Where Online Learning is simpler!
The C and C++ Include Header Files
cat -n /usr/include/c++/15/bits/stl_stack.h
1 // Stack implementation -*- C++ -*- 2 3 // Copyright (C) 2001-2025 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 /* 26 * 27 * Copyright (c) 1994 28 * Hewlett-Packard Company 29 * 30 * Permission to use, copy, modify, distribute and sell this software 31 * and its documentation for any purpose is hereby granted without fee, 32 * provided that the above copyright notice appear in all copies and 33 * that both that copyright notice and this permission notice appear 34 * in supporting documentation. Hewlett-Packard Company makes no 35 * representations about the suitability of this software for any 36 * purpose. It is provided "as is" without express or implied warranty. 37 * 38 * 39 * Copyright (c) 1996,1997 40 * Silicon Graphics Computer Systems, Inc. 41 * 42 * Permission to use, copy, modify, distribute and sell this software 43 * and its documentation for any purpose is hereby granted without fee, 44 * provided that the above copyright notice appear in all copies and 45 * that both that copyright notice and this permission notice appear 46 * in supporting documentation. Silicon Graphics makes no 47 * representations about the suitability of this software for any 48 * purpose. It is provided "as is" without express or implied warranty. 49 */ 50 51 /** @file bits/stl_stack.h 52 * This is an internal header file, included by other library headers. 53 * Do not attempt to use it directly. @headername{stack} 54 */ 55 56 #ifndef _STL_STACK_H 57 #define _STL_STACK_H 1 58 59 #include <bits/concept_check.h> 60 #include <debug/debug.h> 61 #if __cplusplus >= 201103L 62 # include <bits/uses_allocator.h> 63 #endif 64 #if __glibcxx_containers_ranges // C++ >= 23 65 # include <ranges> // ranges::to 66 # include <bits/ranges_algobase.h> // ranges::copy 67 #endif 68 69 namespace std _GLIBCXX_VISIBILITY(default) 70 { 71 _GLIBCXX_BEGIN_NAMESPACE_VERSION 72 73 #if __glibcxx_format_ranges 74 template<typename, typename> class formatter; 75 #endif 76 77 /** 78 * @brief A standard container giving FILO behavior. 79 * 80 * @ingroup sequences 81 * 82 * @tparam _Tp Type of element. 83 * @tparam _Sequence Type of underlying sequence, defaults to deque<_Tp>. 84 * 85 * Meets many of the requirements of a 86 * <a href="tables.html#65">container</a>, 87 * but does not define anything to do with iterators. Very few of the 88 * other standard container interfaces are defined. 89 * 90 * This is not a true container, but an @e adaptor. It holds 91 * another container, and provides a wrapper interface to that 92 * container. The wrapper is what enforces strict 93 * first-in-last-out %stack behavior. 94 * 95 * The second template parameter defines the type of the underlying 96 * sequence/container. It defaults to std::deque, but it can be 97 * any type that supports @c back, @c push_back, and @c pop_back, 98 * such as std::list, std::vector, or an appropriate user-defined 99 * type. 100 * 101 * Members not found in @a normal containers are @c container_type, 102 * which is a typedef for the second Sequence parameter, and @c 103 * push, @c pop, and @c top, which are standard %stack/FILO 104 * operations. 