qqmlmetaobject_p.h

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// Copyright (C) 2019 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
 
#ifndef QQMLMETAOBJECT_P_H
#define QQMLMETAOBJECT_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/qqmlpropertycache_p.h>
 
#include <QtQml/qtqmlglobal.h>
#include <QtCore/qvarlengtharray.h>
#include <QtCore/qmetaobject.h>
 
QT_BEGIN_NAMESPACE
 
// QQmlMetaObject serves as a wrapper around either QMetaObject or QQmlPropertyCache.
// This is necessary as we delay creation of QMetaObject for synthesized QObjects, but
// we don't want to needlessly generate QQmlPropertyCaches every time we encounter a
// QObject type used in assignment or when we don't have a QQmlEngine etc.
//
// This class does NOT reference the propertycache.
class QQmlEnginePrivate;
class QQmlPropertyData;
class Q_QML_EXPORT QQmlMetaObject
{
public:
    typedef QVarLengthArray<QMetaType, 9> ArgTypeStorage;
 
    inline QQmlMetaObject() = default;
    inline QQmlMetaObject(const QObject *);
    inline QQmlMetaObject(const QMetaObject *);
    inline QQmlMetaObject(const QQmlPropertyCache::ConstPtr &);
    inline QQmlMetaObject(const QQmlMetaObject &);
 
    inline QQmlMetaObject &operator=(const QQmlMetaObject &);
 
    inline bool isNull() const;
 
    inline const char *className() const;
    inline int propertyCount() const;
 
    inline const QMetaObject *metaObject() const;
 
    QMetaType methodReturnType(const QQmlPropertyData &data, QByteArray *unknownTypeError) const;
    bool methodParameterTypes(int index, ArgTypeStorage *argStorage,
                              QByteArray *unknownTypeError) const;
    bool constructorParameterTypes(int index, ArgTypeStorage *dummy, QByteArray *unknownTypeError) const;
 
 
    static bool canConvert(const QQmlMetaObject &from, const QQmlMetaObject &to)
    {
        Q_ASSERT(!from.isNull() && !to.isNull());
        return from.metaObject()->inherits(to.metaObject());
    }
 
    // static_metacall (on Gadgets) doesn't call the base implementation and therefore
    // we need a helper to find the correct meta object and property/method index.
    static void resolveGadgetMethodOrPropertyIndex(QMetaObject::Call type, const QMetaObject **metaObject, int *index);
 
    static bool methodParameterTypes(const QMetaMethod &method, ArgTypeStorage *argStorage,
                              QByteArray *unknownTypeError);
protected:
    const QMetaObject *_m = nullptr;
 
};
 
QQmlMetaObject::QQmlMetaObject(const QObject *o)
{
    if (o)
        _m = o->metaObject();
}
 
QQmlMetaObject::QQmlMetaObject(const QMetaObject *m)
    : _m(m)
{
}
 
QQmlMetaObject::QQmlMetaObject(const QQmlPropertyCache::ConstPtr &m)
{
    if (m)
        _m = m->createMetaObject();
}
 
QQmlMetaObject::QQmlMetaObject(const QQmlMetaObject &o)
    : _m(o._m)
{
}
 
QQmlMetaObject &QQmlMetaObject::operator=(const QQmlMetaObject &o)
{
    _m = o._m;
    return *this;
}
 
bool QQmlMetaObject::isNull() const
{
    return !_m;
}
 
const char *QQmlMetaObject::className() const
{
    if (!_m)
        return nullptr;
    return metaObject()->className();
}
 
int QQmlMetaObject::propertyCount() const
{
    if (!_m)
        return 0;
    return metaObject()->propertyCount();
}
 
const QMetaObject *QQmlMetaObject::metaObject() const
{
    return _m;
}
 
QT_END_NAMESPACE
 
#endif // QQMLMETAOBJECT_P_H