katie/src/declarative/util/qdeclarativepropertymap.cpp

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** Copyright (C) 2015 The Qt Company Ltd.
** Copyright (C) 2016-2019 Ivailo Monev
**
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#include "qdeclarativepropertymap.h"

#include "qmetaobjectbuilder_p.h"
#include "qdeclarativeopenmetaobject_p.h"

#include <QDebug>

QT_BEGIN_NAMESPACE

//QDeclarativePropertyMapMetaObject lets us listen for changes coming from QML
//so we can emit the changed signal.
class QDeclarativePropertyMapMetaObject : public QDeclarativeOpenMetaObject
{
public:
    QDeclarativePropertyMapMetaObject(QDeclarativePropertyMap *obj, QDeclarativePropertyMapPrivate *objPriv);

protected:
    virtual void propertyWritten(int index);
    virtual void propertyCreated(int, QMetaPropertyBuilder &);

private:
    QDeclarativePropertyMap *map;
    QDeclarativePropertyMapPrivate *priv;
};

class QDeclarativePropertyMapPrivate : public QObjectPrivate
{
    Q_DECLARE_PUBLIC(QDeclarativePropertyMap)
public:
    QDeclarativePropertyMapMetaObject *mo;
    QStringList keys;
    void emitChanged(const QString &key, const QVariant &value);
};

void QDeclarativePropertyMapPrivate::emitChanged(const QString &key, const QVariant &value)
{
    Q_Q(QDeclarativePropertyMap);
    emit q->valueChanged(key, value);
}

QDeclarativePropertyMapMetaObject::QDeclarativePropertyMapMetaObject(QDeclarativePropertyMap *obj, QDeclarativePropertyMapPrivate *objPriv) : QDeclarativeOpenMetaObject(obj)
{
    map = obj;
    priv = objPriv;
}

void QDeclarativePropertyMapMetaObject::propertyWritten(int index)
{
    priv->emitChanged(QString::fromUtf8(name(index)), operator[](index));
}

void QDeclarativePropertyMapMetaObject::propertyCreated(int, QMetaPropertyBuilder &b)
{
    priv->keys.append(QString::fromUtf8(b.name()));
}

/*!
    \class QDeclarativePropertyMap
    \since 4.7
    \brief The QDeclarativePropertyMap class allows you to set key-value pairs that can be used in QML bindings.

    QDeclarativePropertyMap provides a convenient way to expose domain data to the UI layer.
    The following example shows how you might declare data in C++ and then
    access it in QML.

    In the C++ file:
    \code
    // create our data
    QDeclarativePropertyMap ownerData;
    ownerData.insert("name", QVariant(QString("John Smith")));
    ownerData.insert("phone", QVariant(QString("555-5555")));

    // expose it to the UI layer
    QDeclarativeView view;
    QDeclarativeContext *ctxt = view.rootContext();
    ctxt->setContextProperty("owner", &ownerData);

    view.setSource(QUrl::fromLocalFile("main.qml"));
    view.show();
    \endcode

    Then, in \c main.qml:
    \code
    Text { text: owner.name + " " + owner.phone }
    \endcode

    The binding is dynamic - whenever a key's value is updated, anything bound to that
    key will be updated as well.

    To detect value changes made in the UI layer you can connect to the valueChanged() signal.
    However, note that valueChanged() is \bold NOT emitted when changes are made by calling insert()
    or clear() - it is only emitted when a value is updated from QML.

    \note It is not possible to remove keys from the map; once a key has been added, you can only
    modify or clear its associated value.
*/

/*!
    Constructs a bindable map with parent object \a parent.
*/
QDeclarativePropertyMap::QDeclarativePropertyMap(QObject *parent)
: QObject(*(new QDeclarativePropertyMapPrivate), parent)
{
    Q_D(QDeclarativePropertyMap);
    d->mo = new QDeclarativePropertyMapMetaObject(this, d);
}

/*!
    Destroys the bindable map.
*/
QDeclarativePropertyMap::~QDeclarativePropertyMap()
{
}

/*!
    Clears the value (if any) associated with \a key.
*/
void QDeclarativePropertyMap::clear(const QString &key)
{
    Q_D(QDeclarativePropertyMap);
    d->mo->setValue(key.toUtf8(), QVariant());
}

/*!
    Returns the value associated with \a key.

    If no value has been set for this key (or if the value has been cleared),
    an invalid QVariant is returned.
*/
QVariant QDeclarativePropertyMap::value(const QString &key) const
{
    Q_D(const QDeclarativePropertyMap);
    return d->mo->value(key.toUtf8());
}

/*!
    Sets the value associated with \a key to \a value.

    If the key doesn't exist, it is automatically created.
*/
void QDeclarativePropertyMap::insert(const QString &key, const QVariant &value)
{
    Q_D(QDeclarativePropertyMap);
    //The following strings shouldn't be used as property names
    if (key != QLatin1String("keys")
     && key != QLatin1String("valueChanged")
     && key != QLatin1String("QObject")
     && key != QLatin1String("destroyed")
     && key != QLatin1String("deleteLater")) {
        d->mo->setValue(key.toUtf8(), value);
    } else {
        qWarning() << "Creating property with name"
                   << key
                   << "is not permitted, conflicts with internal symbols.";
    }
}

/*!
    Returns the list of keys.

    Keys that have been cleared will still appear in this list, even though their
    associated values are invalid QVariants.
*/
QStringList QDeclarativePropertyMap::keys() const
{
    Q_D(const QDeclarativePropertyMap);
    return d->keys;
}

/*!
    \overload

    Same as size().
*/
int QDeclarativePropertyMap::count() const
{
    Q_D(const QDeclarativePropertyMap);
    return d->keys.count();
}

/*!
    Returns the number of keys in the map.

    \sa isEmpty(), count()
*/
int QDeclarativePropertyMap::size() const
{
    Q_D(const QDeclarativePropertyMap);
    return d->keys.size();
}

/*!
    Returns true if the map contains no keys; otherwise returns
    false.

    \sa size()
*/
bool QDeclarativePropertyMap::isEmpty() const
{
    Q_D(const QDeclarativePropertyMap);
    return d->keys.isEmpty();
}

/*!
    Returns true if the map contains \a key.

    \sa size()
*/
bool QDeclarativePropertyMap::contains(const QString &key) const
{
    Q_D(const QDeclarativePropertyMap);
    return d->keys.contains(key);
}

/*!
    Returns the value associated with the key \a key as a modifiable
    reference.

    If the map contains no item with key \a key, the function inserts
    an invalid QVariant into the map with key \a key, and
    returns a reference to it.

    \sa insert(), value()
*/
QVariant &QDeclarativePropertyMap::operator[](const QString &key)
{
    //### optimize
    Q_D(QDeclarativePropertyMap);
    QByteArray utf8key = key.toUtf8();
    if (!d->keys.contains(key))
        insert(key, QVariant());//force creation -- needed below

    return (*(d->mo))[utf8key];
}

/*!
    \overload

    Same as value().
*/
QVariant QDeclarativePropertyMap::operator[](const QString &key) const
{
    return value(key);
}

/*!
    \fn void QDeclarativePropertyMap::valueChanged(const QString &key, const QVariant &value)
    This signal is emitted whenever one of the values in the map is changed. \a key
    is the key corresponding to the \a value that was changed.

    \note valueChanged() is \bold NOT emitted when changes are made by calling insert()
    or clear() - it is only emitted when a value is updated from QML.
*/

QT_END_NAMESPACE
#include <moc_qdeclarativepropertymap.h>