        if (sysMinus.size())
            minus = QStringView{sysMinus};
        sysPlus = getString(QSystemLocale::PositiveSign);
        if (sysPlus.size())
            plus = QStringView{sysPlus};
        setZero(getString(QSystemLocale::ZeroDigit));
    }
#endif
}

namespace {
// A bit like QStringIterator but rather specialized ... and some of the tokens
// it recognizes aren't single Unicode code-points (but it does map each to a
// single character).
class NumericTokenizer
{
    // TODO: use deterministic finite-state-automata.
    // TODO QTBUG-95460: CLDR has Inf/NaN representations per locale.
    static constexpr char lettersInfNaN[] = "afin"; // Letters of Inf, NaN
    static constexpr auto matchInfNaN = QtPrivate::makeCharacterSetMatch<lettersInfNaN>();
    const QStringView m_text;
    const QLocaleData::NumericData m_guide;
    qsizetype m_index;
    const QLocaleData::NumberMode m_mode;
    static_assert('+' + 1 == ',' && ',' + 1 == '-' && '-' + 1 == '.');
    char lastMark; // C locale accepts '+' through lastMark.
public:
    NumericTokenizer(QStringView text, QLocaleData::NumericData &&guide,
                     QLocaleData::NumberMode mode, qsizetype from = 0)
        : m_text(text), m_guide(guide), m_index(from), m_mode(mode),
          lastMark(mode == QLocaleData::IntegerMode ? '-' : '.')
    {
        Q_ASSERT(m_guide.isValid(mode));
    }
    bool done() const { return !(m_index < m_text.size()); }
    qsizetype index() const { return m_index; }
    int digitValue(char32_t digit) const { return m_guide.digitValue(digit); }
    bool isInfNanChar(char ch) const { return matchInfNaN.matches(ch); }
    char nextToken();
    bool fractionGroupClash() const
    {
        // If the user's hand-configuration of the system makes group and
        // fractional part separators coincide, we have some kludges to apply,
        // though we can skip them in integer mode.
        return Q_UNLIKELY(m_mode != QLocaleData::IntegerMode && m_guide.fractionalIsGroup());
    }
    const QLocaleData::GroupSizes &groupSizes() { return m_guide.groupSizes(); }
};

char NumericTokenizer::nextToken()
{
    // As long as caller stops iterating on a zero return, those don't need to
    // keep m_index correctly updated.
    Q_ASSERT(!done());
    do {
        // Mauls non-letters above 'Z' but we don't care:
        const auto asciiLower = [](unsigned char c) { return c >= 'A' ? c | 0x20 : c; };
        const QStringView tail = m_text.sliced(m_index);
        const QChar ch = tail.front();
        if (ch == u'\u2212') {
            // Special case: match the "proper" minus sign, for all locales.
            ++m_index;
            return '-';
        }
        if (m_guide.isC) {
            // "Conversion" to C locale is just a filter:
            if (Q_LIKELY(ch.unicode() < 256)) {
                unsigned char ascii = asciiLower(ch.toLatin1());
                if (Q_LIKELY(isAsciiDigit(ascii) || ('+' <= ascii && ascii <= lastMark)
                             // No caller presently (6.5) passes DoubleStandardMode,
                             // so !IntegerMode implies scientific, for now.
                             || (m_mode != QLocaleData::IntegerMode && isInfNanChar(ascii))
                             || (m_mode == QLocaleData::DoubleScientificMode && ascii == 'e'))) {
                    ++m_index;
                    return ascii;
                }
            }
            return 0;
        }
        if (ch.unicode() < 256) {
            // Accept the C locale's digits and signs in all locales:
            char ascii = asciiLower(ch.toLatin1());
            if (isAsciiDigit(ascii) || ascii == '-' || ascii == '+'
                // Also its Inf and NaN letters:
                || (m_mode != QLocaleData::IntegerMode && isInfNanChar(ascii))) {
                ++m_index;
                return ascii;
            }
        }

        // Other locales may be trickier:
        if (tail.startsWith(m_guide.minus)) {
            m_index += m_guide.minus.size();
            return '-';
        }
        if (tail.startsWith(m_guide.plus)) {
            m_index += m_guide.plus.size();
            return '+';
        }
        if (!m_guide.group.isEmpty() && tail.startsWith(m_guide.group)) {
            m_index += m_guide.group.size();
            // When group and decimal coincide, and a fractional part is not
            // unexpected, treat the last as a fractional part separator (and leave
            // the caller to special-case the situations where that causes a
            // parse-fail that we can dodge by not reading it that way).
            if (fractionGroupClash() && tail.indexOf(m_guide.decimal, m_guide.group.size()) == -1)
                return '.';
            return ',';
        }
        if (m_mode != QLocaleData::IntegerMode && tail.startsWith(m_guide.decimal)) {
            m_index += m_guide.decimal.size();
            return '.';
        }
        if (m_mode == QLocaleData::DoubleScientificMode
            && tail.startsWith(m_guide.exponent, Qt::CaseInsensitive)) {
            m_index += m_guide.exponent.size();
            return 'e';
        }

        // Must match qlocale_tools.h's unicodeForDigit()
        if (m_guide.zeroLen == 1) {
            if (!ch.isSurrogate()) {
                if (const int gap = digitValue(char32_t(ch.unicode())); gap >= 0) {
                    ++m_index;
                    return '0' + gap;
                }
            } else if (ch.isHighSurrogate() && tail.size() > 1 && tail.at(1).isLowSurrogate()) {
                return 0;
            }
            // There remain one or two things a non-surrogate might be ...
        } else if (ch.isHighSurrogate()) {
            // None of the corner cases below matches a surrogate, so return
            // early if we don't have a digit.
            if (tail.size() > 1) {
                if (const QChar low = tail.at(1); low.isLowSurrogate()) {
                    if (const int gap = digitValue(QChar::surrogateToUcs4(ch, low)); gap >= 0) {
                        m_index += 2;
                        return '0' + gap;
                    }
                }
            }
            return 0;
        }

