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/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the QtQml module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Digia. For licensing terms and
** conditions see http://qt.digia.com/licensing. For further information
** use the contact form at http://qt.digia.com/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Digia gives you certain additional
** rights. These rights are described in the Digia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef QQMLABSTRACTBINDING_P_H
#define QQMLABSTRACTBINDING_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 <QtCore/qsharedpointer.h>
#include <private/qtqmlglobal_p.h>
#include <private/qqmlproperty_p.h>
#include <private/qpointervaluepair_p.h>
QT_BEGIN_NAMESPACE
class QQmlObjectCreator;
class Q_QML_PRIVATE_EXPORT QQmlAbstractBinding
{
public:
enum DestroyMode {
// The binding should disconnect itself upon destroy
DisconnectBinding,
// The binding doesn't need to disconnect itself, but it can if it wants to.
//
// This is used in QQmlData::destroyed() - at the point at which the bindings are
// destroyed, the notifiers are already disconnected, so no need to disconnect each
// binding again.
//
// Bindings can use this flag to speed up destruction, especially for v4 bindings
// disconnecting a single binding might be slow.
KeepBindingConnected
};
struct VTable {
void (*destroy)(QQmlAbstractBinding *, DestroyMode destroyMode);
QString (*expression)(const QQmlAbstractBinding *);
int (*propertyIndex)(const QQmlAbstractBinding *);
QObject *(*object)(const QQmlAbstractBinding *);
void (*setEnabled)(QQmlAbstractBinding *, bool, QQmlPropertyPrivate::WriteFlags);
void (*update)(QQmlAbstractBinding *, QQmlPropertyPrivate::WriteFlags);
void (*retargetBinding)(QQmlAbstractBinding *, QObject *, int);
};
typedef QWeakPointer<QQmlAbstractBinding> Pointer;
enum BindingType { Binding = 0, ValueTypeProxy = 1 };
inline BindingType bindingType() const;
// Destroy the binding. Use this instead of calling delete.
// Bindings are free to implement their own memory management, so the delete operator is
// not necessarily safe. The default implementation clears the binding, removes it from
// the object and calls delete.
void destroy(DestroyMode destroyMode = DisconnectBinding)
{ vtable()->destroy(this, destroyMode); }
QString expression() const { return vtable()->expression(this); }
// Should return the encoded property index for the binding. Should return this value
// even if the binding is not enabled or added to an object.
// Encoding is: coreIndex | (valueTypeIndex << 16)
int propertyIndex() const { return vtable()->propertyIndex(this); }
// Should return the object for the binding. Should return this object even if the
// binding is not enabled or added to the object.
QObject *object() const { return vtable()->object(this); }
void setEnabled(bool e) { setEnabled(e, QQmlPropertyPrivate::DontRemoveBinding); }
void setEnabled(bool e, QQmlPropertyPrivate::WriteFlags f) { vtable()->setEnabled(this, e, f); }
void update() { update(QQmlPropertyPrivate::DontRemoveBinding); }
void update(QQmlPropertyPrivate::WriteFlags f) { vtable()->update(this, f); }
void addToObject();
void removeFromObject();
static inline Pointer getPointer(QQmlAbstractBinding *p);
static void printBindingLoopError(QQmlProperty &prop);
// Default implementation for some VTable functions
template<typename T>
static void default_destroy(QQmlAbstractBinding *, DestroyMode);
static QString default_expression(const QQmlAbstractBinding *);
static void default_retargetBinding(QQmlAbstractBinding *, QObject *, int);
protected:
QQmlAbstractBinding(BindingType);
~QQmlAbstractBinding();
void clear();
// Called by QQmlPropertyPrivate to "move" a binding to a different property.
// This is only used for alias properties. The default implementation qFatal()'s
// to ensure that the method is never called for binding types that don't support it.
void retargetBinding(QObject *o, int i) { vtable()->retargetBinding(this, o, i); }
private:
Pointer weakPointer();
friend class QQmlData;
friend class QQmlComponentPrivate;
friend class QQmlValueTypeProxyBinding;
friend class QQmlPropertyPrivate;
friend class QtSharedPointer::ExternalRefCount<QQmlAbstractBinding>;
friend class QV4Bindings;
friend class QQmlObjectCreator;
typedef QSharedPointer<QQmlAbstractBinding> SharedPointer;
// To save memory, we also store the rarely used weakPointer() instance in here
// We also use the flag bits:
// m_mePtr.flag1: added to object
QPointerValuePair<QQmlAbstractBinding*, SharedPointer> m_mePtr;
inline void setAddedToObject(bool v);
inline bool isAddedToObject() const;
inline QQmlAbstractBinding *nextBinding() const;
inline void setNextBinding(QQmlAbstractBinding *);
// Pointer to the next binding in the linked list of bindings.
// Being a pointer, the address is always aligned to at least 4 bytes, which means the last two
// bits of the pointer are free to be used for something else. They are used to store the binding
// type. The binding type serves as an index into the static vTables array, which is used instead
// of a compiler-generated vTable. Instead of virtual functions, pointers to static functions in
// the vTables array are used for dispatching.
// This saves a compiler-generated pointer to a compiler-generated vTable, and thus reduces
// the binding object size by sizeof(void*).
qintptr m_nextBindingPtr;
static VTable *vTables[];
inline const VTable *vtable() const { return vTables[bindingType()]; }
};
QQmlAbstractBinding::Pointer
QQmlAbstractBinding::getPointer(QQmlAbstractBinding *p)
{
return p ? p->weakPointer() : Pointer();
}
void QQmlAbstractBinding::setAddedToObject(bool v)
{
m_mePtr.setFlagValue(v);
}
bool QQmlAbstractBinding::isAddedToObject() const
{
return m_mePtr.flag();
}
QQmlAbstractBinding *QQmlAbstractBinding::nextBinding() const
{
return (QQmlAbstractBinding *)(m_nextBindingPtr & ~0x3);
}
void QQmlAbstractBinding::setNextBinding(QQmlAbstractBinding *b)
{
m_nextBindingPtr = qintptr(b) | (m_nextBindingPtr & 0x3);
}
QQmlAbstractBinding::BindingType QQmlAbstractBinding::bindingType() const
{
return (BindingType)(m_nextBindingPtr & 0x3);
}
template<typename T>
void QQmlAbstractBinding::default_destroy(QQmlAbstractBinding *This, DestroyMode mode)
{
// Assume the binding disconnects itself in the destructor, which for example QQmlBinding
// does in the destructor of its base class, QQmlJavaScriptExpression
Q_UNUSED(mode);
This->removeFromObject();
This->clear();
delete static_cast<T *>(This);
}
QT_END_NAMESPACE
#endif // QQMLABSTRACTBINDING_P_H
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