refcount.hpp

SRI international 发布的OAA框架软件

#ifndef INC_RefCount_hpp__
#define INC_RefCount_hpp__

/**
 * <b>SOFTWARE RIGHTS</b>
 * <p>
 * ANTLR 2.6.0 MageLang Insitute, 1999
 * <p>
 * We reserve no legal rights to the ANTLR--it is fully in the
 * public domain. An individual or company may do whatever
 * they wish with source code distributed with ANTLR or the
 * code generated by ANTLR, including the incorporation of
 * ANTLR, or its output, into commerical software.
 * <p>
 * We encourage users to develop software with ANTLR. However,
 * we do ask that credit is given to us for developing
 * ANTLR. By "credit", we mean that if you use ANTLR or
 * incorporate any source code into one of your programs
 * (commercial product, research project, or otherwise) that
 * you acknowledge this fact somewhere in the documentation,
 * research report, etc... If you like ANTLR and have
 * developed a nice tool with the output, please mention that
 * you developed it using ANTLR. In addition, we ask that the
 * headers remain intact in our source code. As long as these
 * guidelines are kept, we expect to continue enhancing this
 * system and expect to make other tools available as they are
 * completed.
 * <p>
 * The ANTLR gang:
 * @version ANTLR 2.6.0 MageLang Insitute, 1999
 * @author Terence Parr, <a href=http://www.MageLang.com>MageLang Institute</a>
 * @author <br>John Lilley, <a href=http://www.Empathy.com>Empathy Software</a>
 * @author <br><a href="mailto:[e-mail]">Pete Wells</a>
 */

#include "antlr/config.hpp"

ANTLR_BEGIN_NAMESPACE(antlr)

template<class T>
class RefCount {
private:
	struct Ref {
		T* const ptr;
		unsigned int count;

		Ref(T* p) : ptr(p), count(1) {}
		~Ref() {delete ptr;}
		Ref* increment() {++count;return this;}
		bool decrement() {return (--count==0);}
	private:
		Ref(const Ref&);
		Ref& operator=(const Ref&);
	}* ref;

public:
	explicit RefCount(T* p=0) 
		: ref(p ? new Ref(p) : 0)
	{
	}
	RefCount(const RefCount<T>& other) 
		: ref(other.ref ? other.ref->increment() : 0)
	{
	}
	~RefCount()
	{
		if (ref && ref->decrement()) delete ref;
	}
	RefCount<T>& operator=(const RefCount<T>& other)
	{
		Ref* tmp=other.ref ? other.ref->increment() : 0;
		if (ref && ref->decrement()) delete ref;
		ref=tmp;
		return *this;
	}

	operator T* () const
		{ return ref ? ref->ptr : 0; }
	T* operator->() const
		{ return ref ? ref->ptr : 0; }
	T* get() const
		{ return ref ? ref->ptr : 0; }
};

ANTLR_END_NAMESPACE

#endif //INC_RefCount_hpp__