qqmlconnections.cpp

Go to the documentation of this file.

// 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
 
#include "qqmlconnections_p.h"
 
#include <private/qqmlboundsignal_p.h>
#include <private/qqmlcontext_p.h>
#include <private/qqmlexpression_p.h>
#include <private/qqmlproperty_p.h>
#include <private/qqmlsignalnames_p.h>
#include <private/qqmlvmemetaobject_p.h>
#include <private/qv4jscall_p.h>
#include <private/qv4qobjectwrapper_p.h>
 
#include <QtQml/qqmlcontext.h>
#include <QtQml/qqmlinfo.h>
 
#include <QtCore/qdebug.h>
#include <QtCore/qloggingcategory.h>
#include <QtCore/qstringlist.h>
 
#include <private/qobject_p.h>
 
QT_BEGIN_NAMESPACE
 
Q_LOGGING_CATEGORY(lcQmlConnections, "qt.qml.connections")
 
// This is the equivalent of QQmlBoundSignal for C++ methods as as slots.
// If a type derived from QQmlConnnections is compiled using qmltc, the
// JavaScript functions it contains are turned into C++ methods and we cannot
// use QQmlBoundSignal to connect to those.
struct QQmlConnectionSlotDispatcher : public QtPrivate::QSlotObjectBase
{
    QV4::ExecutionEngine *v4 = nullptr;
    QObject *receiver = nullptr;
 
    // Signals rarely have more than one argument.
    QQmlMetaObject::ArgTypeStorage<2> signalMetaTypes;
    QQmlMetaObject::ArgTypeStorage<2> slotMetaTypes;
 
    QMetaObject::Connection connection;
 
    int slotIndex = -1;
    bool enabled = true;
 
    QQmlConnectionSlotDispatcher(
            QV4::ExecutionEngine *v4, QObject *sender, int signalIndex,
            QObject *receiver, int slotIndex, bool enabled)
        : QtPrivate::QSlotObjectBase(&impl)
        , v4(v4)
        , receiver(receiver)
        , slotIndex(slotIndex)
        , enabled(enabled)
    {
        QMetaMethod signal = sender->metaObject()->method(signalIndex);
        QQmlMetaObject::methodReturnAndParameterTypes(signal, &signalMetaTypes, nullptr);
 
        QMetaMethod slot = receiver->metaObject()->method(slotIndex);
        QQmlMetaObject::methodReturnAndParameterTypes(slot, &slotMetaTypes, nullptr);
    }
 
    template<typename ArgTypeStorage>
    struct TypedFunction
    {
        Q_DISABLE_COPY_MOVE(TypedFunction)
    public:
        TypedFunction(const ArgTypeStorage *storage) : storage(storage) {}
 
        QMetaType returnMetaType() const { return storage->at(0); }
        qsizetype parameterCount() const { return storage->size() - 1; }
        QMetaType parameterMetaType(qsizetype i) const { return storage->at(i + 1); }
 
    private:
        const ArgTypeStorage *storage;
    };
 
    static void impl(int which, QSlotObjectBase *base, QObject *, void **metaArgs, bool *ret)
    {
        switch (which) {
        case Destroy: {
            delete static_cast<QQmlConnectionSlotDispatcher *>(base);
            break;
        }
        case Call: {
            QQmlConnectionSlotDispatcher *self = static_cast<QQmlConnectionSlotDispatcher *>(base);
            QV4::ExecutionEngine *v4 = self->v4;
            if (!v4)
                break;
 
            if (!self->enabled)
                break;
 
            TypedFunction typedFunction(&self->slotMetaTypes);
            QV4::coerceAndCall(
                    v4, &typedFunction, metaArgs,
                    self->signalMetaTypes.data(), self->signalMetaTypes.size() - 1,
                    [&](void **argv, int) {
                        self->receiver->metaObject()->metacall(
                                self->receiver, QMetaObject::InvokeMetaMethod,
                                self->slotIndex, argv);
                    });
 
            if (v4->hasException) {
                QQmlError error = v4->catchExceptionAsQmlError();
                if (QQmlEngine *qmlEngine = v4->qmlEngine()) {
                    QQmlEnginePrivate::get(qmlEngine)->warning(error);
                } else {
                    QMessageLogger(
                            qPrintable(error.url().toString()), error.line(), nullptr)
                                    .warning().noquote()
                            << error.toString();
                }
            }
            break;
        }
        case Compare:
            // We're not implementing the Compare protocol here. It's insane.
            // QQmlConnectionSlotDispatcher compares false to anything. We use
            // the regular QObject::disconnect with QMetaObject::Connection.
            *ret = false;
            break;
        case NumOperations:
            break;
        }
    };
};
 
class QQmlConnectionsPrivate : public QObjectPrivate
{
public:
    QList<QBiPointer<QQmlBoundSignal, QQmlConnectionSlotDispatcher>> boundsignals;
    QQmlGuard<QObject> target;
 
    bool enabled = true;
    bool targetSet = false;
    bool ignoreUnknownSignals = false;
    bool componentcomplete = true;
 
