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 #ifndef OCCT_NO_RVALUE_REFERENCE
75 handle (handle&& theHandle) : entity(theHandle.entity)
87 //! Nullify the handle
93 //! Check for being null
94 bool IsNull() const { return entity == 0; }
96 //! Reset by new pointer
97 void reset (T* thePtr)
102 //! Assignment operator
103 handle& operator= (const handle& theHandle)
105 Assign (theHandle.entity);
109 //! Assignment to pointer
110 handle& operator= (const T* thePtr)
112 Assign (const_cast<T*>(thePtr));
116 #ifndef OCCT_NO_RVALUE_REFERENCE
118 handle& operator= (handle&& theHandle)
120 std::swap (this->entity, theHandle.entity);
125 //! STL-like cast to pointer to referred object (note non-const).
126 //! @sa std::shared_ptr::get()
127 T* get() const { return static_cast<T*>(this->entity); }
129 //! Member access operator (note non-const)
130 T* operator-> () const { return static_cast<T*>(this->entity); }
132 //! Dereferencing operator (note non-const)
133 T& operator* () const { return *get(); }
135 //! Check for equality
137 bool operator== (const handle<T2>& theHandle) const
139 return get() == theHandle.get();
142 //! Check for equality
144 bool operator== (const T2 *thePtr) const
146 return get() == thePtr;
149 //! Check for equality
151 friend bool operator== (const T2 *left, const handle& right)
153 return left == right.get();
156 //! Check for inequality
158 bool operator!= (const handle<T2>& theHandle) const
160 return get() != theHandle.get();
163 //! Check for inequality
165 bool operator!= (const T2 *thePtr) const
167 return get() != thePtr;
170 //! Check for inequality
172 friend bool operator!= (const T2 *left, const handle& right)
174 return left != right.get();
177 //! Compare operator for possible use in std::map<> etc.
179 bool operator< (const handle<T2>& theHandle) const
181 return get() < theHandle.get();
184 //! Down casting operator from handle to base type
186 static typename opencascade::std::enable_if<is_base_but_not_same<T2, T>::value, handle>::type
187 DownCast (const handle<T2>& theObject)
189 return handle (dynamic_cast<T*>(const_cast<T2*>(theObject.get())));
192 //! Down casting operator from pointer to base type
194 static typename opencascade::std::enable_if<is_base_but_not_same<T2, T>::value, handle>::type
195 DownCast (const T2* thePtr)
197 return handle (dynamic_cast<T*>(const_cast<T2*>(thePtr)));
200 //! For compatibility, define down casting operator from non-base type, as deprecated
202 Standard_DEPRECATED("down-casting from object of the same or unrelated type is meaningless")
203 static handle DownCast (const handle<T2>& theObject, typename opencascade::std::enable_if<!is_base_but_not_same<T2, T>::value, void*>::type = 0)
205 return handle (dynamic_cast<T*>(const_cast<T2*>(theObject.get())));
208 //! For compatibility, define down casting operator from non-base type, as deprecated
210 Standard_DEPRECATED("down-casting from object of the same or unrelated type is meaningless")
211 static handle DownCast (const T2* thePtr, typename opencascade::std::enable_if<!is_base_but_not_same<T2, T>::value, void*>::type = 0)
213 return handle (dynamic_cast<T*>(const_cast<T2*>(thePtr)));
216 #if (defined(__clang__)) || (defined(__INTEL_COMPILER) && __INTEL_COMPILER >= 1300) || \
217 (defined(_MSC_VER) && _MSC_VER >= 1800) || \
218 (defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)))
220 //! Conversion to bool for use in conditional expressions
221 explicit operator bool () const
223 return entity != nullptr;
226 #else /* fallback version for compilers not supporting explicit conversion operators (VC10, VC11, GCC below 4.5) */
228 //! Conversion to bool-compatible type for use in conditional expressions
229 operator Standard_Transient* handle::* () const
231 return entity ? &handle::entity : 0;
236 // Support of conversions to handle of base type:
237 // - copy and move constructors and assignment operators if OCCT_HANDLE_NOCAST is defined
238 // - operators of upcast to const reference to base type otherwise
239 #if (defined(__clang__)) || (defined(__INTEL_COMPILER) && __INTEL_COMPILER >= 1206) || \
240 (defined(_MSC_VER) && _MSC_VER >= 1800) || \
241 (defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)))
243 #ifdef OCCT_HANDLE_NOCAST
245 //! Generalized copy constructor.
246 //! Constructs handle holding entity of base type (T) from the one which holds entity of derived type (T2).
247 template <class T2, typename = typename std::enable_if <is_base_but_not_same <T, T2>::value>::type>
248 handle (const handle<T2>& theHandle) :
249 entity(theHandle.entity)
254 //! Generalized move constructor
255 template <class T2, typename = typename std::enable_if <is_base_but_not_same <T, T2>::value>::type>
256 handle (handle<T2>&& theHandle)
257 : entity(theHandle.entity)
259 theHandle.entity = 0;
262 //! Generalized assignment operator
263 template <class T2, typename = typename std::enable_if <is_base_but_not_same <T, T2>::value>::type>
264 handle operator = (const handle<T2>& theHandle)
266 Assign (theHandle.entity);
270 //! Generalized move operator
271 template <class T2, typename = typename std::enable_if <is_base_but_not_same <T, T2>::value>::type>
272 handle& operator= (handle<T2>&& theHandle)
274 std::swap (this->entity, theHandle.entity);
280 //! Upcast to const reference to base type.
281 template <class T2, typename = typename std::enable_if<is_base_but_not_same<T2, T>::value>::type>
282 operator const handle<T2>& () const
284 return reinterpret_cast<const handle<T2>&>(*this);
287 //! Upcast to non-const reference to base type.
