qqmlenginedebugservice.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
// Qt-Security score:significant
 
#include "qqmlenginedebugservice.h"
#include "qqmlwatcher.h"
 
#include <private/qqmldebugstatesdelegate_p.h>
#include <private/qqmlboundsignal_p.h>
#include <qqmlengine.h>
#include <private/qqmlmetatype_p.h>
#include <qqmlproperty.h>
#include <private/qqmlproperty_p.h>
#include <private/qqmlbinding_p.h>
#include <private/qqmlcontext_p.h>
#include <private/qqmlvaluetype_p.h>
#include <private/qqmlvmemetaobject_p.h>
#include <private/qqmlexpression_p.h>
#include <private/qqmlsignalnames_p.h>
 
#include <QtCore/qdebug.h>
#include <QtCore/qmetaobject.h>
#include <QtCore/qfileinfo.h>
#include <QtCore/qjsonvalue.h>
#include <QtCore/qjsonobject.h>
#include <QtCore/qjsonarray.h>
#include <QtCore/qjsondocument.h>
 
#include <private/qmetaobject_p.h>
#include <private/qqmldebugconnector_p.h>
#include <private/qversionedpacket_p.h>
 
QT_BEGIN_NAMESPACE
 
using QQmlDebugPacket = QVersionedPacket<QQmlDebugConnector>;
 
class NullDevice : public QIODevice
{
public:
    NullDevice() { open(QIODevice::ReadWrite); }
 
protected:
    qint64 readData(char *data, qint64 maxlen) final;
    qint64 writeData(const char *data, qint64 len) final;
};
 
qint64 NullDevice::readData(char *data, qint64 maxlen)
{
    Q_UNUSED(data);
    return maxlen;
}
 
qint64 NullDevice::writeData(const char *data, qint64 len)
{
    Q_UNUSED(data);
    return len;
}
 
// check whether the data can be saved
// (otherwise we assert in QVariant::operator<< when actually saving it)
static bool isSaveable(const QVariant &value)
{
    const int valType = static_cast<int>(value.userType());
    if (valType >= QMetaType::User)
        return false;
    NullDevice nullDevice;
    QDataStream fakeStream(&nullDevice);
    return QMetaType(valType).save(fakeStream, value.constData());
}
 
QQmlEngineDebugServiceImpl::QQmlEngineDebugServiceImpl(QObject *parent) :
    QQmlEngineDebugService(2, parent), m_watch(new QQmlWatcher(this)), m_statesDelegate(nullptr)
{
    connect(m_watch, &QQmlWatcher::propertyChanged,
            this, &QQmlEngineDebugServiceImpl::propertyChanged);
 
    // Move the message into the correct thread for processing
    connect(this, &QQmlEngineDebugServiceImpl::scheduleMessage,
            this, &QQmlEngineDebugServiceImpl::processMessage, Qt::QueuedConnection);
}
 
QQmlEngineDebugServiceImpl::~QQmlEngineDebugServiceImpl()
{
    delete m_statesDelegate;
}
 
QDataStream &operator<<(QDataStream &ds,
                        const QQmlEngineDebugServiceImpl::QQmlObjectData &data)
{
    ds << data.url << data.lineNumber << data.columnNumber << data.idString
       << data.objectName << data.objectType << data.objectId << data.contextId
       << data.parentId;
    return ds;
}
 
QDataStream &operator>>(QDataStream &ds,
                        QQmlEngineDebugServiceImpl::QQmlObjectData &data)
{
    ds >> data.url >> data.lineNumber >> data.columnNumber >> data.idString
       >> data.objectName >> data.objectType >> data.objectId >> data.contextId
       >> data.parentId;
    return ds;
}
 
QDataStream &operator<<(QDataStream &ds,
                        const QQmlEngineDebugServiceImpl::QQmlObjectProperty &data)
{
    ds << (int)data.type << data.name;
    ds << (isSaveable(data.value) ? data.value : QVariant());
    ds << data.valueTypeName << data.binding << data.hasNotifySignal;
    return ds;
}
 
