libstdc++
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00001 // Implementation of std::function -*- C++ -*- 00002 00003 // Copyright (C) 2004-2019 Free Software Foundation, Inc. 00004 // 00005 // This file is part of the GNU ISO C++ Library. This library is free 00006 // software; you can redistribute it and/or modify it under the 00007 // terms of the GNU General Public License as published by the 00008 // Free Software Foundation; either version 3, or (at your option) 00009 // any later version. 00010 00011 // This library is distributed in the hope that it will be useful, 00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 // GNU General Public License for more details. 00015 00016 // Under Section 7 of GPL version 3, you are granted additional 00017 // permissions described in the GCC Runtime Library Exception, version 00018 // 3.1, as published by the Free Software Foundation. 00019 00020 // You should have received a copy of the GNU General Public License and 00021 // a copy of the GCC Runtime Library Exception along with this program; 00022 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00023 // <http://www.gnu.org/licenses/>. 00024 00025 /** @file include/bits/std_function.h 00026 * This is an internal header file, included by other library headers. 00027 * Do not attempt to use it directly. @headername{functional} 00028 */ 00029 00030 #ifndef _GLIBCXX_STD_FUNCTION_H 00031 #define _GLIBCXX_STD_FUNCTION_H 1 00032 00033 #pragma GCC system_header 00034 00035 #if __cplusplus < 201103L 00036 # include <bits/c++0x_warning.h> 00037 #else 00038 00039 #if __cpp_rtti 00040 # include <typeinfo> 00041 #endif 00042 #include <bits/stl_function.h> 00043 #include <bits/invoke.h> 00044 #include <bits/refwrap.h> 00045 #include <bits/functexcept.h> 00046 00047 namespace std _GLIBCXX_VISIBILITY(default) 00048 { 00049 _GLIBCXX_BEGIN_NAMESPACE_VERSION 00050 00051 /** 00052 * @brief Exception class thrown when class template function's 00053 * operator() is called with an empty target. 00054 * @ingroup exceptions 00055 */ 00056 class bad_function_call : public std::exception 00057 { 00058 public: 00059 virtual ~bad_function_call() noexcept; 00060 00061 const char* what() const noexcept; 00062 }; 00063 00064 /** 00065 * Trait identifying "location-invariant" types, meaning that the 00066 * address of the object (or any of its members) will not escape. 00067 * Trivially copyable types are location-invariant and users can 00068 * specialize this trait for other types. 00069 */ 00070 template<typename _Tp> 00071 struct __is_location_invariant 00072 : is_trivially_copyable<_Tp>::type 00073 { }; 00074 00075 class _Undefined_class; 00076 00077 union _Nocopy_types 00078 { 00079 void* _M_object; 00080 const void* _M_const_object; 00081 void (*_M_function_pointer)(); 00082 void (_Undefined_class::*_M_member_pointer)(); 00083 }; 00084 00085 union [[gnu::may_alias]] _Any_data 00086 { 00087 void* _M_access() { return &_M_pod_data[0]; } 00088 const void* _M_access() const { return &_M_pod_data[0]; } 00089 00090 template<typename _Tp> 00091 _Tp& 00092 _M_access() 00093 { return *static_cast<_Tp*>(_M_access()); } 00094 00095 template<typename _Tp> 00096 const _Tp& 00097 _M_access() const 00098 { return *static_cast<const _Tp*>(_M_access()); } 00099 00100 _Nocopy_types _M_unused; 00101 char _M_pod_data[sizeof(_Nocopy_types)]; 00102 }; 00103 00104 enum _Manager_operation 00105 { 00106 __get_type_info, 00107 __get_functor_ptr, 00108 __clone_functor, 00109 __destroy_functor 00110 }; 00111 00112 // Simple type wrapper that helps avoid annoying const problems 00113 // when casting between void pointers and pointers-to-pointers. 