288 //! NB: this cast can be dangerous, but required for legacy code; see #26377
289 template <class T2, typename = typename std::enable_if<is_base_but_not_same<T2, T>::value>::type>
290 operator handle<T2>& ()
292 return reinterpret_cast<handle<T2>&>(*this);
295 #endif /* OCCT_HANDLE_NOCAST */
297 #else /* fallback version for compilers not supporting default arguments of function templates (VC10, VC11, GCC below 4.3) */
299 #ifdef OCCT_HANDLE_NOCAST
301 //! Generalized copy constructor.
302 //! Constructs handle holding entity of base type (T) from the one which holds entity of derived type (T2).
304 handle (const handle<T2>& theHandle, typename std::enable_if <is_base_but_not_same <T, T2>::value>::type* = nullptr) :
305 entity(theHandle.entity)
310 #ifndef OCCT_NO_RVALUE_REFERENCE
311 //! Generalized move constructor
313 handle (handle<T2>&& theHandle, typename std::enable_if <is_base_but_not_same <T, T2>::value>::type* = nullptr)
314 : entity(theHandle.entity)
316 theHandle.entity = 0;
320 //! Generalized assignment operator.
322 handle operator = (const handle<T2>& theHandle)
324 std::enable_if <is_base_but_not_same <T, T2>::value, void*>::type aTypeCheckHelperVar;
325 (void)aTypeCheckHelperVar;
326 Assign (theHandle.entity);
330 #ifndef OCCT_NO_RVALUE_REFERENCE
331 //! Generalized move operator
333 handle& operator= (handle<T2>&& theHandle)
335 std::enable_if <is_base_but_not_same <T, T2>::value, void*>::type aTypeCheckHelperVar;
336 (void)aTypeCheckHelperVar;
337 std::swap (this->entity, theHandle.entity);
344 //! Upcast to const reference to base type.
345 //! NB: this implementation will cause ambiguity errors on calls to overloaded
346 //! functions accepting handles to different types, since compatibility is
347 //! checked in the cast code rather than ensured by SFINAE (possible with C++11)
349 operator const handle<T2>& () const
351 // error "type is not a member of enable_if" will be generated if T2 is not sub-type of T
352 // (handle is being cast to const& to handle of non-base type)
353 return reinterpret_cast<typename opencascade::std::enable_if<is_base_but_not_same<T2, T>::value, const handle<T2>&>::type>(*this);
356 //! Upcast to non-const reference to base type.
357 //! NB: this cast can be dangerous, but required for legacy code; see #26377
359 Standard_DEPRECATED("Passing non-const reference to handle of base type in function is unsafe; use variable of exact type")
360 operator handle<T2>& ()
362 // error "type is not a member of enable_if" will be generated if T2 is not sub-type of T
363 // (handle is being cast to const& to handle of non-base type)
364 return reinterpret_cast<typename opencascade::std::enable_if<is_base_but_not_same<T2, T>::value, handle<T2>&>::type>(*this);
367 #endif /* OCCT_HANDLE_NOCAST */
369 #endif /* compiler switch */
374 void Assign (Standard_Transient *thePtr)
376 if (thePtr == entity)
383 //! Increment reference counter of referred object
387 entity->IncrementRefCounter();
390 //! Decrement reference counter and if 0, destroy referred object
393 if (entity != 0 && entity->DecrementRefCounter() == 0)
398 template <class T2> friend class handle;
401 Standard_Transient* entity;
404 } // namespace opencascade
406 //! Define Handle() macro
407 #define Handle(Class) opencascade::handle<Class>
409 //! Computes a hash code for the standard handle, in the range [1, theUpperBound]
410 //! @param theHandle the handle which hash code is to be computed
411 //! @param theUpperBound the upper bound of the range a computing hash code must be within
412 //! @return a computed hash code, in the range [1, theUpperBound]
413 template <class TheTransientType>
414 Standard_Integer HashCode (const Handle (TheTransientType) & theHandle, const Standard_Integer theUpperBound)
416 return ::HashCode (theHandle.get(), theUpperBound);
419 //! For compatibility with previous versions of OCCT, define Handle_Class alias for opencascade::handle<Class>.
420 #if (defined(_MSC_VER) && _MSC_VER >= 1800)
421 //! For Visual Studio 2013+, define Handle_Class as non-template class to allow exporting this type in C++/CLI.
422 #define DEFINE_STANDARD_HANDLECLASS(C1,C2,BC) class C1; class Handle_##C1 : public Handle(C1) \
426 Handle_##C1(Handle(C1)&& theHandle) : Handle(C1)(theHandle) {} \
427 template <class T2, typename = typename std::enable_if <std::is_base_of <C1,T2>::value>::type> \
428 inline Handle_##C1(const opencascade::handle<T2>& theOther) : Handle(C1)(theOther) {} \
429 template <class T2, typename = typename std::enable_if <std::is_base_of <C1,T2>::value>::type> \
430 inline Handle_##C1(const T2* theOther) : Handle(C1)(theOther) {} \
431 template<typename T> inline Handle_##C1& operator=(T theOther) { Handle(C1)::operator=(theOther); return *this; } \
434 //! For other compilers, use simple typedef
435 #define DEFINE_STANDARD_HANDLECLASS(C1,C2,BC) class C1; typedef Handle(C1) Handle_##C1;
438 #define DEFINE_STANDARD_HANDLE(C1,C2) DEFINE_STANDARD_HANDLECLASS(C1,C2,Standard_Transient)
439 #define DEFINE_STANDARD_PHANDLE(C1,C2) DEFINE_STANDARD_HANDLECLASS(C1,C2,Standard_Persistent)