QDataStream &operator>>(QDataStream &ds,
                        QQmlEngineDebugServiceImpl::QQmlObjectProperty &data)
{
    int type;
    ds >> type >> data.name >> data.value >> data.valueTypeName
       >> data.binding >> data.hasNotifySignal;
    data.type = (QQmlEngineDebugServiceImpl::QQmlObjectProperty::Type)type;
    return ds;
}
 
static bool hasValidSignal(QObject *object, const QString &propertyName)
{
    auto signalName = QQmlSignalNames::handlerNameToSignalName(propertyName);
    if (!signalName)
        return false;
 
    int sigIdx = QQmlPropertyPrivate::findSignalByName(object->metaObject(), signalName->toLatin1())
                         .methodIndex();
 
    if (sigIdx == -1)
        return false;
 
    return true;
}
 
QQmlEngineDebugServiceImpl::QQmlObjectProperty
QQmlEngineDebugServiceImpl::propertyData(QObject *obj, int propIdx)
{
    QQmlObjectProperty rv;
 
    QMetaProperty prop = obj->metaObject()->property(propIdx);
 
    rv.type = QQmlObjectProperty::Unknown;
    rv.valueTypeName = QString::fromUtf8(prop.typeName());
    rv.name = QString::fromUtf8(prop.name());
    rv.hasNotifySignal = prop.hasNotifySignal();
    QQmlAbstractBinding *binding =
            QQmlPropertyPrivate::binding(QQmlProperty(obj, rv.name));
    if (binding)
        rv.binding = binding->expression();
 
    rv.value = valueContents(prop.read(obj));
 
    if (prop.metaType().flags().testFlag(QMetaType::PointerToQObject))  {
        rv.type = QQmlObjectProperty::Object;
    } else if (QQmlMetaType::isList(prop.metaType())) {
        rv.type = QQmlObjectProperty::List;
    } else if (prop.userType() == QMetaType::QVariant) {
        rv.type = QQmlObjectProperty::Variant;
    } else if (rv.value.isValid()) {
        rv.type = QQmlObjectProperty::Basic;
    }
 
    return rv;
}
 
QVariant QQmlEngineDebugServiceImpl::valueContents(QVariant value) const
{
    // We can't send JS objects across the wire, so transform them to variant
    // maps for serialization.
    if (value.userType() == qMetaTypeId<QJSValue>())
        value = value.value<QJSValue>().toVariant();
    const QMetaType metaType = value.metaType();
    const int metaTypeId = metaType.id();
 
    //QObject * is not streamable.
    //Convert all such instances to a String value
 
    if (value.userType() == QMetaType::QVariantList) {
        QVariantList contents;
        QVariantList list = value.toList();
        int count = list.size();
        contents.reserve(count);
        for (int i = 0; i < count; i++)
            contents << valueContents(list.at(i));
        return contents;
    }
 
    if (value.userType() == QMetaType::QVariantMap) {
        QVariantMap contents;
        const auto map = value.toMap();
        for (auto i = map.cbegin(), end = map.cend(); i != end; ++i)
             contents.insert(i.key(), valueContents(i.value()));
        return contents;
    }
 
    switch (metaTypeId) {
    case QMetaType::QRect:
    case QMetaType::QRectF:
    case QMetaType::QPoint:
    case QMetaType::QPointF:
    case QMetaType::QSize:
    case QMetaType::QSizeF:
    case QMetaType::QFont:
        // Don't call the toString() method on those. The stream operators are better.
        return value;
    case QMetaType::QJsonValue:
        return value.toJsonValue().toVariant();
    case QMetaType::QJsonObject:
        return value.toJsonObject().toVariantMap();
    case QMetaType::QJsonArray:
        return value.toJsonArray().toVariantList();
    case QMetaType::QJsonDocument:
        return value.toJsonDocument().toVariant();
    default:
        if (QQmlMetaType::isValueType(metaType)) {
            const QMetaObject *mo = QQmlMetaType::metaObjectForValueType(metaType);
            if (mo) {
                int toStringIndex = mo->indexOfMethod("toString()");
                if (toStringIndex != -1) {
                    QMetaMethod mm = mo->method(toStringIndex);
                    QString s;
                    if (mm.invokeOnGadget(value.data(), Q_RETURN_ARG(QString, s)))
                        return s;
                }
            }
        }
 