        // All cases where tail starts with properly-matched surrogate pair
        // have been handled by this point.
        Q_ASSERT(!(ch.isHighSurrogate() && tail.size() > 1 && tail.at(1).isLowSurrogate()));

        // Weird corner cases (code above assumes these match no surrogates):
        switch (ch.unicode()) {
            // Skip over inivisble marks commonly found in numeric forms:
        case 0x061C: // Arabic Letter Mark (before signs in standard Arabic)
        case 0x200E: // Left-to-Right marker
        case 0x200F: // Right-to-Left marker
            ++m_index;
            continue;

        case u' ':
            // Some locales use a non-breaking space (U+00A0) or its thin
            // version (U+202f) for grouping. These look like spaces, so people
            // (and thus some of our tests) use a regular space instead and
            // complain if it doesn't work.
            // Should this be extended generally to any case where group is a space ?
            if (m_guide.group == u"\u00a0" || m_guide.group == u"\u202f") {
                ++m_index;
                return ',';
            }
            break;

            // Case-insensitive match:
        case u'E':
        case u'e':
        case u'\u0415': // Cyrillic E
        case u'\u0435': // Cyrillic e
            // Cyrillic E is used by Ukrainian as exponent; but others writing
            // Cyrillic may well use that; and Ukrainians might well use E.
            // All other Cyrillic locales (officially) use plain ASCII E.
            if (m_guide.exponentCyrillic) { // Only true in scientific float mode.
                ++m_index;
                return 'e';
            }
            break;
        }

        break;
    } while (!done());
    return 0;
}
} // namespace with no name

/*!
    \internal
    \since 6.12
    \class QLocaleData::DigitSequence
    \brief Descriptor for a digit sequence within a text.

    Packages the ASCII equivalent (optional sign and) digit sequence, along with
    a description of which parts come from where in the original text.

    Supports construction or assignment by moving or copying. Modifying its
    members, other than by assigning a newly constructed value or a result of
    taking a subsequence, may lead to undefined behaviour.

    \sa sliced(), first(), last()
*/
// Exists for the benefit of date-time parsing, but could be used for anything
// else that doesn't do fractional parts, exponents or digit-grouping.

/*!
    \fn qsizetype QLocaleData::DigitSequence::size()

    Returns the number of ASCII characters describing the digit sequence.

    This is the number of digits plus, if present, one for the sign. It is the
    number of characters \l transcribeTo() will transcribe. For the number of
    digits found, use \c {digits.size()}. Note that this may be less than the
    length of the text parsed, for example when the digits are surrogate pairs
    or the sign includes special Unicode markers, such as those for text
    direction.

    \sa isEmpty()
*/

/*!
    \fn void QLocaleData::DigitSequence::transcribeTo(CharBuff *buff)

    Transcribes the ASCII form of this digit sequence to \a buff.

    \sa size()
*/

/*!
    \since 6.12
    \enum QLocaleData::DigitSequence::Option

    Options to modify how digit sequences are parsed.

    \value Default The null option value.
    \value AllowSign A leading sign character may be present.

    In the numeric fields of a date, only a year field ever has a sign, all
    others use ungrouped digits. Zero-padding on the left of day and month
    fields is common (and it may also appear in year fields). The hour field of
    a zone-offset may also have a sign. Otherwise all numeric time fields are
    similar to numeric month and day fields.

    In numeric fields of a time, the least-significant given (be it hour, minute
    or second) may have a fractional part in some formats. The handling of this
    is left for the caller to take care of. Likewise, the caller is expected to
    deal with leading and trailing space appropriately.
*/

/*!
    \fn bool QLocaleData::DigitSequence::isEmpty() const

    Returns true precisely if this digit sequence represents nothing.

    This arises when the constructor found no digits and (when allowed) not even
    a sign. It may also result from extracting an empty subsequence of a digit
    sequence that was originally parsed. It is equivalent to \l
    {QLocaleData::DigitSequence::}{size()} == 0. To test whether any digits were
    found, use \c {digits.isEmpty()}, which may be true even though \c
    {isEmpty()} is false. That arises when only a sign was found (making
    \c{size() == 1}).

    \sa size()
*/

/*!
    \fn bool QLocaleData::DigitSequence::hasSign() const

    Returns true precisely if the digit sequence parsed includes a leading sign.
    It is equivalent to \c{sign != '\0'}.
*/

/*!
    \fn QStringView QLocaleData::DigitSequence::used(QStringView text, qsizetype from) const
    \fn QStringView QLocaleData::DigitSequence::used(QStringView text) const

    Returns the slice of \a text described by this digit sequence.

    The given \a text should be the one passed to the constructor either of this
    digit sequence or of one from which it was obtained by some combination of
    \l first(), \l sliced() and \l last(). In the directly-constructed case, or
    in the case of (optionally repeatedly) applying only \l first(), \a from may
    be passed: it should be the like-named offset passed to the original
    constructor, or 0 if no offset was passed. In that case, the whole text
    parsed for this digit sequence (alibeit possibly a prefix of the text
    originally parsed) is returned.  Otherwise, \a from should be omitted and
    this function returns the text described by just the digits of this
    sequence, omitting (even when relevant) the sign.

    \sa {QLocaleData::DigitSequence::}{DigitSequence()}
*/

/*!
    \fn QLocaleData::DigitSequence QLocaleData::DigitSequence::first(qsizetype count) const

    Returns a DigitSequence describing a prefix of this.

    The result describes the first \a count ASCII characters to which the
    sequence corresponds and their positions within the parsed text. The value
    of \a count must not be negative or exceed \c size().
*/

/*!
    \fn QLocaleData::DigitSequence QLocaleData::DigitSequence::last(qsizetype count) const

    Returns a DigitSequence describing a tail of this.

    The result describes the last \a count ASCII characters to which the
    sequence corresponds. The value of \a count must not be negative or exceed
    \c size(). The result is equivalent to \c{sliced(size() - count)}.
*/

/*!
    \fn QLocaleData::DigitSequence QLocaleData::DigitSequence::sliced(qsizetype from) const

    Returns a DigitSequence describing a tail of this.

