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1 : // Copyright 2013 Google Inc. All Rights Reserved.
2 : //
3 : // Redistribution and use in source and binary forms, with or without
4 : // modification, are permitted provided that the following conditions are
5 : // met:
6 : //
7 : // * Redistributions of source code must retain the above copyright
8 : // notice, this list of conditions and the following disclaimer.
9 : // * Redistributions in binary form must reproduce the above
10 : // copyright notice, this list of conditions and the following disclaimer
11 : // in the documentation and/or other materials provided with the
12 : // distribution.
13 : // * Neither the name of Google Inc. nor the names of its
14 : // contributors may be used to endorse or promote products derived from
15 : // this software without specific prior written permission.
16 : //
17 : // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18 : // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19 : // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20 : // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
21 : // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22 : // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23 : // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 : // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 : // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 : // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27 : // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 :
29 : // Scopers help you manage ownership of a pointer, helping you easily manage the
30 : // a pointer within a scope, and automatically destroying the pointer at the
31 : // end of a scope. There are two main classes you will use, which correspond
32 : // to the operators new/delete and new[]/delete[].
33 : //
34 : // Example usage (scoped_ptr):
35 : // {
36 : // scoped_ptr<Foo> foo(new Foo("wee"));
37 : // } // foo goes out of scope, releasing the pointer with it.
38 : //
39 : // {
40 : // scoped_ptr<Foo> foo; // No pointer managed.
41 : // foo.reset(new Foo("wee")); // Now a pointer is managed.
42 : // foo.reset(new Foo("wee2")); // Foo("wee") was destroyed.
43 : // foo.reset(new Foo("wee3")); // Foo("wee2") was destroyed.
44 : // foo->Method(); // Foo::Method() called.
45 : // foo.get()->Method(); // Foo::Method() called.
46 : // SomeFunc(foo.release()); // SomeFunc takes ownership, foo no longer
47 : // // manages a pointer.
48 : // foo.reset(new Foo("wee4")); // foo manages a pointer again.
49 : // foo.reset(); // Foo("wee4") destroyed, foo no longer
50 : // // manages a pointer.
51 : // } // foo wasn't managing a pointer, so nothing was destroyed.
52 : //
53 : // Example usage (scoped_array):
54 : // {
55 : // scoped_array<Foo> foo(new Foo[100]);
56 : // foo.get()->Method(); // Foo::Method on the 0th element.
57 : // foo[10].Method(); // Foo::Method on the 10th element.
58 : // }
59 :
60 : #ifndef COMMON_SCOPED_PTR_H_
61 : #define COMMON_SCOPED_PTR_H_
62 :
63 : // This is an implementation designed to match the anticipated future TR2
64 : // implementation of the scoped_ptr class, and its closely-related brethren,
65 : // scoped_array, scoped_ptr_malloc.
66 :
67 : #include <assert.h>
68 : #include <stddef.h>
69 : #include <stdlib.h>
70 :
71 : namespace google_breakpad {
72 :
73 : // A scoped_ptr<T> is like a T*, except that the destructor of scoped_ptr<T>
74 : // automatically deletes the pointer it holds (if any).
75 : // That is, scoped_ptr<T> owns the T object that it points to.
76 : // Like a T*, a scoped_ptr<T> may hold either NULL or a pointer to a T object.
77 : // Also like T*, scoped_ptr<T> is thread-compatible, and once you
78 : // dereference it, you get the threadsafety guarantees of T.
79 : //
80 : // The size of a scoped_ptr is small:
81 : // sizeof(scoped_ptr<C>) == sizeof(C*)
82 : template <class C>
83 : class scoped_ptr {
84 : public:
85 :
86 : // The element type
87 : typedef C element_type;
88 :
89 : // Constructor. Defaults to initializing with NULL.
90 : // There is no way to create an uninitialized scoped_ptr.
91 : // The input parameter must be allocated with new.
92 0 : explicit scoped_ptr(C* p = NULL) : ptr_(p) { }
93 :
94 : // Destructor. If there is a C object, delete it.
95 : // We don't need to test ptr_ == NULL because C++ does that for us.
96 0 : ~scoped_ptr() {
97 : enum { type_must_be_complete = sizeof(C) };
98 0 : delete ptr_;
99 0 : }
100 :
101 : // Reset. Deletes the current owned object, if any.
102 : // Then takes ownership of a new object, if given.
103 : // this->reset(this->get()) works.
104 0 : void reset(C* p = NULL) {
105 0 : if (p != ptr_) {
106 : enum { type_must_be_complete = sizeof(C) };
107 0 : delete ptr_;
108 0 : ptr_ = p;
109 : }
110 0 : }
111 :
112 : // Accessors to get the owned object.
113 : // operator* and operator-> will assert() if there is no current object.
114 : C& operator*() const {
115 : assert(ptr_ != NULL);
116 : return *ptr_;
117 : }
118 0 : C* operator->() const {
119 0 : assert(ptr_ != NULL);
120 0 : return ptr_;
121 : }
122 0 : C* get() const { return ptr_; }
123 :
124 : // Comparison operators.
