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/*=========================================================================
Program: Visualization Toolkit
Module: vtkSmartPointer.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 vtkSmartPointer
* @brief Hold a reference to a vtkObjectBase instance.
*
* vtkSmartPointer is a class template that provides automatic casting
* for objects held by the vtkSmartPointerBase superclass.
*/
#ifndef vtkSmartPointer_h
#define vtkSmartPointer_h
#include "vtkSmartPointerBase.h"
#include "vtkMeta.h" // for IsComplete
#include "vtkNew.h" // for vtkNew.h
#include <type_traits> // for is_base_of
#include <utility> // for std::move
template <class T>
class vtkSmartPointer : public vtkSmartPointerBase
{
// 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,
"vtkSmartPointer<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 "
"vtkSmartPointer. Missing include?");
static_assert(std::is_base_of<T, U>::value,
"Argument type is not compatible with vtkSmartPointer<T>'s "
"T type.");
static_assert(std::is_base_of<vtkObjectBase, T>::value,
"vtkSmartPointer can only be used with subclasses of "
"vtkObjectBase.");
}
public:
/**
* Initialize smart pointer to nullptr.
*/
vtkSmartPointer() noexcept : vtkSmartPointerBase() {}
/**
* Initialize smart pointer with a new reference to the same object
* referenced by given smart pointer.
* @{
*/
// Need both overloads because the copy-constructor must be non-templated:
vtkSmartPointer(const vtkSmartPointer& r)
: vtkSmartPointerBase(r)
{
}
template <class U>
vtkSmartPointer(const vtkSmartPointer<U>& r)
: vtkSmartPointerBase(r)
{
vtkSmartPointer::CheckTypes<U>();
}
/* @} **/
/**
* Move the contents of @a r into @a this.
* @{
*/
// Need both overloads because the move-constructor must be non-templated:
vtkSmartPointer(vtkSmartPointer&& r) noexcept : vtkSmartPointerBase(std::move(r)) {}
template <class U>
vtkSmartPointer(vtkSmartPointer<U>&& r) noexcept : vtkSmartPointerBase(std::move(r))
{
vtkSmartPointer::CheckTypes<U>();
}
/**@}*/
/**
* Initialize smart pointer to given object.
* @{
*/
vtkSmartPointer(T* r)
: vtkSmartPointerBase(r)
{
vtkSmartPointer::CheckTypes();
}
template <typename U>
vtkSmartPointer(const vtkNew<U>& r)
: vtkSmartPointerBase(r.Object)
{ // Create a new reference on copy
vtkSmartPointer::CheckTypes<U>();
}
//@}
/**
* Move the pointer from the vtkNew smart pointer to the new vtkSmartPointer,
* stealing its reference and resetting the vtkNew object to nullptr.
*/
template <typename U>
vtkSmartPointer(vtkNew<U>&& r) noexcept
: vtkSmartPointerBase(r.Object, vtkSmartPointerBase::NoReference{})
{ // Steal the reference on move
vtkSmartPointer::CheckTypes<U>();
r.Object = nullptr;
}
//@{
/**
* Assign object to reference. This removes any reference to an old
* object.
*/
// Need this since the compiler won't recognize template functions as
// assignment operators.
vtkSmartPointer& operator=(const vtkSmartPointer& r)
{
this->vtkSmartPointerBase::operator=(r.GetPointer());
return *this;
}
template <class U>
vtkSmartPointer& operator=(const vtkSmartPointer<U>& r)
{
vtkSmartPointer::CheckTypes<U>();
this->vtkSmartPointerBase::operator=(r.GetPointer());
return *this;
}
//@}
/**
* Assign object to reference. This removes any reference to an old
* object.
*/
template <typename U>
vtkSmartPointer& operator=(const vtkNew<U>& r)
{
vtkSmartPointer::CheckTypes<U>();
this->vtkSmartPointerBase::operator=(r.Object);
return *this;
}
/**
* Assign object to reference. This adds a new reference to an old
* object.
*/
template <typename U>
vtkSmartPointer& operator=(U* r)
{
vtkSmartPointer::CheckTypes<U>();
this->vtkSmartPointerBase::operator=(r);
return *this;
}
//@{
/**
* Get the contained pointer.
*/
T* GetPointer() const noexcept { return static_cast<T*>(this->Object); }
T* Get() const noexcept { return static_cast<T*>(this->Object); }
//@}
/**
* Get the contained pointer.
*/
operator T*() const noexcept { return static_cast<T*>(this->Object); }
/**
* Dereference the pointer and return a reference to the contained
* object.
*/
T& operator*() const noexcept { return *static_cast<T*>(this->Object); }
/**
* Provides normal pointer target member access using operator ->.
*/
T* operator->() const noexcept { return static_cast<T*>(this->Object); }
/**
* Transfer ownership of one reference to the given VTK object to
* this smart pointer. This does not increment the reference count
* of the object, but will decrement it later. The caller is
* effectively passing ownership of one reference to the smart
* pointer. This is useful for code like:
* vtkSmartPointer<vtkFoo> foo;
* foo.TakeReference(bar->NewFoo());
* The input argument may not be another smart pointer.
