1 // Copyright (c) 2014 OPEN CASCADE SAS
3 // This file is part of Open CASCADE Technology software library.
5 // This library is free software; you can redistribute it and/or modify it under
6 // the terms of the GNU Lesser General Public License version 2.1 as published
7 // by the Free Software Foundation, with special exception defined in the file
8 // OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
9 // distribution for complete text of the license and disclaimer of any warranty.
11 // Alternatively, this file may be used under the terms of Open CASCADE
12 // commercial license or contractual agreement.
14 #ifndef _Standard_Handle_HeaderFile
15 #define _Standard_Handle_HeaderFile
17 #include <Standard_Address.hxx>
18 #include <Standard_Std.hxx>
19 #include <Standard_Stream.hxx>
20 #include <Standard_Transient.hxx>
22 class Standard_Transient;
24 //! Namespace opencascade is intended for low-level template classes and functions
25 namespace opencascade {
27 //! Intrusive smart pointer for use with Standard_Transient class and its descendants.
29 //! This class is similar to boost::intrusive_ptr<>. The reference counter
30 //! is part of the base class (Standard_Transient), thus creation of a handle
31 //! does not require allocation of additional memory for the counter.
32 //! All handles to the same object share the common counter; object is deleted
33 //! when the last handle pointing on it is destroyed. It is safe to create a new
34 //! handle from plain C pointer to the object already pointed by another handle.
35 //! The same object can be referenced by handles of different types (as soon as
36 //! they are compatible with the object type).
38 //! Handle has type cast operator to const reference to handle to the base
39 //! types, which allows it to be passed by reference in functions accepting
40 //! reference to handle to base class, without copying.
42 //! By default, the type cast operator is provided also for non-const reference.
43 //! These casts (potentially unsafe) can be disabled by defining macro
44 //! OCCT_HANDLE_NOCAST; if it is defined, generalized copy constructor
45 //! and assignment operators are defined allowing to initialize handle
46 //! of base type from handle to derived type.
48 //! Weak pointers are not supported.
53 //! STL-compliant typedef of contained type
54 typedef T element_type;
59 handle () : entity(0) {}
61 //! Constructor from pointer to new object
62 handle (const T *thePtr) : entity(const_cast<T*>(thePtr))
68 handle (const handle& theHandle) : entity(theHandle.entity)
73 #if(defined(_MSC_VER) && (_MSC_VER < 1600))
76 handle (handle&& theHandle) : entity(theHandle.entity)
88 //! Nullify the handle
94 //! Check for being null
95 bool IsNull() const { return entity == 0; }
97 //! Reset by new pointer
98 void reset (T* thePtr)
103 //! Assignment operator
104 handle& operator= (const handle& theHandle)
106 Assign (theHandle.entity);
110 //! Assignment to pointer
111 handle& operator= (const T* thePtr)
113 Assign (const_cast<T*>(thePtr));
117 #if(defined(_MSC_VER) && (_MSC_VER < 1600))
120 handle& operator= (handle&& theHandle)
122 std::swap (this->entity, theHandle.entity);
127 //! STL-like cast to pointer to referred object (note non-const).
128 //! @sa std::shared_ptr::get()
129 T* get() const { return static_cast<T*>(this->entity); }
131 //! Member access operator (note non-const)
132 T* operator-> () const { return static_cast<T*>(this->entity); }
134 //! Dereferencing operator (note non-const)
135 T& operator* () const { return *get(); }
137 //! Check for equality
139 bool operator== (const handle<T2>& theHandle) const
141 return get() == theHandle.get();
144 //! Check for equality
146 bool operator== (const T2 *thePtr) const
148 return get() == thePtr;
151 //! Check for equality
153 friend bool operator== (const T2 *left, const handle& right)
155 return left == right.get();
158 //! Check for inequality
160 bool operator!= (const handle<T2>& theHandle) const
162 return get() != theHandle.get();
165 //! Check for inequality
167 bool operator!= (const T2 *thePtr) const
169 return get() != thePtr;
172 //! Check for inequality
174 friend bool operator!= (const T2 *left, const handle& right)
176 return left != right.get();
179 //! Compare operator for possible use in std::map<> etc.
