libstdc++
stl_stack.h
Go to the documentation of this file.
1 // Stack implementation -*- C++ -*-
2 
3 // Copyright (C) 2001-2024 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 
65 namespace std _GLIBCXX_VISIBILITY(default)
66 {
67 _GLIBCXX_BEGIN_NAMESPACE_VERSION
68 
69  /**
70  * @brief A standard container giving FILO behavior.
71  *
72  * @ingroup sequences
73  *
74  * @tparam _Tp Type of element.
75  * @tparam _Sequence Type of underlying sequence, defaults to deque<_Tp>.
76  *
77  * Meets many of the requirements of a
78  * <a href="tables.html#65">container</a>,
79  * but does not define anything to do with iterators. Very few of the
80  * other standard container interfaces are defined.
81  *
82  * This is not a true container, but an @e adaptor. It holds
83  * another container, and provides a wrapper interface to that
84  * container. The wrapper is what enforces strict
85  * first-in-last-out %stack behavior.
86  *
87  * The second template parameter defines the type of the underlying
88  * sequence/container. It defaults to std::deque, but it can be
89  * any type that supports @c back, @c push_back, and @c pop_back,
90  * such as std::list, std::vector, or an appropriate user-defined
91  * type.
92  *
93  * Members not found in @a normal containers are @c container_type,
94  * which is a typedef for the second Sequence parameter, and @c
95  * push, @c pop, and @c top, which are standard %stack/FILO
96  * operations.
97  */
98  template<typename _Tp, typename _Sequence = deque<_Tp> >
99  class stack
100  {
101 #ifdef _GLIBCXX_CONCEPT_CHECKS
102  // concept requirements
103  typedef typename _Sequence::value_type _Sequence_value_type;
104 # if __cplusplus < 201103L
105  __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
106  __glibcxx_class_requires(_Sequence, _BackInsertionSequenceConcept)
107 # endif
108  __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept)
109 #endif
110 
111  template<typename _Tp1, typename _Seq1>
112  friend bool
113  operator==(const stack<_Tp1, _Seq1>&, const stack<_Tp1, _Seq1>&);
114 
115  template<typename _Tp1, typename _Seq1>
116  friend bool
117  operator<(const stack<_Tp1, _Seq1>&, const stack<_Tp1, _Seq1>&);
118 
119 #if __cpp_lib_three_way_comparison
120  template<typename _Tp1, three_way_comparable _Seq1>
122  operator<=>(const stack<_Tp1, _Seq1>&, const stack<_Tp1, _Seq1>&);
123 #endif
124 
125 #if __cplusplus >= 201103L
126  template<typename _Alloc>
127  using _Uses = typename
129 
130 #if __cplusplus >= 201703L
131  // _GLIBCXX_RESOLVE_LIB_DEFECTS
132  // 2566. Requirements on the first template parameter of container
133  // adaptors
135  "value_type must be the same as the underlying container");
136 #endif // C++17
137 #endif // C++11
138 
139  public:
140  typedef typename _Sequence::value_type value_type;
141  typedef typename _Sequence::reference reference;
142  typedef typename _Sequence::const_reference const_reference;
143  typedef typename _Sequence::size_type size_type;
144  typedef _Sequence container_type;
145 
146  protected:
147  // See queue::c for notes on this name.
148  _Sequence c;
149 
150  public:
151  // XXX removed old def ctor, added def arg to this one to match 14882
152  /**
153  * @brief Default constructor creates no elements.
154  */
155 #if __cplusplus < 201103L
156  explicit
157  stack(const _Sequence& __c = _Sequence())
158  : c(__c) { }
159 #else
160  template<typename _Seq = _Sequence, typename _Requires = typename
163  : c() { }
164 
165  explicit
166  stack(const _Sequence& __c)
167  : c(__c) { }
168 
169  explicit
170  stack(_Sequence&& __c)
171  : c(std::move(__c)) { }
172 
173 #ifdef __glibcxx_adaptor_iterator_pair_constructor // C++ >= 23 && HOSTED
174  template<typename _InputIterator,
175  typename = _RequireInputIter<_InputIterator>>
176  stack(_InputIterator __first, _InputIterator __last)
177  : c(__first, __last) { }
178 #endif
179 
180 
181  template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
182  explicit
183  stack(const _Alloc& __a)
184  : c(__a) { }
185 
186  template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
187  stack(const _Sequence& __c, const _Alloc& __a)
188  : c(__c, __a) { }
189 
190  template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
191  stack(_Sequence&& __c, const _Alloc& __a)
192  : c(std::move(__c), __a) { }
193 
194  template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
195  stack(const stack& __q, const _Alloc& __a)
196  : c(__q.c, __a) { }
197 
198  template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
199  stack(stack&& __q, const _Alloc& __a)
200  : c(std::move(__q.c), __a) { }
201 
202 #if __cplusplus > 202002L
203  template<typename _InputIterator, typename _Alloc,
204  typename = _RequireInputIter<_InputIterator>,
205  typename = _Uses<_Alloc>>
206  stack(_InputIterator __first, _InputIterator __last, const _Alloc& __a)
207  : c(__first, __last, __a) { }
208 #endif
209 #endif
210 
211  /**
212  * Returns true if the %stack is empty.
