/*          
 *             Copyright (C) 2005 Maarten Keijzer
 *
 *          This program is free software; you can redistribute it and/or modify
 *          it under the terms of version 2 of the GNU General Public License as 
 *          published by the Free Software Foundation. 
 *
 *          This program is distributed in the hope that it will be useful,
 *          but WITHOUT ANY WARRANTY; without even the implied warranty of
 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *          GNU General Public License for more details.
 *
 *          You should have received a copy of the GNU General Public License
 *          along with this program; if not, write to the Free Software
 *          Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifndef _SHARED_PTR_H
#define _SHARED_PTR_H

template <class T> class weak_ptr;

namespace compat {

template <class T>
class shared_ptr {
   private:
      T* ptr;
      unsigned* count; //
      /* special case, null pointer (nil-code) */
      static unsigned* nil() { static unsigned nil_counter(1); return &nil_counter; }

      void decref() { if (--(*count) == 0) { delete ptr; delete count; }} 
      void incref() { ++(*count); }

      friend class weak_ptr<T>;

   public:

      shared_ptr() : ptr(0), count(nil()) { incref(); }
      ~shared_ptr() { decref(); }

      shared_ptr(const shared_ptr<T>& o) : ptr(o.ptr), count(o.count) { incref(); }
      shared_ptr(T* p) : ptr(p), count(new unsigned(1)) {}
      explicit shared_ptr(const weak_ptr<T>& w) : ptr(w.ptr), count(w.count) { incref(); }

      shared_ptr<T>& operator=(const shared_ptr<T>& o) {
         if (ptr == o.ptr) return *this;
         decref();
         ptr = o.ptr;
         count = o.count;
         incref();
         return *this;
      }

      void reset() { *this = 0; };

      T* get() { return ptr; }
      T* operator->() { return ptr; }
      T& operator*()  { return *ptr; }

      const T* get() const { return ptr; }
      const T* operator->() const { return ptr; }
      const T& operator*() const { return *ptr; }

      bool operator==(const shared_ptr<T>& o) const { return ptr == o.ptr; }
      bool operator!=(const shared_ptr<T>& o) const { return ptr != o.ptr; }
      bool operator<(const shared_ptr<T>& o) const { return ptr < o.ptr; }    

      unsigned refcount() const { return *count; }
      operator bool() { return ptr; }
};
template <class T>

class weak_ptr {
   T* ptr;
   unsigned* count;

   friend class shared_ptr<T>;

   public:

   weak_ptr() : ptr(0), count(shared_ptr<T>::nil()) {}
   explicit weak_ptr( const shared_ptr<T>& s) : ptr(s.ptr), count(s.count) {}

   shared_ptr<T> lock() const { return shared_ptr<T>(*this); }

   T* get() { return ptr; }
   T* operator->() { return ptr; }
   T& operator*()  { return *ptr; }

   const T* get() const { return ptr; }
   const T* operator->() const { return ptr; }
   const T& operator*() const { return *ptr; }

   bool operator==(const shared_ptr<T>& o) const { return ptr == o.ptr; }
   bool operator!=(const shared_ptr<T>& o) const { return ptr != o.ptr; }
   bool operator<(const shared_ptr<T>& o) const { return ptr < o.ptr; }    

   unsigned refcount() const { return *count; }
};

}
#endif
