qdatetime.cpp

QT 开发环境里面一个很重要的文件

/*!
    Constructs a datetime with the given \a date, and a valid
    time (00:00:00.000).
*/

QDateTime::QDateTime(const QDate &date)
{
    d = new QDateTimePrivate;
    d->date = date;
    d->time = QTime(0, 0, 0);
}

/*!
    Constructs a datetime with the given \a date and \a time, using
    the time specification defined by \a spec.

    If \a date is valid and \a time is not, the time will be set to midnight.
*/

QDateTime::QDateTime(const QDate &date, const QTime &time, Qt::TimeSpec spec)
{
    d = new QDateTimePrivate;
    d->date = date;
    d->time = date.isValid() && !time.isValid() ? QTime(0, 0, 0) : time;
    d->spec = (spec == Qt::UTC) ? QDateTimePrivate::UTC : QDateTimePrivate::LocalUnknown;
}

/*!
    Constructs a copy of the \a other datetime.
*/

QDateTime::QDateTime(const QDateTime &other)
{
    d = other.d;
    d->ref.ref();
}

/*!
    Destroys the datetime.
*/
QDateTime::~QDateTime()
{
    if (!d->ref.deref())
        delete d;
}

/*!
    Makes a copy of the \a other datetime and returns a reference to the
    copy.
*/

QDateTime &QDateTime::operator=(const QDateTime &other)
{
    qAtomicAssign(d, other.d);
    return *this;
}

/*!
    Returns true if both the date and the time are null; otherwise
    returns false. A null datetime is invalid.

    \sa QDate::isNull(), QTime::isNull(), isValid()
*/

bool QDateTime::isNull() const
{
    return d->date.isNull() && d->time.isNull();
}

/*!
    Returns true if both the date and the time are valid; otherwise
    returns false.

    \sa QDate::isValid(), QTime::isValid()
*/

bool QDateTime::isValid() const
{
    return d->date.isValid() && d->time.isValid();
}

/*!
    Returns the date part of the datetime.

    \sa setDate(), time(), timeSpec()
*/

QDate QDateTime::date() const
{
    return d->date;
}

/*!
    Returns the time part of the datetime.

    \sa setTime(), date(), timeSpec()
*/

QTime QDateTime::time() const
{
    return d->time;
}

/*!
    Returns the time specification of the datetime.

    \sa setTimeSpec(), date(), time(), Qt::TimeSpec
*/

Qt::TimeSpec QDateTime::timeSpec() const
{
    return d->spec == QDateTimePrivate::UTC ? Qt::UTC : Qt::LocalTime;
}

/*!
    Sets the date part of this datetime to \a date.
    If no time is set, it is set to midnight.

    \sa date(), setTime(), setTimeSpec()
*/

void QDateTime::setDate(const QDate &date)
{
    detach();
    d->date = date;
    if (date.isValid() && !d->time.isValid())
        d->time = QTime(0, 0, 0);
}

/*!
    Sets the time part of this datetime to \a time.

    \sa time(), setDate(), setTimeSpec()
*/

void QDateTime::setTime(const QTime &time)
{
    detach();
    d->time = time;
}

/*!
    Sets the time specification used in this datetime to \a spec.

    \sa timeSpec(), setDate(), setTime(), Qt::TimeSpec
*/

void QDateTime::setTimeSpec(Qt::TimeSpec spec)
{
    detach();
    d->spec = (spec == Qt::UTC) ? QDateTimePrivate::UTC : QDateTimePrivate::LocalUnknown;
}

static uint toTime_t(const QDate &utcDate, const QTime &utcTime)
{
    int days = QDate(1970, 1, 1).daysTo(utcDate);
    int secs = QTime().secsTo(utcTime);
    if (days < 0 || (days == 0 && secs < 0))
        return uint(-1);

    qlonglong retval = (qlonglong(days) * SECS_PER_DAY) + secs;
    if (retval >= Q_INT64_C(0xFFFFFFFF))
        return uint(-1);
    return uint(retval);
}

/*!
    Returns the datetime as the number of seconds that have passed
    since 1970-01-01T00:00:00, Coordinated Universal Time (Qt::UTC).

    On systems that do not support timezones, this function will
    behave as if local time were Qt::UTC.

    \sa setTime_t()
*/

uint QDateTime::toTime_t() const
{
    QDate utcDate;
    QTime utcTime;
    d->getUTC(utcDate, utcTime);

    return ::toTime_t(utcDate, utcTime);
}

/*!
    \fn void QDateTime::setTime_t(uint seconds)

    Sets the date and time given the number of \a seconds that have
    passed since 1970-01-01T00:00:00, Coordinated Universal Time
    (Qt::UTC). On systems that do not support timezones this function
    will behave as if local time were Qt::UTC.