    This skips over the text to which the first \a from ASCII characters of the
    sequence correspond, to describe the remainder and their positions within
    the parsed text. The value of \a from must not be negative or exceed \c
    size().
*/

/*!
    \overload
    \fn QLocaleData::DigitSequence QLocaleData::DigitSequence::sliced(qsizetype from, qsizetype count) const

    Returns a DigitSequence describing a subsequence of this.

    This skips over the portion of the text to which first \a from ASCII
    characters correspond and describes the portion described by the next \a
    count ASCII characters. The value of \a from must not be negative or exceed
    \c size(). The value of \a count must not be negative or exceed \c{size() -
    from}. The result is equivalent to \c{sliced(from).first(count)}.
*/

/*!
    Scan \a text for an initial sequence of digits.

    The given \a numeric provides data relevant to number-parsing, including
    what constitute digits. Options in \a flags control whether a leading sign
    may be included. If \a from is passed, the scan starts at this index in \a
    text, otherwise from the start.

    The resulting \l {QLocaleData::}{DigitSequence} contains the parsed digit
    sequence, \c digits, describes the positions of digits within \a text, by \c
    digitStart and \c digitWidth, and (where allowed) reports any sign.

    When \c digits is empty, \c digitStart is the end of the text parsed: this
    is either where the sign ended, when \c hasSign(), or the value of \c from
    passed to the constructor. Otherwise, each \c{digits[i]} represents
    \c{text.sliced(digitStart + i * digitWidth, digitWidth)} and the whole text
    parsed is \c{text.first(digitStart + digits.size() *
    digitWidth).sliced(from)}. Either way, if \c hasSign(), it represents
    \c{text.first(endIndex()).sliced(from)}.

    \sa {QLocaleData::DigitSequence::}{used()}
*/
QLocaleData::DigitSequence::DigitSequence(QStringView text, NumericData &&numeric,
                                          Options flags, qsizetype from)
    : digitStart(from), digitWidth(numeric.zeroWidth())
{
    NumericTokenizer tokens(text, std::move(numeric), IntegerMode, from);
    if (tokens.done())
        return;
    char currentToken = tokens.nextToken();
    if (!currentToken)
        return;

    // Handle any leading sign:
    if (currentToken == '+' || currentToken == '-') {
        if (!flags.testFlag(Option::AllowSign))
            return;
        digitStart = tokens.index();
        sign = currentToken;
        currentToken = '\0';
    }

    // Iterate what remains:
    while (currentToken || !tokens.done()) {
        if (!currentToken)
            currentToken = tokens.nextToken();
        if (!currentToken)
            return;

        if (currentToken < '0' || currentToken > '9')
            return; // What we got was not a digit in our locale.

        // We have a digit.
        digits.push_back(currentToken);
        currentToken = '\0';
    }
}

/*!
    \internal
    QLocaleData::DigitSequence QLocaleData::digitSequence(QStringView text, QLocaleData::DigitSequence::Options, qsizetype from)
    \brief Returns a DigitSequence describing some portion of \a text starting at \a from.

    As for the \l{QLocaleData::}{DigitSequence} constructor, supplying the
    \l{QLocaleData::}{NumericData} for this QLocaleData instance and the
    IntegerMode as the relevant argument to it.
*/

/*
    Converts a number in locale representation to the C locale equivalent.

    Only has to guarantee that a string that is a correct representation of a
    number will be converted. Checks signs, separators and digits appear in all
    the places they should, and nowhere else.

    Returns true precisely if the number appears to be well-formed, modulo
    things a parser for C Locale strings (without digit-grouping separators;
    they're stripped) will catch. When it returns true, it records (and
    '\0'-terminates) the C locale representation in *result.

    Note: only QString integer-parsing methods have a base parameter (hence need
    to cope with letters as possible digits); but these are now all routed via
    byteArrayToU?LongLong(), so no longer come via here. The QLocale
    number-parsers only work in decimal, so don't have to cope with any digits
    other than 0 through 9.
*/
bool QLocaleData::numberToCLocale(QStringView s, QLocale::NumberOptions number_options,
                                  NumberMode mode, CharBuff *result) const
{
    s = s.trimmed();
    if (s.size() < 1)
        return false;
    NumericTokenizer tokens(s, NumericData(this, mode), mode);

    // Reflects order constraints on possible parts of a number:
    enum { Whole, Grouped, Fraction, Exponent, Name } stage = Whole;
    // Grouped is just Whole with some digit-grouping separators in it.
    // Name is Inf or NaN; excludes all others (so none can be after it).

    // Fractional part *or* whole-number part can be empty, but not both, unless
    // we have Name. Exponent must have some digits in it.
    bool wantDigits = true;

    // Digit-grouping details (all modes):
    bool needHigherGroup = false; // Set when first group is too short to be the only one
    qsizetype digitsInGroup = 0;
    const QLocaleData::GroupSizes &grouping = tokens.groupSizes();
    const auto badLeastGroup = [&]() {
        // In principle we could object to a complete absence of grouping, when
        // digitsInGroup >= qMax(grouping.first, grouping.least), unless the
        // locale itself would omit them. However, when merely not rejecting
        // grouping separators, we have historically accepted ungrouped digits,
        // so objecting now would break existing code.
        if (stage == Grouped) {
            Q_ASSERT(!number_options.testFlag(QLocale::RejectGroupSeparator));
            // First group was invalid if it was short and we've not seen a separator since:
            if (needHigherGroup)
                return true;
            // Were there enough digits since the last group separator?
            if (digitsInGroup != grouping.least)
                return true;
        }
        return false;
    };

    char last = '\0';
    while (!tokens.done()) {
        char out = tokens.nextToken();
        if (out == 0)
            return false;