125 : // These return whether two scoped_ptr refer to the same object, not just to
126 : // two different but equal objects.
127 : bool operator==(C* p) const { return ptr_ == p; }
128 : bool operator!=(C* p) const { return ptr_ != p; }
129 :
130 : // Swap two scoped pointers.
131 : void swap(scoped_ptr& p2) {
132 : C* tmp = ptr_;
133 : ptr_ = p2.ptr_;
134 : p2.ptr_ = tmp;
135 : }
136 :
137 : // Release a pointer.
138 : // The return value is the current pointer held by this object.
139 : // If this object holds a NULL pointer, the return value is NULL.
140 : // After this operation, this object will hold a NULL pointer,
141 : // and will not own the object any more.
142 : C* release() {
143 : C* retVal = ptr_;
144 : ptr_ = NULL;
145 : return retVal;
146 : }
147 :
148 : private:
149 : C* ptr_;
150 :
151 : // Forbid comparison of scoped_ptr types. If C2 != C, it totally doesn't
152 : // make sense, and if C2 == C, it still doesn't make sense because you should
153 : // never have the same object owned by two different scoped_ptrs.
154 : template <class C2> bool operator==(scoped_ptr<C2> const& p2) const;
155 : template <class C2> bool operator!=(scoped_ptr<C2> const& p2) const;
156 :
157 : // Disallow evil constructors
158 : scoped_ptr(const scoped_ptr&);
159 : void operator=(const scoped_ptr&);
160 : };
161 :
162 : // Free functions
163 : template <class C>
164 : void swap(scoped_ptr<C>& p1, scoped_ptr<C>& p2) {
165 : p1.swap(p2);
166 : }
167 :
168 : template <class C>
169 : bool operator==(C* p1, const scoped_ptr<C>& p2) {
170 : return p1 == p2.get();
171 : }
172 :
173 : template <class C>
174 : bool operator!=(C* p1, const scoped_ptr<C>& p2) {
175 : return p1 != p2.get();
176 : }
177 :
178 : // scoped_array<C> is like scoped_ptr<C>, except that the caller must allocate
179 : // with new [] and the destructor deletes objects with delete [].
180 : //
181 : // As with scoped_ptr<C>, a scoped_array<C> either points to an object
182 : // or is NULL. A scoped_array<C> owns the object that it points to.
183 : // scoped_array<T> is thread-compatible, and once you index into it,
184 : // the returned objects have only the threadsafety guarantees of T.
185 : //
186 : // Size: sizeof(scoped_array<C>) == sizeof(C*)
187 : template <class C>
188 : class scoped_array {
189 : public:
190 :
191 : // The element type
192 : typedef C element_type;
193 :
194 : // Constructor. Defaults to intializing with NULL.
195 : // There is no way to create an uninitialized scoped_array.
196 : // The input parameter must be allocated with new [].
197 0 : explicit scoped_array(C* p = NULL) : array_(p) { }
198 :
199 : // Destructor. If there is a C object, delete it.
200 : // We don't need to test ptr_ == NULL because C++ does that for us.
201 0 : ~scoped_array() {
202 : enum { type_must_be_complete = sizeof(C) };
203 0 : delete[] array_;
204 0 : }
205 :
206 : // Reset. Deletes the current owned object, if any.
207 : // Then takes ownership of a new object, if given.
208 : // this->reset(this->get()) works.
209 0 : void reset(C* p = NULL) {
210 0 : if (p != array_) {
211 : enum { type_must_be_complete = sizeof(C) };
212 0 : delete[] array_;
213 0 : array_ = p;
214 : }
215 0 : }
216 :
217 : // Get one element of the current object.
218 : // Will assert() if there is no current object, or index i is negative.
219 : C& operator[](ptrdiff_t i) const {
220 : assert(i >= 0);
221 : assert(array_ != NULL);
222 : return array_[i];
223 : }
224 :
225 : // Get a pointer to the zeroth element of the current object.
226 : // If there is no current object, return NULL.
227 0 : C* get() const {
228 0 : return array_;
229 : }
230 :
231 : // Comparison operators.
232 : // These return whether two scoped_array refer to the same object, not just to
233 : // two different but equal objects.
234 : bool operator==(C* p) const { return array_ == p; }
235 : bool operator!=(C* p) const { return array_ != p; }
236 :
237 : // Swap two scoped arrays.
238 : void swap(scoped_array& p2) {
239 : C* tmp = array_;
240 : array_ = p2.array_;
241 : p2.array_ = tmp;
242 : }
243 :
244 : // Release an array.
245 : // The return value is the current pointer held by this object.
246 : // If this object holds a NULL pointer, the return value is NULL.
247 : // After this operation, this object will hold a NULL pointer,
248 : // and will not own the object any more.
249 : C* release() {
250 : C* retVal = array_;
251 : array_ = NULL;
252 : return retVal;
253 : }
254 :
255 : private:
256 : C* array_;
257 :
258 : // Forbid comparison of different scoped_array types.