213  */
214  _GLIBCXX_NODISCARD bool
215  empty() const
216  { return c.empty(); }
217 
218  /** Returns the number of elements in the %stack. */
219  _GLIBCXX_NODISCARD
220  size_type
221  size() const
222  { return c.size(); }
223 
224  /**
225  * Returns a read/write reference to the data at the first
226  * element of the %stack.
227  */
228  _GLIBCXX_NODISCARD
229  reference
230  top()
231  {
232  __glibcxx_requires_nonempty();
233  return c.back();
234  }
235 
236  /**
237  * Returns a read-only (constant) reference to the data at the first
238  * element of the %stack.
239  */
240  _GLIBCXX_NODISCARD
241  const_reference
242  top() const
243  {
244  __glibcxx_requires_nonempty();
245  return c.back();
246  }
247 
248  /**
249  * @brief Add data to the top of the %stack.
250  * @param __x Data to be added.
251  *
252  * This is a typical %stack operation. The function creates an
253  * element at the top of the %stack and assigns the given data
254  * to it. The time complexity of the operation depends on the
255  * underlying sequence.
256  */
257  void
258  push(const value_type& __x)
259  { c.push_back(__x); }
260 
261 #if __cplusplus >= 201103L
262  void
263  push(value_type&& __x)
264  { c.push_back(std::move(__x)); }
265 
266 #if __cplusplus > 201402L
267  template<typename... _Args>
268  decltype(auto)
269  emplace(_Args&&... __args)
270  { return c.emplace_back(std::forward<_Args>(__args)...); }
271 #else
272  template<typename... _Args>
273  void
274  emplace(_Args&&... __args)
275  { c.emplace_back(std::forward<_Args>(__args)...); }
276 #endif
277 #endif
278 
279  /**
280  * @brief Removes first element.
281  *
282  * This is a typical %stack operation. It shrinks the %stack
283  * by one. The time complexity of the operation depends on the
284  * underlying sequence.
285  *
286  * Note that no data is returned, and if the first element's
287  * data is needed, it should be retrieved before pop() is
288  * called.
289  */
290  void
291  pop()
292  {
293  __glibcxx_requires_nonempty();
294  c.pop_back();
295  }
296 
297 #if __cplusplus >= 201103L
298  void
299  swap(stack& __s)
300 #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
301  noexcept(__is_nothrow_swappable<_Sequence>::value)
302 #else
303  noexcept(__is_nothrow_swappable<_Tp>::value)
304 #endif
305  {
306  using std::swap;
307  swap(c, __s.c);
308  }
309 #endif // __cplusplus >= 201103L
310  };
311 
312 #if __cpp_deduction_guides >= 201606
313  template<typename _Container,
314  typename = _RequireNotAllocator<_Container>>
315  stack(_Container) -> stack<typename _Container::value_type, _Container>;
316 
317  template<typename _Container, typename _Allocator,
318  typename = _RequireNotAllocator<_Container>>
319  stack(_Container, _Allocator)
320  -> stack<typename _Container::value_type, _Container>;
321 
322 #ifdef __glibcxx_adaptor_iterator_pair_constructor
323  template<typename _InputIterator,
324  typename _ValT
325  = typename iterator_traits<_InputIterator>::value_type,
326  typename = _RequireInputIter<_InputIterator>>
327  stack(_InputIterator, _InputIterator) -> stack<_ValT>;
328 
329  template<typename _InputIterator, typename _Allocator,
330  typename _ValT
331  = typename iterator_traits<_InputIterator>::value_type,
332  typename = _RequireInputIter<_InputIterator>,
333  typename = _RequireAllocator<_Allocator>>
334  stack(_InputIterator, _InputIterator, _Allocator)
335  -> stack<_ValT, deque<_ValT, _Allocator>>;
336 #endif
337 #endif
338 
339  /**
340  * @brief Stack equality comparison.