        // Note that out can only be '.', 'e' or an inf/NaN character if the
        // mode allows it (else nextToken() would return 0 instead), so we don't
        // need to check mode.
        if (out == '.') {
            if (stage > Grouped) // Too late to start a fractional part.
                return false;

            if (tokens.fractionGroupClash() && badLeastGroup()
                && digitsInGroup == grouping.higher) {
                // Reinterpret '.' as ',' (as they're indistinguishable) to
                // interpret the recent digits as a group, with the least to
                // follow (hopefully of a suitable length):
                out = ',';
                stage = Grouped;
                needHigherGroup = false;
                digitsInGroup = 0;
            } else {
                // That's the end of the integral part - check size of last group:
                if (badLeastGroup())
                    return false;
                stage = Fraction;
            }
        } else if (out == 'e') {
            if (wantDigits || stage == Name || stage > Fraction)
                return false;

            if (stage < Fraction) {
                // The 'e' ends the whole-number part, so check its last group:
                if (badLeastGroup())
                    return false;
            } else if (number_options.testFlag(QLocale::RejectTrailingZeroesAfterDot)) {
                // In a fractional part, a 0 just before the exponent is trailing:
                if (last == '0')
                    return false;
            }
            stage = Exponent;
            wantDigits = true; // We need some in the exponent
        } else if (out == ',') {
            // (If tokens.fractionGroupClash(), a comma only comes out of
            // nextToken() if there's a later separator, since the last is
            // always treated as dot. So if we have a comma here, treating it as
            // a dot wouldn't save the parse: the later dot-or-comma would make
            // the text malformed.)
            if (number_options.testFlag(QLocale::RejectGroupSeparator))
                return false;

            switch (stage) {
            case Whole:
                // Check size of most significant group
                if (digitsInGroup == 0
                    || digitsInGroup > qMax(grouping.first, grouping.higher)) {
                    return false;
                }
                Q_ASSERT(!needHigherGroup);
                // First group is only allowed fewer than grouping.first digits
                // if it's followed by a grouping.higher group, i.e. there's a
                // later group separator:
                if (grouping.first > digitsInGroup)
                    needHigherGroup = true;
                stage = Grouped;
                break;
            case Grouped:
                // Check size of group between two separators:
                if (digitsInGroup != grouping.higher)
                    return false;
                needHigherGroup = false; // We just found it, if needed.
                break;
            // Only allow group chars within the whole-number part:
            case Fraction:
            case Exponent:
            case Name:
                return false;
            }
            digitsInGroup = 0;
        } else if (isAsciiDigit(out)) {
            if (stage == Name)
                return false;
            if (out == '0' && number_options.testFlag(QLocale::RejectLeadingZeroInExponent)
                && stage > Fraction && !tokens.done() && !isAsciiDigit(last)) {
                // After the exponent there can only be '+', '-' or digits.  If
                // we find a '0' directly after some non-digit, then that is a
                // leading zero, acceptable only if it is the whole exponent.
                return false;
            }
            wantDigits = false;
            ++digitsInGroup;
        } else if (stage == Whole && tokens.isInfNanChar(out)) {
            if (!wantDigits) // Mixed digits with Inf/NaN
                return false;
            wantDigits = false;
            stage = Name;
        }
        // else: nothing special to do.

        last = out;
        if (out != ',') // Leave group separators out of the result.
            result->append(out);
    }
    if (wantDigits)
        return false;

    if (!number_options.testFlag(QLocale::RejectGroupSeparator)) {
        // If this is the end of the whole-part, check least significant group:
        if (stage < Fraction && badLeastGroup())
            return false;
    }

    if (number_options.testFlag(QLocale::RejectTrailingZeroesAfterDot) && stage == Fraction) {
        // In the fractional part, a final zero is trailing:
        if (last == '0')
            return false;
    }

    return true;
}

QLocaleData::ParsingResult
QLocaleData::validateChars(QStringView str, NumberMode numMode, int decDigits,
                           QLocale::NumberOptions number_options) const
{
    ParsingResult result;
    result.buff.reserve(str.size());

    enum { Whole, Fractional, Exponent } state = Whole;
    const bool scientific = numMode == DoubleScientificMode;
    NumericTokenizer tokens(str, NumericData(this, numMode), numMode);
    char last = '\0';

    while (!tokens.done()) {
        char c = tokens.nextToken();

        if (isAsciiDigit(c)) {
            switch (state) {
            case Whole:
                // Nothing special to do (unless we want to check grouping sizes).
                break;
            case Fractional:
                // If a double has too many digits in its fractional part it is Invalid.
                if (decDigits-- == 0)
                    return {};
                break;
            case Exponent:
                if (!isAsciiDigit(last)) {
                    // This is the first digit in the exponent (there may have beena '+'
                    // or '-' in before). If it's a zero, the exponent is zero-padded.
                    if (c == '0' && (number_options & QLocale::RejectLeadingZeroInExponent))
                        return {};
                }
                break;
            }

        } else {
            switch (c) {
            case '.':
                // If an integer has a decimal point, it is Invalid.
                // A double can only have one, at the end of its whole-number part.
                if (numMode == IntegerMode || state != Whole)
                    return {};
                // Even when decDigits is 0, we do allow the decimal point to be
                // present - just as long as no digits follow it.

                state = Fractional;
                break;

            case '+':
            case '-':
                // A sign can only appear at the start or after the e of scientific:
                if (last != '\0' && !(scientific && last == 'e'))
                    return {};
                break;

            case ',':
                // Grouping is only allowed after a digit in the whole-number portion:
                if ((number_options & QLocale::RejectGroupSeparator) || state != Whole
                        || !isAsciiDigit(last)) {
                    return {};
                }
                // We could check grouping sizes are correct, but fixup()s are
                // probably better off correcting any misplacement instead.
                break;

            case 'e':
                // Only one e is allowed and only in scientific:
                if (!scientific || state == Exponent)
                    return {};
                state = Exponent;
                break;

            default:
                // Nothing else can validly appear in a number.
                // NumericTokenizer allows letters of "inf" and "nan", but
                // validators don't accept those values.
                // For anything else, tokens.nextToken() must have returned 0.
                Q_ASSERT(!c || c == 'a' || c == 'f' || c == 'i' || c == 'n');
                return {};
            }
        }

        last = c;
        if (c != ',') // Skip grouping
            result.buff.append(c);
    }

    result.state = ParsingResult::Acceptable;