181 bool operator< (const handle<T2>& theHandle) const
183 return get() < theHandle.get();
186 //! Down casting operator from handle to base type
188 static typename opencascade::std::enable_if<is_base_but_not_same<T2, T>::value, handle>::type
189 DownCast (const handle<T2>& theObject)
191 return handle (dynamic_cast<T*>(const_cast<T2*>(theObject.get())));
194 //! Down casting operator from pointer to base type
196 static typename opencascade::std::enable_if<is_base_but_not_same<T2, T>::value, handle>::type
197 DownCast (const T2* thePtr)
199 return handle (dynamic_cast<T*>(const_cast<T2*>(thePtr)));
202 //! For compatibility, define down casting operator from non-base type, as deprecated
204 Standard_DEPRECATED("down-casting from object of the same or unrelated type is meaningless")
205 static handle DownCast (const handle<T2>& theObject, typename opencascade::std::enable_if<!is_base_but_not_same<T2, T>::value, void*>::type = 0)
207 return handle (dynamic_cast<T*>(const_cast<T2*>(theObject.get())));
210 //! For compatibility, define down casting operator from non-base type, as deprecated
212 Standard_DEPRECATED("down-casting from object of the same or unrelated type is meaningless")
213 static handle DownCast (const T2* thePtr, typename opencascade::std::enable_if<!is_base_but_not_same<T2, T>::value, void*>::type = 0)
215 return handle (dynamic_cast<T*>(const_cast<T2*>(thePtr)));
218 #if (defined(__clang__)) || (defined(__INTEL_COMPILER) && __INTEL_COMPILER >= 1300) || \
219 (defined(_MSC_VER) && _MSC_VER >= 1800) || \
220 (defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)))
222 //! Conversion to bool for use in conditional expressions
223 explicit operator bool () const
225 return entity != nullptr;
228 #else /* fallback version for compilers not supporting explicit conversion operators (VC10, VC11, GCC below 4.5) */
230 //! Conversion to bool-compatible type for use in conditional expressions
231 operator Standard_Transient* handle::* () const
233 return entity ? &handle::entity : 0;
238 // Support of conversions to handle of base type:
239 // - copy and move constructors and assignment operators if OCCT_HANDLE_NOCAST is defined
240 // - operators of upcast to const reference to base type otherwise
241 #if (defined(__clang__)) || (defined(__INTEL_COMPILER) && __INTEL_COMPILER >= 1206) || \
242 (defined(_MSC_VER) && _MSC_VER >= 1800) || \
243 (defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)))
245 #ifdef OCCT_HANDLE_NOCAST
247 //! Generalized copy constructor.
248 //! Constructs handle holding entity of base type (T) from the one which holds entity of derived type (T2).
249 template <class T2, typename = typename std::enable_if <is_base_but_not_same <T, T2>::value>::type>
250 handle (const handle<T2>& theHandle) :
251 entity(theHandle.entity)
256 //! Generalized move constructor
257 template <class T2, typename = typename std::enable_if <is_base_but_not_same <T, T2>::value>::type>
258 handle (handle<T2>&& theHandle)
259 : entity(theHandle.entity)
261 theHandle.entity = 0;
264 //! Generalized assignment operator
265 template <class T2, typename = typename std::enable_if <is_base_but_not_same <T, T2>::value>::type>
266 handle operator = (const handle<T2>& theHandle)
268 Assign (theHandle.entity);
272 //! Generalized move operator
273 template <class T2, typename = typename std::enable_if <is_base_but_not_same <T, T2>::value>::type>
274 handle& operator= (handle<T2>&& theHandle)
276 std::swap (this->entity, theHandle.entity);
282 //! Upcast to const reference to base type.
283 template <class T2, typename = typename std::enable_if<is_base_but_not_same<T2, T>::value>::type>
284 operator const handle<T2>& () const
286 return reinterpret_cast<const handle<T2>&>(*this);
289 //! Upcast to non-const reference to base type.
290 //! NB: this cast can be dangerous, but required for legacy code; see #26377
291 template <class T2, typename = typename std::enable_if<is_base_but_not_same<T2, T>::value>::type>
292 operator handle<T2>& ()
294 return reinterpret_cast<handle<T2>&>(*this);
297 #endif /* OCCT_HANDLE_NOCAST */
299 #else /* fallback version for compilers not supporting default arguments of function templates (VC10, VC11, GCC below 4.3) */
301 #ifdef OCCT_HANDLE_NOCAST
303 //! Generalized copy constructor.
304 //! Constructs handle holding entity of base type (T) from the one which holds entity of derived type (T2).
306 handle (const handle<T2>& theHandle, typename std::enable_if <is_base_but_not_same <T, T2>::value>::type* = nullptr) :
307 entity(theHandle.entity)
312 #if(defined(_MSC_VER) && (_MSC_VER < 1600))
314 //! Generalized move constructor
316 handle (handle<T2>&& theHandle, typename std::enable_if <is_base_but_not_same <T, T2>::value>::type* = nullptr)
317 : entity(theHandle.entity)
319 theHandle.entity = 0;
323 //! Generalized assignment operator.
