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/*=========================================================================
Program: Visualization Toolkit
Module: vtkNew.h
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notice for more information.
=========================================================================*/
/**
* @class vtkNew
* @brief Allocate and hold a VTK object.
*
* vtkNew is a class template that on construction allocates and
* initializes an instance of its template argument using T::New().
* It assumes ownership of one reference during its lifetime, and calls
* T->Delete() on destruction.
*
* Automatic casting to raw pointer is available for convenience, but
* users of this method should ensure that they do not
* return this pointer if the vtkNew will go out of scope without
* incrementing its reference count.
*
* vtkNew is a drop in replacement for vtkSmartPointer, for example,
*
* \code
* vtkNew<vtkRenderer> ren;
* vtkNew<vtkRenderWindow> renWin;
* renWin->AddRenderer(ren);
* vtkNew<vtkRenderWindowInteractor> iren;
* iren->SetRenderWindow(renWin);
* \endcode
*
*
* @sa
* vtkSmartPointer vtkWeakPointer
*/
#ifndef vtkNew_h
#define vtkNew_h
#include "vtkIOStream.h"
#include "vtkMeta.h" // for IsComplete
#include <type_traits> // for is_base_of
VTK_ABI_NAMESPACE_BEGIN
class vtkObjectBase;
template <class T>
class vtkNew
{
// Allow other smart pointers friend access:
template <typename U>
friend class vtkNew;
template <typename U>
friend class vtkSmartPointer;
template <typename U>
friend class vtkWeakPointer;
// These static asserts only fire when the function calling CheckTypes is
// used. Thus, this smart pointer class may still be used as a member variable
// with a forward declared T, so long as T is defined by the time the calling
// function is used.
template <typename U = T>
static void CheckTypes() noexcept
{
static_assert(vtk::detail::IsComplete<T>::value,
"vtkNew<T>'s T type has not been defined. Missing include?");
static_assert(vtk::detail::IsComplete<U>::value,
"Cannot store an object with undefined type in "
"vtkNew. Missing include?");
static_assert(std::is_base_of<T, U>::value,
"Argument type is not compatible with vtkNew<T>'s "
"T type.");
static_assert(std::is_base_of<vtkObjectBase, T>::value,
"vtkNew can only be used with subclasses of vtkObjectBase.");
}
public:
/**
* Create a new T on construction.
*/
vtkNew()
: Object(T::New())
{
vtkNew::CheckTypes();
}
/**
* Move the object into the constructed vtkNew wrapper, stealing its
* reference. The argument is reset to nullptr.
* @{
*/
vtkNew(vtkNew&& o) noexcept
: Object(o.Object)
{
o.Object = nullptr;
}
template <typename U>
vtkNew(vtkNew<U>&& o) noexcept
: Object(o.Object)
{
vtkNew::CheckTypes<U>();
o.Object = nullptr;
}
///@}
///@{
/**
* Deletes reference to instance of T.
*/
~vtkNew() { this->Reset(); }
void Reset()
{
T* obj = this->Object;
if (obj)
{
this->Object = nullptr;
obj->Delete();
}
}
///@}
/**
* Enable pointer-like dereference syntax. Returns a pointer to the contained
* object.
*/
T* operator->() const noexcept { return this->Object; }
///@{
/**
* Get a raw pointer to the contained object. When using this function be
* careful that the reference count does not drop to 0 when using the pointer
* returned. This will happen when the vtkNew object goes out of
* scope for example.
*/
T* GetPointer() const noexcept { return this->Object; }
T* Get() const noexcept { return this->Object; }
operator T*() const noexcept { return static_cast<T*>(this->Object); }
///@}
/**
* Dereference the pointer and return a reference to the contained object.
* When using this function be careful that the reference count does not
* drop to 0 when using the pointer returned.
* This will happen when the vtkNew object goes out of scope for example.
*/
T& operator*() const noexcept { return *static_cast<T*>(this->Object); }
/**
* Move assignment operator.
*/
vtkNew<T>& operator=(vtkNew<T>&& other) noexcept
{
this->Reset();
this->Object = other.Object;
other.Object = nullptr;
return *this;
}
private:
vtkNew(vtkNew<T> const&) = delete;
void operator=(vtkNew<T> const&) = delete;
T* Object;
};
VTK_ABI_NAMESPACE_END
#endif
// VTK-HeaderTest-Exclude: vtkNew.h
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