KRef_Ptr.h

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/*********************************************************************
Copyright 2013 Karl Jones
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*********************************************************************/

/********************************************************************
class:      KRef_Ptr
created:    2009/07/22
author:     Karl Jones

purpose:    Implementation of a referenced smart pointer.
            Holds a counter of how many references are currently held of a pointer.
            When the final reference is released the memory is released.

            -*How To Use:*-

            KRef_Ptr<MyClass> pObj = new MyClass;

            pObj can now be used like a normal pointer.

            E.G

            pObj->func();
            *pObj.func();

            -*Note:*-

            Be carefull of the following mistakes:

            - MyClass * p = pObj.GetPtr(); // p is not safe. It could be deleted when the KRef_Ptr goes out of scope leaving you with a NULL pointer.

            - KRef_Ptr<MyClass> pRef = pObj.GetPtr(); // This will create a second reference to the pointer which will cause problems.

              instead use

              KRef_Ptr<MyClass> pRef = pObj;
*********************************************************************/

#pragma once

#include "./../KDefines.h"

namespace KDIS {
namespace UTILS {

typedef KDIS::KUINT16 RefCounter; // Change the counter to KUINT32 if you expect to have over 65,535 references.

template<class Type>
class KRef_Ptr
{
private:

    Type * m_pRef;

    RefCounter * m_piCount;

    //************************************
    // FullName:    KRef_Ptr<Type>::ref
    //!Description: Increments reference counter
    //************************************
    void ref()
    {
        if( m_pRef )++( *m_piCount );
    };

    //************************************
    // FullName:    KRef_Ptr<Type>::unRef
    //!Description: Decrements reference counter, cleans
    //!             up if no other references exist.
    //************************************
    void unRef()
    {
        if( m_pRef )
        {
            --( *m_piCount );
            if( *m_piCount == 0 )
            {
                delete m_piCount;
                delete m_pRef;
                m_piCount = NULL;
                m_pRef = NULL;
            }
        }
    };

public:

    KRef_Ptr() :
        m_pRef( NULL ),
        m_piCount( NULL )
    {
    };

    KRef_Ptr( Type * p )
    {
        m_pRef = p;
        m_piCount = new RefCounter;
        *m_piCount = 0;
        ref();
    };

    KRef_Ptr( const KRef_Ptr<Type> & p ) :
        m_pRef( p.m_pRef ),
        m_piCount( p.m_piCount )
    {
        ref();
    };

    virtual ~KRef_Ptr()
    {
        unRef();
    };

    //************************************
    // FullName:    KRef_Ptr<Type>::Clear
    //!Description: Removes the current reference held.
    //************************************
    void Clear()
    {
        unRef();
        m_pRef = NULL;
        m_piCount = NULL;
    };

    //************************************
    // FullName:    KRef_Ptr<Type>::GetPtr
    //!Description: Returns pointer to the current reference
    //!             or NULL if no reference exists.
    //!             Note: The returned pointer will not be safe. Avoid using this function.
    //************************************
    Type * GetPtr() const
    {
        return m_pRef;
    };

    //************************************
    // FullName:    KRef_Ptr<Type>::GetCount
    //!Description: Returns number of reference that currently exist
    //!             for this pointer or 0 if no reference is held.
    //************************************
    RefCounter GetCount() const
    {
        if( m_piCount )return *m_piCount;
    };

    //************************************
    // FullName:    KRef_Ptr<Type>::operator=
    //!Description: Assignment of an other KRef_Ptr.
    // Parameter:   const KRef_Ptr<Type> & p
    //************************************
    KRef_Ptr<Type> & operator=( const KRef_Ptr<Type> & p )
    {
        if( m_pRef == p.m_pRef )return *this;
        unRef();
        m_pRef = p.m_pRef;
        m_piCount = p.m_piCount;
        ref();
        return *this;
    };

