1// <experimental/any> -*- C++ -*- 2 3// Copyright (C) 2014-2015 Free Software Foundation, Inc. 4// 5// This file is part of the GNU ISO C++ Library. This library is free 6// software; you can redistribute it and/or modify it under the 7// terms of the GNU General Public License as published by the 8// Free Software Foundation; either version 3, or (at your option) 9// any later version. 10 11// This library is distributed in the hope that it will be useful, 12// but WITHOUT ANY WARRANTY; without even the implied warranty of 13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14// GNU General Public License for more details. 15 16// Under Section 7 of GPL version 3, you are granted additional 17// permissions described in the GCC Runtime Library Exception, version 18// 3.1, as published by the Free Software Foundation. 19 20// You should have received a copy of the GNU General Public License and 21// a copy of the GCC Runtime Library Exception along with this program; 22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23// <http://www.gnu.org/licenses/>. 24 25/** @file experimental/any 26 * This is a TS C++ Library header. 27 */ 28 29#ifndef _GLIBCXX_EXPERIMENTAL_ANY 30#define _GLIBCXX_EXPERIMENTAL_ANY 1 31 32#pragma GCC system_header 33 34#if __cplusplus <= 201103L 35# include <bits/c++14_warning.h> 36#else 37 38#include <typeinfo> 39#include <new> 40#include <utility> 41#include <type_traits> 42 43namespace std _GLIBCXX_VISIBILITY(default) 44{ 45namespace experimental 46{ 47inline namespace fundamentals_v1 48{ 49_GLIBCXX_BEGIN_NAMESPACE_VERSION 50 51 /** 52 * @defgroup any Type-safe container of any type 53 * @ingroup experimental 54 * 55 * A type-safe container for single values of value types, as 56 * described in n3804 "Any Library Proposal (Revision 3)". 57 * 58 * @{ 59 */ 60 61#define __cpp_lib_experimental_any 201411 62 63 /** 64 * @brief Exception class thrown by a failed @c any_cast 65 * @ingroup exceptions 66 */ 67 class bad_any_cast : public bad_cast 68 { 69 public: 70 virtual const char* what() const noexcept { return "bad any_cast"; } 71 }; 72 73 [[gnu::noreturn]] inline void __throw_bad_any_cast() 74 { 75#if __cpp_exceptions 76 throw bad_any_cast{}; 77#else 78 __builtin_abort(); 79#endif 80 } 81 82 /** 83 * @brief A type-safe container of any type. 84 * 85 * An @c any object's state is either empty or it stores a contained object 86 * of CopyConstructible type. 87 */ 88 class any 89 { 90 // Holds either pointer to a heap object or the contained object itself. 91 union _Storage 92 { 93 void* _M_ptr; 94 std::aligned_storage<sizeof(_M_ptr), sizeof(_M_ptr)>::type _M_buffer; 95 }; 96 97 template<typename _Tp, typename _Safe = is_trivially_copyable<_Tp>, 98 bool _Fits = (sizeof(_Tp) <= sizeof(_Storage))> 99 using _Internal = std::integral_constant<bool, _Safe::value && _Fits>; 100 101 template<typename _Tp> 102 struct _Manager_internal; // uses small-object optimization 103 104 template<typename _Tp> 105 struct _Manager_external; // creates contained object on the heap 106 107 template<typename _Tp> 108 using _Manager = conditional_t<_Internal<_Tp>::value, 109 _Manager_internal<_Tp>, 110 _Manager_external<_Tp>>; 111 112 template<typename _Tp, typename _Decayed = decay_t<_Tp>> 113 using _Decay = enable_if_t<!is_same<_Decayed, any>::value, _Decayed>; 114 115 public: 116 // construct/destruct 117 118 /// Default constructor, creates an empty object. 119 any() noexcept : _M_manager(nullptr) { } 120 121 /// Copy constructor, copies the state of @p __other 122 any(const any& __other) : _M_manager(__other._M_manager) 123 { 124 if (!__other.empty()) 125 { 126 _Arg __arg; 127 __arg._M_any = this; 128 _M_manager(_Op_clone, &__other, &__arg); 129 } 130 } 131 132 /** 133 * @brief Move constructor, transfer the state from @p __other 134 * 135 * @post @c __other.empty() (not guaranteed for other implementations) 136 */ 137 any(any&& __other) noexcept 138 : _M_manager(__other._M_manager), 139 _M_storage(__other._M_storage) 140 { __other._M_manager = nullptr; } 141 142 /// Construct with a copy of @p __value as the contained object. 