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54c1bf78 | 1 | // <memory> -*- C++ -*- |
de96ac46 | 2 | |
6b20f9b5 | 3 | // Copyright (C) 2001, 2002 Free Software Foundation, Inc. |
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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 2, 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 | // You should have received a copy of the GNU General Public License along | |
17 | // with this library; see the file COPYING. If not, write to the Free | |
18 | // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, | |
19 | // USA. | |
20 | ||
21 | // As a special exception, you may use this file as part of a free software | |
22 | // library without restriction. Specifically, if other files instantiate | |
23 | // templates or use macros or inline functions from this file, or you compile | |
24 | // this file and link it with other files to produce an executable, this | |
25 | // file does not by itself cause the resulting executable to be covered by | |
26 | // the GNU General Public License. This exception does not however | |
27 | // invalidate any other reasons why the executable file might be covered by | |
28 | // the GNU General Public License. | |
29 | ||
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30 | /* |
31 | * Copyright (c) 1997-1999 | |
32 | * Silicon Graphics Computer Systems, Inc. | |
33 | * | |
34 | * Permission to use, copy, modify, distribute and sell this software | |
35 | * and its documentation for any purpose is hereby granted without fee, | |
36 | * provided that the above copyright notice appear in all copies and | |
37 | * that both that copyright notice and this permission notice appear | |
38 | * in supporting documentation. Silicon Graphics makes no | |
39 | * representations about the suitability of this software for any | |
40 | * purpose. It is provided "as is" without express or implied warranty. | |
41 | * | |
42 | */ | |
43 | ||
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44 | /** @file memory |
45 | * This is a Standard C++ Library header. You should @c #include this header | |
46 | * in your programs, rather than any of the "st[dl]_*.h" implementation files. | |
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47 | */ |
48 | ||
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49 | #ifndef _MEMORY |
50 | #define _MEMORY 1 | |
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51 | |
52 | #pragma GCC system_header | |
53 | ||
54 | #include <bits/stl_algobase.h> | |
1ff9402d | 55 | #include <bits/allocator.h> |
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56 | #include <bits/stl_construct.h> |
57 | #include <bits/stl_iterator_base_types.h> //for iterator_traits | |
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58 | #include <bits/stl_uninitialized.h> |
59 | #include <bits/stl_raw_storage_iter.h> | |
60 | ||
61 | namespace std | |
62 | { | |
16ad69a1 | 63 | /** |
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64 | * @if maint |
65 | * This is a helper function. The unused second parameter exists to | |
66 | * permit the real get_temporary_buffer to use template parameter deduction. | |
16ad69a1 | 67 | * |
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68 | * XXX This should perhaps use the pool. |
69 | * @endif | |
70 | */ | |
71 | template<typename _Tp> | |
72 | pair<_Tp*, ptrdiff_t> | |
73 | __get_temporary_buffer(ptrdiff_t __len, _Tp*) | |
16ad69a1 | 74 | { |
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75 | if (__len > ptrdiff_t(INT_MAX / sizeof(_Tp))) |
76 | __len = INT_MAX / sizeof(_Tp); | |
77 | ||
78 | while (__len > 0) | |
79 | { | |
80 | _Tp* __tmp = (_Tp*) std::malloc((std::size_t)__len * sizeof(_Tp)); | |
81 | if (__tmp != 0) | |
82 | return pair<_Tp*, ptrdiff_t>(__tmp, __len); | |
83 | __len /= 2; | |
84 | } | |
85 | return pair<_Tp*, ptrdiff_t>((_Tp*)0, 0); | |
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86 | } |
87 | ||
88 | /** | |
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89 | * @brief This is a mostly-useless wrapper around malloc(). |
90 | * @param len The number of objects of type Tp. | |
91 | * @return See full description. | |
16ad69a1 | 92 | * |
5acf59f8 | 93 | * Reinventing the wheel, but this time with prettier spokes! |
16ad69a1 | 94 | * |
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95 | * This function tries to obtain storage for @c len adjacent Tp objects. |
96 | * The objects themselves are not constructed, of course. A pair<> is | |
97 | * returned containing "the buffer s address and capacity (in the units of | |
98 | * sizeof(Tp)), or a pair of 0 values if no storage can be obtained." | |
99 | * Note that the capacity obtained may be less than that requested if the | |
100 | * memory is unavailable; you should compare len with the .second return | |
101 | * value. | |
102 | */ | |
103 | template<typename _Tp> | |
104 | inline pair<_Tp*,ptrdiff_t> | |
