qtdeclarative/src/qml/qml/qqmldata_p.h

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#ifndef QQMLDATA_P_H
#define QQMLDATA_P_H

//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists purely as an
// implementation detail.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//

#include <private/qtqmlglobal_p.h>
#include <private/qobject_p.h>
#include <private/qqmlpropertyindex_p.h>
#include <private/qv4value_p.h>
#include <private/qv4persistent_p.h>
#include <private/qqmlrefcount_p.h>
#include <qqmlprivate.h>
#include <qjsengine.h>
#include <qvector.h>

QT_BEGIN_NAMESPACE

template <class Key, class T> class QHash;
class QQmlEngine;
class QQmlGuardImpl;
class QQmlAbstractBinding;
class QQmlBoundSignal;
class QQmlContext;
class QQmlPropertyCache;
class QQmlContextData;
class QQmlNotifier;
class QQmlDataExtended;
class QQmlNotifierEndpoint;
class QQmlPropertyObserver;

namespace QV4 {
class ExecutableCompilationUnit;
namespace CompiledData {
struct Binding;
}
}

// This class is structured in such a way, that simply zero'ing it is the
// default state for elemental object allocations.  This is crucial in the
// workings of the QQmlInstruction::CreateSimpleObject instruction.
// Don't change anything here without first considering that case!
class Q_QML_PRIVATE_EXPORT QQmlData : public QAbstractDeclarativeData
{
public:
    QQmlData();
    ~QQmlData();

    static inline void init() {
        static bool initialized = false;
        if (!initialized) {
            initialized = true;
            QAbstractDeclarativeData::destroyed = destroyed;
            QAbstractDeclarativeData::parentChanged = nullptr;
            QAbstractDeclarativeData::signalEmitted = signalEmitted;
            QAbstractDeclarativeData::receivers = receivers;
            QAbstractDeclarativeData::isSignalConnected = isSignalConnected;
        }
    }

    static void destroyed(QAbstractDeclarativeData *, QObject *);
    static void signalEmitted(QAbstractDeclarativeData *, QObject *, int, void **);
    static int receivers(QAbstractDeclarativeData *, const QObject *, int);
    static bool isSignalConnected(QAbstractDeclarativeData *, const QObject *, int);

    void destroyed(QObject *);

    void setImplicitDestructible() {
        if (!explicitIndestructibleSet) indestructible = false;
    }

    // If ownMemomry is true, the QQmlData was normally allocated. Otherwise it was allocated
    // with placement new and QQmlData::destroyed is not allowed to free the memory
    quint32 ownMemory:1;
    // indestructible is set if and only if the object has CppOwnership
    // This can be explicitly set with QJSEngine::setObjectOwnership
    // Top level objects generally have CppOwnership (see QQmlcCmponentprivate::beginCreate),
    // unless created by special methods like the QML component.createObject() function
    quint32 indestructible:1;
    // indestructible was explicitly set  with setObjectOwnership
    // or the object is a top-level object
    quint32 explicitIndestructibleSet:1;
    // set when one QObject has been wrapped into QObjectWrapper in multiple engines
    // at the same time - a rather rare case
    quint32 hasTaintedV4Object:1;
    quint32 isQueuedForDeletion:1;
    /*
     * rootObjectInCreation should be true only when creating top level CPP and QML objects,
     * v8 GC will check this flag, only deletes the objects when rootObjectInCreation is false.
     */
    quint32 rootObjectInCreation:1;
    // set when at least one of the object's properties is intercepted
    quint32 hasInterceptorMetaObject:1;
    quint32 hasVMEMetaObject:1;
    quint32 dummy:8;

    // When bindingBitsSize < sizeof(ptr), we store the binding bit flags inside
    // bindingBitsValue. When we need more than sizeof(ptr) bits, we allocated
    // sufficient space and use bindingBits to point to it.
    quint32 bindingBitsArraySize : 16;
    typedef quintptr BindingBitsType;
    enum {
        BitsPerType = sizeof(BindingBitsType) * 8,
        InlineBindingArraySize = 2
    };
    union {
        BindingBitsType *bindingBits;
        BindingBitsType bindingBitsValue[InlineBindingArraySize];
    };

    struct NotifyList {
        quint64 connectionMask;

        quint16 maximumTodoIndex;
        quint16 notifiesSize;

