tnt_i_refvec.h

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/*
*
* Template Numerical Toolkit (TNT)
*
* Mathematical and Computational Sciences Division
* National Institute of Technology,
* Gaithersburg, MD USA
*
*
* This software was developed at the National Institute of Standards and
* Technology (NIST) by employees of the Federal Government in the course
* of their official duties. Pursuant to title 17 Section 105 of the
* United States Code, this software is not subject to copyright protection
* and is in the public domain. NIST assumes no responsibility whatsoever for
* its use by other parties, and makes no guarantees, expressed or implied,
* about its quality, reliability, or any other characteristic.
*
*/



#ifndef TNT_I_REFVEC_H
#define TNT_I_REFVEC_H

#include <cstdlib>
#include <iostream>

#ifdef TNT_BOUNDS_CHECK
#include <assert.h>
#endif

#ifndef NULL
#define NULL 0
#endif

namespace TNT
{
/*
    Internal representation of ref-counted array.  The TNT
    arrays all use this building block.

    <p>
    If an array block is created by TNT, then every time 
    an assignment is made, the left-hand-side reference 
    is decreased by one, and the right-hand-side refernce
    count is increased by one.  If the array block was
    external to TNT, the refernce count is a NULL pointer
    regardless of how many references are made, since the 
    memory is not freed by TNT.


    
*/
template <class T>
class i_refvec
{


  private:
    T* data_;                  
    int *ref_count_;


  public:

             i_refvec();
    explicit i_refvec(int n);
    inline   i_refvec(T* data);
    inline   i_refvec(const i_refvec &v);
    inline   T*      begin();
    inline const T* begin() const;
    inline  T& operator[](int i);
    inline const T& operator[](int i) const;
    inline  i_refvec<T> & operator=(const i_refvec<T> &V);
            void copy_(T* p, const T* q, const T* e); 
            void set_(T* p, const T* b, const T* e); 
    inline  int  ref_count() const;
    inline  int is_null() const;
    inline  void destroy();
             ~i_refvec();
            
};

template <class T>
void i_refvec<T>::copy_(T* p, const T* q, const T* e)
{
    for (T* t=p; q<e; t++, q++)
        *t= *q;
}

template <class T>
i_refvec<T>::i_refvec() : data_(NULL), ref_count_(NULL) {}

template <class T>
i_refvec<T>::i_refvec(int n) : data_(NULL), ref_count_(NULL)
{
    if (n >= 1)
    {
#ifdef TNT_DEBUG
        std::cout  << "new data storage.\n";
#endif
        data_ = new T[n];
        ref_count_ = new int;
        *ref_count_ = 1;
    }
}

template <class T>
inline   i_refvec<T>::i_refvec(const i_refvec<T> &V): data_(V.data_),
    ref_count_(V.ref_count_)
{
    if (V.ref_count_ != NULL)
        (*(V.ref_count_))++;
}


template <class T>
i_refvec<T>::i_refvec(T* data) : data_(data), ref_count_(NULL) {}

template <class T>
inline T* i_refvec<T>::begin()
{
    return data_;
}

template <class T>
inline const T& i_refvec<T>::operator[](int i) const
{
    return data_[i];
}

template <class T>
inline T& i_refvec<T>::operator[](int i)
{
    return data_[i];
}


template <class T>
inline const T* i_refvec<T>::begin() const
{
    return data_;
}



template <class T>
i_refvec<T> & i_refvec<T>::operator=(const i_refvec<T> &V)
{
    if (this == &V)
        return *this;


    if (ref_count_ != NULL)
    {
        (*ref_count_) --;
        if ((*ref_count_) == 0)
            destroy();
    }

    data_ = V.data_;
    ref_count_ = V.ref_count_;

    if (V.ref_count_ != NULL)
        (*(V.ref_count_))++;

    return *this;
}

template <class T>
void i_refvec<T>::destroy()
{
    if (ref_count_ != NULL)
    {
#ifdef TNT_DEBUG
        std::cout << "destorying data... \n";
#endif
        delete ref_count_;

#ifdef TNT_DEBUG
        std::cout << "deleted ref_count_ ...\n";
#endif
        if (data_ != NULL)
            delete []data_;
#ifdef TNT_DEBUG
        std::cout << "deleted data_[] ...\n";
#endif
        data_ = NULL;
    }
}

/*
* return 1 is vector is empty, 0 otherwise
*
* if is_null() is false and ref_count() is 0, then
* 
*/
template<class T>
int i_refvec<T>::is_null() const
{
    return (data_ == NULL ? 1 : 0);
}

/*
*  returns -1 if data is external, 
*  returns 0 if a is NULL array,
*  otherwise returns the positive number of vectors sharing
*       this data space.
*/
template <class T>
int i_refvec<T>::ref_count() const
{
    if (data_ == NULL)
        return 0;
    else
        return (ref_count_ != NULL ? *ref_count_ : -1) ; 
}

template <class T>
i_refvec<T>::~i_refvec()
{
    if (ref_count_ != NULL)
    {
        (*ref_count_)--;

        if (*ref_count_ == 0)
        destroy();
    }
}


} /* namespace TNT */





#endif
/* TNT_I_REFVEC_H */