        if (isSaveable(value))
            return value;
    }
 
    if (metaType.flags().testFlag(QMetaType::PointerToQObject)) {
        QObject *o = QQmlMetaType::toQObject(value);
        if (o) {
            QString name = o->objectName();
            if (name.isEmpty())
                name = QStringLiteral("<unnamed object>");
            return name;
        }
    }
 
    return QString(QStringLiteral("<unknown value>"));
}
 
void QQmlEngineDebugServiceImpl::buildObjectDump(QDataStream &message,
                                                     QObject *object, bool recur, bool dumpProperties)
{
    message << objectData(object);
 
    QObjectList children = object->children();
 
    int childrenCount = children.size();
    for (int ii = 0; ii < children.size(); ++ii) {
        if (qobject_cast<QQmlContext*>(children[ii]))
            --childrenCount;
    }
 
    message << childrenCount << recur;
 
    QList<QQmlObjectProperty> fakeProperties;
 
    for (int ii = 0; ii < children.size(); ++ii) {
        QObject *child = children.at(ii);
        if (qobject_cast<QQmlContext*>(child))
            continue;
         if (recur)
             buildObjectDump(message, child, recur, dumpProperties);
         else
             message << objectData(child);
    }
 
    if (!dumpProperties) {
        message << 0;
        return;
    }
 
    QList<int> propertyIndexes;
    for (int ii = 0; ii < object->metaObject()->propertyCount(); ++ii) {
        if (object->metaObject()->property(ii).isScriptable())
            propertyIndexes << ii;
    }
 
    QQmlData *ddata = QQmlData::get(object);
    if (ddata && ddata->signalHandlers) {
        QQmlBoundSignal *signalHandler = ddata->signalHandlers;
 
        while (signalHandler) {
            QQmlObjectProperty prop;
            prop.type = QQmlObjectProperty::SignalProperty;
            prop.hasNotifySignal = false;
            QQmlBoundSignalExpression *expr = signalHandler->expression();
            if (expr) {
                prop.value = expr->expression();
                QObject *scope = expr->scopeObject();
                if (scope) {
                    const QByteArray methodName = QMetaObjectPrivate::signal(scope->metaObject(),
                                                                             signalHandler->signalIndex()).name();
                    if (!methodName.isEmpty()) {
                        prop.name = QQmlSignalNames::signalNameToHandlerName(methodName);
                    }
                }
            }
            fakeProperties << prop;
 
            signalHandler = nextSignal(signalHandler);
        }
    }
 
    message << int(propertyIndexes.size() + fakeProperties.size());
 
    for (int ii = 0; ii < propertyIndexes.size(); ++ii)
        message << propertyData(object, propertyIndexes.at(ii));
 
    for (int ii = 0; ii < fakeProperties.size(); ++ii)
        message << fakeProperties[ii];
}
 
void QQmlEngineDebugServiceImpl::prepareDeferredObjects(QObject *obj)
{
    qmlExecuteDeferred(obj);
 
    QObjectList children = obj->children();
    for (int ii = 0; ii < children.size(); ++ii) {
        QObject *child = children.at(ii);
        prepareDeferredObjects(child);
    }
 
}
 
void QQmlEngineDebugServiceImpl::storeObjectIds(QObject *co)
{
    QQmlDebugService::idForObject(co);
    QObjectList children = co->children();
    for (int ii = 0; ii < children.size(); ++ii)
        storeObjectIds(children.at(ii));
}
 
void QQmlEngineDebugServiceImpl::buildObjectList(QDataStream &message,
                                             QQmlContext *ctxt,
                                             const QList<QPointer<QObject> > &instances)
{
    if (!ctxt->isValid())
        return;
 
    QQmlRefPointer<QQmlContextData> p = QQmlContextData::get(ctxt);
 
    QString ctxtName = ctxt->objectName();
    int ctxtId = QQmlDebugService::idForObject(ctxt);
    if (ctxt->contextObject())
        storeObjectIds(ctxt->contextObject());
 
    message << ctxtName << ctxtId;
 
    int count = 0;
 
