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acb8a4ef | 1 | // auto_ptr implementation -*- C++ -*- |
b2c50382 | 2 | |
2a60a9f6 | 3 | // Copyright (C) 2007, 2008, 2009, 2010 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 | |
748086b7 | 8 | // Free Software Foundation; either version 3, or (at your option) |
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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 | ||
748086b7 JJ |
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. | |
b2c50382 | 19 | |
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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/>. | |
b2c50382 | 24 | |
40abbf1f | 25 | /** @file backward/auto_ptr.h |
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26 | * This is an internal header file, included by other library headers. |
27 | * You should not attempt to use it directly. | |
28 | */ | |
29 | ||
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30 | #ifndef _STL_AUTO_PTR_H |
31 | #define _STL_AUTO_PTR_H 1 | |
b2c50382 | 32 | |
acb8a4ef | 33 | #include <bits/c++config.h> |
b2c50382 | 34 | #include <debug/debug.h> |
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35 | |
36 | _GLIBCXX_BEGIN_NAMESPACE(std) | |
37 | ||
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38 | /** |
39 | * A wrapper class to provide auto_ptr with reference semantics. | |
40 | * For example, an auto_ptr can be assigned (or constructed from) | |
41 | * the result of a function which returns an auto_ptr by value. | |
42 | * | |
43 | * All the auto_ptr_ref stuff should happen behind the scenes. | |
44 | */ | |
45 | template<typename _Tp1> | |
46 | struct auto_ptr_ref | |
47 | { | |
48 | _Tp1* _M_ptr; | |
49 | ||
50 | explicit | |
51 | auto_ptr_ref(_Tp1* __p): _M_ptr(__p) { } | |
4dd9d9db | 52 | } _GLIBCXX_DEPRECATED_ATTR; |
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53 | |
54 | ||
55 | /** | |
56 | * @brief A simple smart pointer providing strict ownership semantics. | |
57 | * | |
58 | * The Standard says: | |
59 | * <pre> | |
60 | * An @c auto_ptr owns the object it holds a pointer to. Copying | |
61 | * an @c auto_ptr copies the pointer and transfers ownership to the | |
62 | * destination. If more than one @c auto_ptr owns the same object | |
63 | * at the same time the behavior of the program is undefined. | |
64 | * | |
65 | * The uses of @c auto_ptr include providing temporary | |
66 | * exception-safety for dynamically allocated memory, passing | |
67 | * ownership of dynamically allocated memory to a function, and | |
68 | * returning dynamically allocated memory from a function. @c | |
69 | * auto_ptr does not meet the CopyConstructible and Assignable | |
70 | * requirements for Standard Library <a | |
71 | * href="tables.html#65">container</a> elements and thus | |
72 | * instantiating a Standard Library container with an @c auto_ptr | |
73 | * results in undefined behavior. | |
74 | * </pre> | |
75 | * Quoted from [20.4.5]/3. | |
76 | * | |
77 | * Good examples of what can and cannot be done with auto_ptr can | |
78 | * be found in the libstdc++ testsuite. | |
79 | * | |
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80 | * _GLIBCXX_RESOLVE_LIB_DEFECTS |
81 | * 127. auto_ptr<> conversion issues | |
82 | * These resolutions have all been incorporated. | |
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83 | */ |
84 | template<typename _Tp> | |
85 | class auto_ptr | |
86 | { | |
87 | private: | |
88 | _Tp* _M_ptr; | |
89 | ||
90 | public: | |
91 | /// The pointed-to type. | |
92 | typedef _Tp element_type; | |
93 | ||
94 | /** | |
95 | * @brief An %auto_ptr is usually constructed from a raw pointer. | |