*/
void TakeReference(T* t) { *this = vtkSmartPointer<T>(t, NoReference()); }
/**
* Create an instance of a VTK object.
*/
static vtkSmartPointer<T> New() { return vtkSmartPointer<T>(T::New(), NoReference()); }
/**
* Create a new instance of the given VTK object.
*/
static vtkSmartPointer<T> NewInstance(T* t)
{
return vtkSmartPointer<T>(t->NewInstance(), NoReference());
}
/**
* Transfer ownership of one reference to the given VTK object to a
* new smart pointer. The returned smart pointer does not increment
* the reference count of the object on construction but will
* decrement it on destruction. The caller is effectively passing
* ownership of one reference to the smart pointer. This is useful
* for code like:
* vtkSmartPointer<vtkFoo> foo =
* vtkSmartPointer<vtkFoo>::Take(bar->NewFoo());
* The input argument may not be another smart pointer.
*/
static vtkSmartPointer<T> Take(T* t) { return vtkSmartPointer<T>(t, NoReference()); }
// Work-around for HP and IBM overload resolution bug. Since
// NullPointerOnly is a private type the only pointer value that can
// be passed by user code is a null pointer. This operator will be
// chosen by the compiler when comparing against null explicitly and
// avoid the bogus ambiguous overload error.
#if defined(__HP_aCC) || defined(__IBMCPP__)
#define VTK_SMART_POINTER_DEFINE_OPERATOR_WORKAROUND(op) \
bool operator op(NullPointerOnly*) const { return ::operator op(*this, 0); }
private:
class NullPointerOnly
{
};
public:
VTK_SMART_POINTER_DEFINE_OPERATOR_WORKAROUND(==)
VTK_SMART_POINTER_DEFINE_OPERATOR_WORKAROUND(!=)
VTK_SMART_POINTER_DEFINE_OPERATOR_WORKAROUND(<)
VTK_SMART_POINTER_DEFINE_OPERATOR_WORKAROUND(<=)
VTK_SMART_POINTER_DEFINE_OPERATOR_WORKAROUND(>)
VTK_SMART_POINTER_DEFINE_OPERATOR_WORKAROUND(>=)
#undef VTK_SMART_POINTER_DEFINE_OPERATOR_WORKAROUND
#endif
protected:
vtkSmartPointer(T* r, const NoReference& n)
: vtkSmartPointerBase(r, n)
{
}
private:
// These are purposely not implemented to prevent callers from
// trying to take references from other smart pointers.
void TakeReference(const vtkSmartPointerBase&) = delete;
static void Take(const vtkSmartPointerBase&) = delete;
};
#define VTK_SMART_POINTER_DEFINE_OPERATOR(op) \
template <class T, class U> \
inline bool operator op(const vtkSmartPointer<T>& l, const vtkSmartPointer<U>& r) \
{ \
return (l.GetPointer() op r.GetPointer()); \
} \
template <class T, class U> \
inline bool operator op(T* l, const vtkSmartPointer<U>& r) \
{ \
return (l op r.GetPointer()); \
} \
template <class T, class U> \
inline bool operator op(const vtkSmartPointer<T>& l, U* r) \
{ \
return (l.GetPointer() op r); \
} \
template <class T, class U> \
inline bool operator op(const vtkNew<T>& l, const vtkSmartPointer<U>& r) \
{ \
return (l.GetPointer() op r.GetPointer()); \
} \
template <class T, class U> \
inline bool operator op(const vtkSmartPointer<T>& l, const vtkNew<U>& r) \
{ \
return (l.GetPointer() op r.GetPointer); \
}
/**
* Compare smart pointer values.
*/
VTK_SMART_POINTER_DEFINE_OPERATOR(==)
VTK_SMART_POINTER_DEFINE_OPERATOR(!=)
VTK_SMART_POINTER_DEFINE_OPERATOR(<)
VTK_SMART_POINTER_DEFINE_OPERATOR(<=)
VTK_SMART_POINTER_DEFINE_OPERATOR(>)
VTK_SMART_POINTER_DEFINE_OPERATOR(>=)
#undef VTK_SMART_POINTER_DEFINE_OPERATOR
namespace vtk
{
/// Construct a vtkSmartPointer<T> containing @a obj. A new reference is added
/// to @a obj.
template <typename T>
vtkSmartPointer<T> MakeSmartPointer(T* obj)
{
return vtkSmartPointer<T>{ obj };
}
/// Construct a vtkSmartPointer<T> containing @a obj. @a obj's reference count
/// is not changed.
template <typename T>
vtkSmartPointer<T> TakeSmartPointer(T* obj)
{
return vtkSmartPointer<T>::Take(obj);
}
} // end namespace vtk
/**
* Streaming operator to print smart pointer like regular pointers.
*/
template <class T>
inline ostream& operator<<(ostream& os, const vtkSmartPointer<T>& p)
{
return os << static_cast<const vtkSmartPointerBase&>(p);
}
#endif
// VTK-HeaderTest-Exclude: vtkSmartPointer.h