    QQmlRefPointer<QQmlContextData> child = p->childContexts();
    while (child) {
        ++count;
        child = child->nextChild();
    }
 
    message << count;
 
    child = p->childContexts();
    while (child) {
        buildObjectList(message, child->asQQmlContext(), instances);
        child = child->nextChild();
    }
 
    count = 0;
    for (int ii = 0; ii < instances.size(); ++ii) {
        QQmlData *data = QQmlData::get(instances.at(ii));
        if (data->context == p.data())
            count ++;
    }
    message << count;
 
    for (int ii = 0; ii < instances.size(); ++ii) {
        QQmlData *data = QQmlData::get(instances.at(ii));
        if (data->context == p.data())
            message << objectData(instances.at(ii));
    }
}
 
void QQmlEngineDebugServiceImpl::buildStatesList(bool cleanList,
                                             const QList<QPointer<QObject> > &instances)
{
    if (auto delegate = statesDelegate())
        delegate->buildStatesList(cleanList, instances);
}
 
QQmlEngineDebugServiceImpl::QQmlObjectData
QQmlEngineDebugServiceImpl::objectData(QObject *object)
{
    QQmlData *ddata = QQmlData::get(object);
    QQmlObjectData rv;
    if (ddata && ddata->outerContext) {
        rv.url = ddata->outerContext->url();
        rv.lineNumber = ddata->lineNumber;
        rv.columnNumber = ddata->columnNumber;
    } else {
        rv.lineNumber = -1;
        rv.columnNumber = -1;
    }
 
    QQmlContext *context = qmlContext(object);
    if (context && context->isValid())
        rv.idString = QQmlContextData::get(context)->findObjectId(object);
 
    rv.objectName = object->objectName();
    rv.objectId = QQmlDebugService::idForObject(object);
    rv.contextId = QQmlDebugService::idForObject(qmlContext(object));
    rv.parentId = QQmlDebugService::idForObject(object->parent());
    rv.objectType = QQmlMetaType::prettyTypeName(object);
    return rv;
}
 
void QQmlEngineDebugServiceImpl::messageReceived(const QByteArray &message)
{
    emit scheduleMessage(message);
}
 
/*!
    Returns a list of objects matching the given filename, line and column.
*/
QList<QObject*> QQmlEngineDebugServiceImpl::objectForLocationInfo(const QString &filename,
                                                              int lineNumber, int columnNumber)
{
    QList<QObject *> objects;
    const QHash<int, QObject *> &hash = objectsForIds();
    for (QHash<int, QObject *>::ConstIterator i = hash.constBegin(); i != hash.constEnd(); ++i) {
        QQmlData *ddata = QQmlData::get(i.value());
        if (ddata && ddata->outerContext && ddata->outerContext->isValid()) {
            if (QFileInfo(ddata->outerContext->urlString()).fileName() == filename &&
                ddata->lineNumber == lineNumber &&
                ddata->columnNumber >= columnNumber) {
                objects << i.value();
            }
        }
    }
    return objects;
}
 
void QQmlEngineDebugServiceImpl::processMessage(const QByteArray &message)
{
    QQmlDebugPacket ds(message);
 
    QByteArray type;
    qint32 queryId;
    ds >> type >> queryId;
 
    QQmlDebugPacket rs;
 
    if (type == "LIST_ENGINES") {
        rs << QByteArray("LIST_ENGINES_R");
        rs << queryId << int(m_engines.size());
 
        for (int ii = 0; ii < m_engines.size(); ++ii) {
            QJSEngine *engine = m_engines.at(ii);
 
            QString engineName = engine->objectName();
            qint32 engineId = QQmlDebugService::idForObject(engine);
 
            rs << engineName << engineId;
        }
 
    } else if (type == "LIST_OBJECTS") {
        qint32 engineId = -1;
        ds >> engineId;
 
        QQmlEngine *engine =
                qobject_cast<QQmlEngine *>(QQmlDebugService::objectForId(engineId));
 
        rs << QByteArray("LIST_OBJECTS_R") << queryId;
 
        if (engine) {
            QQmlContext *rootContext = engine->rootContext();
            QQmlContextPrivate *ctxtPriv = QQmlContextPrivate::get(rootContext);
            ctxtPriv->cleanInstances(); // Clean deleted objects
            const QList<QPointer<QObject>> instances = ctxtPriv->instances();
            buildObjectList(rs, rootContext, instances);
            buildStatesList(true, instances);
        }
 
