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+/*
+ * Copyright 2011 The WebRTC Project Authors. All rights reserved.
+ *
+ * Use of this source code is governed by a BSD-style license
+ * that can be found in the LICENSE file in the root of the source
+ * tree. An additional intellectual property rights grant can be found
+ * in the file PATENTS. All contributing project authors may
+ * be found in the AUTHORS file in the root of the source tree.
+ */
+
+// Originally these classes are from Chromium.
+// http://src.chromium.org/viewvc/chrome/trunk/src/base/memory/ref_counted.h?view=markup
+
+//
+// A smart pointer class for reference counted objects. Use this class instead
+// of calling AddRef and Release manually on a reference counted object to
+// avoid common memory leaks caused by forgetting to Release an object
+// reference. Sample usage:
+//
+// class MyFoo : public RefCounted<MyFoo> {
+// ...
+// };
+//
+// void some_function() {
+// scoped_refptr<MyFoo> foo = new MyFoo();
+// foo->Method(param);
+// // |foo| is released when this function returns
+// }
+//
+// void some_other_function() {
+// scoped_refptr<MyFoo> foo = new MyFoo();
+// ...
+// foo = NULL; // explicitly releases |foo|
+// ...
+// if (foo)
+// foo->Method(param);
+// }
+//
+// The above examples show how scoped_refptr<T> acts like a pointer to T.
+// Given two scoped_refptr<T> classes, it is also possible to exchange
+// references between the two objects, like so:
+//
+// {
+// scoped_refptr<MyFoo> a = new MyFoo();
+// scoped_refptr<MyFoo> b;
+//
+// b.swap(a);
+// // now, |b| references the MyFoo object, and |a| references NULL.
+// }
+//
+// To make both |a| and |b| in the above example reference the same MyFoo
+// object, simply use the assignment operator:
+//
+// {
+// scoped_refptr<MyFoo> a = new MyFoo();
+// scoped_refptr<MyFoo> b;
+//
+// b = a;
+// // now, |a| and |b| each own a reference to the same MyFoo object.
+// }
+//
+
+#ifndef WEBRTC_BASE_SCOPED_REF_PTR_H_
+#define WEBRTC_BASE_SCOPED_REF_PTR_H_
+
+#include <stddef.h>
+
+namespace rtc {
+
+template <class T>
+class scoped_refptr {
+ public:
+ scoped_refptr() : ptr_(NULL) {
+ }
+
+ scoped_refptr(T* p) : ptr_(p) {
+ if (ptr_)
+ ptr_->AddRef();
+ }
+
+ scoped_refptr(const scoped_refptr<T>& r) : ptr_(r.ptr_) {
+ if (ptr_)
+ ptr_->AddRef();
+ }
+
+ template <typename U>
+ scoped_refptr(const scoped_refptr<U>& r) : ptr_(r.get()) {
+ if (ptr_)
+ ptr_->AddRef();
+ }
+
+ ~scoped_refptr() {
+ if (ptr_)
+ ptr_->Release();
+ }
+
+ T* get() const { return ptr_; }
+ operator T*() const { return ptr_; }
+ T* operator->() const { return ptr_; }
+
+ // Release a pointer.
+ // The return value is the current pointer held by this object.
+ // If this object holds a NULL pointer, the return value is NULL.
+ // After this operation, this object will hold a NULL pointer,
+ // and will not own the object any more.
+ T* release() {
+ T* retVal = ptr_;
+ ptr_ = NULL;
+ return retVal;
+ }
+
+ scoped_refptr<T>& operator=(T* p) {
+ // AddRef first so that self assignment should work
+ if (p)
+ p->AddRef();
+ if (ptr_ )
+ ptr_ ->Release();
+ ptr_ = p;
+ return *this;
+ }
+
+ scoped_refptr<T>& operator=(const scoped_refptr<T>& r) {
+ return *this = r.ptr_;
+ }
+
+ template <typename U>
+ scoped_refptr<T>& operator=(const scoped_refptr<U>& r) {
+ return *this = r.get();
+ }
+
+ void swap(T** pp) {
+ T* p = ptr_;
+ ptr_ = *pp;
+ *pp = p;
+ }
+
+ void swap(scoped_refptr<T>& r) {
+ swap(&r.ptr_);
+ }
+
+ protected:
+ T* ptr_;
+};
+
+} // namespace rtc
+
+#endif // WEBRTC_BASE_SCOPED_REF_PTR_H_