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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 : typedef T * (self::* safe_bool )();
82 :
83 : /// Now, pass_heapObject is owned by this.
84 : explicit heap_ptr(
85 : T * pass_heapObject = 0 );
86 : ~heap_ptr();
87 :
88 :
89 : /** Identical to reset(), except of the return value.
90 : @see heap_ptr<>::reset()
91 : */
92 : self & operator=(
93 : T * pass_heapObject );
94 : const T & operator*() const;
95 : T & operator*();
96 : const T * operator->() const;
97 : T * operator->();
98 :
99 : operator safe_bool() const;
100 :
101 : /** This deletes any prevoiusly existing ->pHeapObject.
102 : Now, pass_heapObject, if != 0, is owned by this.
103 :
104 : @onerror
105 : Ignores self-assignment.
106 : Such, multiple assignment of the same pointer to the same
107 : instance of heap_ptr<> is possible (though not recommended).
108 : */
109 : void reset(
110 : T * pass_heapObject );
111 : /** @return An object on the heap that must be deleted by the caller,
112 : or 0.
113 :
114 : @postcond get() == 0;
115 : */
116 : T * release();
117 : void swap(
118 : self & io_other );
119 :
120 : /// True, if pHeapObject != 0.
121 : bool is() const;
122 : const T * get() const;
123 : T * get();
124 :
125 : private:
126 : // Forbidden functions:
127 : heap_ptr( const self & ); /// Prevent copies.
128 : self & operator=( const self & ); /// Prevent copies.
129 :
130 : /// @attention Does not set ->pHeapObject = 0.
131 : void internal_delete();
132 :
133 : // DATA
134 : /// Will be deleted, when *this is destroyed.
135 : T * pHeapObject;
136 : };
137 :
138 :
139 : /** Supports the semantic of std::swap(). Provided as an aid to
140 : generic programming.
141 : */
142 : template<class T>
143 : inline void
144 : swap( heap_ptr<T> & io_a,
145 : heap_ptr<T> & io_b )
146 : {
147 : io_a.swap(io_b);
148 : }
149 :
150 :
151 :
152 : // IMPLEMENTATION
153 :
154 : template <class T>
155 : inline void
156 0 : heap_ptr<T>::internal_delete()
157 : {
158 0 : ::boost::checked_delete(pHeapObject);
159 :
160 : // Do not set pHeapObject to 0, because
161 : // that is reset to a value in all code
162 : // where internal_delete() is used.
163 0 : }
164 :
165 : template <class T>
166 : inline
167 0 : heap_ptr<T>::heap_ptr( T * pass_heapObject )
168 0 : : pHeapObject(pass_heapObject)
169 : {
170 0 : }
171 :
172 : template <class T>
173 : inline
174 0 : heap_ptr<T>::~heap_ptr()
175 : {
176 0 : internal_delete();
177 0 : }
178 :
179 : template <class T>
180 : inline heap_ptr<T> &
181 : heap_ptr<T>::operator=(T * pass_heapObject)
182 : {
183 : reset(pass_heapObject);
184 : return *this;
185 : }
186 :
187 : template <class T>
188 : inline const T &
189 : heap_ptr<T>::operator*() const
190 : {
191 : BOOST_ASSERT( pHeapObject != 0
192 : && "Accessing a heap_ptr<>(0)." );
193 : return *pHeapObject;
194 : }
195 :
196 : template <class T>
197 : inline T &
198 : heap_ptr<T>::operator*()
199 : {
200 : BOOST_ASSERT( pHeapObject != 0
201 : && "Accessing a heap_ptr<>(0)." );
202 : return *pHeapObject;
203 : }
204 :
205 : template <class T>
206 : inline const T *
207 : heap_ptr<T>::operator->() const
208 : {
209 : return pHeapObject;
210 : }
211 :
212 : template <class T>
213 : inline T *
214 : heap_ptr<T>::operator->()
215 : {
216 : return pHeapObject;
217 : }
218 :
219 : template <class T>
220 : inline
221 : heap_ptr<T>::operator typename heap_ptr<T>::safe_bool() const
222 : {
223 : return is()
224 : ? safe_bool(&self::get)
225 : : safe_bool(0);
226 : }
227 :
228 : template <class T>
229 : void
230 0 : heap_ptr<T>::reset(T * pass_heapObject)
231 : {
232 0 : if ( pHeapObject != 0
233 : && pHeapObject == pass_heapObject)
234 0 : return;
235 :
236 0 : internal_delete();
237 0 : pHeapObject = pass_heapObject;
238 : }
239 :
240 : template <class T>
241 : T *
242 0 : heap_ptr<T>::release()
243 : {
244 0 : T * ret = pHeapObject;
245 0 : pHeapObject = 0;
246 0 : return ret;
247 : }
248 :
249 : template <class T>
250 : void
251 : heap_ptr<T>::swap(self & io_other)
252 : {
253 : T * temp = io_other.pHeapObject;
254 : io_other.pHeapObject = pHeapObject;
255 : pHeapObject = temp;
256 : }
257 :
258 : template <class T>
259 : inline bool
260 : heap_ptr<T>::is() const
261 : {
262 : return pHeapObject != 0;
263 : }
264 :
265 : template <class T>
266 : inline const T *
267 : heap_ptr<T>::get() const
268 : {
269 : return pHeapObject;
270 : }
271 :
272 : template <class T>
273 : inline T *
274 0 : heap_ptr<T>::get()
275 : {
276 0 : return pHeapObject;
277 : }
278 :
279 :
280 : } // namespace o3tl
281 : #endif
282 :
283 : /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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