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1 : /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
2 : /*
3 : * This file is part of the LibreOffice project.
4 : *
5 : * This Source Code Form is subject to the terms of the Mozilla Public
6 : * License, v. 2.0. If a copy of the MPL was not distributed with this
7 : * file, You can obtain one at http://mozilla.org/MPL/2.0/.
8 : *
9 : * This file incorporates work covered by the following license notice:
10 : *
11 : * Licensed to the Apache Software Foundation (ASF) under one or more
12 : * contributor license agreements. See the NOTICE file distributed
13 : * with this work for additional information regarding copyright
14 : * ownership. The ASF licenses this file to you under the Apache
15 : * License, Version 2.0 (the "License"); you may not use this file
16 : * except in compliance with the License. You may obtain a copy of
17 : * the License at http://www.apache.org/licenses/LICENSE-2.0 .
18 : */
19 :
20 : #ifndef INCLUDED_O3TL_HEAP_PTR_HXX
21 : #define INCLUDED_O3TL_HEAP_PTR_HXX
22 :
23 :
24 : #include <boost/assert.hpp>
25 : #include <boost/checked_delete.hpp>
26 :
27 :
28 : namespace o3tl
29 : {
30 : /** heap_ptr<> owns an object on the heap, which will be automatically
31 : deleted, when ~heap_ptr<>() is called.
32 :
33 : Applicability
34 : -------------
35 : heap_ptr<> can be used for class members on the heap.
36 : - One cannot forget to delete them in the destructor.
37 : - Constness will be transfered from the owning instance.
38 :
39 : heap_ptr<> can also be used as smart pointer in function bodies to
40 : ensure exception safety.
41 :
42 : Special Characteristics
43 : -----------------------
44 : - heap_ptr<> transfers constness from the owning object to
45 : the pointed to object. Such it behaves like if *get() would be
46 : a normal member of the owning object, not a pointer member.
47 : This is preferable to the normal pointer behaviour, because
48 : if an object is owned by another one, it is normally part of
49 : its state.
50 :
51 : - heap_ptr<> provides a ->release() function
52 :
53 : - For reasons of simplicity and portability ->is()
54 : is preferred over the safe-bool idiom.
55 :
56 : Copyability
57 : -----------
58 : heap_ptr is non copyable.
59 : - It forbids the copyconstructor and operator=(self).
60 :
61 : - Owning classes will automatically be non copyable, if they do not
62 : redefine those two functions themselves.
63 :
64 : Incomplete Types
65 : ----------------
66 : heap_ptr<> also works with incomplete types. You only need to write
67 : class T;
68 : but need not include <T>.hxx.
69 :
70 : If you use heap_ptr<> with an incomplete type, the owning class
71 : needs to define a non-inline destructor. Else the compiler will
72 : complain.
73 : */
74 : template <class T>
75 : class heap_ptr
76 : {
77 : public:
78 : typedef T element_type; /// Provided for generic programming.
79 : typedef heap_ptr<T> self;
80 :
81 : #ifndef __SUNPRO_CC
82 : typedef T * (self::* safe_bool )();
83 : #endif
84 :
85 : /// Now, pass_heapObject is owned by this.
86 : explicit heap_ptr(
87 : T * pass_heapObject = 0 );
88 : ~heap_ptr();
89 :
90 :
91 : /** Identical to reset(), except of the return value.
92 : @see heap_ptr<>::reset()
93 : */
94 : self & operator=(
95 : T * pass_heapObject );
96 : const T & operator*() const;
97 : T & operator*();
98 : const T * operator->() const;
99 : T * operator->();
100 :
101 : /// True, if pHeapObject != 0.
102 : #ifndef __SUNPRO_CC
103 : operator safe_bool() const;
104 : #else // workaround opt bug of Sun C++ compiler, when compiling with -xO3
105 : operator bool() const;
106 : #endif
107 :
108 :
109 : /** This deletes any prevoiusly existing ->pHeapObject.
110 : Now, pass_heapObject, if != 0, is owned by this.
111 :
112 : @onerror
113 : Ignores self-assignment.
114 : Such, multiple assignment of the same pointer to the same
115 : instance of heap_ptr<> is possible (though not recommended).
116 : */
117 : void reset(
118 : T * pass_heapObject );
119 : /** @return An object on the heap that must be deleted by the caller,
120 : or 0.
121 :
122 : @postcond get() == 0;
123 : */
124 : T * release();
125 : void swap(
126 : self & io_other );
127 :
128 : /// True, if pHeapObject != 0.
129 : bool is() const;
130 : const T * get() const;
131 : T * get();
132 :
133 : private:
134 : // Forbidden functions:
135 : heap_ptr( const self & ); /// Prevent copies.