00114 template<typename _Tp> 00115 struct _Simple_type_wrapper 00116 { 00117 _Simple_type_wrapper(_Tp __value) : __value(__value) { } 00118 00119 _Tp __value; 00120 }; 00121 00122 template<typename _Tp> 00123 struct __is_location_invariant<_Simple_type_wrapper<_Tp> > 00124 : __is_location_invariant<_Tp> 00125 { }; 00126 00127 template<typename _Signature> 00128 class function; 00129 00130 /// Base class of all polymorphic function object wrappers. 00131 class _Function_base 00132 { 00133 public: 00134 static const size_t _M_max_size = sizeof(_Nocopy_types); 00135 static const size_t _M_max_align = __alignof__(_Nocopy_types); 00136 00137 template<typename _Functor> 00138 class _Base_manager 00139 { 00140 protected: 00141 static const bool __stored_locally = 00142 (__is_location_invariant<_Functor>::value 00143 && sizeof(_Functor) <= _M_max_size 00144 && __alignof__(_Functor) <= _M_max_align 00145 && (_M_max_align % __alignof__(_Functor) == 0)); 00146 00147 typedef integral_constant<bool, __stored_locally> _Local_storage; 00148 00149 // Retrieve a pointer to the function object 00150 static _Functor* 00151 _M_get_pointer(const _Any_data& __source) 00152 { 00153 if _GLIBCXX17_CONSTEXPR (__stored_locally) 00154 { 00155 const _Functor& __f = __source._M_access<_Functor>(); 00156 return const_cast<_Functor*>(std::__addressof(__f)); 00157 } 00158 else // have stored a pointer 00159 return __source._M_access<_Functor*>(); 00160 } 00161 00162 // Clone a location-invariant function object that fits within 00163 // an _Any_data structure. 00164 static void 00165 _M_clone(_Any_data& __dest, const _Any_data& __source, true_type) 00166 { 00167 ::new (__dest._M_access()) _Functor(__source._M_access<_Functor>()); 00168 } 00169 00170 // Clone a function object that is not location-invariant or 00171 // that cannot fit into an _Any_data structure. 00172 static void 00173 _M_clone(_Any_data& __dest, const _Any_data& __source, false_type) 00174 { 00175 __dest._M_access<_Functor*>() = 00176 new _Functor(*__source._M_access<const _Functor*>()); 00177 } 00178 00179 // Destroying a location-invariant object may still require 00180 // destruction. 00181 static void 00182 _M_destroy(_Any_data& __victim, true_type) 00183 { 00184 __victim._M_access<_Functor>().~_Functor(); 00185 } 00186 00187 // Destroying an object located on the heap. 00188 static void 00189 _M_destroy(_Any_data& __victim, false_type) 00190 { 00191 delete __victim._M_access<_Functor*>(); 00192 } 00193 00194 public: 00195 static bool 00196 _M_manager(_Any_data& __dest, const _Any_data& __source, 00197 _Manager_operation __op) 00198 { 00199 switch (__op) 00200 { 00201 #if __cpp_rtti 00202 case __get_type_info: 00203 __dest._M_access<const type_info*>() = &typeid(_Functor); 00204 break; 00205 #endif 00206 case __get_functor_ptr: 00207 __dest._M_access<_Functor*>() = _M_get_pointer(__source); 00208 break; 00209 00210 case __clone_functor: 00211 _M_clone(__dest, __source, _Local_storage()); 00212 break; 00213 00214 case __destroy_functor: 00215 _M_destroy(__dest, _Local_storage()); 00216 break; 00217 } 00218 return false; 00219 } 00220 00221 static void 00222 _M_init_functor(_Any_data& __functor, _Functor&& __f) 00223 { _M_init_functor(__functor, std::move(__f), _Local_storage()); } 00224 00225 template<typename _Signature> 00226 static bool 00227 _M_not_empty_function(const function<_Signature>& __f) 00228 { return static_cast<bool>(__f); } 00229 00230 template<typename _Tp> 00231 static bool 00232 _M_not_empty_function(_Tp* __fp) 00233 { return __fp != nullptr; } 00234 00235 template<typename _Class, typename _Tp> 00236 static bool 00237 _M_not_empty_function(_Tp _Class::* __mp) 00238 { return __mp != nullptr; } 00239 00240 template<typename _Tp> 00241 static bool 00242 _M_not_empty_function(const _Tp&) 00243 { return true; } 00244 00245 private: 00246 static void 00247 _M_init_functor(_Any_data& __functor, _Functor&& __f, true_type) 00248 { ::new (__functor._M_access()) _Functor(std::move(__f)); } 00249 00250 static void 00251 _M_init_functor(_Any_data& __functor, _Functor&& __f, false_type) 00252 { __functor._M_access<_Functor*>() = new _Functor(std::move(__f)); } 00253 }; 00254 00255 _Function_base() : _M_manager(nullptr) { } 00256 00257 ~_Function_base() 00258 { 00259 if (_M_manager) 00260 _M_manager(_M_functor, _M_functor, __destroy_functor); 00261 } 00262 00263 bool _M_empty() const { return !_M_manager; } 00264 00265 typedef bool (*_Manager_type)(_Any_data&, const _Any_data&, 00266 _Manager_operation); 00267 00268 _Any_data _M_functor; 00269 _Manager_type _M_manager; 00270 }; 00271 00272 template<typename _Signature, typename _Functor> 00273 class _Function_handler; 00274 00275 template<typename _Res, typename _Functor, typename... _ArgTypes> 00276 class _Function_handler<_Res(_ArgTypes...), _Functor> 00277 : public _Function_base::_Base_manager<_Functor> 00278 { 00279 typedef _Function_base::_Base_manager<_Functor> _Base; 00280 00281 public: 00282 static _Res 00283 _M_invoke(const _Any_data& __functor, _ArgTypes&&... __args) 00284 { 00285 return (*_Base::_M_get_pointer(__functor))( 00286 std::forward<_ArgTypes>(__args)...); 00287 } 00288 }; 00289 00290 template<typename _Functor, typename... _ArgTypes> 00291 class _Function_handler<void(_ArgTypes...), _Functor> 00292 : public _Function_base::_Base_manager<_Functor> 00293 { 00294 typedef _Function_base::_Base_manager<_Functor> _Base; 00295 00296 public: 00297 static void 00298 _M_invoke(const _Any_data& __functor, _ArgTypes&&... __args) 00299 { 00300 (*_Base::_M_get_pointer(__functor))( 00301 std::forward<_ArgTypes>(__args)...); 00302 } 00303 }; 00304 00305 template<typename _Class, typename _Member, typename _Res, 00306 typename... _ArgTypes> 00307 class _Function_handler<_Res(_ArgTypes...), _Member _Class::*> 00308 : public _Function_handler<void(_ArgTypes...), _Member _Class::*> 00309 { 00310 typedef _Function_handler<void(_ArgTypes...), _Member _Class::*> 00311 _Base; 00312 00313 public: 00314 static _Res 00315 _M_invoke(const _Any_data& __functor, _ArgTypes&&... __args) 00316 { 00317 return std::__invoke(_Base::_M_get_pointer(__functor)->__value, 00318 std::forward<_ArgTypes>(__args)...); 00319 } 00320 }; 00321 00322 template<typename _Class, typename _Member, typename... _ArgTypes> 00323 class _Function_handler<void(_ArgTypes...), _Member _Class::*> 00324 : public _Function_base::_Base_manager< 00325 _Simple_type_wrapper< _Member _Class::* > > 00326 { 00327 typedef _Member _Class::* _Functor; 00328 typedef _Simple_type_wrapper<_Functor> _Wrapper; 00329 typedef _Function_base::_Base_manager<_Wrapper> _Base; 00330 00331 public: 00332 static bool 00333 _M_manager(_Any_data& __dest, const _Any_data& __source, 00334 _Manager_operation __op) 00335 { 00336 switch (__op) 00337 { 00338 #if __cpp_rtti 00339 case __get_type_info: 00340 __dest._M_access<const type_info*>() = &typeid(_Functor); 00341 break; 00342 #endif 00343 case __get_functor_ptr: 00344 __dest._M_access<_Functor*>() = 00345 &_Base::_M_get_pointer(__source)->__value; 00346 break; 00347 00348 default: 00349 _Base::_M_manager(__dest, __source, __op); 00350 } 00351 return false; 00352 } 00353 00354 static void 00355 _M_invoke(const _Any_data& __functor, _ArgTypes&&... __args) 00356 { 00357 std::__invoke(_Base::_M_get_pointer(__functor)->__value, 00358 std::forward<_ArgTypes>(__args)...); 00359 } 00360 }; 00361 00362 template<typename _From, typename _To> 00363 using __check_func_return_type 00364 = __or_<is_void<_To>, is_same<_From, _To>, is_convertible<_From, _To>>; 00365 00366 /** 00367 * @brief Primary class template for std::function. 