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/*========================================================================= |
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Program: Insight Segmentation & Registration Toolkit |
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Module: $RCSfile: itkAutoPointer.h.html,v $ |
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Language: C++ |
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Date: $Date: 2006/01/17 19:15:33 $ |
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Version: $Revision: 1.4 $ |
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Copyright (c) Insight Software Consortium. All rights reserved. |
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See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details. |
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This software is distributed WITHOUT ANY WARRANTY; without even |
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the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR |
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PURPOSE. See the above copyright notices for more information. |
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=========================================================================*/ |
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#ifndef __itkAutoPointer_h |
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#define __itkAutoPointer_h |
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#include "itkMacro.h" |
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#include <iostream> |
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namespace itk |
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{ |
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/** \class AutoPointer |
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* \brief Implements an Automatic Pointer to an object. |
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* |
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* AutoPointer is intended to facilitate the construction of |
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* objects on the fly for those objects that are not to be shared. |
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* An AutoPointer destroys its object when it goes out of scope. |
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* Ownership of the object is transferred from one AutoPointer |
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* to another AutoPointer when the assignement operator is used. |
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* An AutoPointer can release ownership of the object it holds. |
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* |
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* This class follows the design of the std::auto_ptr class. The main |
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* reason for not using the std version is to avoid templated methods, |
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* which greatly increase the difficulty of wrapping for Tcl, Python |
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* and Java. |
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* |
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* \ingroup ITKSystemObjects |
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* \ingroup DataAccess |
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*/ |
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template <class TObjectType> |
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class ITK_EXPORT AutoPointer |
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{ |
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public: |
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/** Extract information from template parameter. */ |
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typedef TObjectType ObjectType; |
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typedef AutoPointer Self; |
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/** Constructor. */ |
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AutoPointer (): |
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****m_Pointer(0), |
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****m_IsOwner(false) |
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{ } |
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/** Copy constructor. */ |
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explicit AutoPointer ( AutoPointer & p ) |
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{ |
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m_IsOwner = p.IsOwner(); // Ownership can only be taken from another owner |
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m_Pointer = p.ReleaseOwnership(); // release ownership if appropriate |
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} |
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/** Constructor to pointer p. */ |
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explicit AutoPointer ( ObjectType * p, bool takeOwnership ): |
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********************m_Pointer(p), |
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********************m_IsOwner(takeOwnership) |
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******{ } |
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/** Destructor. */ |
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~AutoPointer () |
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{ |
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if( m_IsOwner && m_Pointer ) |
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{ |
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delete m_Pointer; |
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} |
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m_Pointer = 0; |
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m_IsOwner = false; |
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} |
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/** Overload operator ->. */ |
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ObjectType *operator -> () const |
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{ return m_Pointer; } |
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/** Clear the AutoPointer. If it had a pointer the object |
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******is deleted and the pointer is set to null. */ |
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void Reset( void ) |
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{ |
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if( m_IsOwner && m_Pointer ) |
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{ |
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delete m_Pointer; |
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} |
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m_Pointer = 0; |
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m_IsOwner = false; |
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} |
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/** Explicitly set the ownership */ |
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void TakeOwnership(void) |
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{ m_IsOwner = true; } |
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/** Explicitly set the ownership */ |
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void TakeOwnership(ObjectType * objectptr) |
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{ |
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if( m_IsOwner && m_Pointer ) |
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{ |
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delete m_Pointer; // remove the current one |
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} |
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m_Pointer = objectptr; |
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m_IsOwner = true; |
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} |
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/** Explicitly reject ownership */ |
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void TakeNoOwnership(ObjectType * objectptr) |
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{ |
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if( m_IsOwner && m_Pointer ) |
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{ |
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delete m_Pointer; // remove the current one |
