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#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:
    typedef QWeakPointer<QQmlAbstractBinding> Pointer;

    enum BindingType { Binding = 0, ValueTypeProxy = 1 };
    inline BindingType bindingType() const;

    void destroy() {
        removeFromObject();
        clear();
        delete this;
    }

    virtual QString expression() const;

    // 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)
    virtual int targetPropertyIndex() const = 0;

    // Should return the object for the binding.  Should return this object even if the
    // binding is not enabled or added to the object.
    virtual QObject *targetObject() const = 0;

    virtual void setEnabled(bool e, QQmlPropertyPrivate::WriteFlags f = QQmlPropertyPrivate::DontRemoveBinding) = 0;

    void addToObject();
    void removeFromObject();

    static inline Pointer getPointer(QQmlAbstractBinding *p);
    static void printBindingLoopError(QQmlProperty &prop);

    inline QQmlAbstractBinding *nextBinding() const;

protected:
    QQmlAbstractBinding(BindingType);
    virtual ~QQmlAbstractBinding();
    void clear();

private:
    friend class QQmlData;
    friend class QQmlValueTypeProxyBinding;
    friend class QQmlObjectCreator;

    Pointer weakPointer();

    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 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;
};

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);
}

QT_END_NAMESPACE

#endif // QQMLABSTRACTBINDING_P_H