00368 * @ingroup functors 00369 * 00370 * Polymorphic function wrapper. 00371 */ 00372 template<typename _Res, typename... _ArgTypes> 00373 class function<_Res(_ArgTypes...)> 00374 : public _Maybe_unary_or_binary_function<_Res, _ArgTypes...>, 00375 private _Function_base 00376 { 00377 template<typename _Func, 00378 typename _Res2 = typename result_of<_Func&(_ArgTypes...)>::type> 00379 struct _Callable : __check_func_return_type<_Res2, _Res> { }; 00380 00381 // Used so the return type convertibility checks aren't done when 00382 // performing overload resolution for copy construction/assignment. 00383 template<typename _Tp> 00384 struct _Callable<function, _Tp> : false_type { }; 00385 00386 template<typename _Cond, typename _Tp> 00387 using _Requires = typename enable_if<_Cond::value, _Tp>::type; 00388 00389 public: 00390 typedef _Res result_type; 00391 00392 // [3.7.2.1] construct/copy/destroy 00393 00394 /** 00395 * @brief Default construct creates an empty function call wrapper. 00396 * @post @c !(bool)*this 00397 */ 00398 function() noexcept 00399 : _Function_base() { } 00400 00401 /** 00402 * @brief Creates an empty function call wrapper. 00403 * @post @c !(bool)*this 00404 */ 00405 function(nullptr_t) noexcept 00406 : _Function_base() { } 00407 00408 /** 00409 * @brief %Function copy constructor. 00410 * @param __x A %function object with identical call signature. 00411 * @post @c bool(*this) == bool(__x) 00412 * 00413 * The newly-created %function contains a copy of the target of @a 00414 * __x (if it has one). 00415 */ 00416 function(const function& __x); 00417 00418 /** 00419 * @brief %Function move constructor. 00420 * @param __x A %function object rvalue with identical call signature. 00421 * 00422 * The newly-created %function contains the target of @a __x 00423 * (if it has one). 00424 */ 00425 function(function&& __x) noexcept : _Function_base() 00426 { 00427 __x.swap(*this); 00428 } 00429 00430 /** 00431 * @brief Builds a %function that targets a copy of the incoming 00432 * function object. 00433 * @param __f A %function object that is callable with parameters of 00434 * type @c T1, @c T2, ..., @c TN and returns a value convertible 00435 * to @c Res. 00436 * 00437 * The newly-created %function object will target a copy of 00438 * @a __f. If @a __f is @c reference_wrapper<F>, then this function 00439 * object will contain a reference to the function object @c 00440 * __f.get(). If @a __f is a NULL function pointer or NULL 00441 * pointer-to-member, the newly-created object will be empty. 00442 * 00443 * If @a __f is a non-NULL function pointer or an object of type @c 00444 * reference_wrapper<F>, this function will not throw. 00445 */ 00446 template<typename _Functor, 00447 typename = _Requires<__not_<is_same<_Functor, function>>, void>, 00448 typename = _Requires<_Callable<_Functor>, void>> 00449 function(_Functor); 00450 00451 /** 00452 * @brief %Function assignment operator. 00453 * @param __x A %function with identical call signature. 00454 * @post @c (bool)*this == (bool)x 00455 * @returns @c *this 00456 * 00457 * The target of @a __x is copied to @c *this. If @a __x has no 00458 * target, then @c *this will be empty. 