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/**
* @file icptrholder_cxx.h
* @author wyau (08/29/02)
* @brief C++ template classes for managing C++ pointers returned by
* VComponent::get_..._component, VComponent::get_..._property,
* ICalProperty::get_..._value.
*
* @remarks VComponent::get... functions returns a C++ object that wraps the
* libical implementation. It is important to note that the wrapped
* implementation still belongs to the original component. To stop memory leak,
* caller must delete the pointer. However, the destructor will call the
* appropriate free function. eg. ~VComponent calls icalcomponent_free(imp).
*
* As stated previously, imp still belongs to the original component. To avoid
* freeing the wrapped "imp", caller must set the "imp" to null before deleting
* the pointer.
*
* The template class relieves the burden of memory management when used as a
* stack based object. The class holds a pointer to the C++ Wrapper.
* The destructor set the imp to null before deleting the pointer.
*
* Each C++ Wrapper instantiates a template class in its corresponding .h file.
*
* Usage example:
* VComponentTmpPtr p;// VComponentTmpPtr is an instantiation of this template
* for (p=component.get_first_component; p!= 0; p=component.get_next_component) {
*
* (C) COPYRIGHT 2001, Critical Path
This library is free software; you can redistribute it and/or modify
it under the terms of either:
The LGPL as published by the Free Software Foundation, version
2.1, available at: https://www.gnu.org/licenses/lgpl-2.1.html
Or:
The Mozilla Public License Version 2.0. You may obtain a copy of
the License at https://www.mozilla.org/MPL/
*/
#ifndef ICPTRHOLDER_CXX_H
#define ICPTRHOLDER_CXX_H
#include <cassert>
template < class T > class ICPointerHolder
{
public:
ICPointerHolder()
: ptr(0)
{
}
ICPointerHolder(T *p)
: ptr(p)
{
}
// copy constructor to support assignment
ICPointerHolder(const ICPointerHolder &ip)
: ptr(ip.ptr)
{
// We need to transfer ownership of ptr to this object by setting
// ip's ptr to null. Otherwise, ptr will de deleted twice.
// const ugliness requires us to do the const_cast.
ICPointerHolder *ipp = const_cast < ICPointerHolder * >(&ip);
ipp->ptr = 0;
};
~ICPointerHolder()
{
release();
}
ICPointerHolder &operator=(T *p)
{
this->release();
ptr = p;
return *this;
}
ICPointerHolder &operator=(ICPointerHolder &p)
{
this->release();
ptr = p.ptr; // this transfer ownership of the pointer
p.ptr = 0; // set it to null so the pointer won't get delete twice.
return *this;
}
bool operator!=(T *p)
{
return (ptr != p);
}
bool operator==(T *p)
{
return (ptr == p);
}
operator T *() const
{
return ptr;
}
T *operator->() const
{
assert(ptr);
return ptr;
}
T &operator*()
{
assert(ptr);
return *ptr;
}
private:
void release()
{
if (ptr != 0) {
ptr->detach();
delete ptr;
ptr = 0;
}
}
T *ptr;
};
#endif
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