105 | get_temporary_buffer(ptrdiff_t __len) | |
106 | { return __get_temporary_buffer(__len, (_Tp*) 0); } | |
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107 | |
108 | /** | |
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109 | * @brief The companion to get_temporary_buffer(). |
110 | * @param p A buffer previously allocated by get_temporary_buffer. | |
111 | * @return None. | |
16ad69a1 | 112 | * |
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113 | * Frees the memory pointed to by p. |
114 | */ | |
115 | template<typename _Tp> | |
116 | void | |
117 | return_temporary_buffer(_Tp* __p) | |
118 | { std::free(__p); } | |
54c1bf78 | 119 | |
16ad69a1 | 120 | /** |
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121 | * A wrapper class to provide auto_ptr with reference semantics. For |
122 | * example, an auto_ptr can be assigned (or constructed from) the result of | |
123 | * a function which returns an auto_ptr by value. | |
16ad69a1 | 124 | * |
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125 | * All the auto_ptr_ref stuff should happen behind the scenes. |
126 | */ | |
127 | template<typename _Tp1> | |
128 | struct auto_ptr_ref | |
129 | { | |
130 | _Tp1* _M_ptr; | |
131 | ||
132 | explicit | |
133 | auto_ptr_ref(_Tp1* __p): _M_ptr(__p) { } | |
134 | }; | |
16ad69a1 | 135 | |
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136 | |
137 | /** | |
5acf59f8 | 138 | * @brief A simple smart pointer providing strict ownership semantics. |
16ad69a1 | 139 | * |
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140 | * The Standard says: |
141 | * <pre> | |
142 | * An @c auto_ptr owns the object it holds a pointer to. Copying an | |
143 | * @c auto_ptr copies the pointer and transfers ownership to the destination. | |
144 | * If more than one @c auto_ptr owns the same object at the same time the | |
145 | * behavior of the program is undefined. | |
16ad69a1 | 146 | * |
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147 | * The uses of @c auto_ptr include providing temporary exception-safety for |
148 | * dynamically allocated memory, passing ownership of dynamically allocated | |
149 | * memory to a function, and returning dynamically allocated memory from a | |
150 | * function. @c auto_ptr does not meet the CopyConstructible and Assignable | |
151 | * requirements for Standard Library <a href="tables.html#65">container</a> | |
152 | * elements and thus instantiating a Standard Library container with an | |
153 | * @c auto_ptr results in undefined behavior. | |
154 | * </pre> | |
155 | * Quoted from [20.4.5]/3. | |
16ad69a1 | 156 | * |
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157 | * Good examples of what can and cannot be done with auto_ptr can be found |
158 | * in the libstdc++ testsuite. | |
16ad69a1 | 159 | * |
5acf59f8 | 160 | * @if maint |
3d7c150e | 161 | * _GLIBCXX_RESOLVE_LIB_DEFECTS |
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162 | * 127. auto_ptr<> conversion issues |
163 | * These resolutions have all been incorporated. | |
164 | * @endif | |
165 | */ | |
166 | template<typename _Tp> | |
167 | class auto_ptr | |
16ad69a1 | 168 | { |
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169 | private: |
170 | _Tp* _M_ptr; | |
171 | ||
172 | public: | |
173 | /// The pointed-to type. | |
174 | typedef _Tp element_type; | |
175 | ||
176 | /** | |
177 | * @brief An %auto_ptr is usually constructed from a raw pointer. | |
178 | * @param p A pointer (defaults to NULL). | |
179 | * | |
180 | * This object now @e owns the object pointed to by @a p. | |
181 | */ | |
182 | explicit | |
183 | auto_ptr(element_type* __p = 0) throw() : _M_ptr(__p) { } | |
184 | ||
185 | /** | |
186 | * @brief An %auto_ptr can be constructed from another %auto_ptr. | |
187 | * @param a Another %auto_ptr of the same type. | |
188 | * | |
189 | * This object now @e owns the object previously owned by @a a, | |
190 | * which has given up ownsership. | |
191 | */ | |
192 | auto_ptr(auto_ptr& __a) throw() : _M_ptr(__a.release()) { } | |
193 | ||
194 | /** | |
195 | * @brief An %auto_ptr can be constructed from another %auto_ptr. | |
196 | * @param a Another %auto_ptr of a different but related type. | |
197 | * | |
198 | * A pointer-to-Tp1 must be convertible to a pointer-to-Tp/element_type. | |
199 | * | |
200 | * This object now @e owns the object previously owned by @a a, | |
201 | * which has given up ownsership. | |
202 | */ | |
203 | template<typename _Tp1> | |
204 | auto_ptr(auto_ptr<_Tp1>& __a) throw() : _M_ptr(__a.release()) { } | |
205 | ||
206 | /** | |
207 | * @brief %auto_ptr assignment operator. | |
208 | * @param a Another %auto_ptr of the same type. | |
209 | * | |
210 | * This object now @e owns the object previously owned by @a a, | |
211 | * which has given up ownsership. The object that this one @e | |
212 | * used to own and track has been deleted. | |
213 | */ | |