325 handle operator = (const handle<T2>& theHandle)
327 std::enable_if <is_base_but_not_same <T, T2>::value, void*>::type aTypeCheckHelperVar;
328 (void)aTypeCheckHelperVar;
329 Assign (theHandle.entity);
333 #if(defined(_MSC_VER) && (_MSC_VER < 1600))
335 //! Generalized move operator
337 handle& operator= (handle<T2>&& theHandle)
339 std::enable_if <is_base_but_not_same <T, T2>::value, void*>::type aTypeCheckHelperVar;
340 (void)aTypeCheckHelperVar;
341 std::swap (this->entity, theHandle.entity);
348 //! Upcast to const reference to base type.
349 //! NB: this implementation will cause ambiguity errors on calls to overloaded
350 //! functions accepting handles to different types, since compatibility is
351 //! checked in the cast code rather than ensured by SFINAE (possible with C++11)
353 operator const handle<T2>& () const
355 // error "type is not a member of enable_if" will be generated if T2 is not sub-type of T
356 // (handle is being cast to const& to handle of non-base type)
357 return reinterpret_cast<typename opencascade::std::enable_if<is_base_but_not_same<T2, T>::value, const handle<T2>&>::type>(*this);
360 //! Upcast to non-const reference to base type.
361 //! NB: this cast can be dangerous, but required for legacy code; see #26377
363 Standard_DEPRECATED("Passing non-const reference to handle of base type in function is unsafe; use variable of exact type")
364 operator handle<T2>& ()
366 // error "type is not a member of enable_if" will be generated if T2 is not sub-type of T
367 // (handle is being cast to const& to handle of non-base type)
368 return reinterpret_cast<typename opencascade::std::enable_if<is_base_but_not_same<T2, T>::value, handle<T2>&>::type>(*this);
371 #endif /* OCCT_HANDLE_NOCAST */
373 #endif /* compiler switch */
378 void Assign (Standard_Transient *thePtr)
380 if (thePtr == entity)
387 //! Increment reference counter of referred object
391 entity->IncrementRefCounter();
394 //! Decrement reference counter and if 0, destroy referred object
397 if (entity != 0 && entity->DecrementRefCounter() == 0)
402 template <class T2> friend class handle;
405 Standard_Transient* entity;
408 } // namespace opencascade
410 //! Define Handle() macro
411 #define Handle(Class) opencascade::handle<Class>
413 //! Computes a hash code for the standard handle, in the range [1, theUpperBound]
414 //! @param TheTransientType the type of the object the handle is referred to
415 //! @param theHandle the standard handle which hash code is to be computed
416 //! @param theUpperBound the upper bound of the range a computing hash code must be within
417 //! @return a computed hash code, in the range [1, theUpperBound]
418 template <class TheTransientType>
419 Standard_Integer HashCode (const Handle (TheTransientType) & theHandle, const Standard_Integer theUpperBound)
421 return ::HashCode (theHandle.get(), theUpperBound);
424 //! For compatibility with previous versions of OCCT, define Handle_Class alias for opencascade::handle<Class>.
425 #if (defined(_MSC_VER) && _MSC_VER >= 1800)
426 //! For Visual Studio 2013+, define Handle_Class as non-template class to allow exporting this type in C++/CLI.
427 #define DEFINE_STANDARD_HANDLECLASS(C1,C2,BC) class C1; class Handle_##C1 : public Handle(C1) \
431 Handle_##C1(Handle(C1)&& theHandle) : Handle(C1)(theHandle) {} \
432 template <class T2, typename = typename std::enable_if <std::is_base_of <C1,T2>::value>::type> \
433 inline Handle_##C1(const opencascade::handle<T2>& theOther) : Handle(C1)(theOther) {} \
434 template <class T2, typename = typename std::enable_if <std::is_base_of <C1,T2>::value>::type> \
435 inline Handle_##C1(const T2* theOther) : Handle(C1)(theOther) {} \
436 template<typename T> inline Handle_##C1& operator=(T theOther) { Handle(C1)::operator=(theOther); return *this; } \
439 //! For other compilers, use simple typedef
440 #define DEFINE_STANDARD_HANDLECLASS(C1,C2,BC) class C1; typedef Handle(C1) Handle_##C1;
443 #define DEFINE_STANDARD_HANDLE(C1,C2) DEFINE_STANDARD_HANDLECLASS(C1,C2,Standard_Transient)
444 #define DEFINE_STANDARD_PHANDLE(C1,C2) DEFINE_STANDARD_HANDLECLASS(C1,C2,Standard_Persistent)