00459 * 00460 * If @a __x targets a function pointer or a reference to a function 00461 * object, then this operation will not throw an %exception. 00462 */ 00463 function& 00464 operator=(const function& __x) 00465 { 00466 function(__x).swap(*this); 00467 return *this; 00468 } 00469 00470 /** 00471 * @brief %Function move-assignment operator. 00472 * @param __x A %function rvalue with identical call signature. 00473 * @returns @c *this 00474 * 00475 * The target of @a __x is moved to @c *this. If @a __x has no 00476 * target, then @c *this will be empty. 00477 * 00478 * If @a __x targets a function pointer or a reference to a function 00479 * object, then this operation will not throw an %exception. 00480 */ 00481 function& 00482 operator=(function&& __x) noexcept 00483 { 00484 function(std::move(__x)).swap(*this); 00485 return *this; 00486 } 00487 00488 /** 00489 * @brief %Function assignment to zero. 00490 * @post @c !(bool)*this 00491 * @returns @c *this 00492 * 00493 * The target of @c *this is deallocated, leaving it empty. 00494 */ 00495 function& 00496 operator=(nullptr_t) noexcept 00497 { 00498 if (_M_manager) 00499 { 00500 _M_manager(_M_functor, _M_functor, __destroy_functor); 00501 _M_manager = nullptr; 00502 _M_invoker = nullptr; 00503 } 00504 return *this; 00505 } 00506 00507 /** 00508 * @brief %Function assignment to a new target. 00509 * @param __f A %function object that is callable with parameters of 00510 * type @c T1, @c T2, ..., @c TN and returns a value convertible 00511 * to @c Res. 00512 * @return @c *this 00513 * 00514 * This %function object wrapper will target a copy of @a 00515 * __f. If @a __f is @c reference_wrapper<F>, then this function 00516 * object will contain a reference to the function object @c 00517 * __f.get(). If @a __f is a NULL function pointer or NULL 00518 * pointer-to-member, @c this object will be empty. 00519 * 00520 * If @a __f is a non-NULL function pointer or an object of type @c 00521 * reference_wrapper<F>, this function will not throw. 00522 */ 00523 template<typename _Functor> 00524 _Requires<_Callable<typename decay<_Functor>::type>, function&> 00525 operator=(_Functor&& __f) 00526 { 00527 function(std::forward<_Functor>(__f)).swap(*this); 00528 return *this; 00529 } 00530 00531 /// @overload 00532 template<typename _Functor> 00533 function& 00534 operator=(reference_wrapper<_Functor> __f) noexcept 00535 { 00536 function(__f).swap(*this); 00537 return *this; 00538 } 00539 00540 // [3.7.2.2] function modifiers 00541 00542 /** 00543 * @brief Swap the targets of two %function objects. 00544 * @param __x A %function with identical call signature. 00545 * 00546 * Swap the targets of @c this function object and @a __f. This 00547 * function will not throw an %exception. 00548 */ 00549 void swap(function& __x) noexcept 00550 { 00551 std::swap(_M_functor, __x._M_functor); 00552 std::swap(_M_manager, __x._M_manager); 00553 std::swap(_M_invoker, __x._M_invoker); 00554 } 00555 00556 // [3.7.2.3] function capacity 00557 00558 /** 00559 * @brief Determine if the %function wrapper has a target. 00560 * 00561 * @return @c true when this %function object contains a target, 00562 * or @c false when it is empty. 00563 * 00564 * This function will not throw an %exception. 00565 */ 00566 explicit operator bool() const noexcept 00567 { return !_M_empty(); } 00568 00569 // [3.7.2.4] function invocation 00570 00571 /** 00572 * @brief Invokes the function targeted by @c *this. 00573 * @returns the result of the target. 00574 * @throws bad_function_call when @c !