    // Intermediate if it ends with any character that requires a digit after
    // it to be valid e.g. group separator, sign, or exponent
    if (last == ',' || last == '-' || last == '+' || last == 'e')
        result.state = ParsingResult::Intermediate;

    return result;
}

double QLocaleData::stringToDouble(QStringView str, bool *ok,
                                   QLocale::NumberOptions number_options) const
{
    CharBuff buff;
    if (!numberToCLocale(str, number_options, DoubleScientificMode, &buff)) {
        if (ok != nullptr)
            *ok = false;
        return 0.0;
    }
    auto r = qt_asciiToDouble(buff.constData(), buff.size());
    if (ok != nullptr)
        *ok = r.ok();
    return r.result;
}

QSimpleParsedNumber<qint64>
QLocaleData::stringToLongLong(QStringView str, int base,
                              QLocale::NumberOptions number_options) const
{
    CharBuff buff;
    if (!numberToCLocale(str, number_options, IntegerMode, &buff))
        return {};

    return bytearrayToLongLong(QByteArrayView(buff), base);
}

QSimpleParsedNumber<quint64>
QLocaleData::stringToUnsLongLong(QStringView str, int base,
                                 QLocale::NumberOptions number_options) const
{
    CharBuff buff;
    if (!numberToCLocale(str, number_options, IntegerMode, &buff))
        return {};

    return bytearrayToUnsLongLong(QByteArrayView(buff), base);
}

static bool checkParsed(QByteArrayView num, qsizetype used)
{
    if (used <= 0)
        return false;

    const qsizetype len = num.size();
    if (used < len && num[used] != '\0') {
        while (used < len && ascii_isspace(num[used]))
            ++used;
    }

    if (used < len && num[used] != '\0')
        // we stopped at a non-digit character after converting some digits
        return false;

    return true;
}

QSimpleParsedNumber<qint64> QLocaleData::bytearrayToLongLong(QByteArrayView num, int base)
{
    auto r = qstrntoll(num.data(), num.size(), base);
    if (!checkParsed(num, r.used))
        return {};
    return r;
}

QSimpleParsedNumber<quint64> QLocaleData::bytearrayToUnsLongLong(QByteArrayView num, int base)
{
    auto r = qstrntoull(num.data(), num.size(), base);
    if (!checkParsed(num, r.used))
        return {};
    return r;
}

/*!
    \since 4.8

    \enum QLocale::CurrencySymbolFormat

    Specifies the format of the currency symbol.

    \value CurrencyIsoCode a ISO-4217 code of the currency.
    \value CurrencySymbol a currency symbol.
    \value CurrencyDisplayName a user readable name of the currency.
*/

/*!
    \since 4.8
    Returns a currency symbol according to the \a format.
*/
QString QLocale::currencySymbol(CurrencySymbolFormat format) const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        auto res = systemLocale()->query(QSystemLocale::CurrencySymbol, format).toString();
        if (!res.isEmpty())
            return res;
    }
#endif
    switch (format) {
    case CurrencySymbol:
        return d->m_data->currencySymbol().getData(currency_symbol_data);
    case CurrencyDisplayName:
        return d->m_data->currencyDisplayName().getData(currency_display_name_data);
    case CurrencyIsoCode: {
        const char *code = d->m_data->m_currency_iso_code;
        if (auto len = qstrnlen(code, 3))
            return QString::fromLatin1(code, qsizetype(len));
        break;
    }
    }
    return QString();
}

/*!
    \since 4.8

    Returns a localized string representation of \a value as a currency.
    If the \a symbol is provided it is used instead of the default currency symbol.

    \sa currencySymbol()
*/
QString QLocale::toCurrencyString(qlonglong value, const QString &symbol) const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        QSystemLocale::CurrencyToStringArgument arg(value, symbol);
        auto res = systemLocale()->query(QSystemLocale::CurrencyToString,
                                         QVariant::fromValue(arg)).toString();
        if (!res.isEmpty())
            return res;
    }
#endif
    QLocaleData::DataRange range = d->m_data->currencyFormatNegative();
    if (!range.size || value >= 0)
        range = d->m_data->currencyFormat();
    else
        value = -value;
    QString str = toString(value);
    QString sym = symbol.isNull() ? currencySymbol() : symbol;
    if (sym.isEmpty())
        sym = currencySymbol(CurrencyIsoCode);
    return range.viewData(currency_format_data).arg(str, sym);
}

/*!
    \since 4.8
    \overload
*/
QString QLocale::toCurrencyString(qulonglong value, const QString &symbol) const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        QSystemLocale::CurrencyToStringArgument arg(value, symbol);
        auto res = systemLocale()->query(QSystemLocale::CurrencyToString,
                                         QVariant::fromValue(arg)).toString();
        if (!res.isEmpty())
            return res;
    }
#endif
    QString str = toString(value);
    QString sym = symbol.isNull() ? currencySymbol() : symbol;
    if (sym.isEmpty())
        sym = currencySymbol(CurrencyIsoCode);
    return d->m_data->currencyFormat().getData(currency_format_data).arg(str, sym);
}

/*!
    \since 5.7
    \overload toCurrencyString()

    Returns a localized string representation of \a value as a currency.
    If the \a symbol is provided it is used instead of the default currency symbol.
    If the \a precision is provided it is used to set the precision of the currency value.

    \sa currencySymbol()
 */
QString QLocale::toCurrencyString(double value, const QString &symbol, int precision) const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        QSystemLocale::CurrencyToStringArgument arg(value, symbol);
        auto res = systemLocale()->query(QSystemLocale::CurrencyToString,
                                         QVariant::fromValue(arg)).toString();
        if (!res.isEmpty())
            return res;
    }
#endif
    QLocaleData::DataRange range = d->m_data->currencyFormatNegative();
    if (!range.size || value >= 0)
        range = d->m_data->currencyFormat();
    else
        value = -value;
    QString str = toString(value, 'f', precision == -1 ? d->m_data->m_currency_digits : precision);
    QString sym = symbol.isNull() ? currencySymbol() : symbol;
    if (sym.isEmpty())
        sym = currencySymbol(CurrencyIsoCode);
    return range.viewData(currency_format_data).arg(str, sym);
}

/*!
  \fn QString QLocale::toCurrencyString(float i, const QString &symbol, int precision) const
  \overload toCurrencyString()
*/

/*!
    \since 5.10

    \enum QLocale::DataSizeFormat

    Specifies the format for representation of data quantities.

