source: orxonox.OLD/trunk/src/lib/util/count_pointer.h @ 8998

/*!
 * @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 = 0) // allocate a new counter
        : itsCounter(0) { if (p) itsCounter = new counter(p); }
    virtual ~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; };
    X& operator*()  const { return *itsCounter->ptr; }
    X* operator->() const { return itsCounter->ptr; }
    X* get()        const { return itsCounter ? itsCounter->ptr : 0; }
    bool unique()   const { return (itsCounter ? itsCounter->count == 1 : true); }
    virtual unsigned int count() const { return (this->itsCounter ? itsCounter->count : 0); }
private:

    struct counter {
        counter(X* p = 0, 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 = 0;
        }
    }
};

#endif /* _COUNT_POINTER_H */