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110 lines
2.7 KiB
C++
110 lines
2.7 KiB
C++
/*
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* The contents of this file are subject to the Initial
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* Developer's Public License Version 1.0 (the "License");
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* you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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* http://www.ibphoenix.com/main.nfs?a=ibphoenix&page=ibp_idpl.
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*
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* Software distributed under the License is distributed AS IS,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied.
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* See the License for the specific language governing rights
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* and limitations under the License.
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*
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* The Original Code was created by Claudio Valderrama on 12-Mar-2007
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* for the Firebird Open Source RDBMS project.
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*
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* Copyright (c) 2007 Claudio Valderrama
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* and all contributors signed below.
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*
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* All Rights Reserved.
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* Contributor(s): ______________________________________.
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*
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*/
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#ifndef FB_PTRSENTRY_H
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#define FB_PTRSENTRY_H
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// Helper class to track allocation of single entities and arrays.
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// Hopefully scarcely used as we move to more objects.
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// It simply deletes the given pointer when the container (an object of this clas)
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// goes out of scope or when we call clean() explicitly.
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// It assumes and used C++ memory primitives. It won't work if you used malloc.
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// If you delete the pointer "from outside", you have to call forget().
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template <typename T>
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class PtrSentry
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{
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public:
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PtrSentry();
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PtrSentry(T* ptr, bool is_array);
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~PtrSentry();
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void clean();
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T* exchange(T* ptr, bool is_array);
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void forget();
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private:
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T* m_ptr;
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bool m_is_array;
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};
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template <typename T>
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inline PtrSentry<T>::PtrSentry()
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: m_ptr(0), m_is_array(false)
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{
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}
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template <typename T>
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inline PtrSentry<T>::PtrSentry(T* ptr, bool is_array)
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: m_ptr(ptr), m_is_array(is_array)
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{
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}
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template <typename T>
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inline PtrSentry<T>::~PtrSentry()
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{
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if (m_is_array)
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delete[] m_ptr;
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else
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delete m_ptr;
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}
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// The code assumes the allocation was with C++ new!
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template <typename T>
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inline void PtrSentry<T>::clean()
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{
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if (m_is_array)
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delete[] m_ptr;
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else
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delete m_ptr;
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// We need this because clean() can be called directly. Otherwise, when
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// the destructor calls it, it would try to deallocate an invalid address.
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m_ptr = 0;
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}
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// Gives a new pointer to the object. The other is not deleted; simply forgotten.
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// The old pointer is returned.
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template <typename T>
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T* PtrSentry<T>::exchange(T* ptr, bool is_array)
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{
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if (m_ptr == ptr) // Don't know what else to do to signal error than to return NULL.
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return 0;
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T* const old_ptr = m_ptr;
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m_ptr = ptr;
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m_is_array = is_array;
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return old_ptr;
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}
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// Simply forget the current pointer. For example, we discovered the allocated
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// memory has to survive to return to the caller.
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template <typename T>
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void PtrSentry<T>::forget()
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{
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exchange(0, false);
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}
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#endif // FB_PTRSENTRY_H
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