path: root/src/qml/qml/qqmlnotifier_p.h

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#ifndef QQMLNOTIFIER_P_H
#define QQMLNOTIFIER_P_H

#include "qqmldata_p.h"
#include "qqmlguard_p.h"
#include <QtCore/qmetaobject.h>
#include <private/qmetaobject_p.h>

QT_BEGIN_NAMESPACE

class QQmlNotifierEndpoint;
class Q_QML_PRIVATE_EXPORT QQmlNotifier
{
public:
    inline QQmlNotifier();
    inline ~QQmlNotifier();
    inline void notify();

private:
    friend class QQmlData;
    friend class QQmlNotifierEndpoint;
    friend class QQmlThreadNotifierProxyObject;

    static void emitNotify(QQmlNotifierEndpoint *, void **a);
    QQmlNotifierEndpoint *endpoints;
};

class QQmlEngine;
class QQmlNotifierEndpoint
{
public:
    inline QQmlNotifierEndpoint();
    inline ~QQmlNotifierEndpoint();

    // QQmlNotifierEndpoint can only invoke one of a set of pre-defined callbacks.
    // To add another callback, extend this enum and add the callback to the top
    // of qqmlnotifier.cpp.  Four bits are reserved for the callback, so there can
    // be up to 15 of them (0 is reserved).
    enum Callback {
        None = 0,
        QQmlBoundSignal = 1,
        QQmlJavaScriptExpressionGuard = 2,
        QQmlVMEMetaObjectEndpoint = 3,
        QV4BindingsSubscription = 4
    };

    inline void setCallback(Callback c) { callback = c; }

    inline bool isConnected();
    inline bool isConnected(QObject *source, int sourceSignal);
    inline bool isConnected(QQmlNotifier *);

    void connect(QObject *source, int sourceSignal, QQmlEngine *engine);
    inline void connect(QQmlNotifier *);
    inline void disconnect();

    inline bool isNotifying() const;
    inline void cancelNotify();

private:
    friend class QQmlData;
    friend class QQmlNotifier;

    // Contains either the QObject*, or the QQmlNotifier* that this
    // endpoint is connected to.  While the endpoint is notifying, the
    // senderPtr points to another intptr_t that contains this value.
    intptr_t senderPtr;
    inline QObject *senderAsObject() const;
    inline QQmlNotifier *senderAsNotifier() const;

    Callback callback:4;
    // The index is in the range returned by QObjectPrivate::signalIndex().
    // This is different from QMetaMethod::methodIndex().
    signed int sourceSignal:28;

    QQmlNotifierEndpoint  *next;
    QQmlNotifierEndpoint **prev;
};

QQmlNotifier::QQmlNotifier()
: endpoints(0)
{
}

QQmlNotifier::~QQmlNotifier()
{    
    QQmlNotifierEndpoint *endpoint = endpoints;
    while (endpoint) {
        QQmlNotifierEndpoint *n = endpoint;
        endpoint = n->next;

        if (n->isNotifying()) *((intptr_t *)(n->senderPtr & ~0x1)) = 0;

        n->next = 0;
        n->prev = 0;
        n->senderPtr = 0;
        n->sourceSignal = -1;
    }
    endpoints = 0;
}

void QQmlNotifier::notify()
{
    void *args[] = { 0 };
    if (endpoints) emitNotify(endpoints, args);
}

QQmlNotifierEndpoint::QQmlNotifierEndpoint()
: senderPtr(0), callback(None), sourceSignal(-1), next(0), prev(0)
{
}

QQmlNotifierEndpoint::~QQmlNotifierEndpoint()
{
    disconnect();
}

bool QQmlNotifierEndpoint::isConnected()
{
    return prev != 0;
}

/*! \internal
    \a sourceSignal MUST be in the signal index range (see QObjectPrivate::signalIndex()).
    This is different from QMetaMethod::methodIndex().
*/
bool QQmlNotifierEndpoint::isConnected(QObject *source, int sourceSignal)
{
    return this->sourceSignal != -1 && senderAsObject() == source &&
           this->sourceSignal == sourceSignal;
}

bool QQmlNotifierEndpoint::isConnected(QQmlNotifier *notifier)
{
    return sourceSignal == -1 && senderAsNotifier() == notifier;
}

void QQmlNotifierEndpoint::connect(QQmlNotifier *notifier)
{
    disconnect();

    next = notifier->endpoints;
    if (next) { next->prev = &next; }
    notifier->endpoints = this;
    prev = &notifier->endpoints;
    senderPtr = intptr_t(notifier);
}

void QQmlNotifierEndpoint::disconnect()
{
    // Remove from notifier chain before calling disconnectNotify(), so that that
    // QObject::receivers() returns the correct value in there
    if (next) next->prev = prev;
    if (prev) *prev = next;

    if (sourceSignal != -1) {
        QObject * const obj = senderAsObject();
        QObjectPrivate * const priv = QObjectPrivate::get(obj);
        priv->disconnectNotify(QMetaObjectPrivate::signal(obj->metaObject(), sourceSignal));
    }

    if (isNotifying()) *((intptr_t *)(senderPtr & ~0x1)) = 0;
    next = 0;
    prev = 0;
    senderPtr = 0;
    sourceSignal = -1;
}

/*!
Returns true if a notify is in progress.  This means that the signal or QQmlNotifier
that this endpoing is connected to has been triggered, but this endpoint's callback has not
yet been called.

An in progress notify can be cancelled by calling cancelNotify.
*/
bool QQmlNotifierEndpoint::isNotifying() const
{
    return senderPtr & 0x1;
}

/*!
Cancel any notifies that are in progress.
*/
void QQmlNotifierEndpoint::cancelNotify() 
{
    if (isNotifying()) {
        intptr_t sp = *((intptr_t *)(senderPtr & ~0x1));
        *((intptr_t *)(senderPtr & ~0x1)) = 0;
        senderPtr = sp;
    }
}

QObject *QQmlNotifierEndpoint::senderAsObject() const
{
    return isNotifying()?((QObject *)(*((intptr_t *)(senderPtr & ~0x1)))):((QObject *)senderPtr);
}

QQmlNotifier *QQmlNotifierEndpoint::senderAsNotifier() const
{
    return isNotifying()?((QQmlNotifier *)(*((intptr_t *)(senderPtr & ~0x1)))):((QQmlNotifier *)senderPtr);
}

QT_END_NAMESPACE

#endif // QQMLNOTIFIER_P_H