    \sa toTime_t()
*/

void QDateTime::setTime_t(uint secsSince1Jan1970UTC)
{
    detach();

    QDateTimePrivate::Spec oldSpec = d->spec;

    d->date = QDate(1970, 1, 1).addDays(secsSince1Jan1970UTC / SECS_PER_DAY);
    d->time = QTime().addSecs(secsSince1Jan1970UTC % SECS_PER_DAY);
    d->spec = QDateTimePrivate::UTC;

    if (oldSpec != QDateTimePrivate::UTC)
        d->spec = d->getLocal(d->date, d->time);
}

#ifndef QT_NO_DATESTRING
/*!
    \fn QString QDateTime::toString(Qt::DateFormat format) const

    \overload

    Returns the datetime as a string in the \a format given.

    If the \a format is Qt::TextDate, the string is formatted in
    the default way. QDate::shortDayName(), QDate::shortMonthName(),
    and QTime::toString() are used to generate the string, so the
    day and month names will be localized names. An example of this
    formatting is "Wed May 20 03:40:13 1998".

    If the \a format is Qt::ISODate, the string format corresponds
    to the ISO 8601 extended specification for representations of
    dates and times, taking the form YYYY-MM-DDTHH:MM:SS.

    If the \a format is Qt::LocalDate or Qt::SystemLocaleDate, the string
    format depends on the locale settings of the system. Identical to
    calling QLocale::system().toString(dateTime, QLocale::ShortFormat).
    \e{Qt::LocalDate has been deprecated, please use Qt::SystemLocaleDate
    instead.}

    If the \a format is Qt::LocaleDate, the string
    format depends on the default application locale. This is the
    locale set with QLocale::setDefault(), or the system locale if no
    default locale has been set. Identical to calling
    QLocale().toString(dateTime, QLocale::ShortFormat);

    If the datetime is invalid, an empty string will be returned.

    \warning The Qt::ISODate format is only valid for years in the
    range 0 to 9999. This restriction may apply to Qt::LocalDate as
    well, depending on the locale settings.

    \sa QDate::toString() QTime::toString() Qt::DateFormat
*/

QString QDateTime::toString(Qt::DateFormat f) const
{
    QString buf;
    if (!isValid())
        return buf;

    if (f == Qt::ISODate) {
        buf = d->date.toString(Qt::ISODate);
        if (buf.isEmpty())
            return QString();   // failed to convert
        buf += QLatin1Char('T');
        buf += d->time.toString(Qt::ISODate);
    }
#ifndef QT_NO_TEXTDATE
    else if (f == Qt::TextDate) {
#ifndef Q_WS_WIN
        buf = d->date.shortDayName(d->date.dayOfWeek());
        buf += QLatin1Char(' ');
        buf += d->date.shortMonthName(d->date.month());
        buf += QLatin1Char(' ');
        buf += QString::number(d->date.day());
#else
        QString winstr;
        QT_WA({
            TCHAR out[255];
            GetLocaleInfo(LOCALE_USER_DEFAULT, LOCALE_ILDATE, out, 255);
            winstr = QString::fromUtf16((ushort*)out);
        } , {
            char out[255];
            GetLocaleInfoA(LOCALE_USER_DEFAULT, LOCALE_ILDATE, (char*)&out, 255);
            winstr = QString::fromLocal8Bit(out);
        });
        switch (winstr.toInt()) {
        case 1:
            buf = d->date.shortDayName(d->date.dayOfWeek());
            buf += QLatin1Char(' ');
            buf += QString::number(d->date.day());
            buf += QLatin1String(". ");
            buf += d->date.shortMonthName(d->date.month());
            break;
        default:
            buf = d->date.shortDayName(d->date.dayOfWeek());
            buf += QLatin1Char(' ');
            buf += d->date.shortMonthName(d->date.month());
            buf += QLatin1Char(' ');
            buf += QString::number(d->date.day());
        }
#endif
        buf += QLatin1Char(' ');
        buf += d->time.toString();
        buf += QLatin1Char(' ');
        buf += QString::number(d->date.year());
    }
#endif
    else if (f == Qt::LocaleDate || f == Qt::SystemLocaleDate) {
        buf = d->date.toString(f);
        if (buf.isEmpty())
            return QString();   // failed to convert
        buf += QLatin1Char(' ');
        buf += d->time.toString(f);
    }
    return buf;
}

/*!
    Returns the datetime as a string. The \a format parameter
    determines the format of the result string.

