henrike@webrtc.org | f7795df | 2014-05-13 18:00:26 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2011 The WebRTC Project Authors. All rights reserved. |
| 3 | * |
| 4 | * Use of this source code is governed by a BSD-style license |
| 5 | * that can be found in the LICENSE file in the root of the source |
| 6 | * tree. An additional intellectual property rights grant can be found |
| 7 | * in the file PATENTS. All contributing project authors may |
| 8 | * be found in the AUTHORS file in the root of the source tree. |
| 9 | */ |
| 10 | |
| 11 | // Originally these classes are from Chromium. |
| 12 | // http://src.chromium.org/viewvc/chrome/trunk/src/base/memory/ref_counted.h?view=markup |
| 13 | |
| 14 | // |
| 15 | // A smart pointer class for reference counted objects. Use this class instead |
| 16 | // of calling AddRef and Release manually on a reference counted object to |
| 17 | // avoid common memory leaks caused by forgetting to Release an object |
| 18 | // reference. Sample usage: |
| 19 | // |
| 20 | // class MyFoo : public RefCounted<MyFoo> { |
| 21 | // ... |
| 22 | // }; |
| 23 | // |
| 24 | // void some_function() { |
| 25 | // scoped_refptr<MyFoo> foo = new MyFoo(); |
| 26 | // foo->Method(param); |
| 27 | // // |foo| is released when this function returns |
| 28 | // } |
| 29 | // |
| 30 | // void some_other_function() { |
| 31 | // scoped_refptr<MyFoo> foo = new MyFoo(); |
| 32 | // ... |
| 33 | // foo = NULL; // explicitly releases |foo| |
| 34 | // ... |
| 35 | // if (foo) |
| 36 | // foo->Method(param); |
| 37 | // } |
| 38 | // |
| 39 | // The above examples show how scoped_refptr<T> acts like a pointer to T. |
| 40 | // Given two scoped_refptr<T> classes, it is also possible to exchange |
| 41 | // references between the two objects, like so: |
| 42 | // |
| 43 | // { |
| 44 | // scoped_refptr<MyFoo> a = new MyFoo(); |
| 45 | // scoped_refptr<MyFoo> b; |
| 46 | // |
| 47 | // b.swap(a); |
| 48 | // // now, |b| references the MyFoo object, and |a| references NULL. |
| 49 | // } |
| 50 | // |
| 51 | // To make both |a| and |b| in the above example reference the same MyFoo |
| 52 | // object, simply use the assignment operator: |
| 53 | // |
| 54 | // { |
| 55 | // scoped_refptr<MyFoo> a = new MyFoo(); |
| 56 | // scoped_refptr<MyFoo> b; |
| 57 | // |
| 58 | // b = a; |
| 59 | // // now, |a| and |b| each own a reference to the same MyFoo object. |
| 60 | // } |
| 61 | // |
| 62 | |
| 63 | #ifndef WEBRTC_BASE_SCOPED_REF_PTR_H_ |
| 64 | #define WEBRTC_BASE_SCOPED_REF_PTR_H_ |
| 65 | |
| 66 | #include <stddef.h> |
| 67 | |
| 68 | namespace rtc { |
| 69 | |
| 70 | template <class T> |
| 71 | class scoped_refptr { |
| 72 | public: |
| 73 | scoped_refptr() : ptr_(NULL) { |
| 74 | } |
| 75 | |
| 76 | scoped_refptr(T* p) : ptr_(p) { |
| 77 | if (ptr_) |
| 78 | ptr_->AddRef(); |
| 79 | } |
| 80 | |
| 81 | scoped_refptr(const scoped_refptr<T>& r) : ptr_(r.ptr_) { |
| 82 | if (ptr_) |
| 83 | ptr_->AddRef(); |
| 84 | } |
| 85 | |
| 86 | template <typename U> |
| 87 | scoped_refptr(const scoped_refptr<U>& r) : ptr_(r.get()) { |
| 88 | if (ptr_) |
| 89 | ptr_->AddRef(); |
| 90 | } |
| 91 | |
| 92 | ~scoped_refptr() { |
| 93 | if (ptr_) |
| 94 | ptr_->Release(); |
| 95 | } |
| 96 | |
| 97 | T* get() const { return ptr_; } |
| 98 | operator T*() const { return ptr_; } |
| 99 | T* operator->() const { return ptr_; } |
| 100 | |
| 101 | // Release a pointer. |
| 102 | // The return value is the current pointer held by this object. |
| 103 | // If this object holds a NULL pointer, the return value is NULL. |
| 104 | // After this operation, this object will hold a NULL pointer, |
| 105 | // and will not own the object any more. |
| 106 | T* release() { |
| 107 | T* retVal = ptr_; |
| 108 | ptr_ = NULL; |
| 109 | return retVal; |
| 110 | } |
| 111 | |
| 112 | scoped_refptr<T>& operator=(T* p) { |
| 113 | // AddRef first so that self assignment should work |
| 114 | if (p) |
| 115 | p->AddRef(); |
| 116 | if (ptr_ ) |
| 117 | ptr_ ->Release(); |
| 118 | ptr_ = p; |
| 119 | return *this; |
| 120 | } |
| 121 | |
| 122 | scoped_refptr<T>& operator=(const scoped_refptr<T>& r) { |
| 123 | return *this = r.ptr_; |
| 124 | } |
| 125 | |
| 126 | template <typename U> |
| 127 | scoped_refptr<T>& operator=(const scoped_refptr<U>& r) { |
| 128 | return *this = r.get(); |
| 129 | } |
| 130 | |
| 131 | void swap(T** pp) { |
| 132 | T* p = ptr_; |
| 133 | ptr_ = *pp; |
| 134 | *pp = p; |
| 135 | } |
| 136 | |
| 137 | void swap(scoped_refptr<T>& r) { |
| 138 | swap(&r.ptr_); |
| 139 | } |
| 140 | |
| 141 | protected: |
| 142 | T* ptr_; |
| 143 | }; |
| 144 | |
| 145 | } // namespace rtc |
| 146 | |
| 147 | #endif // WEBRTC_BASE_SCOPED_REF_PTR_H_ |