96 | * @param p A pointer (defaults to NULL). | |
97 | * | |
98 | * This object now @e owns the object pointed to by @a p. | |
99 | */ | |
100 | explicit | |
101 | auto_ptr(element_type* __p = 0) throw() : _M_ptr(__p) { } | |
102 | ||
103 | /** | |
104 | * @brief An %auto_ptr can be constructed from another %auto_ptr. | |
105 | * @param a Another %auto_ptr of the same type. | |
106 | * | |
107 | * This object now @e owns the object previously owned by @a a, | |
28dac70a | 108 | * which has given up ownership. |
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109 | */ |
110 | auto_ptr(auto_ptr& __a) throw() : _M_ptr(__a.release()) { } | |
111 | ||
112 | /** | |
113 | * @brief An %auto_ptr can be constructed from another %auto_ptr. | |
114 | * @param a Another %auto_ptr of a different but related type. | |
115 | * | |
116 | * A pointer-to-Tp1 must be convertible to a | |
117 | * pointer-to-Tp/element_type. | |
118 | * | |
119 | * This object now @e owns the object previously owned by @a a, | |
28dac70a | 120 | * which has given up ownership. |
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121 | */ |
122 | template<typename _Tp1> | |
123 | auto_ptr(auto_ptr<_Tp1>& __a) throw() : _M_ptr(__a.release()) { } | |
124 | ||
125 | /** | |
126 | * @brief %auto_ptr assignment operator. | |
127 | * @param a Another %auto_ptr of the same type. | |
128 | * | |
129 | * This object now @e owns the object previously owned by @a a, | |
28dac70a | 130 | * which has given up ownership. The object that this one @e |
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131 | * used to own and track has been deleted. |
132 | */ | |
133 | auto_ptr& | |
134 | operator=(auto_ptr& __a) throw() | |
135 | { | |
136 | reset(__a.release()); | |
137 | return *this; | |
138 | } | |
139 | ||
140 | /** | |
141 | * @brief %auto_ptr assignment operator. | |
142 | * @param a Another %auto_ptr of a different but related type. | |
143 | * | |
144 | * A pointer-to-Tp1 must be convertible to a pointer-to-Tp/element_type. | |
145 | * | |
146 | * This object now @e owns the object previously owned by @a a, | |
28dac70a | 147 | * which has given up ownership. The object that this one @e |
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148 | * used to own and track has been deleted. |
149 | */ | |
150 | template<typename _Tp1> | |
151 | auto_ptr& | |
152 | operator=(auto_ptr<_Tp1>& __a) throw() | |
153 | { | |
154 | reset(__a.release()); | |
155 | return *this; | |
156 | } | |
157 | ||
158 | /** | |
159 | * When the %auto_ptr goes out of scope, the object it owns is | |
160 | * deleted. If it no longer owns anything (i.e., @c get() is | |
161 | * @c NULL), then this has no effect. | |
162 | * | |
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163 | * The C++ standard says there is supposed to be an empty throw |
164 | * specification here, but omitting it is standard conforming. Its | |
165 | * presence can be detected only if _Tp::~_Tp() throws, but this is | |
166 | * prohibited. [17.4.3.6]/2 | |
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167 | */ |
168 | ~auto_ptr() { delete _M_ptr; } | |
169 | ||
170 | /** | |
171 | * @brief Smart pointer dereferencing. | |
172 | * | |
173 | * If this %auto_ptr no longer owns anything, then this | |
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174 | * operation will crash. (For a smart pointer, <em>no longer owns |
175 | * anything</em> is the same as being a null pointer, and you know | |
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176 | * what happens when you dereference one of those...) |
177 | */ | |
178 | element_type& | |
179 | operator*() const throw() | |
