qvariant.cpp

奇趣公司比较新的qt/emd版本

            return false;
        break;
    case QVariant::Point:
        if (d->type == QVariant::PointF)
            *static_cast<QPoint *>(result) = (v_cast<QPointF>(d))->toPoint();
        else
            return false;
        break;
    case QMetaType::Char:
    {
        *static_cast<qint8 *>(result) = qint8(qConvertToNumber(d, ok));
        return *ok;
    }
#endif
    default:
        return false;
    }
    return true;
}

#if !defined(QT_NO_DEBUG_STREAM) && !defined(Q_BROKEN_DEBUG_STREAM)
static void streamDebug(QDebug dbg, const QVariant &v)
{
    switch (v.type()) {
    case QVariant::Int:
        dbg.nospace() << v.toInt();
        break;
    case QVariant::UInt:
        dbg.nospace() << v.toUInt();
        break;
    case QVariant::LongLong:
        dbg.nospace() << v.toLongLong();
        break;
    case QVariant::ULongLong:
        dbg.nospace() << v.toULongLong();
        break;
    case QVariant::Double:
        dbg.nospace() << v.toDouble();
        break;
    case QVariant::Bool:
        dbg.nospace() << v.toBool();
        break;
    case QVariant::String:
        dbg.nospace() << v.toString();
        break;
    case QVariant::Char:
        dbg.nospace() << v.toChar();
        break;
    case QVariant::StringList:
        dbg.nospace() << v.toStringList();
        break;
    case QVariant::Map:
        dbg.nospace() << v.toMap();
        break;
    case QVariant::List:
        dbg.nospace() << v.toList();
        break;
    case QVariant::Date:
        dbg.nospace() << v.toDate();
        break;
    case QVariant::Time:
        dbg.nospace() << v.toTime();
        break;
    case QVariant::DateTime:
        dbg.nospace() << v.toDateTime();
        break;
    case QVariant::ByteArray:
        dbg.nospace() << v.toByteArray();
        break;
    case QVariant::Url:
        dbg.nospace() << v.toUrl();
        break;
#ifndef QT_NO_GEOM_VARIANT
    case QVariant::Point:
        dbg.nospace() << v.toPoint();
        break;
    case QVariant::PointF:
        dbg.nospace() << v.toPointF();
        break;
    case QVariant::Rect:
        dbg.nospace() << v.toRect();
        break;
    case QVariant::Size:
        dbg.nospace() << v.toSize();
        break;
    case QVariant::SizeF:
        dbg.nospace() << v.toSizeF();
        break;
    case QVariant::Line:
        dbg.nospace() << v.toLine();
        break;
    case QVariant::LineF:
        dbg.nospace() << v.toLineF();
        break;
    case QVariant::RectF:
        dbg.nospace() << v.toRectF();
        break;
#endif
    case QVariant::BitArray:
        //dbg.nospace() << v.toBitArray();
        break;
    default:
        break;
    }
}
#endif

const QVariant::Handler qt_kernel_variant_handler = {
    construct,
    clear,
    isNull,
#ifndef QT_NO_DATASTREAM
    0,
    0,
#endif
    compare,
    convert,
    0,
#if !defined(QT_NO_DEBUG_STREAM) && !defined(Q_BROKEN_DEBUG_STREAM)
    streamDebug
#else
    0
#endif
};

Q_CORE_EXPORT const QVariant::Handler *qcoreVariantHandler()
{
    return &qt_kernel_variant_handler;
}


const QVariant::Handler *QVariant::handler = &qt_kernel_variant_handler;

/*!
    \class QVariant
    \brief The QVariant class acts like a union for the most common Qt data types.

    \ingroup objectmodel
    \ingroup misc
    \ingroup shared
    \mainclass

    Because C++ forbids unions from including types that have
    non-default constructors or destructors, most interesting Qt
    classes cannot be used in unions. Without QVariant, this would be
    a problem for QObject::property() and for database work, etc.

    A QVariant object holds a single value of a single type() at a
    time. (Some type()s are multi-valued, for example a string list.)
    You can find out what type, T, the variant holds, convert it to a
    different type using convert(), get its value using one of the
    toT() functions (e.g., toSize()) and check whether the type can
    be converted to a particular type using canConvert().