    } else if (type == "FETCH_OBJECT") {
        qint32 objectId;
        bool recurse;
        bool dumpProperties = true;
 
        ds >> objectId >> recurse >> dumpProperties;
 
        QObject *object = QQmlDebugService::objectForId(objectId);
 
        rs << QByteArray("FETCH_OBJECT_R") << queryId;
 
        if (object) {
            if (recurse)
                prepareDeferredObjects(object);
            buildObjectDump(rs, object, recurse, dumpProperties);
        }
 
    } else if (type == "FETCH_OBJECTS_FOR_LOCATION") {
        QString file;
        qint32 lineNumber;
        qint32 columnNumber;
        bool recurse;
        bool dumpProperties = true;
 
        ds >> file >> lineNumber >> columnNumber >> recurse >> dumpProperties;
 
        const QList<QObject*> objects = objectForLocationInfo(file, lineNumber, columnNumber);
 
        rs << QByteArray("FETCH_OBJECTS_FOR_LOCATION_R") << queryId
           << int(objects.size());
 
        for (QObject *object : objects) {
            if (recurse)
                prepareDeferredObjects(object);
            buildObjectDump(rs, object, recurse, dumpProperties);
        }
 
    } else if (type == "WATCH_OBJECT") {
        qint32 objectId;
 
        ds >> objectId;
        bool ok = m_watch->addWatch(queryId, objectId);
 
        rs << QByteArray("WATCH_OBJECT_R") << queryId << ok;
 
    } else if (type == "WATCH_PROPERTY") {
        qint32 objectId;
        QByteArray property;
 
        ds >> objectId >> property;
        bool ok = m_watch->addWatch(queryId, objectId, property);
 
        rs << QByteArray("WATCH_PROPERTY_R") << queryId << ok;
 
    } else if (type == "WATCH_EXPR_OBJECT") {
        qint32 debugId;
        QString expr;
 
        ds >> debugId >> expr;
        bool ok = m_watch->addWatch(queryId, debugId, expr);
 
        rs << QByteArray("WATCH_EXPR_OBJECT_R") << queryId << ok;
 
    } else if (type == "NO_WATCH") {
        bool ok = m_watch->removeWatch(queryId);
 
        rs << QByteArray("NO_WATCH_R") << queryId << ok;
 
    } else if (type == "EVAL_EXPRESSION") {
        qint32 objectId;
        QString expr;
 
        ds >> objectId >> expr;
        qint32 engineId = -1;
        if (!ds.atEnd())
            ds >> engineId;
 
        QObject *object = QQmlDebugService::objectForId(objectId);
        QQmlContext *context = qmlContext(object);
        if (!context || !context->isValid()) {
            QQmlEngine *engine = qobject_cast<QQmlEngine *>(
                        QQmlDebugService::objectForId(engineId));
            if (engine && m_engines.contains(engine))
                context = engine->rootContext();
        }
        QVariant result;
        if (context && context->isValid()) {
            QQmlExpression exprObj(context, object, expr);
            bool undefined = false;
            QVariant value = exprObj.evaluate(&undefined);
            if (undefined)
                result = QString(QStringLiteral("<undefined>"));
            else
                result = valueContents(value);
        } else {
            result = QString(QStringLiteral("<unknown context>"));
        }
 
        rs << QByteArray("EVAL_EXPRESSION_R") << queryId << result;
 
    } else if (type == "SET_BINDING") {
        qint32 objectId;
        QString propertyName;
        QVariant expr;
        bool isLiteralValue;
        QString filename;
        qint32 line;
        ds >> objectId >> propertyName >> expr >> isLiteralValue >>
              filename >> line;
        bool ok = setBinding(objectId, propertyName, expr, isLiteralValue,
                             filename, line);
 
        rs << QByteArray("SET_BINDING_R") << queryId << ok;
 