214 | auto_ptr& | |
215 | operator=(auto_ptr& __a) throw() | |
216 | { | |
217 | reset(__a.release()); | |
218 | return *this; | |
219 | } | |
220 | ||
221 | /** | |
222 | * @brief %auto_ptr assignment operator. | |
223 | * @param a Another %auto_ptr of a different but related type. | |
224 | * | |
225 | * A pointer-to-Tp1 must be convertible to a pointer-to-Tp/element_type. | |
226 | * | |
227 | * This object now @e owns the object previously owned by @a a, | |
228 | * which has given up ownsership. The object that this one @e | |
229 | * used to own and track has been deleted. | |
230 | */ | |
231 | template<typename _Tp1> | |
232 | auto_ptr& | |
233 | operator=(auto_ptr<_Tp1>& __a) throw() | |
16ad69a1 | 234 | { |
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235 | reset(__a.release()); |
236 | return *this; | |
237 | } | |
238 | ||
239 | /** | |
240 | * When the %auto_ptr goes out of scope, the object it owns is deleted. | |
241 | * If it no longer owns anything (i.e., @c get() is @c NULL), then this | |
242 | * has no effect. | |
243 | * | |
244 | * @if maint | |
245 | * The C++ standard says there is supposed to be an empty throw | |
246 | * specification here, but omitting it is standard conforming. Its | |
247 | * presence can be detected only if _Tp::~_Tp() throws, but this is | |
248 | * prohibited. [17.4.3.6]/2 | |
249 | * @end maint | |
250 | */ | |
251 | ~auto_ptr() { delete _M_ptr; } | |
252 | ||
253 | /** | |
254 | * @brief Smart pointer dereferencing. | |
255 | * | |
256 | * If this %auto_ptr no longer owns anything, then this | |
257 | * operation will crash. (For a smart pointer, "no longer owns | |
258 | * anything" is the same as being a null pointer, and you know | |
259 | * what happens when you dereference one of those...) | |
260 | */ | |
261 | element_type& | |
262 | operator*() const throw() { return *_M_ptr; } | |
263 | ||
264 | /** | |
265 | * @brief Smart pointer dereferencing. | |
266 | * | |
267 | * This returns the pointer itself, which the language then will | |
268 | * automatically cause to be dereferenced. | |
269 | */ | |
270 | element_type* | |
271 | operator->() const throw() { return _M_ptr; } | |
272 | ||
273 | /** | |
274 | * @brief Bypassing the smart pointer. | |
275 | * @return The raw pointer being managed. | |
276 | * | |
277 | * You can get a copy of the pointer that this object owns, for | |
278 | * situations such as passing to a function which only accepts a raw | |
279 | * pointer. | |
280 | * | |
281 | * @note This %auto_ptr still owns the memory. | |
282 | */ | |
283 | element_type* | |
284 | get() const throw() { return _M_ptr; } | |
285 | ||
286 | /** | |
287 | * @brief Bypassing the smart pointer. | |
288 | * @return The raw pointer being managed. | |
289 | * | |
290 | * You can get a copy of the pointer that this object owns, for | |
291 | * situations such as passing to a function which only accepts a raw | |
292 | * pointer. | |
293 | * | |
294 | * @note This %auto_ptr no longer owns the memory. When this object | |
295 | * goes out of scope, nothing will happen. | |
296 | */ | |
297 | element_type* | |
298 | release() throw() | |
299 | { | |
300 | element_type* __tmp = _M_ptr; | |
301 | _M_ptr = 0; | |
302 | return __tmp; | |
303 | } | |
304 | ||
305 | /** | |
306 | * @brief Forcibly deletes the managed object. | |
307 | * @param p A pointer (defaults to NULL). | |
308 | * | |
309 | * This object now @e owns the object pointed to by @a p. The previous | |
310 | * object has been deleted. | |
311 | */ | |
312 | void | |
313 | reset(element_type* __p = 0) throw() | |
314 | { | |
315 | if (__p != _M_ptr) | |
316 | { | |
317 | delete _M_ptr; | |
318 | _M_ptr = __p; | |
319 | } | |
320 | } | |
321 | ||
322 | /** @{ | |
323 | * @brief Automatic conversions | |
324 | * | |
325 | * These operations convert an %auto_ptr into and from an auto_ptr_ref | |
326 | * automatically as needed. This allows constructs such as | |
327 | * @code | |
328 | * auto_ptr<Derived> func_returning_auto_ptr(.....); | |
329 | * ... | |
330 | * auto_ptr<Base> ptr = func_returning_auto_ptr(.....); | |
331 | * @endcode | |
332 | */ | |
333 | auto_ptr(auto_ptr_ref<element_type> __ref) throw() | |
334 | : _M_ptr(__ref._M_ptr) { } | |
335 | ||
336 | auto_ptr& | |
337 | operator=(auto_ptr_ref<element_type> __ref) throw() | |
338 | { | |
339 | if (__ref._M_ptr != this->get()) | |
340 | { | |
341 | delete _M_ptr; | |
342 | _M_ptr = __ref._M_ptr; | |
343 | } | |
344 | return *this; | |
345 | } | |
346 | ||
347 | template<typename _Tp1> | |
348 | operator auto_ptr_ref<_Tp1>() throw() | |
349 | { return auto_ptr_ref<_Tp1>(this->release()); } | |
350 | ||
351 | template<typename _Tp1> | |
352 | operator auto_ptr<_Tp1>() throw() | |
353 | { return auto_ptr<_Tp1>(this->release()); } | |
354 | /** @} */ | |
355 | }; | |
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356 | } // namespace std |
357 | ||
5acf59f8 | 358 | #endif |