(bool)*this 00575 * 00576 * The function call operator invokes the target function object 00577 * stored by @c this. 00578 */ 00579 _Res operator()(_ArgTypes... __args) const; 00580 00581 #if __cpp_rtti 00582 // [3.7.2.5] function target access 00583 /** 00584 * @brief Determine the type of the target of this function object 00585 * wrapper. 00586 * 00587 * @returns the type identifier of the target function object, or 00588 * @c typeid(void) if @c !(bool)*this. 00589 * 00590 * This function will not throw an %exception. 00591 */ 00592 const type_info& target_type() const noexcept; 00593 00594 /** 00595 * @brief Access the stored target function object. 00596 * 00597 * @return Returns a pointer to the stored target function object, 00598 * if @c typeid(_Functor).equals(target_type()); otherwise, a NULL 00599 * pointer. 00600 * 00601 * This function does not throw exceptions. 00602 * 00603 * @{ 00604 */ 00605 template<typename _Functor> _Functor* target() noexcept; 00606 00607 template<typename _Functor> const _Functor* target() const noexcept; 00608 // @} 00609 #endif 00610 00611 private: 00612 using _Invoker_type = _Res (*)(const _Any_data&, _ArgTypes&&...); 00613 _Invoker_type _M_invoker; 00614 }; 00615 00616 #if __cpp_deduction_guides >= 201606 00617 template<typename> 00618 struct __function_guide_helper 00619 { }; 00620 00621 template<typename _Res, typename _Tp, bool _Nx, typename... _Args> 00622 struct __function_guide_helper< 00623 _Res (_Tp::*) (_Args...) noexcept(_Nx) 00624 > 00625 { using type = _Res(_Args...); }; 00626 00627 template<typename _Res, typename _Tp, bool _Nx, typename... _Args> 00628 struct __function_guide_helper< 00629 _Res (_Tp::*) (_Args...) & noexcept(_Nx) 00630 > 00631 { using type = _Res(_Args...); }; 00632 00633 template<typename _Res, typename _Tp, bool _Nx, typename... _Args> 00634 struct __function_guide_helper< 00635 _Res (_Tp::*) (_Args...) const noexcept(_Nx) 00636 > 00637 { using type = _Res(_Args...); }; 00638 00639 template<typename _Res, typename _Tp, bool _Nx, typename... _Args> 00640 struct __function_guide_helper< 00641 _Res (_Tp::*) (_Args...) const & noexcept(_Nx) 00642 > 00643 { using type = _Res(_Args...); }; 00644 00645 template<typename _Res, typename... _ArgTypes> 00646 function(_Res(*)(_ArgTypes...)) -> function<_Res(_ArgTypes...)>; 00647 00648 template<typename _Functor, typename _Signature = typename 00649 __function_guide_helper<decltype(&_Functor::operator())>::type> 00650 function(_Functor) -> function<_Signature>; 00651 #endif 00652 00653 // Out-of-line member definitions. 00654 template<typename _Res, typename... _ArgTypes> 00655 function<_Res(_ArgTypes...)>:: 00656 function(const function& __x) 00657 : _Function_base() 00658 { 00659 if (static_cast<bool>(__x)) 00660 { 00661 __x._M_manager(_M_functor, __x._M_functor, __clone_functor); 00662 _M_invoker = __x._M_invoker; 00663 _M_manager = __x._M_manager; 00664 } 00665 } 00666 00667 template<typename _Res, typename... _ArgTypes> 00668 template<typename _Functor, typename, typename> 00669 function<_Res(_ArgTypes...)>:: 00670 function(_Functor __f) 00671 : _Function_base() 00672 { 00673 typedef _Function_handler<_Res(_ArgTypes...), _Functor> _My_handler; 00674 00675 if (_My_handler::_M_not_empty_function(__f)) 00676 { 00677 _My_handler::_M_init_functor(_M_functor, std::move(__f)); 00678 _M_invoker = &_My_handler::_M_invoke; 00679 _M_manager = &_My_handler::_M_manager; 00680 } 00681 } 00682 00683 template<typename _Res, typename... _ArgTypes> 00684 _Res 00685 function<_Res(_ArgTypes...)>:: 00686 operator()(_ArgTypes... __args) const 00687 { 00688 if (_M_empty()) 00689 __throw_bad_function_call(); 00690 return _M_invoker(_M_functor, std::forward<_ArgTypes>(__args)...); 00691 } 00692 00693 #if __cpp_rtti 00694 template<typename _Res, typename... _ArgTypes> 00695 const type_info& 00696 function<_Res(_ArgTypes...)