    QQmlRefPointer<QV4::ExecutableCompilationUnit> compilationUnit;
    QList<const QV4::CompiledData::Binding *> bindings;
};
 
QQmlConnections::QQmlConnections(QObject *parent) :
    QObject(*(new QQmlConnectionsPrivate), parent)
{
}
 
QQmlConnections::~QQmlConnections()
{
    Q_D(QQmlConnections);
 
    // The slot dispatchers hold cyclic references to their connections. Clear them.
    for (const auto &bound : std::as_const(d->boundsignals)) {
        if (QQmlConnectionSlotDispatcher *dispatcher = bound.isT2() ? bound.asT2() : nullptr) {
            // No need to explicitly disconnect anymore since 'this' is the receiver.
            // But to be safe, explicitly break any cyclic references between the connection
            // and the slot object.
            dispatcher->connection = {};
            dispatcher->destroyIfLastRef();
        }
    }
}
 
QObject *QQmlConnections::target() const
{
    Q_D(const QQmlConnections);
    return d->targetSet ? d->target.data() : parent();
}
 
class QQmlBoundSignalDeleter : public QObject
{
public:
    QQmlBoundSignalDeleter(QQmlBoundSignal *signal) : m_signal(signal) { m_signal->removeFromObject(); }
    ~QQmlBoundSignalDeleter() { delete m_signal; }
 
private:
    QQmlBoundSignal *m_signal;
};
 
void QQmlConnections::setTarget(QObject *obj)
{
    Q_D(QQmlConnections);
    if (d->targetSet && d->target == obj)
        return;
    d->targetSet = true; // even if setting to 0, it is *set*
    for (const auto &bound : std::as_const(d->boundsignals)) {
        // It is possible that target is being changed due to one of our signal
        // handlers -> use deleteLater().
        if (QQmlBoundSignal *signal = bound.isT1() ? bound.asT1() : nullptr) {
            if (signal->isNotifying())
                (new QQmlBoundSignalDeleter(signal))->deleteLater();
            else
                delete signal;
        } else {
            QQmlConnectionSlotDispatcher *dispatcher = bound.asT2();
            QObject::disconnect(std::exchange(dispatcher->connection, {}));
            dispatcher->destroyIfLastRef();
        }
    }
    d->boundsignals.clear();
    d->target = obj;
    connectSignals();
    emit targetChanged();
}
 
bool QQmlConnections::isEnabled() const
{
    Q_D(const QQmlConnections);
    return d->enabled;
}
 
void QQmlConnections::setEnabled(bool enabled)
{
    Q_D(QQmlConnections);
    if (d->enabled == enabled)
        return;
 
    d->enabled = enabled;
 
    for (const auto &bound : std::as_const(d->boundsignals)) {
        if (QQmlBoundSignal *signal = bound.isT1() ? bound.asT1() : nullptr)
            signal->setEnabled(d->enabled);
        else
            bound.asT2()->enabled = enabled;
    }
 
    emit enabledChanged();
}
 
bool QQmlConnections::ignoreUnknownSignals() const
{
    Q_D(const QQmlConnections);
    return d->ignoreUnknownSignals;
}
 
void QQmlConnections::setIgnoreUnknownSignals(bool ignore)
{
    Q_D(QQmlConnections);
    d->ignoreUnknownSignals = ignore;
}
 
void QQmlConnectionsParser::verifyBindings(const QQmlRefPointer<QV4::ExecutableCompilationUnit> &compilationUnit, const QList<const QV4::CompiledData::Binding *> &props)
{
    for (int ii = 0; ii < props.size(); ++ii) {
        const QV4::CompiledData::Binding *binding = props.at(ii);
        const QString &propName = compilationUnit->stringAt(binding->propertyNameIndex);
 
        if (!QQmlSignalNames::isHandlerName(propName)) {
            error(props.at(ii), QQmlConnections::tr("Cannot assign to non-existent property \"%1\"").arg(propName));
            return;
        }
 
        if (binding->type() == QV4::CompiledData::Binding::Type_Script)
            continue;
 
        if (binding->type() >= QV4::CompiledData::Binding::Type_Object) {
            const QV4::CompiledData::Object *target = compilationUnit->objectAt(binding->value.objectIndex);
            if (!compilationUnit->stringAt(target->inheritedTypeNameIndex).isEmpty())
                error(binding, QQmlConnections::tr("Connections: nested objects not allowed"));
            else
                error(binding, QQmlConnections::tr("Connections: syntax error"));
            return;
        }
 
        error(binding, QQmlConnections::tr("Connections: script expected"));
        return;
    }
}
 
void QQmlConnectionsParser::applyBindings(QObject *object, const QQmlRefPointer<QV4::ExecutableCompilationUnit> &compilationUnit, const QList<const QV4::CompiledData::Binding *> &bindings)
{
    QQmlConnectionsPrivate *p =
        static_cast<QQmlConnectionsPrivate *>(QObjectPrivate::get(object));
    p->compilationUnit = compilationUnit;
    p->bindings = bindings;
}
 
void QQmlConnections::connectSignals()
{
    Q_D(QQmlConnections);
    if (!d->componentcomplete || (d->targetSet && !target()))
        return;
 
    if (d->bindings.isEmpty()) {
        connectSignalsToMethods();
    } else {
        if (lcQmlConnections().isWarningEnabled()) {
            qmlWarning(this) << tr("Implicitly defined onFoo properties in Connections are deprecated. "
                                    "Use this syntax instead: function onFoo(<arguments>) { ... }");
        }
        connectSignalsToBindings();
    }
}
 
void QQmlConnections::connectSignalsToMethods()
{
    Q_D(QQmlConnections);
 