    \omitvalue DataSizeBase1000
    \omitvalue DataSizeSIQuantifiers
    \value DataSizeIecFormat            format using base 1024 and IEC prefixes: KiB, MiB, GiB, ...
    \value DataSizeTraditionalFormat    format using base 1024 and SI prefixes: kB, MB, GB, ...
    \value DataSizeSIFormat             format using base 1000 and SI prefixes: kB, MB, GB, ...

    \sa formattedDataSize()
*/

/*!
    \since 5.10

    Converts a size in bytes to a human-readable localized string, comprising a
    number and a quantified unit. The quantifier is chosen such that the number
    is at least one, and as small as possible. For example if \a bytes is
    16384, \a precision is 2, and \a format is \l DataSizeIecFormat (the
    default), this function returns "16.00 KiB"; for 1330409069609 bytes it
    returns "1.21 GiB"; and so on. If \a format is \l DataSizeIecFormat or
    \l DataSizeTraditionalFormat, the given number of bytes is divided by a
    power of 1024, with result less than 1024; for \l DataSizeSIFormat, it is
    divided by a power of 1000, with result less than 1000.
    \c DataSizeIecFormat uses the new IEC standard quantifiers Ki, Mi and so on,
    whereas \c DataSizeSIFormat uses the older SI quantifiers k, M, etc., and
    \c DataSizeTraditionalFormat abuses them.
*/
QString QLocale::formattedDataSize(qint64 bytes, int precision, DataSizeFormats format) const
{
    int power, base = 1000;
    if (!bytes) {
        power = 0;
    } else if (format & DataSizeBase1000) {
        constexpr auto log10_1000 = 3; // std::log10(1000U)
        power = int(std::log10(QtPrivate::qUnsignedAbs(bytes))) / log10_1000;
    } else {
        constexpr auto log2_1024 = 10; // QtPrivate::log2i(1024U);
        power = QtPrivate::log2i(QtPrivate::qUnsignedAbs(bytes)) / log2_1024;
        base = 1024;
    }
    // Only go to doubles if we'll be using a quantifier:
    const QString number = power
        ? toString(bytes / std::pow(double(base), power), 'f', qMin(precision, 3 * power))
        : toString(bytes);

    // We don't support sizes in units larger than exbibytes because
    // the number of bytes would not fit into qint64.
    Q_ASSERT(power <= 6 && power >= 0);
    QStringView unit;
    if (power > 0) {
        QLocaleData::DataRange range = (format & DataSizeSIQuantifiers)
            ? d->m_data->byteAmountSI() : d->m_data->byteAmountIEC();
        unit = range.viewListEntry(byte_unit_data, power - 1);
    } else {
        unit = d->m_data->byteCount().viewData(byte_unit_data);
    }

    return number + u' ' + unit;
}

/*!
    \since 4.8
    \brief List of locale names for use in selecting translations

    Each entry in the returned list is the name of a locale suitable to the
    user's preferences for what to translate the UI into. Where a name in the
    list is composed of several tags, they are joined as indicated by \a
    separator. Prior to Qt 6.7 a dash was used as separator.

    For example, using the default separator QLocale::TagSeparator::Dash, if the
    user has configured their system to use English as used in the USA, the list
    would be "en-Latn-US", "en-US", "en-Latn", "en". The order of entries is the
    order in which to check for translations; earlier items in the list are to
    be preferred over later ones. If your translation files (or other resources
    specific to locale) use underscores, rather than dashes, to separate locale
    tags, pass QLocale::TagSeparator::Underscore as \a separator.

    Returns a list of locale names. This may include multiple languages,
    especially for the system locale when multiple UI translation languages are
    configured. The order of entries is significant. For example, for the system
    locale, it reflects user preferences.

    Prior to Qt 6.9, the list only contained explicitly configured locales and
    their equivalents. This led some callers to add truncations (such as from
    'en-Latn-DE' to 'en') as fallbacks. This could sometimes result in
    inappropriate choices, especially if these were tried before later entries
    that would be more appropriate fallbacks.

    Starting from Qt 6.9, reasonable truncations are included in the returned
    list \e after all entries equivalent to the explicitly specified
    locales. This change allows for more accurate fallback options without
    callers needing to do any truncation.

    Users can explicitly include preferred fallback locales (such as en-US) in
    their system configuration to control the order of preference. You are
    advised to rely on the order of entries in uiLanguages() rather than using
    custom fallback methods.

    Most likely you do not need to use this function directly, but just pass the
    QLocale object to the QTranslator::load() function.