    //************************************
    // FullName:    KRef_Ptr<Other>::operator=
    //!Description: Assignment of an other KRef_Ptr of a different type.
    // Parameter:   const KRef_Ptr<Other> & p
    //************************************
    template<class Other>
    KRef_Ptr<Type> & operator=( const KRef_Ptr<Other> & p )
    {
        unRef();
        m_pRef = p.m_pRef;
        m_piCount = p.m_piCount;
        ref();
        return *this;
    };

    //************************************
    // FullName:    KRef_Ptr<Type>::operator=
    //!Description: Assignment of a new reference.
    // Parameter:   Type * p
    //************************************
    KRef_Ptr<Type> & operator=( Type * p )
    {
        if( m_pRef == p )return *this;
        unRef();
        m_pRef = p;
        m_piCount = new RefCounter;
        *m_piCount = 0;
        ref();
        return *this;
    };

    //************************************
    // FullName:    KRef_Ptr<Other>::operator=
    //!Description: Assignment of a new reference of a different type.
    // Parameter:   Other * p
    //************************************
    template<class Other>
    KRef_Ptr<Type> & operator=( Other * p )
    {
        unRef();
        m_pRef = p;
        m_piCount = new RefCounter;
        *m_piCount = 0;
        ref();
        return *this;
    };

    //************************************
    // FullName:    KRef_Ptr<Type>::operator==
    //!Description: Comparison equals. Checks if both references are the same.
    // Parameter:   const KRef_Ptr<Type> & p
    //************************************
    KBOOL operator==( const KRef_Ptr<Type> & p )const
    {
        return m_pRef == p.m_pRef;
    };

    //************************************
    // FullName:    KRef_Ptr<Other>::operator==
    //!Description: Comparison equals. Checks if both references are the same of a
    //!             different type.
    //!             E.G An upast/downcast of the current type.
    // Parameter:   const KRef_Ptr<Other> & p
    //************************************
    template<class Other>
    KBOOL operator==( const KRef_Ptr<Other> & p )const
    {
        return m_pRef == p.m_pRef;
    };

    //************************************
    // FullName:    KRef_Ptr<Type>::operator*
    //!Description: When referencing the KRef_Ptr return our referenced object.
    //************************************
    Type & operator*() const
    {
        return *m_pRef;
    };

    //************************************
    // FullName:    KRef_Ptr<Type>::operator->
    //!Description: Returns the referenced pointer.
    //************************************
    Type * operator->() const
    {
        return m_pRef;
    };

    //************************************
    // FullName:    KRef_Ptr<Type>::operator!=
    //!Description: Comparison does not equals. Compares the referenced pointer to an unsafe pointer.
    // Parameter:   const Type * p
    //************************************
    KBOOL operator!= ( const Type * p ) const
    {
        return m_pRef != p;
    };

    //************************************
    // FullName:    KRef_Ptr<Other>::operator!=
    //!Description: Comparison does not equals. Compares the referenced pointer to an unsafe pointer of a different type.
    //!             E.G a derrived type.
    // Parameter:   const Other * p
    //************************************
    template<class Other>
    KBOOL operator!= ( const Other * p ) const
    {
        return m_pRef != p;
    };

    //************************************
    // FullName:    KRef_Ptr<Type>::operator!=
    //!Description: Comparison does not equals. Compares the referenced pointer to an other KRef_Ptr.
    // Parameter:   const KRef_Ptr<Type> & p
    //************************************
    KBOOL operator!= ( const KRef_Ptr<Type> & p ) const
    {
        return m_pRef != p.m_pRef;
    };

    //************************************
    // FullName:    KRef_Ptr<Other>::operator!=
    //!Description: Comparison does not equals. Compares the referenced pointer to an other KRef_Ptr of a different type.
    // Parameter:   const KRef_Ptr<Other> & p
    //************************************
    template<class Other>
    KBOOL operator!= ( const KRef_Ptr<Other> & p ) const
    {
        return m_pRef != p.m_pRef;
    };
};


} // END namespace UTILS
} // END namespace KDIS