RefCounter.hpp

// ********** DO NOT REMOVE THIS BANNER **********
// ORIG-DATE:    29 fev 2005  
// -*- Mode : c++ -*-
//
// SUMMARY  : array modelisation 
// USAGE    : LGPL      
// ORG      : LJLL Universite Pierre et Marie Curie, Paris,  FRANCE 
// AUTHOR   : Frederic Hecht
// E-MAIL   : frederic.hecht@ann.jussieu.fr
//

/*
 
 
 
 Freefem++ is free software; you can redistribute it and/or modify
 it under the terms of the GNU Lesser General Public License as published by
 the Free Software Foundation; either version 2.1 of the License, or
 (at your option) any later version.
 
 Freefem++  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 Lesser General Public License for more details.
 
 You should have received a copy of the GNU Lesser General Public License
 along with Freefem++; if not, write to the Free Software
 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 
 
 */

#ifndef REFCOUNTER_HPP
#define REFCOUNTER_HPP

#include "showverb.hpp" 
#include "error.hpp" 

class RefCounter; 
class baseCountPointer;


// ruse pour utiliser le prive c RefCounter de 
//  pas de syntaxe pour des friends template 
class baseCountPointer { protected:
 void  add(const  RefCounter * c)  const; 
 void  destroyPtr(const RefCounter *  c)  const;
};

// <<RefCounter>>
class RefCounter {
  static RefCounter *tnull; 
  mutable int count;
  protected:
  virtual ~RefCounter() {}
  RefCounter() : count(0) {}
  public:
  int destroy() const { 
      if(this!=tnull) {throwassert(count>=0);
        if ( count--==0) {
	            SHOWVERB( cout << "True  destruction of " << this <<  endl);
             delete this;
             return true;} 
        else{ SHOWVERB(cout << " no destruction count=" << count+1 << " " << this <<  endl);
              return false;}}
   else return false;} 
   void increment() const {count++;SHOWVERB( cout << "increment  of " << this << " "<< count <<  endl);}
    void decrement() const {destroy();}// count--;SHOWVERB( cout << "decrement  of " << this << " "<< count <<  endl);ffassert(count>=0);}
 friend   class baseCountPointer;
// private:
  RefCounter(const RefCounter &) : count(0) {} 
  void operator=(const RefCounter &) { count=0;}
 

};

inline void baseCountPointer::add(const RefCounter * c)  const 
   { if (c) c->count++;}    
inline void baseCountPointer::destroyPtr(const RefCounter *   c)  const 
   { if (c) c->destroy();}    
 
template<class T>
class CountPointer: private baseCountPointer {
 T * c;
 public: 
 CountPointer() : c(0) {}
 CountPointer( T * a,bool mmaster=false) :c(a) { if(!mmaster) add(c);} 
 CountPointer(  T & a) :c(&a) { add(c);}
 CountPointer(const CountPointer & a) :c(a.c) { add(c);}
 ~CountPointer()  { destroyPtr(c);c=0;}
 //void destroy() const { destroyPtr(c);}
 void destroy()  { destroyPtr(c);c=0;}
 operator  T * ()   const { return c;}
 operator   T & () const  {return *c;}
  T& operator*() const {return *c;}
  T* operator->() const {return c;}
 bool operator==(const  CountPointer & n) const {return  n.c ==c;}
 bool operator!=(const  CountPointer & n) const {return  n.c !=c;}
 bool operator!() const { return !c;}
 void operator=(const  CountPointer & n) {
  if(*this != n) { destroyPtr(c); 
                c=n.c;
                add(c);               
              }}
                           
 void operator=( T * t) {
  if( c != t) { if(c) destroyPtr(c); 
                c=t;
                add(c);               
              }} 
//  for the compile time               
 void init() {c=0;} // 
 void master(T *t) {
     destroyPtr(c); 
     c=t;}
};

#endif