105 */ 106 template<typename _Tp, typename _Sequence = deque<_Tp> > 107 class stack 108 { 109 #ifdef _GLIBCXX_CONCEPT_CHECKS 110 // concept requirements 111 typedef typename _Sequence::value_type _Sequence_value_type; 112 # if __cplusplus < 201103L 113 __glibcxx_class_requires(_Tp, _SGIAssignableConcept) 114 __glibcxx_class_requires(_Sequence, _BackInsertionSequenceConcept) 115 # endif 116 __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept) 117 #endif 118 119 template<typename _Tp1, typename _Seq1> 120 friend bool 121 operator==(const stack<_Tp1, _Seq1>&, const stack<_Tp1, _Seq1>&); 122 123 template<typename _Tp1, typename _Seq1> 124 friend bool 125 operator<(const stack<_Tp1, _Seq1>&, const stack<_Tp1, _Seq1>&); 126 127 #if __cpp_lib_three_way_comparison 128 template<typename _Tp1, three_way_comparable _Seq1> 129 friend compare_three_way_result_t<_Seq1> 130 operator<=>(const stack<_Tp1, _Seq1>&, const stack<_Tp1, _Seq1>&); 131 #endif 132 133 #if __cplusplus >= 201103L 134 template<typename _Alloc> 135 using _Uses = typename 136 enable_if<uses_allocator<_Sequence, _Alloc>::value>::type; 137 138 #if __cplusplus >= 201703L 139 // _GLIBCXX_RESOLVE_LIB_DEFECTS 140 // 2566. Requirements on the first template parameter of container 141 // adaptors 142 static_assert(is_same<_Tp, typename _Sequence::value_type>::value, 143 "value_type must be the same as the underlying container"); 144 #endif // C++17 145 #endif // C++11 146 147 public: 148 typedef typename _Sequence::value_type value_type; 149 typedef typename _Sequence::reference reference; 150 typedef typename _Sequence::const_reference const_reference; 151 typedef typename _Sequence::size_type size_type; 152 typedef _Sequence container_type; 153 154 protected: 155 // See queue::c for notes on this name. 156 _Sequence c; 157 158 public: 159 // XXX removed old def ctor, added def arg to this one to match 14882 160 /** 161 * @brief Default constructor creates no elements. 162 */ 163 #if __cplusplus < 201103L 164 explicit 165 stack(const _Sequence& __c = _Sequence()) 166 : c(__c) { } 167 #else 168 template<typename _Seq = _Sequence, typename _Requires = typename 169 enable_if<is_default_constructible<_Seq>::value>::type> 170 stack() 171 : c() { } 172 173 explicit 174 stack(const _Sequence& __c) 175 : c(__c) { } 176 177 explicit 178 stack(_Sequence&& __c) 179 : c(std::move(__c)) { } 180 181 #ifdef __glibcxx_adaptor_iterator_pair_constructor // C++ >= 23 && HOSTED 182 template<typename _InputIterator, 183 typename = _RequireInputIter<_InputIterator>> 184 stack(_InputIterator __first, _InputIterator __last) 185 : c(__first, __last) { } 186 #endif 187 188 #if __glibcxx_containers_ranges // C++ >= 23 189 /** 190 * @brief Construct a stack from a range. 191 * @since C++23 192 */ 193 template<__detail::__container_compatible_range<_Tp> _Rg> 194 stack(from_range_t, _Rg&& __rg) 195 : c(ranges::to<_Sequence>(std::forward<_Rg>(__rg))) 196 { } 197 198 /** 199 * @brief Construct a stack from a range. 200 * @since C++23 201 */ 202 template<__detail::__container_compatible_range<_Tp> _Rg, 203 typename _Alloc> 204 stack(from_range_t, _Rg&& __rg, const _Alloc& __a) 205 : c(ranges::to<_Sequence>(std::forward<_Rg>(__rg), __a)) 206 { } 207 #endif 208 209 template<typename _Alloc, typename _Requires = _Uses<_Alloc>> 210 explicit 211 stack(const _Alloc& __a) 212 : c(__a) { } 213 214 template<typename _Alloc, typename _Requires = _Uses<_Alloc>> 215 stack(const _Sequence& __c, const _Alloc& __a) 216 : c(__c, __a) { } 217 218 template<typename _Alloc, typename _Requires = _Uses<_Alloc>> 219 stack(_Sequence&& __c, const _Alloc& __a) 220 : c(std::move(__c), __a) { } 221 222 template<typename _Alloc, typename _Requires = _Uses<_Alloc>> 223 stack(const stack& __q, const _Alloc& __a) 224 : c(__q.c, __a) { } 225 226 template<typename _Alloc, typename _Requires = _Uses<_Alloc>> 227 stack(stack&& __q, const _Alloc& __a) 228 : c(std::move(__q.c), __a) { } 229 230 #if __cplusplus > 202002L 231 template<typename _InputIterator, typename _Alloc, 232 typename = _RequireInputIter<_InputIterator>, 233 typename = _Uses<_Alloc>> 234 stack(_InputIterator __first, _InputIterator __last, const _Alloc& __a) 235 : c(__first, __last, __a) { } 236 #endif 237 #endif 238 239 /** 240 * Returns true if the %stack is empty. 