259 : template <class C2> bool operator==(scoped_array<C2> const& p2) const;
260 : template <class C2> bool operator!=(scoped_array<C2> const& p2) const;
261 :
262 : // Disallow evil constructors
263 : scoped_array(const scoped_array&);
264 : void operator=(const scoped_array&);
265 : };
266 :
267 : // Free functions
268 : template <class C>
269 : void swap(scoped_array<C>& p1, scoped_array<C>& p2) {
270 : p1.swap(p2);
271 : }
272 :
273 : template <class C>
274 : bool operator==(C* p1, const scoped_array<C>& p2) {
275 : return p1 == p2.get();
276 : }
277 :
278 : template <class C>
279 : bool operator!=(C* p1, const scoped_array<C>& p2) {
280 : return p1 != p2.get();
281 : }
282 :
283 : // This class wraps the c library function free() in a class that can be
284 : // passed as a template argument to scoped_ptr_malloc below.
285 : class ScopedPtrMallocFree {
286 : public:
287 : inline void operator()(void* x) const {
288 : free(x);
289 : }
290 : };
291 :
292 : // scoped_ptr_malloc<> is similar to scoped_ptr<>, but it accepts a
293 : // second template argument, the functor used to free the object.
294 :
295 : template<class C, class FreeProc = ScopedPtrMallocFree>
296 : class scoped_ptr_malloc {
297 : public:
298 :
299 : // The element type
300 : typedef C element_type;
301 :
302 : // Constructor. Defaults to initializing with NULL.
303 : // There is no way to create an uninitialized scoped_ptr.
304 : // The input parameter must be allocated with an allocator that matches the
305 : // Free functor. For the default Free functor, this is malloc, calloc, or
306 : // realloc.
307 : explicit scoped_ptr_malloc(C* p = NULL): ptr_(p) {}
308 :
309 : // Destructor. If there is a C object, call the Free functor.
310 : ~scoped_ptr_malloc() {
311 : reset();
312 : }
313 :
314 : // Reset. Calls the Free functor on the current owned object, if any.
315 : // Then takes ownership of a new object, if given.
316 : // this->reset(this->get()) works.
317 : void reset(C* p = NULL) {
318 : if (ptr_ != p) {
319 : FreeProc free_proc;
320 : free_proc(ptr_);
321 : ptr_ = p;
322 : }
323 : }
324 :
325 : // Get the current object.
326 : // operator* and operator-> will cause an assert() failure if there is
327 : // no current object.
328 : C& operator*() const {
329 : assert(ptr_ != NULL);
330 : return *ptr_;
331 : }
332 :
333 : C* operator->() const {
334 : assert(ptr_ != NULL);
335 : return ptr_;
336 : }
337 :
338 : C* get() const {
339 : return ptr_;
340 : }
341 :
342 : // Comparison operators.
343 : // These return whether a scoped_ptr_malloc and a plain pointer refer
344 : // to the same object, not just to two different but equal objects.
345 : // For compatibility with the boost-derived implementation, these
346 : // take non-const arguments.
347 : bool operator==(C* p) const {
348 : return ptr_ == p;
349 : }
350 :
351 : bool operator!=(C* p) const {
352 : return ptr_ != p;
353 : }
354 :
355 : // Swap two scoped pointers.
356 : void swap(scoped_ptr_malloc & b) {
357 : C* tmp = b.ptr_;
358 : b.ptr_ = ptr_;
359 : ptr_ = tmp;
360 : }
361 :
362 : // Release a pointer.
363 : // The return value is the current pointer held by this object.
364 : // If this object holds a NULL pointer, the return value is NULL.
365 : // After this operation, this object will hold a NULL pointer,
366 : // and will not own the object any more.
367 : C* release() {
368 : C* tmp = ptr_;
369 : ptr_ = NULL;
370 : return tmp;
371 : }
372 :
373 : private:
374 : C* ptr_;
375 :
376 : // no reason to use these: each scoped_ptr_malloc should have its own object
377 : template <class C2, class GP>
378 : bool operator==(scoped_ptr_malloc<C2, GP> const& p) const;
379 : template <class C2, class GP>
380 : bool operator!=(scoped_ptr_malloc<C2, GP> const& p) const;
381 :
382 : // Disallow evil constructors
383 : scoped_ptr_malloc(const scoped_ptr_malloc&);
384 : void operator=(const scoped_ptr_malloc&);
385 : };
386 :
387 : template<class C, class FP> inline
388 : void swap(scoped_ptr_malloc<C, FP>& a, scoped_ptr_malloc<C, FP>& b) {
389 : a.swap(b);
390 : }
391 :
392 : template<class C, class FP> inline
393 : bool operator==(C* p, const scoped_ptr_malloc<C, FP>& b) {
394 : return p == b.get();
395 : }
396 :
397 : template<class C, class FP> inline
398 : bool operator!=(C* p, const scoped_ptr_malloc<C, FP>& b) {
399 : return p != b.get();
400 : }
401 :
402 : } // namespace google_breakpad
403 :
404 : #endif // COMMON_SCOPED_PTR_H_
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