    The methods named toT() (e.g., toInt(), toString()) are const. If
    you ask for the stored type, they return a copy of the stored
    object. If you ask for a type that can be generated from the
    stored type, toT() copies and converts and leaves the object
    itself unchanged. If you ask for a type that cannot be generated
    from the stored type, the result depends on the type; see the
    function documentation for details.

    Here is some example code to demonstrate the use of QVariant:

    \code
        QDataStream out(...);
        QVariant v(123);                // The variant now contains an int
        int x = v.toInt();              // x = 123
        out << v;                       // Writes a type tag and an int to out
        v = QVariant("hello");          // The variant now contains a QByteArray
        v = QVariant(tr("hello"));      // The variant now contains a QString
        int y = v.toInt();              // y = 0 since v cannot be converted to an int
        QString s = v.toString();       // s = tr("hello")  (see QObject::tr())
        out << v;                       // Writes a type tag and a QString to out
        ...
        QDataStream in(...);            // (opening the previously written stream)
        in >> v;                        // Reads an Int variant
        int z = v.toInt();              // z = 123
        qDebug("Type is %s",            // prints "Type is int"
                v.typeName());
        v = v.toInt() + 100;            // The variant now hold the value 223
        v = QVariant(QStringList());
    \endcode

    You can even store QList<QVariant> and QMap<QString, QVariant>
    values in a variant, so you can easily construct arbitrarily
    complex data structures of arbitrary types. This is very powerful
    and versatile, but may prove less memory and speed efficient than
    storing specific types in standard data structures.

    QVariant also supports the notion of null values, where you have
    a defined type with no value set.

    \code
        QVariant x, y(QString()), z(QString(""));
        x.convert(QVariant::Int);
        // x.isNull() == true
        // y.isNull() == true, z.isNull() == false
        // y.isEmpty() == true, z.isEmpty() == true
    \endcode

    QVariant can be extended to support other types than those
    mentioned in the \l Type enum. See the \l QMetaType documentation
    for details.

    \section1 A Note on GUI Types

    Because QVariant is part of the QtCore library, it cannot provide
    conversion functions to data types defined in QtGui, such as
    QColor, QImage, and QPixmap. In other words, there is no \c
    toColor() function. Instead, you can use the QVariant::value() or
    the qVariantValue() template function. For example:

    \code
        QVariant variant;
        ...
        QColor color = variant.value<QColor>();
    \endcode

    The inverse conversion (e.g., from QColor to QVariant) is
    automatic for all data types supported by QVariant, including
    GUI-related types:

    \code
        QColor color = palette().background().color();
        QVariant variant = color;
    \endcode

    \section1 Using canConvert() and convert() Consecutively

    When using canConvert() and convert() consecutively, it is possible for
    canConvert() to return true, but convert() to return false. This
    is typically because canConvert() only reports the general ability of
    QVariant to convert between types given suitable data; it is still
    possible to supply data which cannot actually be converted.

    For example, canConvert() would return true when called on a variant
    containing a string because, in principle, QVariant is able to convert
    strings of numbers to integers.
    However, if the string contains non-numeric characters, it cannot be
    converted to an integer, and any attempt to convert it will fail.
    Hence, it is important to have both functions return true for a
    successful conversion.

    \sa QMetaType
*/

/*!
    \enum QVariant::Type

    This enum type defines the types of variable that a QVariant can
    contain.

    \value Invalid  no type
    \value BitArray  a QBitArray
    \value Bitmap  a QBitmap
    \value Bool  a bool
    \value Brush  a QBrush
    \value ByteArray  a QByteArray
    \value Char  a QChar
    \value Color  a QColor
    \value Cursor  a QCursor
    \value Date  a QDate
    \value DateTime  a QDateTime
    \value Double  a double
    \value Font  a QFont
    \value Icon  a QIcon
    \value Image  a QImage
    \value Int  an int
    \value KeySequence  a QKeySequence
    \value Line  a QLine
    \value LineF  a QLineF
    \value List  a QVariantList
    \value Locale  a QLocale
    \value LongLong a \l qlonglong
    \value Map  a QVariantMap
    \value Matrix  a QMatrix
    \value Transform  a QTransform
    \value Palette  a QPalette
    \value Pen  a QPen
    \value Pixmap  a QPixmap
    \value Point  a QPoint
    \value PointArray  a QPointArray
    \value PointF  a QPointF
    \value Polygon a QPolygon
    \value Rect  a QRect
    \value RectF  a QRectF
    \value RegExp  a QRegExp
    \value Region  a QRegion
    \value Size  a QSize
    \value SizeF  a QSizeF
    \value SizePolicy  a QSizePolicy
    \value String  a QString
    \value StringList  a QStringList
    \value TextFormat  a QTextFormat
    \value TextLength  a QTextLength
    \value Time  a QTime
    \value UInt  a \l uint
    \value ULongLong a \l qulonglong
    \value Url  a QUrl

    \value UserType Base value for user-defined types.

