qml/qml/qqmlabstractbinding.cpp

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#include "qqmlabstractbinding_p.h"

#include <QtQml/qqmlinfo.h>
#include <private/qqmlbinding_p.h>
#include <private/qqmlvaluetypeproxybinding_p.h>

QT_BEGIN_NAMESPACE

QQmlAbstractBinding::QQmlAbstractBinding()
    : m_targetIndex(-1)
{
    Q_ASSERT(!isAddedToObject());
}

QQmlAbstractBinding::~QQmlAbstractBinding()
{
    Q_ASSERT(!ref);
    Q_ASSERT(!isAddedToObject());

    if (m_nextBinding.data() && !m_nextBinding->ref.deref())
        delete m_nextBinding.data();
}

/*!
Add this binding to \a object.

This transfers ownership of the binding to the object, marks the object's property as
being bound.

However, it does not enable the binding itself or call update() on it.
*/
void QQmlAbstractBinding::addToObject()
{
    Q_ASSERT(!nextBinding());
    Q_ASSERT(isAddedToObject() == false);

    QObject *obj = targetObject();
    Q_ASSERT(obj);

    QQmlData *data = QQmlData::get(obj, true);

    int coreIndex = targetPropertyIndex().coreIndex();
    if (targetPropertyIndex().hasValueTypeIndex()) {
        // Value type

        // Find the value type proxy (if there is one)
        QQmlValueTypeProxyBinding *proxy = nullptr;
        if (data->hasBindingBit(coreIndex)) {
            QQmlAbstractBinding *b = data->bindings;
            while (b && (b->targetPropertyIndex().coreIndex() != coreIndex ||
                         b->targetPropertyIndex().hasValueTypeIndex()))
                b = b->nextBinding();
            Q_ASSERT(b && b->isValueTypeProxy());
            proxy = static_cast<QQmlValueTypeProxyBinding *>(b);
        }

        if (!proxy) {
            proxy = new QQmlValueTypeProxyBinding(obj, QQmlPropertyIndex(coreIndex));

            Q_ASSERT(proxy->targetPropertyIndex().coreIndex() == coreIndex);
            Q_ASSERT(!proxy->targetPropertyIndex().hasValueTypeIndex());
            Q_ASSERT(proxy->targetObject() == obj);

            proxy->addToObject();
        }

        setNextBinding(proxy->m_bindings.data());
        proxy->m_bindings = this;

    } else {
        setNextBinding(data->bindings);
        if (data->bindings) {
            data->bindings->ref.deref();
            Q_ASSERT(data->bindings->ref.refCount > 0);
        }
        data->bindings = this;
        ref.ref();

        data->setBindingBit(obj, coreIndex);
    }

    setAddedToObject(true);
}

/*!
Remove the binding from the object.
*/
void QQmlAbstractBinding::removeFromObject()
{
    if (!isAddedToObject())
        return;

    setAddedToObject(false);

    QObject *obj = targetObject();
    QQmlData *data = QQmlData::get(obj, false);
    Q_ASSERT(data);

    QQmlAbstractBinding::Ptr next;
    next = nextBinding();
    setNextBinding(nullptr);

    int coreIndex = targetPropertyIndex().coreIndex();
    if (targetPropertyIndex().hasValueTypeIndex()) {

        // Find the value type binding
        QQmlAbstractBinding *vtbinding = data->bindings;
        while (vtbinding && (vtbinding->targetPropertyIndex().coreIndex() != coreIndex ||
                             vtbinding->targetPropertyIndex().hasValueTypeIndex())) {
            vtbinding = vtbinding->nextBinding();
            Q_ASSERT(vtbinding);
        }
        Q_ASSERT(vtbinding->isValueTypeProxy());

        QQmlValueTypeProxyBinding *vtproxybinding =
            static_cast<QQmlValueTypeProxyBinding *>(vtbinding);

        QQmlAbstractBinding *binding = vtproxybinding->m_bindings.data();
        if (binding == this) {
            vtproxybinding->m_bindings = next;
        } else {
           while (binding->nextBinding() != this) {
              binding = binding->nextBinding();
              Q_ASSERT(binding);
           }
           binding->setNextBinding(next.data());
        }

        // Value type - we don't remove the proxy from the object.  It will sit their happily
        // doing nothing until it is removed by a write, a binding change or it is reused
        // to hold more sub-bindings.
        return;
    }

    if (data->bindings == this) {
        if (next.data())
            next->ref.ref();
        data->bindings = next.data();
        if (!ref.deref())
            delete this;
    } else {
        QQmlAbstractBinding *binding = data->bindings;
        while (binding->nextBinding() != this) {
            binding = binding->nextBinding();
            Q_ASSERT(binding);
        }
        binding->setNextBinding(next.data());
    }

    data->clearBindingBit(coreIndex);
}

void QQmlAbstractBinding::printBindingLoopError(QQmlProperty &prop)
{
    qmlWarning(prop.object()) << QString(QLatin1String("Binding loop detected for property \"%1\"")).arg(prop.name());
}

QString QQmlAbstractBinding::expression() const
{
    return QLatin1String("<Unknown>");
}

bool QQmlAbstractBinding::isValueTypeProxy() const
{
    return false;
}

QT_END_NAMESPACE