    QObject *target = this->target();
    QQmlData *ddata = QQmlData::get(this);
    if (!ddata)
        return;
 
    QV4::ExecutionEngine *engine = ddata->context->engine()->handle();
 
    QQmlRefPointer<QQmlContextData> ctxtdata = ddata->outerContext;
    for (int i = ddata->propertyCache->methodOffset(),
             end = ddata->propertyCache->methodOffset() + ddata->propertyCache->methodCount();
         i < end;
         ++i) {
 
        const QQmlPropertyData *handler = ddata->propertyCache->method(i);
        if (!handler)
            continue;
 
        const QString propName = handler->name(this);
 
        QQmlProperty prop(target, propName);
        if (prop.isValid() && (prop.type() & QQmlProperty::SignalProperty)) {
            QV4::Scope scope(engine);
            QV4::ScopedContext global(scope, engine->rootContext());
 
            if (QQmlVMEMetaObject *vmeMetaObject = QQmlVMEMetaObject::get(this)) {
                int signalIndex = QQmlPropertyPrivate::get(prop)->signalIndex();
                auto *signal = new QQmlBoundSignal(target, signalIndex, this, qmlEngine(this));
                signal->setEnabled(d->enabled);
 
                QV4::Scoped<QV4::JavaScriptFunctionObject> method(
                        scope, vmeMetaObject->vmeMethod(handler->coreIndex()));
 
                QQmlBoundSignalExpression *expression = ctxtdata
                        ? new QQmlBoundSignalExpression(
                                target, signalIndex, ctxtdata, this, method->function())
                        : nullptr;
 
                signal->takeExpression(expression);
                d->boundsignals += signal;
            } else {
                QQmlConnectionSlotDispatcher *slot = new QQmlConnectionSlotDispatcher(
                        scope.engine, target, prop.index(),
                        this, handler->coreIndex(), d->enabled);
                slot->connection = QObjectPrivate::connect(
                        target, prop.index(), slot, Qt::AutoConnection);
                slot->ref();
                d->boundsignals += slot;
            }
        } else if (!d->ignoreUnknownSignals
                   && propName.startsWith(QLatin1String("on")) && propName.size() > 2
                   && propName.at(2).isUpper()) {
            qmlWarning(this) << tr("Detected function \"%1\" in Connections element. "
                                   "This is probably intended to be a signal handler but no "
                                   "signal of the target matches the name.").arg(propName);
        }
    }
}
 
// TODO: Drop this as soon as we can
void QQmlConnections::connectSignalsToBindings()
{
    Q_D(QQmlConnections);
    QObject *target = this->target();
    QQmlData *ddata = QQmlData::get(this);
    QQmlRefPointer<QQmlContextData> ctxtdata = ddata ? ddata->outerContext : nullptr;
 
    for (const QV4::CompiledData::Binding *binding : std::as_const(d->bindings)) {
        Q_ASSERT(binding->type() == QV4::CompiledData::Binding::Type_Script);
        QString propName = d->compilationUnit->stringAt(binding->propertyNameIndex);
 
        QQmlProperty prop(target, propName);
        if (prop.isValid() && (prop.type() & QQmlProperty::SignalProperty)) {
            int signalIndex = QQmlPropertyPrivate::get(prop)->signalIndex();
            QQmlBoundSignal *signal =
                new QQmlBoundSignal(target, signalIndex, this, qmlEngine(this));
            signal->setEnabled(d->enabled);
 
            auto f = d->compilationUnit->runtimeFunctions[binding->value.compiledScriptIndex];
            QQmlBoundSignalExpression *expression =
                    ctxtdata ? new QQmlBoundSignalExpression(target, signalIndex, ctxtdata, this, f)
                             : nullptr;
            signal->takeExpression(expression);
            d->boundsignals += signal;
        } else {
            if (!d->ignoreUnknownSignals)
                qmlWarning(this) << tr("Cannot assign to non-existent property \"%1\"").arg(propName);
        }
    }
}
 
void QQmlConnections::classBegin()
{
    Q_D(QQmlConnections);
    d->componentcomplete=false;
}
 
void QQmlConnections::componentComplete()
{
    Q_D(QQmlConnections);
    d->componentcomplete=true;
    connectSignals();
}
 
QT_END_NAMESPACE
 
#include "moc_qqmlconnections_p.cpp"