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1 | |
2 /* | |
3 * Copyright 2011 Google Inc. | |
4 * | |
5 * Use of this source code is governed by a BSD-style license that can be | |
6 * found in the LICENSE file. | |
7 */ | |
8 | |
9 | |
10 #ifndef SkTScopedPtr_DEFINED | |
11 #define SkTScopedPtr_DEFINED | |
12 | |
13 #include "SkTypes.h" | |
14 | |
15 /** \class SkTScopedPtr | |
16 A SkTScopedPtr<T> is like a T*, except that the destructor of SkTScopedPtr<T> | |
17 automatically deletes the pointer it holds (if any). That is, SkTScopedPtr<T> | |
18 owns the T object that it points to. Like a T*, a SkTScopedPtr<T> may hold | |
19 either NULL or a pointer to a T object. Also like T*, SkTScopedPtr<T> is | |
20 thread-compatible, and once you dereference it, you get the threadsafety | |
21 guarantees of T. | |
22 | |
23 The size of a SkTScopedPtr is small: sizeof(SkTScopedPtr<T>) == sizeof(T*) | |
24 */ | |
25 template <typename T> class SkTScopedPtr : SkNoncopyable { | |
26 public: | |
27 explicit SkTScopedPtr(T* o = NULL) : fObj(o) {} | |
28 ~SkTScopedPtr() { | |
29 enum { kTypeMustBeComplete = sizeof(T) }; | |
30 delete fObj; | |
31 } | |
32 | |
33 /** Delete the current object, if any. Then take ownership of the | |
34 passed object. | |
35 */ | |
36 void reset(T* o = NULL) { | |
37 if (o != fObj) { | |
38 enum { kTypeMustBeComplete = sizeof(T) }; | |
39 delete fObj; | |
40 fObj = o; | |
41 } | |
42 } | |
43 | |
44 /** Without deleting the current object, return it and forget about it. | |
45 Similar to calling get() and reset(), but the object is not deleted. | |
46 */ | |
47 T* release() { | |
48 T* retVal = fObj; | |
49 fObj = NULL; | |
50 return retVal; | |
51 } | |
52 | |
53 T& operator*() const { | |
54 SkASSERT(fObj != NULL); | |
55 return *fObj; | |
56 } | |
57 T* operator->() const { | |
58 SkASSERT(fObj != NULL); | |
59 return fObj; | |
60 } | |
61 T* get() const { return fObj; } | |
62 | |
63 bool operator==(T* o) const { return fObj == o; } | |
64 bool operator!=(T* o) const { return fObj != o; } | |
65 | |
66 private: | |
67 T* fObj; | |
68 | |
69 // Forbid comparison of SkTScopedPtr types. If T2 != T, it doesn't make | |
70 // sense, and if T2 == T, it still doesn't make sense because the same | |
71 // object can't be owned by two different scoped_ptrs. | |
72 template <class T2> bool operator==(SkTScopedPtr<T2> const& o2) const; | |
73 template <class T2> bool operator!=(SkTScopedPtr<T2> const& o2) const; | |
74 }; | |
75 | |
76 #endif | |
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