143 template <typename _ValueType, typename _Tp = _Decay<_ValueType>, 144 typename _Mgr = _Manager<_Tp>> 145 any(_ValueType&& __value) 146 : _M_manager(&_Mgr::_S_manage), 147 _M_storage(_Mgr::_S_create(std::forward<_ValueType>(__value))) 148 { 149 static_assert(is_copy_constructible<_Tp>::value, 150 "The contained object must be CopyConstructible"); 151 } 152 153 /// Destructor, calls @c clear() 154 ~any() { clear(); } 155 156 // assignments 157 158 /// Copy the state of 159 any& operator=(const any& __rhs) 160 { 161 any(__rhs).swap(*this); 162 return *this; 163 } 164 165 /** 166 * @brief Move assignment operator 167 * 168 * @post @c __rhs.empty() (not guaranteed for other implementations) 169 */ 170 any& operator=(any&& __rhs) noexcept 171 { 172 any(std::move(__rhs)).swap(*this); 173 return *this; 174 } 175 176 /// Store a copy of @p __rhs as the contained object. 177 template<typename _ValueType> 178 any& operator=(_ValueType&& __rhs) 179 { 180 any(std::forward<_ValueType>(__rhs)).swap(*this); 181 return *this; 182 } 183 184 // modifiers 185 186 /// If not empty, destroy the contained object. 187 void clear() noexcept 188 { 189 if (!empty()) 190 { 191 _M_manager(_Op_destroy, this, nullptr); 192 _M_manager = nullptr; 193 } 194 } 195 196 /// Exchange state with another object. 197 void swap(any& __rhs) noexcept 198 { 199 std::swap(_M_manager, __rhs._M_manager); 200 std::swap(_M_storage, __rhs._M_storage); 201 } 202 203 // observers 204 205 /// Reports whether there is a contained object or not. 206 bool empty() const noexcept { return _M_manager == nullptr; } 207 208#if __cpp_rtti 209 /// The @c typeid of the contained object, or @c typeid(void) if empty. 210 const type_info& type() const noexcept 211 { 212 if (empty()) 213 return typeid(void); 214 _Arg __arg; 215 _M_manager(_Op_get_type_info, this, &__arg); 216 return *__arg._M_typeinfo; 217 } 218#endif 219 220 template<typename _Tp> 221 static constexpr bool __is_valid_cast() 222 { return __or_<is_reference<_Tp>, is_copy_constructible<_Tp>>::value; } 223 224 private: 225 enum _Op { _Op_access, _Op_get_type_info, _Op_clone, _Op_destroy }; 226 227 union _Arg 228 { 229 void* _M_obj; 230 const std::type_info* _M_typeinfo; 231 any* _M_any; 232 }; 233 234 void (*_M_manager)(_Op, const any*, _Arg*); 235 _Storage _M_storage; 236 237 template<typename _Tp> 238 friend void* __any_caster(const any* __any) 239 { 240 if (__any->_M_manager != &_Manager<decay_t<_Tp>>::_S_manage) 241 return nullptr; 242 _Arg __arg; 243 __any->_M_manager(_Op_access, __any, &__arg); 244 return __arg._M_obj; 245 } 246 247 // Manage in-place contained object. 248 template<typename _Tp> 249 struct _Manager_internal 250 { 251 static void 252 _S_manage(_Op __which, const any* __anyp, _Arg* __arg); 253 254 template<typename _Up> 255 static _Storage 256 _S_create(_Up&& __value) 257 { 258 _Storage __storage; 259 void* __addr = &__storage._M_buffer; 260 ::new (__addr) _Tp(std::forward<_Up>(__value)); 261 return __storage; 262 } 263 264 template<typename _Alloc, typename _Up> 265 static _Storage 266 _S_alloc(const _Alloc&, _Up&& __value) 267 { 268 return _S_create(std::forward<_Up>(__value)); 269 } 270 }; 271 272 // Manage external contained object. 273 template<typename _Tp> 274 struct _Manager_external 275 { 276 static void 277 _S_manage(_Op __which, const any* __anyp, _Arg* __arg); 278 279 template<typename _Up> 280 static _Storage 281 _S_create(_Up&& __value) 282 { 283 _Storage __storage; 284 __storage._M_ptr = new _Tp(std::forward<_Up>(__value)); 285 return __storage; 286 } 287 }; 288 }; 289 290 /// Exchange the states of two @c any objects. 291 inline void swap(any& __x, any& __y) noexcept { __x.swap(__y); } 292 293 /** 294 * @brief Access the contained object. 