    \sa QTranslator, bcp47Name()
*/
QStringList QLocale::uiLanguages(TagSeparator separator) const
{
    const char sep = char(separator);
    QStringList uiLanguages;
    if (uchar(sep) > 0x7f) {
        badSeparatorWarning("uiLanguages", sep);
        return uiLanguages;
    }
    QList<QLocaleId> localeIds;
#ifdef QT_NO_SYSTEMLOCALE
    constexpr bool isSystem = false;
#else
    const bool isSystem = d->m_data == &systemLocaleData;
    if (isSystem) {
        uiLanguages = systemLocale()->query(QSystemLocale::UILanguages).toStringList();
        if (separator != TagSeparator::Dash) {
            // Map from default separator, Dash, used by backends:
            const QChar join = QLatin1Char(sep);
            uiLanguages.replaceInStrings(u"-", QStringView(&join, 1));
        }
        // ... but we need to include likely-adjusted forms of each of those, too.
        // For now, collect up locale Ids representing the entries, for later processing:
        for (const auto &entry : std::as_const(uiLanguages))
            localeIds.append(QLocaleId::fromName(entry));
        if (localeIds.isEmpty())
            localeIds.append(systemLocale()->fallbackLocale().d->m_data->id());
        /* Note: Darwin allows entirely independent choice of locale and of
           preferred languages, so it's possible the locale implied by
           LanguageId, ScriptId and TerritoryId is absent from the UILanguages
           list and that this faithfully reflects the user's wishes. None the
           less, we include it (if it isn't C) in the list below, after the last
           with the same language and script or (if none has) at the end, in
           case there is no better option available. (See, QTBUG-104930.)
        */
        const QString name = QString::fromLatin1(d->m_data->id().name(sep)); // Raw name
        if (!name.isEmpty() && language() != C && !uiLanguages.contains(name)) {
            // That uses contains(name) as a cheap pre-test, but there may be an
            // entry that matches this on purging likely subtags.
            const QLocaleId id = d->m_data->id();
            const QLocaleId max = id.withLikelySubtagsAdded();
            const QLocaleId mine = max.withLikelySubtagsRemoved();
            // Default to putting at the end:
            qsizetype lastAlike = uiLanguages.size() - 1;
            bool seen = false;
            for (qsizetype i = 0; !seen && i < uiLanguages.size(); ++i) {
                const auto its = QLocaleId::fromName(uiLanguages.at(i)).withLikelySubtagsAdded();
                seen = its.withLikelySubtagsRemoved() == mine;
                if (!seen && its.language_id == max.language_id && its.script_id == max.script_id)
                    lastAlike = i;
            }
            if (!seen) {
                localeIds.insert(lastAlike + 1, id);
                uiLanguages.insert(lastAlike + 1, QString::fromLatin1(id.name(sep)));
            }
        }
    } else
#endif
    {
        localeIds.append(d->m_data->id());
    }

    for (qsizetype i = localeIds.size(); i-- > 0; ) {
        const QLocaleId id = localeIds.at(i);
        Q_ASSERT(id.language_id);
        if (id.language_id == C) {
            if (!uiLanguages.contains(u"C"_s))
                uiLanguages.append(u"C"_s);
            // Attempt no likely sub-tag amendments to C.
            continue;
        }

        qsizetype j;
        const QByteArray prior = id.name(sep);
        bool faithful = true; // prior matches uiLanguages.at(j - 1)
        if (isSystem && i < uiLanguages.size()) {
            // Adding likely-adjusted forms to system locale's list.
            faithful = uiLanguages.at(i) == QLatin1StringView(prior);
            Q_ASSERT(faithful
                     // A legacy code may get mapped to an ID with a different name:
                     || QLocaleId::fromName(uiLanguages.at(i)).name(sep) == prior);
            // Insert just after the entry we're supplementing:
            j = i + 1;
        } else {
            // Plain locale or empty system uiLanguages; just append.
            if (!uiLanguages.contains(QLatin1StringView(prior)))
                uiLanguages.append(QString::fromLatin1(prior));
            j = uiLanguages.size();
        }

        const QLocaleId max = id.withLikelySubtagsAdded();
        Q_ASSERT(max.language_id);
        Q_ASSERT(max.language_id == id.language_id);
        // We can't say the same for script or territory, though.

        // We have various candidates to consider.
        const auto addIfEquivalent = [&j, &uiLanguages, max, sep, &prior, faithful](QLocaleId cid) {
            if (cid.withLikelySubtagsAdded() == max) {
                if (const QByteArray name = cid.name(sep); name != prior)
                    uiLanguages.insert(j, QString::fromLatin1(name));
                else if (faithful) // Later candidates are more specific, so go before.
                    --j;
            }
        };
        // language
        addIfEquivalent({ max.language_id, 0, 0 });
        // language-script
        if (max.script_id)
            addIfEquivalent({ max.language_id, max.script_id, 0 });
        if (id.script_id && id.script_id != max.script_id)
            addIfEquivalent({ id.language_id, id.script_id, 0 });
        // language-territory
        if (max.territory_id)
            addIfEquivalent({ max.language_id, 0, max.territory_id });
        if (id.territory_id && id.territory_id != max.territory_id)
            addIfEquivalent({ id.language_id, 0, id.territory_id });
        // full
        if (max.territory_id && max.script_id)
            addIfEquivalent(max);
        if (max.territory_id && id.script_id && id.script_id != max.script_id)
            addIfEquivalent({ id.language_id, id.script_id, max.territory_id });
        if (max.script_id && id.territory_id && id.territory_id != max.territory_id)
            addIfEquivalent({ id.language_id, max.script_id, id.territory_id });
        if (id.territory_id && id.territory_id != max.territory_id
            && id.script_id && id.script_id != max.script_id) {
            addIfEquivalent(id);
        }
    }

    // Second pass: deduplicate.
    // Can't use QStringList::removeDuplicates() here, because we still need
    // the QDuplicateTracker, later.
    QDuplicateTracker<QString> known(uiLanguages.size());
    uiLanguages.removeIf([&](const QString &s) { return known.hasSeen(s); });

