120 lines
3.2 KiB
C
120 lines
3.2 KiB
C
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/****************************************************************************
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* Core Library Version 1.7, August 2004
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* Copyright (c) 1995-2004 Exact Computation Project
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* All rights reserved.
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*
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* This file is part of CGAL (www.cgal.org).
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* You can redistribute it and/or modify it under the terms of the GNU
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* Lesser General Public License as published by the Free Software Foundation,
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* either version 3 of the License, or (at your option) any later version.
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*
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* Licensees holding a valid commercial license may use this file in
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* accordance with the commercial license agreement provided with the
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* software.
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*
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* This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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* WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*
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*
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* File: RefCount.h
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* Synopsis:
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* 1. This file defines two templated classes:
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* RCRepImpl<class N>
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* to create Reps of the class N. The basic functions provided by
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* this class is reference counting. The other class is
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* RCImpl<class T>
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* for implementing the envelop-letter paradigm for a class whose Rep
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* is the class T. So, T is the "letter", and RCImpl<T> the "envelop".
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*
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* 2. All Rep classes (BigIntRep, BigFloatRep, BigRatRep, ExprRep, etc)
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* are derived from RCRepImpl<N>. E.g.,
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*
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* class BigRatRep : public RCRepImp<BigRatRep> {
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* ...
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* }
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* (Note the recursive use of "BigRatRep").
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*
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* 3. All Number classes (BigInt, BigFloat, BigRat, Expr, etc)
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* are derived from RCImpl<T>. E.g.
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*
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* typedef RCImpl<BigRatRep> RCBigRat;
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* class BigRat : public RCBigRat {
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* ...
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* }
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*
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* Written by
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* Zilin Du <zilin@cs.nyu.edu>
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* Chee Yap <yap@cs.nyu.edu>
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*
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* WWW URL: http://cs.nyu.edu/exact/
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* Email: exact@cs.nyu.edu
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*
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* $URL$
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* $Id$
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* SPDX-License-Identifier: LGPL-3.0+
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***************************************************************************/
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#ifndef _CORE_REFCOUNT_H_
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#define _CORE_REFCOUNT_H_
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namespace CORE {
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template<class Deriving>
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class RCRepImpl {
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public:
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RCRepImpl() : refCount(1) {}
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void incRef() {
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++refCount;
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}
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// Without static_cast this to Deriving*,
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// the destructor of Deriving class will never been called.
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// this is an example of simulating dynamic binding from ATL.
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void decRef() {
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if (--refCount == 0)
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delete static_cast<Deriving*>(this);
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}
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int getRefCount() const {
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return refCount;
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}
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private:
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int refCount;
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};
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template<class T>
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class RCImpl {
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protected:
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RCImpl(T* p) : rep(p) {}
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RCImpl(const RCImpl& x) : rep(x.rep) {}
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T* rep; ///<= rep is the actual representation
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public:
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/// get rep (const)
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const T& getRep() const {
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return *rep;
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}
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/// get rep (non-const)
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T& getRep() {
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return *rep;
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}
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/// clone data
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void makeCopy() {
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if (rep->getRefCount() > 1) {
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T* oldValue = rep;
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rep->decRef(); // safe since rep has been referred at least once.
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rep = oldValue ? new T(*oldValue) : 0;
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}
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}
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#ifdef CORE_RC_DEBUG
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/// get counter
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int getRefCount() const {
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return rep->getRefCount();
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}
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#endif
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};
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} //namespace CORE
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#endif // _CORE_REFCOUNT_H_
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