241 */ 242 _GLIBCXX_NODISCARD bool 243 empty() const 244 { return c.empty(); } 245 246 /** Returns the number of elements in the %stack. */ 247 _GLIBCXX_NODISCARD 248 size_type 249 size() const 250 { return c.size(); } 251 252 /** 253 * Returns a read/write reference to the data at the first 254 * element of the %stack. 255 */ 256 _GLIBCXX_NODISCARD 257 reference 258 top() 259 { 260 __glibcxx_requires_nonempty(); 261 return c.back(); 262 } 263 264 /** 265 * Returns a read-only (constant) reference to the data at the first 266 * element of the %stack. 267 */ 268 _GLIBCXX_NODISCARD 269 const_reference 270 top() const 271 { 272 __glibcxx_requires_nonempty(); 273 return c.back(); 274 } 275 276 /** 277 * @brief Add data to the top of the %stack. 278 * @param __x Data to be added. 279 * 280 * This is a typical %stack operation. The function creates an 281 * element at the top of the %stack and assigns the given data 282 * to it. The time complexity of the operation depends on the 283 * underlying sequence. 284 */ 285 void 286 push(const value_type& __x) 287 { c.push_back(__x); } 288 289 #if __cplusplus >= 201103L 290 void 291 push(value_type&& __x) 292 { c.push_back(std::move(__x)); } 293 294 #if __cplusplus > 201402L 295 template<typename... _Args> 296 decltype(auto) 297 emplace(_Args&&... __args) 298 { return c.emplace_back(std::forward<_Args>(__args)...); } 299 #else 300 template<typename... _Args> 301 void 302 emplace(_Args&&... __args) 303 { c.emplace_back(std::forward<_Args>(__args)...); } 304 #endif 305 #endif 306 307 #if __glibcxx_containers_ranges // C++ >= 23 308 template<__detail::__container_compatible_range<_Tp> _Rg> 309 void 310 push_range(_Rg&& __rg) 311 { 312 if constexpr (requires { c.append_range(std::forward<_Rg>(__rg)); }) 313 c.append_range(std::forward<_Rg>(__rg)); 314 else 315 ranges::copy(__rg, std::back_inserter(c)); 316 } 317 #endif 318 319 /** 320 * @brief Removes first element. 321 * 322 * This is a typical %stack operation. It shrinks the %stack 323 * by one. The time complexity of the operation depends on the 324 * underlying sequence. 325 * 326 * Note that no data is returned, and if the first element's 327 * data is needed, it should be retrieved before pop() is 328 * called. 329 */ 330 void 331 pop() 332 { 333 __glibcxx_requires_nonempty(); 334 c.pop_back(); 335 } 336 337 #if __cplusplus >= 201103L 338 void 339 swap(stack& __s) 340 #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11 341 noexcept(__is_nothrow_swappable<_Sequence>::value) 342 #else 343 noexcept(__is_nothrow_swappable<_Tp>::value) 344 #endif 345 { 346 using std::swap; 347 swap(c, __s.c); 348 } 349 #endif // __cplusplus >= 201103L 350 351 #if __glibcxx_format_ranges 352 friend class formatter<stack<_Tp, _Sequence>, char>; 353 friend class formatter<stack<_Tp, _Sequence>, wchar_t>; 354 #endif 355 }; 356 357 #if __cpp_deduction_guides >= 201606 358 template<typename _Container, 359 typename = _RequireNotAllocator<_Container>> 360 stack(_Container) -> stack<typename _Container::value_type, _Container>; 361 362 template<typename _Container, typename _Allocator, 363 typename = _RequireNotAllocator<_Container>> 364 stack(_Container, _Allocator) 365 -> stack<typename _Container::value_type, _Container>; 366 367 #ifdef __glibcxx_adaptor_iterator_pair_constructor 368 template<typename _InputIterator, 369 typename _ValT 370 = typename iterator_traits<_InputIterator>::value_type, 371 typename = _RequireInputIter<_InputIterator>> 372 stack(_InputIterator, _InputIterator) -> stack<_ValT>; 373 374 template<typename _InputIterator, typename _Allocator, 375 typename _ValT 376 = typename iterator_traits<_InputIterator>::value_type, 377 typename = _RequireInputIter<_InputIterator>, 378 