341  * @param __x A %stack.
342  * @param __y A %stack of the same type as @a __x.
343  * @return True iff the size and elements of the stacks are equal.
344  *
345  * This is an equivalence relation. Complexity and semantics
346  * depend on the underlying sequence type, but the expected rules
347  * are: this relation is linear in the size of the sequences, and
348  * stacks are considered equivalent if their sequences compare
349  * equal.
350  */
351  template<typename _Tp, typename _Seq>
352  _GLIBCXX_NODISCARD
353  inline bool
354  operator==(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)
355  { return __x.c == __y.c; }
356 
357  /**
358  * @brief Stack ordering relation.
359  * @param __x A %stack.
360  * @param __y A %stack of the same type as @a x.
361  * @return True iff @a x is lexicographically less than @a __y.
362  *
363  * This is an total ordering relation. Complexity and semantics
364  * depend on the underlying sequence type, but the expected rules
365  * are: this relation is linear in the size of the sequences, the
366  * elements must be comparable with @c <, and
367  * std::lexicographical_compare() is usually used to make the
368  * determination.
369  */
370  template<typename _Tp, typename _Seq>
371  _GLIBCXX_NODISCARD
372  inline bool
373  operator<(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)
374  { return __x.c < __y.c; }
375 
376  /// Based on operator==
377  template<typename _Tp, typename _Seq>
378  _GLIBCXX_NODISCARD
379  inline bool
380  operator!=(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)
381  { return !(__x == __y); }
382 
383  /// Based on operator<
384  template<typename _Tp, typename _Seq>
385  _GLIBCXX_NODISCARD
386  inline bool
387  operator>(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)
388  { return __y < __x; }
389 
390  /// Based on operator<
391  template<typename _Tp, typename _Seq>
392  _GLIBCXX_NODISCARD
393  inline bool
394  operator<=(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)
395  { return !(__y < __x); }
396 
397  /// Based on operator<
398  template<typename _Tp, typename _Seq>
399  _GLIBCXX_NODISCARD
400  inline bool
401  operator>=(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)
402  { return !(__x < __y); }
403 
404 #if __cpp_lib_three_way_comparison
405  template<typename _Tp, three_way_comparable _Seq>
406  [[nodiscard]]
407  inline compare_three_way_result_t<_Seq>
408  operator<=>(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)
409  { return __x.c <=> __y.c; }
410 #endif
411 
412 #if __cplusplus >= 201103L
413  template<typename _Tp, typename _Seq>
414  inline
415 #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
416  // Constrained free swap overload, see p0185r1
417  typename enable_if<__is_swappable<_Seq>::value>::type
418 #else
419  void
420 #endif
421  swap(stack<_Tp, _Seq>& __x, stack<_Tp, _Seq>& __y)
422  noexcept(noexcept(__x.swap(__y)))
423  { __x.swap(__y); }
424 
425  template<typename _Tp, typename _Seq, typename _Alloc>
426  struct uses_allocator<stack<_Tp, _Seq>, _Alloc>
427  : public uses_allocator<_Seq, _Alloc>::type { };
428 #endif // __cplusplus >= 201103L
429 
430 _GLIBCXX_END_NAMESPACE_VERSION
431 } // namespace
432 
433 #endif /* _STL_STACK_H */
ISO C++ entities toplevel namespace is std.
is_same
Definition: type_traits:780
void push(const value_type &__x)
Add data to the top of the stack.
Definition: stl_stack.h:258
stack()
Default constructor creates no elements.
Definition: stl_stack.h:162
A standard container giving FILO behavior.
Definition: stl_stack.h:99
size_type size() const
Definition: stl_stack.h:221
void pop()
Removes first element.
Definition: stl_stack.h:291
bool empty() const
Definition: stl_stack.h:215
Define a member typedef type only if a boolean constant is true.
Definition: type_traits:128
reference top()
Definition: stl_stack.h:230
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:137
typename __detail::__cmp3way_res_impl< _Tp, _Up >::type compare_three_way_result_t
[cmp.result], result of three-way comparison
Definition: compare:520
const_reference top() const
Definition: stl_stack.h:242