136 : self & operator=( const self & ); /// Prevent copies.
137 :
138 : /// @attention Does not set ->pHeapObject = 0.
139 : void internal_delete();
140 :
141 : // DATA
142 : /// Will be deleted, when *this is destroyed.
143 : T * pHeapObject;
144 : };
145 :
146 :
147 : /** Supports the semantic of std::swap(). Provided as an aid to
148 : generic programming.
149 : */
150 : template<class T>
151 : inline void
152 1 : swap( heap_ptr<T> & io_a,
153 : heap_ptr<T> & io_b )
154 : {
155 1 : io_a.swap(io_b);
156 1 : }
157 :
158 :
159 :
160 : // IMPLEMENTATION
161 :
162 : template <class T>
163 : inline void
164 9 : heap_ptr<T>::internal_delete()
165 : {
166 9 : ::boost::checked_delete(pHeapObject);
167 :
168 : // Do not set pHeapObject to 0, because
169 : // that is reset to a value in all code
170 : // where internal_delete() is used.
171 9 : }
172 :
173 : template <class T>
174 : inline
175 5 : heap_ptr<T>::heap_ptr( T * pass_heapObject )
176 5 : : pHeapObject(pass_heapObject)
177 : {
178 5 : }
179 :
180 : template <class T>
181 : inline
182 5 : heap_ptr<T>::~heap_ptr()
183 : {
184 5 : internal_delete();
185 5 : }
186 :
187 : template <class T>
188 : inline heap_ptr<T> &
189 3 : heap_ptr<T>::operator=(T * pass_heapObject)
190 : {
191 3 : reset(pass_heapObject);
192 3 : return *this;
193 : }
194 :
195 : template <class T>
196 : inline const T &
197 2 : heap_ptr<T>::operator*() const
198 : {
199 : BOOST_ASSERT( pHeapObject != 0
200 : && "Accessing a heap_ptr<>(0)." );
201 2 : return *pHeapObject;
202 : }
203 :
204 : template <class T>
205 : inline T &
206 3 : heap_ptr<T>::operator*()
207 : {
208 : BOOST_ASSERT( pHeapObject != 0
209 : && "Accessing a heap_ptr<>(0)." );
210 3 : return *pHeapObject;
211 : }
212 :
213 : template <class T>
214 : inline const T *
215 2 : heap_ptr<T>::operator->() const
216 : {
217 2 : return pHeapObject;
218 : }
219 :
220 : template <class T>
221 : inline T *
222 7 : heap_ptr<T>::operator->()
223 : {
224 7 : return pHeapObject;
225 : }
226 :
227 : #ifndef __SUNPRO_CC
228 :
229 : template <class T>
230 : inline
231 3 : heap_ptr<T>::operator typename heap_ptr<T>::safe_bool() const
232 : {
233 : return is()
234 : ? safe_bool(&self::get)
235 3 : : safe_bool(0);
236 : }
237 :
238 : #else
239 :
240 : template <class T>
241 : inline heap_ptr<T>::operator bool() const
242 : {
243 : return is();
244 : }
245 :
246 : #endif // !defined(__SUNPRO_CC)
247 :
248 :
249 :
250 : template <class T>
251 : void
252 5 : heap_ptr<T>::reset(T * pass_heapObject)
253 : {
254 5 : if ( pHeapObject != 0
255 : && pHeapObject == pass_heapObject)
256 6 : return;
257 :
258 4 : internal_delete();
259 4 : pHeapObject = pass_heapObject;
260 : }
261 :
262 : template <class T>
263 : T *
264 2 : heap_ptr<T>::release()
265 : {
266 2 : T * ret = pHeapObject;
267 2 : pHeapObject = 0;
268 2 : return ret;
269 : }
270 :
271 : template <class T>
272 : void
273 2 : heap_ptr<T>::swap(self & io_other)
274 : {
275 2 : T * temp = io_other.pHeapObject;
276 2 : io_other.pHeapObject = pHeapObject;
277 2 : pHeapObject = temp;
278 2 : }
279 :
280 : template <class T>
281 : inline bool
282 14 : heap_ptr<T>::is() const
283 : {
284 14 : return pHeapObject != 0;
285 : }
286 :
287 : template <class T>
288 : inline const T *
289 2 : heap_ptr<T>::get() const
290 : {
291 2 : return pHeapObject;
292 : }
293 :
294 : template <class T>
295 : inline T *
296 5 : heap_ptr<T>::get()
297 : {
298 5 : return pHeapObject;
299 : }
300 :
301 :
302 : } // namespace o3tl
303 : #endif
304 :
305 : /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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