    // Third pass: add truncations, when not already present.
    // Cubic in list length, but hopefully that's at most a dozen or so.
    const QLatin1Char cut(sep);
    const auto hasPrefix = [cut](auto name, QStringView stem) {
        // A prefix only counts if it's either full or followed by a separator.
        return name.startsWith(stem)
            && (name.size() == stem.size() || name.at(stem.size()) == cut);
    };
    // As we now forward-traverse the list, we need to keep track of the
    // positions just after (a) the block of things added above that are
    // equivalent to the current entry and (b) the block of truncations (if any)
    // added just after this block. All truncations of entries in (a) belong at
    // the end of (b); once i advances to the end of (a) it must jump to just
    // after (b). The more specific entries in (a) may well have truncations
    // that can also arise from less specific ones later in (a); for the
    // purposes of determining whether such truncations go at the end of (b) or
    // the end of the list, we thus need to ignore these matches.
    qsizetype afterEquivs = 0;
    qsizetype afterTruncs = 0;
    // From here onwards, we only have the truncations we're adding, whose
    // truncations should all have been included already.
    // If advancing i brings us to the end of block (a), jump to the end of (b):
    for (qsizetype i = 0; i < uiLanguages.size(); ++i >= afterEquivs && (i = afterTruncs)) {
        const QString entry = uiLanguages.at(i);
        const QLocaleId max = QLocaleId::fromName(entry).withLikelySubtagsAdded();
        // Keep track of our two blocks:
        if (i >= afterEquivs) {
            Q_ASSERT(i >= afterTruncs); // i.e. we just skipped past the end of a block
            afterEquivs = i + 1;
            // Advance past equivalents of entry:
            while (afterEquivs < uiLanguages.size()
                   && QLocaleId::fromName(uiLanguages.at(afterEquivs))
                           .withLikelySubtagsAdded() == max) {
                ++afterEquivs;
            }
            // We'll add any truncations starting there:
            afterTruncs = afterEquivs;
        }
        if (hasPrefix(entry, u"C") || hasPrefix(entry, u"und"))
            continue;
        qsizetype stopAt = uiLanguages.size();
        qsizetype at = entry.size(); // if 0, calls lastIndexOf(cut, -1), which is in-contract
        while ((at = entry.lastIndexOf(cut, at - 1)) > 0) {
            QString prefix = entry.first(at);
            // Don't test with hasSeen() as we might defer adding to later, when
            // we'll need known to see the later entry's offering of this prefix
            // as a new entry.
            bool found = known.contains(prefix);
            /* By default we append but if no later entry has this as a prefix
               and the locale it implies would use the same script as entry, put
               it after the block of consecutive equivalents of which entry is a
               part instead. Thus [en-NL, nl-NL, en-GB] will append en but
               [en-NL, en-GB, nl-NL] will put it before nl-NL, for example. We
               require a script match so we don't pick translations that the
               user cannot read, despite knowing the language. (Ideally that
               would be a constraint the caller can opt into / out of. See
               QTBUG-112765.)
            */
            bool justAfter
                = (QLocaleId::fromName(prefix).withLikelySubtagsAdded().script_id == max.script_id);
            for (qsizetype j = afterTruncs; !found && j < stopAt; ++j) {
                QString later = uiLanguages.at(j);
                if (!later.startsWith(prefix)) {
                    const QByteArray laterFull =
                        QLocaleId::fromName(later.replace(cut, u'-')
                            ).withLikelySubtagsAdded().name(sep);
                    // When prefix matches a later entry's max, it belongs later.
                    if (hasPrefix(QLatin1StringView(laterFull), prefix))
                        justAfter = false;
                    continue;
                }
                // The duplicate tracker would already have spotted if equal:
                Q_ASSERT(later.size() > prefix.size());
                if (later.at(prefix.size()) == cut) {
                    justAfter = false;
                    // Prefix match. Shall produce the same prefix, but possibly
                    // after prefixes of other entries in the list. If later has
                    // a longer prefix not yet in the list, we want that before
                    // this shorter prefix, so leave this for later, otherwise,
                    // we include this prefix right away.
                    QStringView head{later};
                    for (qsizetype as = head.lastIndexOf(cut);
                         !found && as > prefix.size(); as = head.lastIndexOf(cut)) {
                        head = head.first(as);
                        bool seen = false;
                        for (qsizetype k = j + 1; !seen && k < uiLanguages.size(); ++k)
                            seen = uiLanguages.at(k) == head;
                        if (!seen)
                            found = true;
                    }
                }
            }
            if (found) // Don't duplicate.
                continue; // Some shorter truncations may still be missing.
            // Now we're committed to adding it, get it into known:
            (void) known.hasSeen(prefix);
            if (justAfter) {
                uiLanguages.insert(afterTruncs++, std::move(prefix));
                ++stopAt; // All later entries have moved one step later.
            } else {
                uiLanguages.append(std::move(prefix));
            }
        }
    }

    return uiLanguages;
}

/*!
  \since 5.13

  Returns the locale to use for collation.

  The result is usually this locale; however, the system locale (which is
  commonly the default locale) will return the system collation locale.
  The result is suitable for passing to QCollator's constructor.

  \sa QCollator
*/
QLocale QLocale::collation() const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        const auto res = systemLocale()->query(QSystemLocale::Collation).toString();
        if (!res.isEmpty())
            return QLocale(res);
    }
#endif
    return *this;
}

/*!
    \since 4.8

    Returns a native name of the language for the locale. For example
    "Schweizer Hochdeutsch" for the Swiss-German locale.

    \sa nativeTerritoryName(), languageToString()
*/
QString QLocale::nativeLanguageName() const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        auto res = systemLocale()->query(QSystemLocale::NativeLanguageName).toString();
        if (!res.isEmpty())
            return res;
    }
#endif
    return d->m_data->endonymLanguage().getData(endonyms_data);
}

/*!
    \since 6.2

    Returns a native name of the territory for the locale. For example
    "España" for Spanish/Spain locale.

    \sa nativeLanguageName(), territoryToString()
*/
QString QLocale::nativeTerritoryName() const
{
#ifndef QT_NO_SYSTEMLOCALE
    if (d->m_data == &systemLocaleData) {
        auto res = systemLocale()->query(QSystemLocale::NativeTerritoryName).toString();
        if (!res.isEmpty())
            return res;
    }
#endif
    return d->m_data->endonymTerritory().getData(endonyms_data);
}

#if QT_DEPRECATED_SINCE(6, 6)
/*!
    \deprecated [6.6] Use \l nativeTerritoryName() instead.
    \since 4.8

    Returns a native name of the territory for the locale. For example
    "España" for Spanish/Spain locale.

    \sa nativeLanguageName(), territoryToString()
*/
QString QLocale::nativeCountryName() const
{
    return nativeTerritoryName();
}
#endif

#ifndef QT_NO_DEBUG_STREAM
QDebug operator<<(QDebug dbg, const QLocale &l)
{
    QDebugStateSaver saver(dbg);
    const bool isSys = l == QLocale::system();
    dbg.nospace().noquote()
        << (isSys ? "QLocale::system()/* " : "QLocale(")
        << QLocale::languageToString(l.language()) << ", "
        << QLocale::scriptToString(l.script()) << ", "
        << QLocale::territoryToString(l.territory()) << (isSys ? " */" : ")");
    return dbg;
}
#endif
QT_END_NAMESPACE

#ifndef QT_NO_QOBJECT
#include "moc_qlocale.cpp"
#endif
