autoptr.h

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//
// AutoPtr.h
//
// $Id: //poco/Main/Foundation/include/Foundation/AutoPtr.h#5 $
//
// Definition of the AutoPtr template class.
//
// Copyright (c) 2004, Guenter Obiltschnig/Applied Informatics.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//
// 3. Redistributions in any form must be accompanied by information on
//    how to obtain complete source code for this software and any
//    accompanying software that uses this software.  The source code
//    must either be included in the distribution or be available for no
//    more than the cost of distribution plus a nominal fee, and must be
//    freely redistributable under reasonable conditions.  For an
//    executable file, complete source code means the source code for all
//    modules it contains.  It does not include source code for modules or
//    files that typically accompany the major components of the operating
//    system on which the executable file runs.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//


#ifndef Foundation_AutoPtr_INCLUDED
#define Foundation_AutoPtr_INCLUDED


#ifndef Foundation_Foundation_INCLUDED
#include "Foundation/Foundation.h"
#endif
#ifndef Foundation_Exception_INCLUDED
#include "Foundation/Exception.h"
#endif


Foundation_BEGIN


template <class C>
class AutoPtr
	/// AutoPtr is a "smart" pointer for classes implementing
	/// reference counting based garbage collection.
	/// To be usable with the AutoPtr template, a class must
	/// implement the following behaviour:
	/// A class must maintain a reference count.
	/// The constructors of the object initialize the reference
	/// count to one.
	/// The class must implement a public duplicate() method:
	///     void duplicate();
	/// that increments the reference count by one.
	/// The class must implement a public release() method:
	///     void release()
	/// that decrements the reference count by one, and,
	/// if the reference count reaches zero, deletes the
	/// class.
	/// AutoPtr works in the following way:
	/// If an AutoPtr is assigned an ordinary pointer to
	/// an object (via the constructor or the assignment operator),
	/// it takes ownership of the object and the object's reference 
	/// count remains unchanged.
	/// If the AutoPtr is assigned another AutoPtr, the
	/// object's reference count is incremented by one by
	/// calling duplicate() on its object.
	/// The destructor of AutoPtr calls release() on its
	/// object.
	/// AutoPtr supports dereferencing with both the ->
	/// and the * operator. An attempt to dereference a null
	/// AutoPtr results in a NullPointerException being thrown.
	/// AutoPtr also implements all relational operators.
{
public:
	AutoPtr(): _ptr(0)
	{
	}

	AutoPtr(C* ptr): _ptr(ptr)
	{
	}

	AutoPtr(C* ptr, bool shared): _ptr(ptr)
	{
		if (shared && _ptr) _ptr->duplicate();
	}

	AutoPtr(const AutoPtr& ptr): _ptr(ptr._ptr)
	{
		if (_ptr) _ptr->duplicate();
	}

	template <class Other> 
	AutoPtr(const AutoPtr<Other>& ptr): _ptr(const_cast<Other*>(ptr.get()))
	{
		if (_ptr) _ptr->duplicate();
	}

	~AutoPtr()
	{
		if (_ptr) _ptr->release();
	}

	AutoPtr& operator = (C* ptr)
	{
		if (_ptr != ptr)
		{
			if (_ptr) _ptr->release();
			_ptr = ptr;
		}
		return *this;
	}

	AutoPtr& operator = (const AutoPtr& ptr)
	{
		if (&ptr != this)
		{
			if (_ptr) _ptr->release();
			_ptr = ptr._ptr;
			if (_ptr) _ptr->duplicate();
		}
		return *this;
	}
	
	template <class Other> 
	AutoPtr& operator = (const AutoPtr<Other>& ptr)
	{
		if (ptr.get() != _ptr)
		{
			if (_ptr) _ptr->release();
			_ptr = const_cast<Other*>(ptr.get());
			if (_ptr) _ptr->duplicate();
		}
		return *this;
	}

	C* operator -> ()
	{
		if (_ptr)
			return _ptr;
		else
			throw NullPointerException();
	}

	const C* operator -> () const
	{
		if (_ptr)
			return _ptr;
		else
			throw NullPointerException();
	}

	C& operator * ()
	{
		if (_ptr)
			return *_ptr;
		else
			throw NullPointerException();
	}

	const C& operator * () const
	{
		if (_ptr)
			return *_ptr;
		else
			throw NullPointerException();
	}

	C* get()
	{
		return _ptr;
	}
	
	operator C* ()
	{
		return _ptr;
	}
	
	operator const C* () const
	{
		return _ptr;
	}

	const C* get() const
	{
		return _ptr;
	}

	C* duplicate()
	{
		if (_ptr) _ptr->duplicate();
		return _ptr;
	}

	bool operator == (const AutoPtr& ptr) const
	{
		return _ptr == ptr._ptr;
	}

	bool operator == (const C* ptr) const
	{
		return _ptr == ptr;
	}

	bool operator == (C* ptr) const
	{
		return _ptr == ptr;
	}

	bool operator != (const AutoPtr& ptr) const
	{
		return _ptr != ptr._ptr;
	}

	bool operator != (const C* ptr) const
	{
		return _ptr != ptr;
	}

	bool operator != (C* ptr) const
	{
		return _ptr != ptr;
	}

	bool operator < (const AutoPtr& ptr) const
	{
		return _ptr < ptr._ptr;
	}

	bool operator < (const C* ptr) const
	{
		return _ptr < ptr;
	}

	bool operator < (C* ptr) const
	{
		return _ptr < ptr;
	}

	bool operator <= (const AutoPtr& ptr) const
	{
		return _ptr <= ptr._ptr;
	}

	bool operator <= (const C* ptr) const
	{
		return _ptr <= ptr;
	}

	bool operator <= (C* ptr) const
	{
		return _ptr <= ptr;
	}

	bool operator > (const AutoPtr& ptr) const
	{
		return _ptr > ptr._ptr;
	}

	bool operator > (const C* ptr) const
	{
		return _ptr > ptr;
	}

	bool operator > (C* ptr) const
	{
		return _ptr > ptr;
	}

	bool operator >= (const AutoPtr& ptr) const
	{
		return _ptr >= ptr._ptr;
	}

	bool operator >= (const C* ptr) const
	{
		return _ptr >= ptr;
	}

	bool operator >= (C* ptr) const
	{
		return _ptr >= ptr;
	}

private:
	C* _ptr;
};


Foundation_END


#endif // Foundation_AutoPtr_INCLUDED