    } else if (type == "RESET_BINDING") {
        qint32 objectId;
        QString propertyName;
        ds >> objectId >> propertyName;
        bool ok = resetBinding(objectId, propertyName);
 
        rs << QByteArray("RESET_BINDING_R") << queryId << ok;
 
    } else if (type == "SET_METHOD_BODY") {
        qint32 objectId;
        QString methodName;
        QString methodBody;
        ds >> objectId >> methodName >> methodBody;
        bool ok = setMethodBody(objectId, methodName, methodBody);
 
        rs << QByteArray("SET_METHOD_BODY_R") << queryId << ok;
 
    }
    emit messageToClient(name(), rs.data());
}
 
bool QQmlEngineDebugServiceImpl::setBinding(int objectId,
                                                const QString &propertyName,
                                                const QVariant &expression,
                                                bool isLiteralValue,
                                                QString filename,
                                                int line,
                                                int column)
{
    bool ok = true;
    QObject *object = objectForId(objectId);
    QQmlContext *context = qmlContext(object);
 
    if (object && context && context->isValid()) {
        QQmlProperty property(object, propertyName, context);
        if (property.isValid()) {
 
            bool inBaseState = true;
            if (auto delegate = statesDelegate()) {
                delegate->updateBinding(context, property, expression, isLiteralValue,
                                                filename, line, column, &inBaseState);
            }
 
            if (inBaseState) {
                if (isLiteralValue) {
                    property.write(expression);
                } else if (hasValidSignal(object, propertyName)) {
                    QQmlBoundSignalExpression *qmlExpression = new QQmlBoundSignalExpression(object, QQmlPropertyPrivate::get(property)->signalIndex(),
                                                                                             QQmlContextData::get(context), object, expression.toString(),
                                                                                             filename, line, column);
                    QQmlPropertyPrivate::takeSignalExpression(property, qmlExpression);
                } else if (property.isProperty()) {
                    QQmlBinding *binding = QQmlBinding::create(&QQmlPropertyPrivate::get(property)->core, expression.toString(), object, QQmlContextData::get(context), filename, line);
                    binding->setTarget(property);
                    QQmlPropertyPrivate::setBinding(binding);
                    binding->update();
                } else {
                    ok = false;
                    qWarning() << "QQmlEngineDebugService::setBinding: unable to set property" << propertyName << "on object" << object;
                }
            }
 
        } else {
            // not a valid property
            if (auto delegate = statesDelegate())
                ok = delegate->setBindingForInvalidProperty(object, propertyName, expression, isLiteralValue);
            if (!ok)
                qWarning() << "QQmlEngineDebugService::setBinding: unable to set property" << propertyName << "on object" << object;
        }
    }
    return ok;
}
 
bool QQmlEngineDebugServiceImpl::resetBinding(int objectId, const QString &propertyName)
{
    QObject *object = objectForId(objectId);
    QQmlContext *context = qmlContext(object);
 
    if (object && context && context->isValid()) {
        QStringView parentPropertyRef(propertyName);
        const int idx = parentPropertyRef.indexOf(QLatin1Char('.'));
        if (idx != -1)
            parentPropertyRef = parentPropertyRef.left(idx);
 
        const QByteArray parentProperty = parentPropertyRef.toLatin1();
        if (object->property(parentProperty).isValid()) {
            QQmlProperty property(object, propertyName);
            QQmlPropertyPrivate::removeBinding(property);
            if (property.isResettable()) {
                // Note: this will reset the property in any case, without regard to states
                // Right now almost no QQuickItem has reset methods for its properties (with the
                // notable exception of QQuickAnchors), so this is not a big issue
                // later on, setBinding does take states into account
                property.reset();
            } else {
                // overwrite with default value
                QQmlType objType = QQmlMetaType::qmlType(object->metaObject());
                if (objType.isValid()) {
                    if (QObject *emptyObject = objType.create()) {
                        if (emptyObject->property(parentProperty).isValid()) {
                            QVariant defaultValue = QQmlProperty(emptyObject, propertyName).read();
                            if (defaultValue.isValid()) {
                                setBinding(objectId, propertyName, defaultValue, true);
                            }
                        }
                        delete emptyObject;
                    }
                }
            }
            return true;
        }
 