295 * 296 * @tparam _ValueType A const-reference or CopyConstructible type. 297 * @param __any The object to access. 298 * @return The contained object. 299 * @throw bad_any_cast If <code> 300 * __any.type() != typeid(remove_reference_t<_ValueType>) 301 * </code> 302 */ 303 template<typename _ValueType> 304 inline _ValueType any_cast(const any& __any) 305 { 306 static_assert(any::__is_valid_cast<_ValueType>(), 307 "Template argument must be a reference or CopyConstructible type"); 308 auto __p = any_cast<add_const_t<remove_reference_t<_ValueType>>>(&__any); 309 if (__p) 310 return *__p; 311 __throw_bad_any_cast(); 312 } 313 314 /** 315 * @brief Access the contained object. 316 * 317 * @tparam _ValueType A reference or CopyConstructible type. 318 * @param __any The object to access. 319 * @return The contained object. 320 * @throw bad_any_cast If <code> 321 * __any.type() != typeid(remove_reference_t<_ValueType>) 322 * </code> 323 * 324 * @{ 325 */ 326 template<typename _ValueType> 327 inline _ValueType any_cast(any& __any) 328 { 329 static_assert(any::__is_valid_cast<_ValueType>(), 330 "Template argument must be a reference or CopyConstructible type"); 331 auto __p = any_cast<remove_reference_t<_ValueType>>(&__any); 332 if (__p) 333 return *__p; 334 __throw_bad_any_cast(); 335 } 336 337 template<typename _ValueType> 338 inline _ValueType any_cast(any&& __any) 339 { 340 static_assert(any::__is_valid_cast<_ValueType>(), 341 "Template argument must be a reference or CopyConstructible type"); 342 auto __p = any_cast<remove_reference_t<_ValueType>>(&__any); 343 if (__p) 344 return *__p; 345 __throw_bad_any_cast(); 346 } 347 // @} 348 349 /** 350 * @brief Access the contained object. 351 * 352 * @tparam _ValueType The type of the contained object. 353 * @param __any A pointer to the object to access. 354 * @return The address of the contained object if <code> 355 * __any != nullptr && __any.type() == typeid(_ValueType) 356 * </code>, otherwise a null pointer. 357 * 358 * @{ 359 */ 360 template<typename _ValueType> 361 inline const _ValueType* any_cast(const any* __any) noexcept 362 { 363 if (__any) 364 return static_cast<_ValueType*>(__any_caster<_ValueType>(__any)); 365 return nullptr; 366 } 367 368 template<typename _ValueType> 369 inline _ValueType* any_cast(any* __any) noexcept 370 { 371 if (__any) 372 return static_cast<_ValueType*>(__any_caster<_ValueType>(__any)); 373 return nullptr; 374 } 375 // @} 376 377 template<typename _Tp> 378 void 379 any::_Manager_internal<_Tp>:: 380 _S_manage(_Op __which, const any* __any, _Arg* __arg) 381 { 382 // The contained object is in _M_storage._M_buffer 383 auto __ptr = reinterpret_cast<const _Tp*>(&__any->_M_storage._M_buffer); 384 switch (__which) 385 { 386 case _Op_access: 387 __arg->_M_obj = const_cast<_Tp*>(__ptr); 388 break; 389 case _Op_get_type_info: 390#if __cpp_rtti 391 __arg->_M_typeinfo = &typeid(_Tp); 392#endif 393 break; 394 case _Op_clone: 395 ::new(&__arg->_M_any->_M_storage._M_buffer) _Tp(*__ptr); 396 break; 397 case _Op_destroy: 398 __ptr->~_Tp(); 399 break; 400 } 401 } 402 403 template<typename _Tp> 404 void 405 any::_Manager_external<_Tp>:: 406 _S_manage(_Op __which, const any* __any, _Arg* __arg) 407 { 408 // The contained object is *_M_storage._M_ptr 409 auto __ptr = static_cast<const _Tp*>(__any->_M_storage._M_ptr); 410 switch (__which) 411 { 412 case _Op_access: 413 __arg->_M_obj = const_cast<_Tp*>(__ptr); 414 break; 415 case _Op_get_type_info: 416#if __cpp_rtti 417 __arg->_M_typeinfo = &typeid(_Tp); 418#endif 419 break; 420 case _Op_clone: 421 __arg->_M_any->_M_storage._M_ptr = new _Tp(*__ptr); 422 break; 423 case _Op_destroy: 424 delete __ptr; 425 break; 426 } 427 } 428 429 // @} group any 430_GLIBCXX_END_NAMESPACE_VERSION 431} // namespace fundamentals_v1 432} // namespace experimental 433} // namespace std 434 435#endif // C++14 436 437#endif // _GLIBCXX_EXPERIMENTAL_ANY 438