Line data    Source code

       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 <memory>
      67             : 
      68             : namespace rtc {
      69             : 
      70             : template <class T>
      71             : class scoped_refptr {
      72             :  public:
      73           0 :   scoped_refptr() : ptr_(NULL) {
      74           0 :   }
      75             : 
      76           0 :   scoped_refptr(T* p) : ptr_(p) {
      77           0 :     if (ptr_)
      78           0 :       ptr_->AddRef();
      79           0 :   }
      80             : 
      81           0 :   scoped_refptr(const scoped_refptr<T>& r) : ptr_(r.ptr_) {
      82           0 :     if (ptr_)
      83           0 :       ptr_->AddRef();
      84           0 :   }
      85             : 
      86             :   template <typename U>
      87           0 :   scoped_refptr(const scoped_refptr<U>& r) : ptr_(r.get()) {
      88           0 :     if (ptr_)
      89           0 :       ptr_->AddRef();
      90           0 :   }
      91             : 
      92             :   // Move constructors.
      93           0 :   scoped_refptr(scoped_refptr<T>&& r) : ptr_(r.release()) {}
      94             : 
      95             :   template <typename U>
      96           0 :   scoped_refptr(scoped_refptr<U>&& r) : ptr_(r.release()) {}
      97             : 
      98           0 :   ~scoped_refptr() {
      99           0 :     if (ptr_)
     100           0 :       ptr_->Release();
     101           0 :   }
     102             : 
     103           0 :   T* get() const { return ptr_; }
     104           0 :   operator T*() const { return ptr_; }
     105           0 :   T* operator->() const { return ptr_; }
     106             : 
     107             :   // Release a pointer.
     108             :   // The return value is the current pointer held by this object.
     109             :   // If this object holds a NULL pointer, the return value is NULL.
     110             :   // After this operation, this object will hold a NULL pointer,
     111             :   // and will not own the object any more.
     112           0 :   T* release() {
     113           0 :     T* retVal = ptr_;
     114           0 :     ptr_ = NULL;
     115           0 :     return retVal;
     116             :   }
     117             : 
     118           0 :   scoped_refptr<T>& operator=(T* p) {
     119             :     // AddRef first so that self assignment should work
     120           0 :     if (p)
     121           0 :       p->AddRef();
     122           0 :     if (ptr_ )
     123           0 :       ptr_ ->Release();
     124           0 :     ptr_ = p;
     125           0 :     return *this;
     126             :   }
     127             : 
     128           0 :   scoped_refptr<T>& operator=(const scoped_refptr<T>& r) {
     129           0 :     return *this = r.ptr_;
     130             :   }
     131             : 
     132             :   template <typename U>
     133           0 :   scoped_refptr<T>& operator=(const scoped_refptr<U>& r) {
     134           0 :     return *this = r.get();
     135             :   }
     136             : 
     137           0 :   scoped_refptr<T>& operator=(scoped_refptr<T>&& r) {
     138           0 :     scoped_refptr<T>(std::move(r)).swap(*this);
     139           0 :     return *this;
     140             :   }
     141             : 
     142             :   template <typename U>
     143             :   scoped_refptr<T>& operator=(scoped_refptr<U>&& r) {
     144             :     scoped_refptr<T>(std::move(r)).swap(*this);
     145             :     return *this;
     146             :   }
     147             : 
     148           0 :   void swap(T** pp) {
     149           0 :     T* p = ptr_;
     150           0 :     ptr_ = *pp;
     151           0 :     *pp = p;
     152           0 :   }
     153             : 
     154           0 :   void swap(scoped_refptr<T>& r) {
     155           0 :     swap(&r.ptr_);
     156           0 :   }
     157             : 
     158             :  protected:
     159             :   T* ptr_;
     160             : };
     161             : 
     162             : }  // namespace rtc
     163             : 
     164             : #endif  // WEBRTC_BASE_SCOPED_REF_PTR_H_