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// File: NCollection_Handle.hxx
// Created: Fri Jan 30 15:15:17 2009
// Author: Andrey BETENEV (abv)
// Copyright: Open CASCADE 2009
#ifndef NCollection_Handle_HeaderFile
#define NCollection_Handle_HeaderFile
#include <MMgt_TShared.hxx>
//! Standard type function allowing to check that contained object is Handle
Standard_EXPORT const Handle(Standard_Type)& STANDARD_TYPE(NCollection_Handle);
//! Purpose: This template class is used to define Handle adaptor
//! for allocated dynamically objects of arbitrary type.
//!
//! The advantage is that this handle will automatically destroy
//! the object when last referred Handle is destroyed (i.e. it is a
//! typical smart pointer), and that it can be handled as
//! Handle(Standard_Transient) in OCCT components.
//!
//! Use it as follows:
//!
//! NCollection_Handle<T> aPtr = new T (...);
//!
//! aPtr->Method(...);
//!
//! Handle(Standard_Transient) aBase = aPtr;
//! if ( aBase->IsKind(STANDARD_TYPE(NCollection_Handle)) )
//! {
//! NCollection_Handle<T> aPtr2 = NCollection_Handle<T>::DownCast (aBase);
//! if ( ! aPtr2.IsNull() )
//! aPtr2->Method2();
//! }
template <class T>
class NCollection_Handle : public Handle_Standard_Transient
{
private:
//! Internal adaptor class wrapping actual type
//! and enhancing it by reference counter inherited from
//! Standard_Transient
class Ptr : public Standard_Transient
{
public:
//! Constructor: stores pointer to the object
Ptr (T* theObj) { myPtr = theObj; }
//! Destructor deletes the object
~Ptr () { if ( myPtr ) delete myPtr; myPtr = 0; }
//! Implementation of DynamicType() method
const Handle(Standard_Type)& DynamicType() const
{ return STANDARD_TYPE(NCollection_Handle); }
public:
T* myPtr; //!< Pointer to the object
};
//! Constructor of handle from pointer on newly allocated object.
//! Note that additional argument is used to avoid ambiguity with
//! public constructor from pointer when Handle is intilialized by 0.
NCollection_Handle (Ptr* thePtr, int)
: Handle_Standard_Transient (thePtr) {}
public:
//! Default constructor; creates null handle
NCollection_Handle () {}
//! Constructor of handle from pointer on newly allocated object
NCollection_Handle (T* theObject)
: Handle_Standard_Transient (theObject ? new Ptr (theObject) : 0) {}
//! Cast handle to contained type
T* operator -> () { return ((Ptr*)ControlAccess())->myPtr; }
//! Cast handle to contained type
const T* operator -> () const { return ((Ptr*)ControlAccess())->myPtr; }
//! Cast handle to contained type
T& operator * () { return *((Ptr*)ControlAccess())->myPtr; }
//! Cast handle to contained type
const T& operator * () const { return *((Ptr*)ControlAccess())->myPtr; }
//! Downcast arbitrary Handle to the argument type if contained
//! object is Handle for this type; returns null otherwise
static NCollection_Handle<T> DownCast (const Handle(Standard_Transient)& theOther)
{
return NCollection_Handle<T> (theOther.IsNull() ? 0 : dynamic_cast<Ptr*> (theOther.operator->()), 0);
}
};
#endif
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