smartpointer.h

一个非常好的GIS开源新版本

// Tools Library
//
// Copyright (C) 2004  Navel Ltd.
//
// This library 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.
//
// This library 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 this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
//  Email:
//    [e-mail]

#ifndef __tools_smart_pointer_h
#define __tools_smart_pointer_h

namespace Tools
{
	template <class X> class SmartPointer
	{
	public:
		explicit SmartPointer(X* p = 0) throw() : m_pointer(p) { m_prev = m_next = this; }
		~SmartPointer()	{ release(); }
		SmartPointer(const SmartPointer& p) throw() { acquire(p); }
		SmartPointer& operator=(const SmartPointer& p)
		{
			if (this != &p)
			{
				release();
				acquire(p);
			}
			return *this;
		}

		X& operator*() const throw() { return *m_pointer; }
		X* operator->() const throw() { return m_pointer; }
		X* get() const throw() { return m_pointer; }
		bool unique() const throw() { return m_prev ? m_prev == this : true; }

	private:
		X* m_pointer;
		mutable const SmartPointer* m_prev;
		mutable const SmartPointer* m_next;

		void acquire(const SmartPointer& p) throw()
		{
			m_pointer = p.m_pointer;
			m_next = p.m_next;
			m_next->m_prev = this;
			m_prev = &p;
			#ifndef mutable
			p.m_next = this;
			#else
			(const_cast<linked_ptr<X>*>(&p))->m_next = this;
			#endif
		}

		void release()
		{
			if (unique()) delete m_pointer;
			else
			{
				m_prev->m_next = m_next;
				m_next->m_prev = m_prev;
				m_prev = m_next = 0;
			}
			m_pointer = 0;
		}
	};
}

#endif /* __tools_smart_pointer_h */