source: orxonox.OLD/branches/volumetric_fog/src/lib/util/count_pointer.h @ 10609

/*!
 * @file count_pointer.h Contains the Counted Pointer Class, that points to Member-Objects.
 */

#ifndef _COUNT_POINTER_H
#define _COUNT_POINTER_H

template <typename X> class CountPointer
{
public:
  explicit CountPointer(X* p = NULL) // allocate a new counter
      : itsCounter(NULL) { if (p) itsCounter = new counter(p); }
  ~CountPointer() { release(); }
  CountPointer(const CountPointer& r) { acquire(r.itsCounter); }
  CountPointer& operator=(const CountPointer& r)
  {
    if (this != &r)
    {
      release();
      acquire(r.itsCounter);
    }
    return *this;
  }
  bool operator==(const CountPointer& r) const { return this->itsCounter->ptr == r.itsCounter->ptr; };
  inline X& operator*()  const { return *itsCounter->ptr; }
  inline X* operator->() const { return itsCounter->ptr; }
  inline bool unique()   const { return (itsCounter ? itsCounter->count == 1 : true); }
  inline bool isNull()   const { return (!itsCounter); }

  unsigned int count() const { return (this->itsCounter ? itsCounter->count : 0); }
private:

  struct counter
  {
    counter(X* p = NULL, unsigned c = 1) : ptr(p), count(c) {}
    X*          ptr;
    unsigned    count;
  }
  * itsCounter;

  void acquire(counter* c)
  {
    // increment the count
    itsCounter = c;
    if (c) ++c->count;
  }

  void release()
  {
    // decrement the count, delete if it is 0
    if (itsCounter)
    {
      if (--itsCounter->count == 0)
      {
        delete itsCounter->ptr;
        delete itsCounter;
      }
      itsCounter = NULL;
    }
  }
};

#endif /* _COUNT_POINTER_H */