scguardedptr.h

/*
For general Scribus (>=1.3.2) copyright and licensing information please refer
to the COPYING file provided with the program. Following this notice may exist
a copyright and/or license notice that predates the release of Scribus 1.3.2
for which a new license (GPL+exception) is in place.
*/
#ifndef SCGUARDEDPTR_H
#define SCGUARDEDPTR_H

#include "scribusapi.h"
#include "assert.h"
/*
A replacement for QPointer
Does not rely on QObject, and provides faster destructor
*/ 

template<typename T>
class ScGuardedPtrData
{
public:

    int refs;
    T* pointer;

    ScGuardedPtrData(void) { pointer = 0; refs = 0; }
    ScGuardedPtrData(T* ptr) { pointer = ptr; refs = 0; }
};

template<typename T>
class ScGuardedPtr
{
protected:
    ScGuardedPtrData<T> *data;
public:
    ScGuardedPtr(void);
    ScGuardedPtr(T* ptr);
    ScGuardedPtr(const ScGuardedPtr& gPtr);
    ~ScGuardedPtr();

    ScGuardedPtr& operator=(const ScGuardedPtr& gPtr);
    bool operator==( const ScGuardedPtr<T> &p ) const { return (T*)(*this) == (T*) p;}
    bool operator!= ( const ScGuardedPtr<T>& p ) const { return !( *this == p ); }

    bool isNull(void);

    T* operator->() const { return (T*)(data ? data->pointer : 0); }
    T& operator*() const { return *((T*)(data ? data->pointer : 0)); }
    operator T*() const { return (T*)(data ? data->pointer : 0); }

    void deref(void);
};

template<typename T>
class ScGuardedObject : public ScGuardedPtr<T>
{
public:
    ScGuardedObject(T* ptr);
    ScGuardedObject(const ScGuardedObject& gPtr);
    ~ScGuardedObject();

    ScGuardedObject& operator=(const ScGuardedObject& gPtr);
    bool operator==( const ScGuardedObject<T> &p ) const { return (T*)(*this) == (T*) p;}
    bool operator!= ( const ScGuardedObject<T>& p ) const { return !( *this == p ); }

    void nullify(void);
};

template<typename T>
ScGuardedPtr<T>::ScGuardedPtr(void)
{
    data = new ScGuardedPtrData<T>();
    ++(data->refs);
};

template<typename T>
ScGuardedPtr<T>::ScGuardedPtr(T* ptr)
{
    data = new ScGuardedPtrData<T>(ptr);
    ++(data->refs);
};

template<typename T>
ScGuardedPtr<T>::ScGuardedPtr(const ScGuardedPtr& other)
{
    data = other.data;
    ++(data->refs);
};

template<typename T>
ScGuardedPtr<T>::~ScGuardedPtr()
{
    deref();
};

template<typename T>
ScGuardedPtr<T>& ScGuardedPtr<T>::operator=(const ScGuardedPtr& other)
{
    // We do not copy the owner member
    if (data != other.data)
    {
        ++(other.data->refs);
        deref();
        data = other.data;
    }
    return *this;
};

template<typename T>
bool ScGuardedPtr<T>::isNull(void)
{
    if (data)
        return (data->pointer == 0);
    return true;
};

template<typename T>
void ScGuardedPtr<T>::deref(void)
{
    if (data && --(data->refs) == 0)
    {
        delete data;
        data = 0;
    }
};

template<typename T>
ScGuardedObject<T>::ScGuardedObject(T* ptr) : ScGuardedPtr<T>(ptr)
{
};

template<typename T>
ScGuardedObject<T>::ScGuardedObject(const ScGuardedObject& other)
{
    this->data = 0;
    // Must never be used
    assert(false);
};

template<typename T>
ScGuardedObject<T>& ScGuardedObject<T>::operator=(const ScGuardedObject& other)
{
    // We do nothing, think about an object being assigned to another
    // The object being assigned must keep track of its own data
    return *this;
};

template<typename T>
void ScGuardedObject<T>::nullify(void)
{
    if (this->data)
        this->data->pointer = 0;
};

template<typename T>
ScGuardedObject<T>::~ScGuardedObject()
{
    nullify();
    // deref() is called by ScGuardedPtr<T> dtor
};

#endif