1// Stack implementation -*- C++ -*-
2
3// Copyright (C) 2001-2019 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
65namespace 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 __cplusplus >= 201103L
120 template<typename _Alloc>
121 using _Uses = typename
122 enable_if<uses_allocator<_Sequence, _Alloc>::value>::type;
123
124#if __cplusplus >= 201703L
125 // _GLIBCXX_RESOLVE_LIB_DEFECTS
126 // 2566. Requirements on the first template parameter of container
127 // adaptors
128 static_assert(is_same<_Tp, typename _Sequence::value_type>::value,
129 "value_type must be the same as the underlying container");
130#endif // C++17
131#endif // C++11
132
133 public:
134 typedef typename _Sequence::value_type value_type;
135 typedef typename _Sequence::reference reference;
136 typedef typename _Sequence::const_reference const_reference;
137 typedef typename _Sequence::size_type size_type;
138 typedef _Sequence container_type;
139
140 protected:
141 // See queue::c for notes on this name.
142 _Sequence c;
143
144 public:
145 // XXX removed old def ctor, added def arg to this one to match 14882
146 /**
147 * @brief Default constructor creates no elements.
148 */
149#if __cplusplus < 201103L
150 explicit
151 stack(const _Sequence& __c = _Sequence())
152 : c(__c) { }
153#else
154 template<typename _Seq = _Sequence, typename _Requires = typename
155 enable_if<is_default_constructible<_Seq>::value>::type>
156 stack()
157 : c() { }
158
159 explicit
160 stack(const _Sequence& __c)
161 : c(__c) { }
162
163 explicit
164 stack(_Sequence&& __c)
165 : c(std::move(__c)) { }
166
167 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
168 explicit
169 stack(const _Alloc& __a)
170 : c(__a) { }
171
172 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
173 stack(const _Sequence& __c, const _Alloc& __a)
174 : c(__c, __a) { }
175
176 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
177 stack(_Sequence&& __c, const _Alloc& __a)
178 : c(std::move(__c), __a) { }
179
180 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
181 stack(const stack& __q, const _Alloc& __a)
182 : c(__q.c, __a) { }
183
184 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
185 stack(stack&& __q, const _Alloc& __a)
186 : c(std::move(__q.c), __a) { }
187#endif
188
189 /**
190 * Returns true if the %stack is empty.
191 */
192 _GLIBCXX_NODISCARD bool
193 empty() const
194 { return c.empty(); }
195
196 /** Returns the number of elements in the %stack. */
197 size_type
198 size() const
199 { return c.size(); }
200
201 /**
202 * Returns a read/write reference to the data at the first
203 * element of the %stack.
204 */
205 reference
206 top()
207 {
208 __glibcxx_requires_nonempty();
209 return c.back();
210 }
211
212 /**
213 * Returns a read-only (constant) reference to the data at the first
214 * element of the %stack.
215 */
216 const_reference
217 top() const
218 {
219 __glibcxx_requires_nonempty();
220 return c.back();
221 }
222
223 /**
224 * @brief Add data to the top of the %stack.
225 * @param __x Data to be added.
226 *
227 * This is a typical %stack operation. The function creates an
228 * element at the top of the %stack and assigns the given data
229 * to it. The time complexity of the operation depends on the
230 * underlying sequence.
231 */
232 void
233 push(const value_type& __x)
234 { c.push_back(__x); }
235
236#if __cplusplus >= 201103L
237 void
238 push(value_type&& __x)
239 { c.push_back(std::move(__x)); }
240
241#if __cplusplus > 201402L
242 template<typename... _Args>
243 decltype(auto)
244 emplace(_Args&&... __args)
245 { return c.emplace_back(std::forward<_Args>(__args)...); }
246#else
247 template<typename... _Args>
248 void
249 emplace(_Args&&... __args)
250 { c.emplace_back(std::forward<_Args>(__args)...); }
251#endif
252#endif
253
254 /**
255 * @brief Removes first element.