        QQmlNotifierEndpoint *todo;
        QQmlNotifierEndpoint**notifies;
        void layout();
    private:
        void layout(QQmlNotifierEndpoint*);
    };
    NotifyList *notifyList;

    inline QQmlNotifierEndpoint *notify(int index);
    void addNotify(int index, QQmlNotifierEndpoint *);
    int endpointCount(int index);
    bool signalHasEndpoint(int index) const;
    void disconnectNotifiers();

    // The context that created the C++ object; not refcounted to prevent cycles
    QQmlContextData *context = nullptr;
    // The outermost context in which this object lives; not refcounted to prevent cycles
    QQmlContextData *outerContext = nullptr;
    QQmlRefPointer<QQmlContextData> ownContext;

    QQmlAbstractBinding *bindings;
    QQmlBoundSignal *signalHandlers;
    std::vector<QQmlPropertyObserver> propertyObservers;

    // Linked list for QQmlContext::contextObjects
    QQmlData *nextContextObject;
    QQmlData**prevContextObject;

    inline bool hasBindingBit(int) const;
    inline void setBindingBit(QObject *obj, int);
    inline void clearBindingBit(int);

    inline bool hasPendingBindingBit(int index) const;
    inline void setPendingBindingBit(QObject *obj, int);
    inline void clearPendingBindingBit(int);

    quint16 lineNumber;
    quint16 columnNumber;

    quint32 jsEngineId; // id of the engine that created the jsWrapper

    struct DeferredData {
        DeferredData();
        ~DeferredData();
        unsigned int deferredIdx;
        QMultiHash<int, const QV4::CompiledData::Binding *> bindings;

        // Not always the same as the other compilation unit
        QQmlRefPointer<QV4::ExecutableCompilationUnit> compilationUnit;

        // Could be either context or outerContext
        QQmlRefPointer<QQmlContextData> context;
        Q_DISABLE_COPY(DeferredData);
    };
    QQmlRefPointer<QV4::ExecutableCompilationUnit> compilationUnit;
    QVector<DeferredData *> deferredData;

    void deferData(int objectIndex, const QQmlRefPointer<QV4::ExecutableCompilationUnit> &,
                   const QQmlRefPointer<QQmlContextData> &);
    void releaseDeferredData();

    QV4::WeakValue jsWrapper;

    QQmlPropertyCache *propertyCache;

    QQmlGuardImpl *guards;

    static QQmlData *get(const QObject *object, bool create = false) {
        QObjectPrivate *priv = QObjectPrivate::get(const_cast<QObject *>(object));
        // If QObjectData::isDeletingChildren is set then access to QObjectPrivate::declarativeData has
        // to be avoided because QObjectPrivate::currentChildBeingDeleted is in use.
        if (priv->isDeletingChildren || priv->wasDeleted) {
            Q_ASSERT(!create);
            return nullptr;
        } else if (priv->declarativeData) {
            return static_cast<QQmlData *>(priv->declarativeData);
        } else if (create) {
            return createQQmlData(priv);
        } else {
            return nullptr;
        }
    }

    static bool keepAliveDuringGarbageCollection(const QObject *object) {
        QQmlData *ddata = get(object);
        if (!ddata || ddata->indestructible || ddata->rootObjectInCreation)
            return true;
        return false;
    }

    bool hasExtendedData() const { return extendedData != nullptr; }
    QHash<QQmlAttachedPropertiesFunc, QObject *> *attachedProperties() const;

    static inline bool wasDeleted(const QObject *);

    static void markAsDeleted(QObject *);
    static void setQueuedForDeletion(QObject *);

    static inline void flushPendingBinding(QObject *, QQmlPropertyIndex propertyIndex);

    static QQmlPropertyCache *ensurePropertyCache(QJSEngine *engine, QObject *object)
    {
        Q_ASSERT(engine);
        QQmlData *ddata = QQmlData::get(object, /*create*/true);
        if (Q_LIKELY(ddata->propertyCache))
            return ddata->propertyCache;
        return createPropertyCache(engine, object);
    }

    Q_ALWAYS_INLINE static uint offsetForBit(int bit) { return static_cast<uint>(bit) / BitsPerType; }
    Q_ALWAYS_INLINE static BindingBitsType bitFlagForBit(int bit) { return BindingBitsType(1) << (static_cast<uint>(bit) & (BitsPerType - 1)); }

private:
    // For attachedProperties
    mutable QQmlDataExtended *extendedData;

    Q_NEVER_INLINE static QQmlData *createQQmlData(QObjectPrivate *priv);
    Q_NEVER_INLINE static QQmlPropertyCache *createPropertyCache(QJSEngine *engine, QObject *object);

    void flushPendingBindingImpl(QQmlPropertyIndex index);

