alpar@1977: /* -*- C++ -*-
alpar@1977:  *
alpar@1977:  * This file is a part of LEMON, a generic C++ optimization library
alpar@1977:  *
alpar@1977:  * Copyright (C) 2003-2006
alpar@1977:  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
alpar@1977:  * (Egervary Research Group on Combinatorial Optimization, EGRES).
alpar@1977:  *
alpar@1977:  * Permission to use, modify and distribute this software is granted
alpar@1977:  * provided that this copyright notice appears in all copies. For
alpar@1977:  * precise terms see the accompanying LICENSE file.
alpar@1977:  *
alpar@1977:  * This software is provided "AS IS" with no warranty of any kind,
alpar@1977:  * express or implied, and with no claim as to its suitability for any
alpar@1977:  * purpose.
alpar@1977:  *
alpar@1977:  */
alpar@1977: 
alpar@1977: #ifndef LEMON_REFPTR_H
alpar@1977: #define LEMON_REFPTR_H
alpar@1977: 
alpar@1977: ///\ingroup misc
alpar@1977: ///\file
alpar@1977: ///\brief A reference counted pointer implementation.
alpar@1977: ///
alpar@1977: ///\todo Undocumented
alpar@1977: 
alpar@1977: 
alpar@1977: namespace lemon {
alpar@1977: 
alpar@1977:   
alpar@1977:   ///Reference counted pointer
alpar@1977: 
alpar@1977:   ///This is a simple implementation of a reference counted pointer.
alpar@1977:   ///
alpar@1977:   ///\warning Current implementation is far from being thread-safe.
alpar@1977:   template<class T>
alpar@1977:   class RefPtr 
alpar@1977:   {
alpar@1977:     mutable RefPtr *prev, *next;
alpar@1977:     T *ref;
alpar@1977: 
alpar@1977:     void lock() {}
alpar@1977:     void unlock() {}
alpar@1977:     
alpar@1977:     void attach(RefPtr &r) 
alpar@1977:     {
alpar@2151:       if(r.ref) {
alpar@2151: 	prev=&r; next=r.next; ref=r.ref;
alpar@2151: 	r.next=this;
alpar@2151:       }
alpar@1977:     }
alpar@1977:     void attach(const T *p) 
alpar@1977:     {
alpar@1977:       prev=0; next=0; ref=p;
alpar@1977:     }
alpar@1977:     void release() 
alpar@1977:     {
alpar@1977:       if(ref) {
alpar@1977: 	bool fr=true;
alpar@1977: 	if(prev) { fr=false; prev->next=next; }
alpar@1977: 	if(next) { fr=false; next->prev=prev; }
alpar@1977: 	if(fr) delete ref;
alpar@1977: 	ref=0;
alpar@1977:       }
alpar@1977:     }
alpar@1977:   
alpar@1977:   public:
alpar@1977:     ///\e
alpar@1977:     RefPtr() : ref(0) {}
alpar@1977: 
alpar@1977:     ///\e
alpar@1977:     RefPtr(const RefPtr &r) {
alpar@1977:       lock();
alpar@1977:       attach(const_cast<RefPtr&>(r));
alpar@1977:       unlock();
alpar@1977:     }
alpar@1977: 
alpar@1977:     ///\e
alpar@1977:     RefPtr(T *p) : prev(0), next(0), ref(p) {}
alpar@1977: 
alpar@1977:     ///\e
alpar@1977:     ~RefPtr() {
alpar@1977:       lock();
alpar@1977:       release();
alpar@1977:       unlock();
alpar@1977:     }
alpar@1977: 
alpar@1977:     ///\e
alpar@1977:     const RefPtr &operator=(const RefPtr &r) { 
alpar@1977:       if(ref!=r.ref) {
alpar@1977: 	lock();
alpar@1977: 	release(); attach(const_cast<RefPtr&>(r));
alpar@1977: 	unlock();
alpar@1977:       }
alpar@1977:       return *this;
alpar@1977:     }
alpar@1977:   
alpar@1977:     ///\e
alpar@1977:     const RefPtr &operator=(const T* &p) { 
alpar@1977:       if(ref!=p) { lock(); release(); attach(p); unlock(); }
alpar@1977:       return *this;
alpar@1977:     }
alpar@1977:   
alpar@1977:     ///\e
alpar@1977:     void swap(RefPtr &r) {
alpar@1977:       RefPtr *p;
alpar@1977:       T *tp;
alpar@1977:       lock();
alpar@1977:       p=prev; prev=r.prev; r.prev=p;
alpar@1977:       p=next; next=r.next; r.next=p;
alpar@1977:       tp=ref; ref=r.ref; r.ref=tp;
alpar@1977:       unlock();
alpar@1977:     }
alpar@1977: 
alpar@1977:     ///\e
alpar@1977:     void clear() { lock(); release(); unlock(); }
alpar@1977: 
alpar@1977:     ///\e
alpar@1977:     T * operator->() { return ref; }
alpar@1977:     ///\e
alpar@1977:     const T * operator->() const { return ref; }
alpar@1977:     ///\e
alpar@1977:     operator T *() { return ref; }
alpar@1977:     ///\e
alpar@1977:     operator const T *() const { return ref; }
alpar@1977:     
alpar@1977:     ///\e
alpar@1977:     bool operator<(const RefPtr &r) const { return this->ref < r.ref; }
alpar@1977:     ///\e
alpar@1977:     bool operator<=(const RefPtr &r) const { return this->ref <= r.ref; }
alpar@1977:     ///\e
alpar@1977:     bool operator==(const RefPtr &r) const { return this->ref == r.ref; }
alpar@1977:     ///\e
alpar@1977:     bool operator>=(const RefPtr &r) const { return this->ref >= r.ref; }
alpar@1977:     ///\e
alpar@1977:     bool operator>(const RefPtr &r) const { return this->ref > r.ref; }
alpar@1977:     ///\e
alpar@1977:     bool operator!=(const RefPtr &r) const { return this->ref != r.ref; }
alpar@1977:     
alpar@1977:     ///\e
alpar@1977:     operator bool() const { return ref; }
alpar@1977: 
alpar@2151:     ///\e
alpar@2151:     const RefPtr &borrow(const T* &p) { 
alpar@2151:       lock();
alpar@2151:       if(ref==p) {
alpar@2151: 	if(prev) prev->next=next;
alpar@2151: 	if(next) next->prev=prev;
alpar@2151:       }
alpar@2151:       else release();
alpar@2151:       ref=p;
alpar@2151:       next=prev=this;
alpar@2151:       unlock();
alpar@2151:       return *this;
alpar@2151:     }
alpar@2151:     
alpar@2151:     ///\e
alpar@2151:     const RefPtr &borrow() { 
alpar@2151:       lock();
alpar@2151:       if(prev) prev->next=next;
alpar@2151:       if(next) next->prev=prev;
alpar@2151:       next=prev=this;
alpar@2151:       unlock();
alpar@2151:       return *this;
alpar@2151:     }
alpar@2151:     
alpar@1977:   };  //END OF CLASS REFPTR
alpar@1977:   
alpar@1977: } //END OF NAMESPACE LEMON
alpar@1977: 
alpar@1977: #endif