    \omitvalue CString
    \omitvalue ColorGroup
    \omitvalue IconSet
    \omitvalue LastGuiType
    \omitvalue LastCoreType
    \omitvalue LastType
*/

/*!
    \fn QVariant::QVariant()

    Constructs an invalid variant.
*/


/*!
    \fn QVariant::QVariant(int typeOrUserType, const void *copy)

    Constructs variant of type \a typeOrUserType, and initializes with
    \a copy if \a copy is not 0.

    Note that you have to pass the address of the variable you want stored.

    Usually, you never have to use this constructor, use qVariantFromValue()
    instead to construct variants from the pointer types represented by
    \c QMetaType::VoidStar, \c QMetaType::QObjectStar and
    \c QMetaType::QWidgetStar.

    \sa qVariantFromValue(), Type
*/

/*!
    \fn QVariant::QVariant(Type type)

    Constructs a null variant of type \a type.
*/



/*!
    \fn QVariant::create(int type, const void *copy)

    \internal

    Constructs a variant private of type \a type, and initializes with \a copy if
    \a copy is not 0.
*/

void QVariant::create(int type, const void *copy)
{
    d.type = type;
    handler->construct(&d, copy);
}

/*!
    \fn QVariant::~QVariant()

    Destroys the QVariant and the contained object.

    Note that subclasses that reimplement clear() should reimplement
    the destructor to call clear(). This destructor calls clear(), but
    because it is the destructor, QVariant::clear() is called rather
    than a subclass's clear().
*/

QVariant::~QVariant()
{
    if (d.type > Char && (!d.is_shared || !d.data.shared->ref.deref()))
        handler->clear(&d);
}

/*!
  \fn QVariant::QVariant(const QVariant &p)

    Constructs a copy of the variant, \a p, passed as the argument to
    this constructor.
*/

QVariant::QVariant(const QVariant &p)
    : d(p.d)
{
    if (d.is_shared) {
        d.data.shared->ref.ref();
    } else if (p.d.type > Char) {
        handler->construct(&d, p.constData());
        d.is_null = p.d.is_null;
    }
}

#ifndef QT_NO_DATASTREAM
/*!
    Reads the variant from the data stream, \a s.
*/
QVariant::QVariant(QDataStream &s)
{
    d.is_null = true;
    s >> *this;
}
#endif //QT_NO_DATASTREAM

/*!
  \fn QVariant::QVariant(const QString &val)

    Constructs a new variant with a string value, \a val.
*/

/*!
  \fn QVariant::QVariant(const QLatin1String &val)

    Constructs a new variant with a string value, \a val.
*/

/*!
  \fn QVariant::QVariant(const char *val)

    Constructs a new variant with a string value of \a val.
    The variant creates a deep copy of \a val, using the encoding
    set by QTextCodec::setCodecForCStrings().

    You can disable this operator by defining \c
    QT_NO_CAST_FROM_ASCII when you compile your applications.

    \sa QTextCodec::setCodecForCStrings()
*/

#ifndef QT_NO_CAST_FROM_ASCII
QVariant::QVariant(const char *val)
{
    QString s = QString::fromAscii(val);
    create(String, &s);
}
#endif

/*!
  \fn QVariant::QVariant(const QStringList &val)

    Constructs a new variant with a string list value, \a val.
*/

/*!
  \fn QVariant::QVariant(const QMap<QString, QVariant> &val)

    Constructs a new variant with a map of QVariants, \a val.
*/

/*!
  \fn QVariant::QVariant(const QDate &val)

    Constructs a new variant with a date value, \a val.
*/

/*!
  \fn QVariant::QVariant(const QTime &val)

    Constructs a new variant with a time value, \a val.
*/

/*!
  \fn QVariant::QVariant(const QDateTime &val)

    Constructs a new variant with a date/time value, \a val.
*/

/*!
  \fn QVariant::QVariant(const QByteArray &val)

    Constructs a new variant with a bytearray value, \a val.
*/

/*!