    These expressions may be used for the date:

    \table
    \header \i Expression \i Output
    \row \i d \i the day as number without a leading zero (1 to 31)
    \row \i dd \i the day as number with a leading zero (01 to 31)
    \row \i ddd
            \i the abbreviated localized day name (e.g. 'Mon' to 'Sun').
            Uses QDate::shortDayName().
    \row \i dddd
            \i the long localized day name (e.g. 'Qt::Monday' to 'Qt::Sunday').
            Uses QDate::longDayName().
    \row \i M \i the month as number without a leading zero (1-12)
    \row \i MM \i the month as number with a leading zero (01-12)
    \row \i MMM
            \i the abbreviated localized month name (e.g. 'Jan' to 'Dec').
            Uses QDate::shortMonthName().
    \row \i MMMM
            \i the long localized month name (e.g. 'January' to 'December').
            Uses QDate::longMonthName().
    \row \i yy \i the year as two digit number (00-99)
    \row \i yyyy \i the year as four digit number
    \endtable

    These expressions may be used for the time:

    \table
    \header \i Expression \i Output
    \row \i h
         \i the hour without a leading zero (0 to 23 or 1 to 12 if AM/PM display)
    \row \i hh
         \i the hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display)
    \row \i m \i the minute without a leading zero (0 to 59)
    \row \i mm \i the minute with a leading zero (00 to 59)
    \row \i s \i the second without a leading zero (0 to 59)
    \row \i ss \i the second with a leading zero (00 to 59)
    \row \i z \i the milliseconds without leading zeroes (0 to 999)
    \row \i zzz \i the milliseconds with leading zeroes (000 to 999)
    \row \i AP
            \i use AM/PM display. \e AP will be replaced by either "AM" or "PM".
    \row \i ap
            \i use am/pm display. \e ap will be replaced by either "am" or "pm".
    \endtable

    All other input characters will be ignored. Any sequence of characters that
    are enclosed in singlequotes will be treated as text and not be used as an
    expression.

    Example format strings (assumed that the QDateTime is 21 May 2001
    14:13:09):

    \table
    \header \i Format       \i Result
    \row \i dd.MM.yyyy      \i 21.05.2001
    \row \i ddd MMMM d yy   \i Tue May 21 01
    \row \i hh:mm:ss.zzz    \i 14:13:09.042
    \row \i h:m:s ap        \i 2:13:9 pm
    \endtable

    If the datetime is invalid, an empty string will be returned.

    \sa QDate::toString() QTime::toString()
*/
QString QDateTime::toString(const QString& format) const
{
    return fmtDateTime(format, &d->time, &d->date);
}
#endif //QT_NO_DATESTRING

/*!
    Returns a QDateTime object containing a datetime \a ndays days
    later than the datetime of this object (or earlier if \a ndays is
    negative).

    \sa daysTo(), addMonths(), addYears(), addSecs()
*/

QDateTime QDateTime::addDays(int ndays) const
{
    return QDateTime(d->date.addDays(ndays), d->time, timeSpec());
}

/*!
    Returns a QDateTime object containing a datetime \a nmonths months
    later than the datetime of this object (or earlier if \a nmonths
    is negative).

    \sa daysTo(), addDays(), addYears(), addSecs()
*/

QDateTime QDateTime::addMonths(int nmonths) const
{
    return QDateTime(d->date.addMonths(nmonths), d->time, timeSpec());
}

/*!
    Returns a QDateTime object containing a datetime \a nyears years
    later than the datetime of this object (or earlier if \a nyears is
    negative).

    \sa daysTo(), addDays(), addMonths(), addSecs()
*/

QDateTime QDateTime::addYears(int nyears) const
{
    return QDateTime(d->date.addYears(nyears), d->time, timeSpec());
}


QDateTime QDateTimePrivate::addMSecs(const QDateTime &dt, qint64 msecs)
{
    QDate utcDate;
    QTime utcTime;
    dt.d->getUTC(utcDate, utcTime);

    uint dd = utcDate.jd;
    int tt = utcTime.ds();
    int sign = 1;
    if (msecs < 0) {
        msecs = -msecs;
        sign = -1;
    }
    if (msecs >= int(MSECS_PER_DAY)) {
        dd += sign * (msecs / MSECS_PER_DAY);
        msecs %= MSECS_PER_DAY;
    }

    tt += sign * msecs;
    if (tt < 0) {
        tt = MSECS_PER_DAY - tt - 1;
        dd -= tt / MSECS_PER_DAY;
        tt = tt % MSECS_PER_DAY;
        tt = MSECS_PER_DAY - tt - 1;
    } else if (tt >= int(MSECS_PER_DAY)) {
        dd += tt / MSECS_PER_DAY;
        tt = tt % MSECS_PER_DAY;
    }

    utcDate.jd = dd;
    utcTime.mds = tt;
    return QDateTime(utcDate, utcTime, Qt::UTC).toTimeSpec(dt.timeSpec());
}

/*!
    Returns a QDateTime object containing a datetime \a nsecs seconds
    later than the datetime of this object (or earlier if \a nsecs is
    negative).