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/****************************************************************************
* Core Library Version 1.7, August 2004
* Copyright (c) 1995-2004 Exact Computation Project
* All rights reserved.
*
* This file is part of CORE (http://cs.nyu.edu/exact/core/); you may
* redistribute it under the terms of the Q Public License version 1.0.
* See the file LICENSE.QPL distributed with CORE.
*
* Licensees holding a valid commercial license may use this file in
* accordance with the commercial license agreement provided with the
* software.
*
* This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
* WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
*
* File: RefCount.h
* Synopsis:
* 1. This file defines two templated classes:
* RCRepImpl<class N>
* to create Reps of the class N. The basic functions provided by
* this class is reference counting. The other class is
* RCImpl<class T>
* for implementing the envelop-letter paradigm for a class whose Rep
* is the class T. So, T is the "letter", and RCImpl<T> the "envelop".
*
* 2. All Rep classes (BigIntRep, BigFloatRep, BigRatRep, ExprRep, etc)
* are derived from RCRepImpl<N>. E.g.,
*
* class BigRatRep : public RCRepImp<BigRatRep> {
* ...
* }
* (Note the recursive use of "BigRatRep").
*
* 3. All Number classes (BigInt, BigFloat, BigRat, Expr, etc)
* are derived from RCImpl<T>. E.g.
*
* typedef RCImpl<BigRatRep> RCBigRat;
* class BigRat : public RCBigRat {
* ...
* }
*
* Written by
* Zilin Du <zilin@cs.nyu.edu>
* Chee Yap <yap@cs.nyu.edu>
*
* WWW URL: http://cs.nyu.edu/exact/
* Email: exact@cs.nyu.edu
*
* $URL: svn+ssh://scm.gforge.inria.fr/svn/cgal/branches/CGAL-3.2-branch/Core/include/CORE/RefCount.h $
* $Id: RefCount.h 28567 2006-02-16 14:30:13Z lsaboret $
***************************************************************************/
#ifndef _CORE_REFCOUNT_H_
#define _CORE_REFCOUNT_H_
CORE_BEGIN_NAMESPACE
template<class Deriving>
class RCRepImpl {
public:
RCRepImpl() : refCount(1) {}
void incRef() {
++refCount;
}
// Without static_cast this to Deriving*,
// the destructor of Deriving class will never been called.
// this is an example of simulating dynamic binding from ATL.
void decRef() {
if (--refCount == 0)
delete static_cast<Deriving*>(this);
}
int getRefCount() const {
return refCount;
}
private:
int refCount;
};
template<class T>
class RCImpl {
protected:
RCImpl(T* p) : rep(p) {}
RCImpl(const RCImpl& x) : rep(x.rep) {}
T* rep; ///<= rep is the actual representation
public:
/// get rep (const)
const T& getRep() const {
return *rep;
}
/// get rep (non-const)
T& getRep() {
return *rep;
}
/// clone data
void makeCopy() {
if (rep->getRefCount() > 1) {
T* oldValue = rep;
rep->decRef(); // safe since rep has been referred at least once.
rep = oldValue ? new T(*oldValue) : 0;
}
}
#ifdef CORE_RC_DEBUG
/// get counter
int getRefCount() const {
return rep->getRefCount();
}
#endif
};
CORE_END_NAMESPACE
#endif // _CORE_REFCOUNT_H_
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