typename = _RequireAllocator<_Allocator>> 379 stack(_InputIterator, _InputIterator, _Allocator) 380 -> stack<_ValT, deque<_ValT, _Allocator>>; 381 #endif 382 383 #if __glibcxx_containers_ranges // C++ >= 23 384 template<ranges::input_range _Rg> 385 stack(from_range_t, _Rg&&) -> stack<ranges::range_value_t<_Rg>>; 386 387 template<ranges::input_range _Rg, __allocator_like _Alloc> 388 stack(from_range_t, _Rg&&, _Alloc) 389 -> stack<ranges::range_value_t<_Rg>, 390 deque<ranges::range_value_t<_Rg>, _Alloc>>; 391 #endif 392 #endif 393 394 /** 395 * @brief Stack equality comparison. 396 * @param __x A %stack. 397 * @param __y A %stack of the same type as @a __x. 398 * @return True iff the size and elements of the stacks are equal. 399 * 400 * This is an equivalence relation. Complexity and semantics 401 * depend on the underlying sequence type, but the expected rules 402 * are: this relation is linear in the size of the sequences, and 403 * stacks are considered equivalent if their sequences compare 404 * equal. 405 */ 406 template<typename _Tp, typename _Seq> 407 _GLIBCXX_NODISCARD 408 inline bool 409 operator==(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y) 410 { return __x.c == __y.c; } 411 412 /** 413 * @brief Stack ordering relation. 414 * @param __x A %stack. 415 * @param __y A %stack of the same type as @a x. 416 * @return True iff @a x is lexicographically less than @a __y. 417 * 418 * This is an total ordering relation. Complexity and semantics 419 * depend on the underlying sequence type, but the expected rules 420 * are: this relation is linear in the size of the sequences, the 421 * elements must be comparable with @c <, and 422 * std::lexicographical_compare() is usually used to make the 423 * determination. 424 */ 425 template<typename _Tp, typename _Seq> 426 _GLIBCXX_NODISCARD 427 inline bool 428 operator<(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y) 429 { return __x.c < __y.c; } 430 431 /// Based on operator== 432 template<typename _Tp, typename _Seq> 433 _GLIBCXX_NODISCARD 434 inline bool 435 operator!=(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y) 436 { return !(__x == __y); } 437 438 /// Based on operator< 439 template<typename _Tp, typename _Seq> 440 _GLIBCXX_NODISCARD 441 inline bool 442 operator>(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y) 443 { return __y < __x; } 444 445 /// Based on operator< 446 template<typename _Tp, typename _Seq> 447 _GLIBCXX_NODISCARD 448 inline bool 449 operator<=(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y) 450 { return !(__y < __x); } 451 452 /// Based on operator< 453 template<typename _Tp, typename _Seq> 454 _GLIBCXX_NODISCARD 455 inline bool 456 operator>=(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y) 457 { return !(__x < __y); } 458 459 #if __cpp_lib_three_way_comparison 460 template<typename _Tp, three_way_comparable _Seq> 461 [[nodiscard]] 462 inline compare_three_way_result_t<_Seq> 463 operator<=>(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y) 464 { return __x.c <=> __y.c; } 465 #endif 466 467 #if __cplusplus >= 201103L 468 template<typename _Tp, typename _Seq> 469 inline 470 #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11 471 // Constrained free swap overload, see p0185r1 472 typename enable_if<__is_swappable<_Seq>::value>::type 473 #else 474 void 475 #endif 476 swap(stack<_Tp, _Seq>& __x, stack<_Tp, _Seq>& __y) 477 noexcept(noexcept(__x.swap(__y))) 478 { __x.swap(__y); } 479 480 template<typename _Tp, typename _Seq, typename _Alloc> 481 struct uses_allocator<stack<_Tp, _Seq>, _Alloc> 482 : public uses_allocator<_Seq, _Alloc>::type { }; 483 #endif // __cplusplus >= 201103L 484 485 _GLIBCXX_END_NAMESPACE_VERSION 486 } // namespace 487 488 #endif /* _STL_STACK_H */