256 *
257 * This is a typical %stack operation. It shrinks the %stack
258 * by one. The time complexity of the operation depends on the
259 * underlying sequence.
260 *
261 * Note that no data is returned, and if the first element's
262 * data is needed, it should be retrieved before pop() is
263 * called.
264 */
265 void
266 pop()
267 {
268 __glibcxx_requires_nonempty();
269 c.pop_back();
270 }
271
272#if __cplusplus >= 201103L
273 void
274 swap(stack& __s)
275#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
276 noexcept(__is_nothrow_swappable<_Sequence>::value)
277#else
278 noexcept(__is_nothrow_swappable<_Tp>::value)
279#endif
280 {
281 using std::swap;
282 swap(c, __s.c);
283 }
284#endif // __cplusplus >= 201103L
285 };
286
287#if __cpp_deduction_guides >= 201606
288 template<typename _Container,
289 typename = _RequireNotAllocator<_Container>>
290 stack(_Container) -> stack<typename _Container::value_type, _Container>;
291
292 template<typename _Container, typename _Allocator,
293 typename = _RequireNotAllocator<_Container>,
294 typename = _RequireAllocator<_Allocator>>
295 stack(_Container, _Allocator)
296 -> stack<typename _Container::value_type, _Container>;
297#endif
298
299 /**
300 * @brief Stack equality comparison.
301 * @param __x A %stack.
302 * @param __y A %stack of the same type as @a __x.
303 * @return True iff the size and elements of the stacks are equal.
304 *
305 * This is an equivalence relation. Complexity and semantics
306 * depend on the underlying sequence type, but the expected rules
307 * are: this relation is linear in the size of the sequences, and
308 * stacks are considered equivalent if their sequences compare
309 * equal.
310 */
311 template<typename _Tp, typename _Seq>
312 inline bool
313 operator==(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)
314 { return __x.c == __y.c; }
315
316 /**
317 * @brief Stack ordering relation.
318 * @param __x A %stack.
319 * @param __y A %stack of the same type as @a x.
320 * @return True iff @a x is lexicographically less than @a __y.
321 *
322 * This is an total ordering relation. Complexity and semantics
323 * depend on the underlying sequence type, but the expected rules
324 * are: this relation is linear in the size of the sequences, the
325 * elements must be comparable with @c <, and
326 * std::lexicographical_compare() is usually used to make the
327 * determination.
328 */
329 template<typename _Tp, typename _Seq>
330 inline bool
331 operator<(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)
332 { return __x.c < __y.c; }
333
334 /// Based on operator==
335 template<typename _Tp, typename _Seq>
336 inline bool
337 operator!=(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)
338 { return !(__x == __y); }
339
340 /// Based on operator<
341 template<typename _Tp, typename _Seq>
342 inline bool
343 operator>(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)
344 { return __y < __x; }
345
346 /// Based on operator<
347 template<typename _Tp, typename _Seq>
348 inline bool
349 operator<=(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)
350 { return !(__y < __x); }
351
352 /// Based on operator<
353 template<typename _Tp, typename _Seq>
354 inline bool
355 operator>=(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)
356 { return !(__x < __y); }
357
358#if __cplusplus >= 201103L
359 template<typename _Tp, typename _Seq>
360 inline
361#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
362 // Constrained free swap overload, see p0185r1
363 typename enable_if<__is_swappable<_Seq>::value>::type
364#else
365 void
366#endif
367 swap(stack<_Tp, _Seq>& __x, stack<_Tp, _Seq>& __y)
368 noexcept(noexcept(__x.swap(__y)))
369 { __x.swap(__y); }
370
371 template<typename _Tp, typename _Seq, typename _Alloc>
372 struct uses_allocator<stack<_Tp, _Seq>, _Alloc>
373 : public uses_allocator<_Seq, _Alloc>::type { };
374#endif // __cplusplus >= 201103L
375
376_GLIBCXX_END_NAMESPACE_VERSION
377} // namespace
378
379#endif /* _STL_STACK_H */
380