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} |
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m_Pointer = objectptr; |
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m_IsOwner = false; |
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} |
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/** Query for the ownership */ |
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bool IsOwner(void) const |
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{ return m_IsOwner; } |
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/** Release the pointer hold by the current AutoPointer |
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******and return the raw pointer so it can be hold by |
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******another AutoPointer. This operation is intended to |
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******be used for facilitating polymorphism. |
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******Example: if class Cow derives from Mammal, |
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******AutoPointer<Cow> onecow = new Cow; |
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******AutoPointer<Mammal> onemammal = onecow.ReleaseOwnership(); |
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******Note that the AutoPointer still points to the object after the |
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******ReleaseOwnership operation, but it doesn't own the object any |
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******more. |
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*****/ |
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ObjectType * ReleaseOwnership( void ) |
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{ |
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m_IsOwner = false; |
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return m_Pointer; |
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} |
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/** Access function to pointer. */ |
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ObjectType *GetPointer () const |
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{ return m_Pointer; } |
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***/** Comparison of pointers. Equal comparison. */ |
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bool operator == (const AutoPointer &r) const |
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{ return (void*)m_Pointer == (void*) r.m_Pointer; } |
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/** Comparison of pointers. NonEqual comparison. */ |
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bool operator != (const AutoPointer &r) const |
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{ return (void*)m_Pointer != (void*) r.m_Pointer; } |
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/** Comparison of pointers. Less than comparison. */ |
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bool operator < (const AutoPointer &r) const |
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{ return (void*)m_Pointer < (void*) r.m_Pointer; } |
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/** Comparison of pointers. Greater than comparison. */ |
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bool operator > (const AutoPointer &r) const |
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{ return (void*)m_Pointer > (void*) r.m_Pointer; } |
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/** Comparison of pointers. Less than or equal to comparison. */ |
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bool operator <= (const AutoPointer &r) const |
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{ return (void*)m_Pointer <= (void*) r.m_Pointer; } |
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/** Comparison of pointers. Greater than or equal to comparison. */ |
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bool operator >= (const AutoPointer &r) const |
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{ return (void*)m_Pointer >= (void*) r.m_Pointer; } |
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/** Overload operator assignment. */ |
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AutoPointer &operator = (AutoPointer &r) const |
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{ |
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AutoPointer( r ).Swap( *this ); |
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return *this; |
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} |
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/** Casting operator to boolean. This is used in conditional |
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******statments to check the content of the pointer against null */ |
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operator bool () const |
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{ return (m_Pointer!=NULL); } |
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/** Function to print object pointed to. */ |
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ObjectType *Print (std::ostream& os) const |
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{ |
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// This prints the object pointed to by the pointer |
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(*m_Pointer).Print(os); |
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os << "Owner: " << m_IsOwner << std::endl; |
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return m_Pointer; |
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} |
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private: |
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/** Exchange the content of two AutoPointers */ |
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void Swap(AutoPointer &r) throw() |
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{ |
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ObjectType * temp = m_Pointer; |
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m_Pointer = r.m_Pointer; |
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r.m_Pointer = temp; |
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} |
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/** The pointer to the object referrred to by this smart pointer. */ |
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ObjectType* m_Pointer; |
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bool m_IsOwner; |
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}; |
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template <typename T> |
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std::ostream& operator<< (std::ostream& os, AutoPointer<T> p) |
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{ |
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p.Print(os); |
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os << "Owner: " << p.IsOwner() << std::endl; |
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return os; |
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} |
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/** This templated function is intended to facilitate the |
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transfer between AutoPointers of Derived class to Base class */ |
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template <typename TAutoPointerBase, typename TAutoPointerDerived> |
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void |
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ITK_EXPORT TransferAutoPointer(TAutoPointerBase & pa, TAutoPointerDerived & pb) |
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{ |
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pa.TakeNoOwnership( pb.GetPointer() ); // give a chance to natural polymorphism |
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if( pb.IsOwner() ) |
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{ |
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pa.TakeOwnership(); // pa Take Ownership |
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pb.ReleaseOwnership(); // pb Release Ownership and clears |
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} |
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} |
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} // end namespace itk |
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#endif |
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