180 | { | |
181 | _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0); | |
182 | return *_M_ptr; | |
183 | } | |
184 | ||
185 | /** | |
186 | * @brief Smart pointer dereferencing. | |
187 | * | |
188 | * This returns the pointer itself, which the language then will | |
189 | * automatically cause to be dereferenced. | |
190 | */ | |
191 | element_type* | |
192 | operator->() const throw() | |
193 | { | |
194 | _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0); | |
195 | return _M_ptr; | |
196 | } | |
197 | ||
198 | /** | |
199 | * @brief Bypassing the smart pointer. | |
200 | * @return The raw pointer being managed. | |
201 | * | |
202 | * You can get a copy of the pointer that this object owns, for | |
203 | * situations such as passing to a function which only accepts | |
204 | * a raw pointer. | |
205 | * | |
206 | * @note This %auto_ptr still owns the memory. | |
207 | */ | |
208 | element_type* | |
209 | get() const throw() { return _M_ptr; } | |
210 | ||
211 | /** | |
212 | * @brief Bypassing the smart pointer. | |
213 | * @return The raw pointer being managed. | |
214 | * | |
215 | * You can get a copy of the pointer that this object owns, for | |
216 | * situations such as passing to a function which only accepts | |
217 | * a raw pointer. | |
218 | * | |
219 | * @note This %auto_ptr no longer owns the memory. When this object | |
220 | * goes out of scope, nothing will happen. | |
221 | */ | |
222 | element_type* | |
223 | release() throw() | |
224 | { | |
225 | element_type* __tmp = _M_ptr; | |
226 | _M_ptr = 0; | |
227 | return __tmp; | |
228 | } | |
229 | ||
230 | /** | |
231 | * @brief Forcibly deletes the managed object. | |
232 | * @param p A pointer (defaults to NULL). | |
233 | * | |
234 | * This object now @e owns the object pointed to by @a p. The | |
235 | * previous object has been deleted. | |
236 | */ | |
237 | void | |
238 | reset(element_type* __p = 0) throw() | |
239 | { | |
240 | if (__p != _M_ptr) | |
241 | { | |
242 | delete _M_ptr; | |
243 | _M_ptr = __p; | |
244 | } | |
245 | } | |
246 | ||
247 | /** | |
248 | * @brief Automatic conversions | |
249 | * | |
250 | * These operations convert an %auto_ptr into and from an auto_ptr_ref | |
251 | * automatically as needed. This allows constructs such as | |
252 | * @code | |
253 | * auto_ptr<Derived> func_returning_auto_ptr(.....); | |
254 | * ... | |
255 | * auto_ptr<Base> ptr = func_returning_auto_ptr(.....); | |
256 | * @endcode | |
257 | */ | |
258 | auto_ptr(auto_ptr_ref<element_type> __ref) throw() | |
259 | : _M_ptr(__ref._M_ptr) { } | |
260 | ||
261 | auto_ptr& | |
262 | operator=(auto_ptr_ref<element_type> __ref) throw() | |
263 | { | |
264 | if (__ref._M_ptr != this->get()) | |
265 | { | |
266 | delete _M_ptr; | |
267 | _M_ptr = __ref._M_ptr; | |
268 | } | |
269 | return *this; | |
270 | } | |
271 | ||
272 | template<typename _Tp1> | |
273 | operator auto_ptr_ref<_Tp1>() throw() | |
274 | { return auto_ptr_ref<_Tp1>(this->release()); } | |
275 | ||
276 | template<typename _Tp1> | |
277 | operator auto_ptr<_Tp1>() throw() | |
278 | { return auto_ptr<_Tp1>(this->release()); } | |
4dd9d9db | 279 | } _GLIBCXX_DEPRECATED_ATTR; |
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280 | |
281 | // _GLIBCXX_RESOLVE_LIB_DEFECTS | |
282 | // 541. shared_ptr template assignment and void | |
283 | template<> | |
284 | class auto_ptr<void> | |
285 | { | |
286 | public: | |
287 | typedef void element_type; | |
4dd9d9db | 288 | } _GLIBCXX_DEPRECATED_ATTR; |
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289 | |
290 | _GLIBCXX_END_NAMESPACE | |
291 | ||
acb8a4ef | 292 | #endif /* _STL_AUTO_PTR_H */ |