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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 = nullptr; // 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 API_SCOPED_REFPTR_H_
#define API_SCOPED_REFPTR_H_
#include <memory>
#include <utility>
namespace webrtc {
template <class T>
class scoped_refptr {
public:
typedef T element_type;
scoped_refptr() : ptr_(nullptr) {}
scoped_refptr(std::nullptr_t) : ptr_(nullptr) {} // NOLINT(runtime/explicit)
explicit 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();
}
// Move constructors.
scoped_refptr(scoped_refptr<T>&& r) noexcept : ptr_(r.release()) {}
template <typename U>
scoped_refptr(scoped_refptr<U>&& r) noexcept : ptr_(r.release()) {}
~scoped_refptr() {
if (ptr_)
ptr_->Release();
}
T* get() const { return ptr_; }
explicit operator bool() const { return ptr_ != nullptr; }
T& operator*() const { return *ptr_; }
T* operator->() const { return ptr_; }
// Returns the (possibly null) raw pointer, and makes the scoped_refptr hold a
// null pointer, all without touching the reference count of the underlying
// pointed-to object. The object is still reference counted, and the caller of
// release() is now the proud owner of one reference, so it is responsible for
// calling Release() once on the object when no longer using it.
T* release() {
T* retVal = ptr_;
ptr_ = nullptr;
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();
}
scoped_refptr<T>& operator=(scoped_refptr<T>&& r) noexcept {
scoped_refptr<T>(std::move(r)).swap(*this);
return *this;
}
template <typename U>
scoped_refptr<T>& operator=(scoped_refptr<U>&& r) noexcept {
scoped_refptr<T>(std::move(r)).swap(*this);
return *this;
}
void swap(T** pp) noexcept {
T* p = ptr_;
ptr_ = *pp;
*pp = p;
}
void swap(scoped_refptr<T>& r) noexcept { swap(&r.ptr_); }
protected:
T* ptr_;
};
template <typename T, typename U>
bool operator==(const scoped_refptr<T>& a, const scoped_refptr<U>& b) {
return a.get() == b.get();
}
template <typename T, typename U>
bool operator!=(const scoped_refptr<T>& a, const scoped_refptr<U>& b) {
return !(a == b);
}
template <typename T>
bool operator==(const scoped_refptr<T>& a, std::nullptr_t) {
return a.get() == nullptr;
}
template <typename T>
bool operator!=(const scoped_refptr<T>& a, std::nullptr_t) {
return !(a == nullptr);
}
template <typename T>
bool operator==(std::nullptr_t, const scoped_refptr<T>& a) {
return a.get() == nullptr;
}
template <typename T>
bool operator!=(std::nullptr_t, const scoped_refptr<T>& a) {
return !(a == nullptr);
}
// Comparison with raw pointer.
template <typename T, typename U>
bool operator==(const scoped_refptr<T>& a, const U* b) {
return a.get() == b;
}
template <typename T, typename U>
bool operator!=(const scoped_refptr<T>& a, const U* b) {
return !(a == b);
}
template <typename T, typename U>
bool operator==(const T* a, const scoped_refptr<U>& b) {
return a == b.get();
}
template <typename T, typename U>
bool operator!=(const T* a, const scoped_refptr<U>& b) {
return !(a == b);
}
// Ordered comparison, needed for use as a std::map key.
template <typename T, typename U>
bool operator<(const scoped_refptr<T>& a, const scoped_refptr<U>& b) {
return a.get() < b.get();
}
} // namespace webrtc
namespace rtc {
// Backwards compatible alias.
// TODO(bugs.webrtc.org/15622): Deprecate and remove.
template <typename T>
using scoped_refptr = webrtc::scoped_refptr<T>;
} // namespace rtc
#endif // API_SCOPED_REFPTR_H_
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