    Q_ALWAYS_INLINE bool hasBitSet(int bit) const
    {
        uint offset = offsetForBit(bit);
        if (bindingBitsArraySize <= offset)
            return false;

        const BindingBitsType *bits = (bindingBitsArraySize == InlineBindingArraySize) ? bindingBitsValue : bindingBits;
        return bits[offset] & bitFlagForBit(bit);
    }

    Q_ALWAYS_INLINE void clearBit(int bit)
    {
        uint offset = QQmlData::offsetForBit(bit);
        if (bindingBitsArraySize > offset) {
            BindingBitsType *bits = (bindingBitsArraySize == InlineBindingArraySize) ? bindingBitsValue : bindingBits;
            bits[offset] &= ~QQmlData::bitFlagForBit(bit);
        }
    }

    Q_ALWAYS_INLINE void setBit(QObject *obj, int bit)
    {
        uint offset = QQmlData::offsetForBit(bit);
        BindingBitsType *bits = (bindingBitsArraySize == InlineBindingArraySize) ? bindingBitsValue : bindingBits;
        if (Q_UNLIKELY(bindingBitsArraySize <= offset))
            bits = growBits(obj, bit);
        bits[offset] |= QQmlData::bitFlagForBit(bit);
    }

    Q_NEVER_INLINE BindingBitsType *growBits(QObject *obj, int bit);

    Q_DISABLE_COPY(QQmlData);
};

bool QQmlData::wasDeleted(const QObject *object)
{
    if (!object)
        return true;

    const QObjectPrivate *priv = QObjectPrivate::get(object);
    if (!priv || priv->wasDeleted || priv->isDeletingChildren)
        return true;

    const QQmlData *ddata = QQmlData::get(object);
    return ddata && ddata->isQueuedForDeletion;
}

QQmlNotifierEndpoint *QQmlData::notify(int index)
{
    Q_ASSERT(index <= 0xFFFF);

    if (!notifyList || !(notifyList->connectionMask & (1ULL << quint64(index % 64)))) {
        return nullptr;
    } else if (index < notifyList->notifiesSize) {
        return notifyList->notifies[index];
    } else if (index <= notifyList->maximumTodoIndex) {
        notifyList->layout();
    }

    if (index < notifyList->notifiesSize) {
        return notifyList->notifies[index];
    } else {
        return nullptr;
    }
}

/*
    The index MUST be in the range returned by QObjectPrivate::signalIndex()
    This is different than the index returned by QMetaMethod::methodIndex()
*/
inline bool QQmlData::signalHasEndpoint(int index) const
{
    return notifyList && (notifyList->connectionMask & (1ULL << quint64(index % 64)));
}

bool QQmlData::hasBindingBit(int coreIndex) const
{
    Q_ASSERT(coreIndex >= 0);
    Q_ASSERT(coreIndex <= 0xffff);

    return hasBitSet(coreIndex * 2);
}

void QQmlData::setBindingBit(QObject *obj, int coreIndex)
{
    Q_ASSERT(coreIndex >= 0);
    Q_ASSERT(coreIndex <= 0xffff);
    setBit(obj, coreIndex * 2);
}

void QQmlData::clearBindingBit(int coreIndex)
{
    Q_ASSERT(coreIndex >= 0);
    Q_ASSERT(coreIndex <= 0xffff);
    clearBit(coreIndex * 2);
}

bool QQmlData::hasPendingBindingBit(int coreIndex) const
{
    Q_ASSERT(coreIndex >= 0);
    Q_ASSERT(coreIndex <= 0xffff);

    return hasBitSet(coreIndex * 2 + 1);
}

void QQmlData::setPendingBindingBit(QObject *obj, int coreIndex)
{
    Q_ASSERT(coreIndex >= 0);
    Q_ASSERT(coreIndex <= 0xffff);
    setBit(obj, coreIndex * 2 + 1);
}

void QQmlData::clearPendingBindingBit(int coreIndex)
{
    Q_ASSERT(coreIndex >= 0);
    Q_ASSERT(coreIndex <= 0xffff);
    clearBit(coreIndex * 2 + 1);
}

void QQmlData::flushPendingBinding(QObject *o, QQmlPropertyIndex propertyIndex)
{
    QQmlData *data = QQmlData::get(o, false);
    if (data && data->hasPendingBindingBit(propertyIndex.coreIndex()))
        data->flushPendingBindingImpl(propertyIndex);
}

QT_END_NAMESPACE

#endif // QQMLDATA_P_H