        if (hasValidSignal(object, propertyName)) {
            QQmlProperty property(object, propertyName, context);
            QQmlPropertyPrivate::setSignalExpression(property, nullptr);
            return true;
        }
 
        if (auto delegate = statesDelegate()) {
            delegate->resetBindingForInvalidProperty(object, propertyName);
            return true;
        }
 
        return false;
    }
    // object or context null.
    return false;
}
 
bool QQmlEngineDebugServiceImpl::setMethodBody(int objectId, const QString &method, const QString &body)
{
    QObject *object = objectForId(objectId);
    QQmlContext *context = qmlContext(object);
    if (!object || !context || !context->isValid())
        return false;
    QQmlRefPointer<QQmlContextData> contextData = QQmlContextData::get(context);
 
    QQmlPropertyData dummy;
    const QQmlPropertyData *prop = QQmlPropertyCache::property(object, method, contextData, &dummy);
 
    if (!prop || !prop->isVMEFunction())
        return false;
 
    QMetaMethod metaMethod = object->metaObject()->method(prop->coreIndex());
    QList<QByteArray> paramNames = metaMethod.parameterNames();
 
    QString paramStr;
    for (int ii = 0; ii < paramNames.size(); ++ii) {
        if (ii != 0) paramStr.append(QLatin1Char(','));
        paramStr.append(QString::fromUtf8(paramNames.at(ii)));
    }
 
    const QString jsfunction = QLatin1String("(function ") + method + QLatin1Char('(') + paramStr +
            QLatin1String(") {") + body + QLatin1String("\n})");
 
    QQmlVMEMetaObject *vmeMetaObject = QQmlVMEMetaObject::get(object);
    Q_ASSERT(vmeMetaObject); // the fact we found the property above should guarentee this
 
    QV4::ExecutionEngine *v4 = qmlEngine(object)->handle();
    QV4::Scope scope(v4);
 
    int lineNumber = 0;
    QV4::Scoped<QV4::JavaScriptFunctionObject> oldMethod(
            scope, vmeMetaObject->vmeMethod(prop->coreIndex()));
    if (oldMethod && oldMethod->d()->function)
        lineNumber = oldMethod->d()->function->compiledFunction->location.line();
 
    QV4::ScopedValue v(scope, QQmlJavaScriptExpression::evalFunction(contextData, object, jsfunction, contextData->urlString(), lineNumber));
    vmeMetaObject->setVmeMethod(prop->coreIndex(), v);
    return true;
}
 
void QQmlEngineDebugServiceImpl::propertyChanged(
        qint32 id, qint32 objectId, const QMetaProperty &property, const QVariant &value)
{
    QQmlDebugPacket rs;
    rs << QByteArray("UPDATE_WATCH") << id << objectId << QByteArray(property.name()) << valueContents(value);
    emit messageToClient(name(), rs.data());
}
 
void QQmlEngineDebugServiceImpl::engineAboutToBeAdded(QJSEngine *engine)
{
    Q_ASSERT(engine);
    Q_ASSERT(!m_engines.contains(engine));
 
    m_engines.append(engine);
    emit attachedToEngine(engine);
}
 
void QQmlEngineDebugServiceImpl::engineAboutToBeRemoved(QJSEngine *engine)
{
    Q_ASSERT(engine);
    Q_ASSERT(m_engines.contains(engine));
 
    m_engines.removeAll(engine);
    emit detachedFromEngine(engine);
}
 
void QQmlEngineDebugServiceImpl::objectCreated(QJSEngine *engine, QObject *object)
{
    Q_ASSERT(engine);
    if (!m_engines.contains(engine))
        return;
 
    qint32 engineId = QQmlDebugService::idForObject(engine);
    qint32 objectId = QQmlDebugService::idForObject(object);
    qint32 parentId = QQmlDebugService::idForObject(object->parent());
 
    QQmlDebugPacket rs;
 
    //unique queryId -1
    rs << QByteArray("OBJECT_CREATED") << qint32(-1) << engineId << objectId << parentId;
    emit messageToClient(name(), rs.data());
}
 
QT_END_NAMESPACE
 
#include "moc_qqmlenginedebugservice.cpp"