>:: 00697 target_type() const noexcept 00698 { 00699 if (_M_manager) 00700 { 00701 _Any_data __typeinfo_result; 00702 _M_manager(__typeinfo_result, _M_functor, __get_type_info); 00703 return *__typeinfo_result._M_access<const type_info*>(); 00704 } 00705 else 00706 return typeid(void); 00707 } 00708 00709 template<typename _Res, typename... _ArgTypes> 00710 template<typename _Functor> 00711 _Functor* 00712 function<_Res(_ArgTypes...)>:: 00713 target() noexcept 00714 { 00715 const function* __const_this = this; 00716 const _Functor* __func = __const_this->template target<_Functor>(); 00717 return const_cast<_Functor*>(__func); 00718 } 00719 00720 template<typename _Res, typename... _ArgTypes> 00721 template<typename _Functor> 00722 const _Functor* 00723 function<_Res(_ArgTypes...)>:: 00724 target() const noexcept 00725 { 00726 if (typeid(_Functor) == target_type() && _M_manager) 00727 { 00728 _Any_data __ptr; 00729 _M_manager(__ptr, _M_functor, __get_functor_ptr); 00730 return __ptr._M_access<const _Functor*>(); 00731 } 00732 else 00733 return nullptr; 00734 } 00735 #endif 00736 00737 // [20.7.15.2.6] null pointer comparisons 00738 00739 /** 00740 * @brief Compares a polymorphic function object wrapper against 0 00741 * (the NULL pointer). 00742 * @returns @c true if the wrapper has no target, @c false otherwise 00743 * 00744 * This function will not throw an %exception. 00745 */ 00746 template<typename _Res, typename... _Args> 00747 inline bool 00748 operator==(const function<_Res(_Args...)>& __f, nullptr_t) noexcept 00749 { return !static_cast<bool>(__f); } 00750 00751 /// @overload 00752 template<typename _Res, typename... _Args> 00753 inline bool 00754 operator==(nullptr_t, const function<_Res(_Args...)>& __f) noexcept 00755 { return !static_cast<bool>(__f); } 00756 00757 /** 00758 * @brief Compares a polymorphic function object wrapper against 0 00759 * (the NULL pointer). 00760 * @returns @c false if the wrapper has no target, @c true otherwise 00761 * 00762 * This function will not throw an %exception. 00763 */ 00764 template<typename _Res, typename... _Args> 00765 inline bool 00766 operator!=(const function<_Res(_Args...)>& __f, nullptr_t) noexcept 00767 { return static_cast<bool>(__f); } 00768 00769 /// @overload 00770 template<typename _Res, typename... _Args> 00771 inline bool 00772 operator!=(nullptr_t, const function<_Res(_Args...)>& __f) noexcept 00773 { return static_cast<bool>(__f); } 00774 00775 00776 // [20.7.15.2.7] specialized algorithms 00777 00778 /** 00779 * @brief Swap the targets of two polymorphic function object wrappers. 00780 * 00781 * This function will not throw an %exception. 00782 */ 00783 // _GLIBCXX_RESOLVE_LIB_DEFECTS 00784 // 2062. Effect contradictions w/o no-throw guarantee of std::function swaps 00785 template<typename _Res, typename... _Args> 00786 inline void 00787 swap(function<_Res(_Args...)>& __x, function<_Res(_Args...)>& __y) noexcept 00788 { __x.swap(__y); } 00789 00790 #if __cplusplus >= 201703L 00791 namespace __detail::__variant 00792 { 00793 template<typename> struct _Never_valueless_alt; // see <variant> 00794 00795 // Provide the strong exception-safety guarantee when emplacing a 00796 // function into a variant. 00797 template<typename _Signature> 00798 struct _Never_valueless_alt<std::function<_Signature>> 00799 : std::true_type 00800 { }; 00801 } // namespace __detail::__variant 00802 #endif // C++17 00803 00804 _GLIBCXX_END_NAMESPACE_VERSION 00805 } // namespace std 00806 00807 #endif // C++11 00808 #endif // _GLIBCXX_STD_FUNCTION_H