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****************************************************************************/

#ifndef QSHAREDDATA_H

#define QSHAREDDATA_H

#include <QtCore/qglobal.h>

#include <QtCore/qatomic.h>

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

QT_MODULE(Core)

template <class T> class QSharedDataPointer;

class Q_CORE_EXPORT QSharedData

{

public:

    mutable QAtomicInt ref;

    inline QSharedData() : ref(0) { }

    inline QSharedData(const QSharedData &) : ref(0) { }

private:

    // using the assignment operator would lead to corruption in the ref-counting

    QSharedData &operator=(const QSharedData &);

};

template <class T> class QSharedDataPointer

{

public:

    typedef T Type;

    typedef T *pointer;

    inline void detach() { if (d && d->ref != 1) detach_helper(); }

    inline T &operator*() { detach(); return *d; }

    inline const T &operator*() const { return *d; }

    inline T *operator->() { detach(); return d; }

    inline const T *operator->() const { return d; }

    inline operator T *() { detach(); return d; }

    inline operator const T *() const { return d; }

    inline T *data() { detach(); return d; }

    inline const T *data() const { return d; }

    inline const T *constData() const { return d; }

    inline bool operator==(const QSharedDataPointer<T> &other) const { return d == other.d; }

    inline bool operator!=(const QSharedDataPointer<T> &other) const { return d != other.d; }

    inline QSharedDataPointer() { d = 0; }

    inline ~QSharedDataPointer() { if (d && !d->ref.deref()) delete d; }

    explicit QSharedDataPointer(T *data);

    inline QSharedDataPointer(const QSharedDataPointer<T> &o) : d(o.d) { if (d) d->ref.ref(); }

    inline QSharedDataPointer<T> & operator=(const QSharedDataPointer<T> &o) {

        if (o.d != d) {

            if (o.d)

                o.d->ref.ref();

            if (d && !d->ref.deref())

                delete d;

            d = o.d;

        }

        return *this;

    }

    inline QSharedDataPointer &operator=(T *o) {

        if (o != d) {

            if (o)

                o->ref.ref();

            if (d && !d->ref.deref())

                delete d;

            d = o;

        }

        return *this;

    }

    inline bool operator!() const { return !d; }

    inline void swap(QSharedDataPointer &other)

    { qSwap(d, other.d); }

protected:

    T *clone();

private:

    void detach_helper();

    T *d;

};

template <class T> class QExplicitlySharedDataPointer

{

public:

    typedef T Type;

    typedef T *pointer;

    inline T &operator*() const { return *d; }

    inline T *operator->() { return d; }

    inline T *operator->() const { return d; }

    inline T *data() const { return d; }

    inline const T *constData() const { return d; }

    inline void detach() { if (d && d->ref != 1) detach_helper(); }

    inline void reset()

    {

        if(d && !d->ref.deref())

            delete d;

        d = 0;

    }

    inline operator bool () const { return d != 0; }

    inline bool operator==(const QExplicitlySharedDataPointer<T> &other) const { return d == other.d; }

    inline bool operator!=(const QExplicitlySharedDataPointer<T> &other) const { return d != other.d; }

    inline bool operator==(const T *ptr) const { return d == ptr; }

    inline bool operator!=(const T *ptr) const { return d != ptr; }

    inline QExplicitlySharedDataPointer() { d = 0; }

    inline ~QExplicitlySharedDataPointer() { if (d && !d->ref.deref()) delete d; }

    explicit QExplicitlySharedDataPointer(T *data);

    inline QExplicitlySharedDataPointer(const QExplicitlySharedDataPointer<T> &o) : d(o.d) { if (d) d->ref.ref(); }

#ifndef QT_NO_MEMBER_TEMPLATES

    template<class X>

    inline QExplicitlySharedDataPointer(const QExplicitlySharedDataPointer<X> &o) : d(static_cast<T *>(o.data()))

    {

        if(d)

            d->ref.ref();

    }

#endif

    inline QExplicitlySharedDataPointer<T> & operator=(const QExplicitlySharedDataPointer<T> &o) {

        if (o.d != d) {

            if (o.d)

                o.d->ref.ref();

            if (d && !d->ref.deref())

                delete d;

            d = o.d;

        }

        return *this;

    }

    inline QExplicitlySharedDataPointer &operator=(T *o) {

        if (o != d) {

            if (o)

                o->ref.ref();

            if (d && !d->ref.deref())

                delete d;

            d = o;

        }

        return *this;

    }

    inline bool operator!() const { return !d; }

    inline void swap(QExplicitlySharedDataPointer &other)

    { qSwap(d, other.d); }

protected:

    T *clone();

private:

    void detach_helper();

    T *d;

};

template <class T>

Q_INLINE_TEMPLATE QSharedDataPointer<T>::QSharedDataPointer(T *adata) : d(adata)

{ if (d) d->ref.ref(); }

template <class T>

Q_INLINE_TEMPLATE T *QSharedDataPointer<T>::clone()

{

    return new T(*d);

}

template <class T>

Q_OUTOFLINE_TEMPLATE void QSharedDataPointer<T>::detach_helper()

{

    T *x = clone();

    x->ref.ref();

    if (!d->ref.deref())

        delete d;

    d = x;

}

template <class T>

Q_INLINE_TEMPLATE T *QExplicitlySharedDataPointer<T>::clone()

{

    return new T(*d);

}

template <class T>

Q_OUTOFLINE_TEMPLATE void QExplicitlySharedDataPointer<T>::detach_helper()

{

    T *x = clone();

    x->ref.ref();

    if (!d->ref.deref())

        delete d;

    d = x;

}

template <class T>

Q_INLINE_TEMPLATE QExplicitlySharedDataPointer<T>::QExplicitlySharedDataPointer(T *adata) : d(adata)

{ if (d) d->ref.ref(); }

template <class T>

Q_INLINE_TEMPLATE void qSwap(QSharedDataPointer<T> &p1, QSharedDataPointer<T> &p2)

{ p1.swap(p2); }

template <class T>

Q_INLINE_TEMPLATE void qSwap(QExplicitlySharedDataPointer<T> &p1, QExplicitlySharedDataPointer<T> &p2)

{ p1.swap(p2); }

QT_END_NAMESPACE

QT_END_HEADER

#endif // QSHAREDDATA_H