Remove Base Class from ScopedComPtr and Deprecate

base/win/scoped_comptr.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_WIN_SCOPED_COMPTR_H_
 #define BASE_WIN_SCOPED_COMPTR_H_
 
 #include <unknwn.h>
 
 #include "base/logging.h"
-#include "base/memory/ref_counted.h"
 
 namespace base {
 namespace win {
 
+// DEPRECATED: Use Microsoft::WRL::ComPtr instead.
 // A fairly minimalistic smart class for COM interface pointers.
-// Uses scoped_refptr for the basic smart pointer functionality
-// and adds a few IUnknown specific services.
 template <class Interface, const IID* interface_id = &__uuidof(Interface)>
-class ScopedComPtr : public scoped_refptr<Interface> {
+class ScopedComPtr {
  public:
   // Utility template to prevent users of ScopedComPtr from calling AddRef
   // and/or Release() without going through the ScopedComPtr class.
   class BlockIUnknownMethods : public Interface {
    private:
     STDMETHOD(QueryInterface)(REFIID iid, void** object) = 0;
     STDMETHOD_(ULONG, AddRef)() = 0;
     STDMETHOD_(ULONG, Release)() = 0;
   };
 
-  typedef scoped_refptr<Interface> ParentClass;
-
   ScopedComPtr() {
   }
 
-  explicit ScopedComPtr(Interface* p) : ParentClass(p) {
+  explicit ScopedComPtr(Interface* p) : ptr_(p) {
+    if (ptr_)
+      ptr_->AddRef();
   }
 
-  ScopedComPtr(const ScopedComPtr<Interface, interface_id>& p)
-      : ParentClass(p) {
+  ScopedComPtr(const ScopedComPtr<Interface, interface_id>& p) : ptr_(p.get()) {
+    if (ptr_)
+      ptr_->AddRef();
   }
 
   ~ScopedComPtr() {
     // We don't want the smart pointer class to be bigger than the pointer
     // it wraps.
     static_assert(
         sizeof(ScopedComPtr<Interface, interface_id>) == sizeof(Interface*),
         "ScopedComPtrSize");
+    Release();
   }
 
+  Interface* get() const { return ptr_; }
+
+  explicit operator bool() const { return ptr_ != nullptr; }
+
   // Explicit Release() of the held object.  Useful for reuse of the
   // ScopedComPtr instance.
   // Note that this function equates to IUnknown::Release and should not
   // be confused with e.g. unique_ptr::release().
   void Release() {
-    if (this->ptr_ != NULL) {
-      this->ptr_->Release();
-      this->ptr_ = NULL;
+    Interface* temp = ptr_;
+    if (temp) {
+      ptr_ = nullptr;
+      temp->Release();
     }
   }
 
   // Sets the internal pointer to NULL and returns the held object without
   // releasing the reference.
   Interface* Detach() {
-    Interface* p = this->ptr_;
-    this->ptr_ = NULL;
+    Interface* p = ptr_;
+    ptr_ = nullptr;
     return p;
   }
 
   // Accepts an interface pointer that has already been addref-ed.
   void Attach(Interface* p) {
-    DCHECK(!this->ptr_);
-    this->ptr_ = p;
+    DCHECK(!ptr_);
+    ptr_ = p;
   }
 
   // Retrieves the pointer address.
   // Used to receive object pointers as out arguments (and take ownership).
   // The function DCHECKs on the current value being NULL.
   // Usage: Foo(p.Receive());
   Interface** Receive() {
-    DCHECK(!this->ptr_) << "Object leak. Pointer must be NULL";
-    return &this->ptr_;
+    DCHECK(!ptr_) << "Object leak. Pointer must be NULL";
+    return &ptr_;
   }
 
   // A convenience for whenever a void pointer is needed as an out argument.
   void** ReceiveVoid() {
     return reinterpret_cast<void**>(Receive());
   }
 
   template <class Query>
   HRESULT QueryInterface(Query** p) {
-    DCHECK(p != NULL);
-    DCHECK(this->ptr_ != NULL);
+    DCHECK(p);
+    DCHECK(ptr_);
     // IUnknown already has a template version of QueryInterface
     // so the iid parameter is implicit here. The only thing this
     // function adds are the DCHECKs.
-    return this->ptr_->QueryInterface(p);
+    return ptr_->QueryInterface(p);
   }
 
   // QI for times when the IID is not associated with the type.
   HRESULT QueryInterface(const IID& iid, void** obj) {
-    DCHECK(obj != NULL);
-    DCHECK(this->ptr_ != NULL);
-    return this->ptr_->QueryInterface(iid, obj);
+    DCHECK(obj);
+    DCHECK(ptr_);
+    return ptr_->QueryInterface(iid, obj);
   }
 
   // Queries |other| for the interface this object wraps and returns the
   // error code from the other->QueryInterface operation.
   HRESULT QueryFrom(IUnknown* object) {
-    DCHECK(object != NULL);
+    DCHECK(object);
     return object->QueryInterface(Receive());
   }
 
   // Convenience wrapper around CoCreateInstance
-  HRESULT CreateInstance(const CLSID& clsid, IUnknown* outer = NULL,
+  HRESULT CreateInstance(const CLSID& clsid,
+                         IUnknown* outer = nullptr,
                          DWORD context = CLSCTX_ALL) {
-    DCHECK(!this->ptr_);
+    DCHECK(!ptr_);
     HRESULT hr = ::CoCreateInstance(clsid, outer, context, *interface_id,
-                                    reinterpret_cast<void**>(&this->ptr_));
+                                    reinterpret_cast<void**>(&ptr_));
     return hr;
   }
 
   // Checks if the identity of |other| and this object is the same.
   bool IsSameObject(IUnknown* other) {
-    if (!other && !this->ptr_)
+    if (!other && !ptr_)
       return true;
 
-    if (!other || !this->ptr_)
+    if (!other || !ptr_)
       return false;
 
     ScopedComPtr<IUnknown> my_identity;
     QueryInterface(my_identity.Receive());
 
     ScopedComPtr<IUnknown> other_identity;
     other->QueryInterface(other_identity.Receive());
 
     return my_identity == other_identity;
   }
 
   // Provides direct access to the interface.
   // Here we use a well known trick to make sure we block access to
   // IUnknown methods so that something bad like this doesn't happen:
   //    ScopedComPtr<IUnknown> p(Foo());
   //    p->Release();
   //    ... later the destructor runs, which will Release() again.
   // and to get the benefit of the DCHECKs we add to QueryInterface.
   // There's still a way to call these methods if you absolutely must
   // by statically casting the ScopedComPtr instance to the wrapped interface
   // and then making the call... but generally that shouldn't be necessary.
   BlockIUnknownMethods* operator->() const {
-    DCHECK(this->ptr_ != NULL);
-    return reinterpret_cast<BlockIUnknownMethods*>(this->ptr_);
+    DCHECK(ptr_);
+    return reinterpret_cast<BlockIUnknownMethods*>(ptr_);
   }
 
-  // Pull in operator=() from the parent class.
-  using scoped_refptr<Interface>::operator=;
+  ScopedComPtr<Interface, interface_id>& operator=(Interface* rhs) {
+    // AddRef first so that self assignment should work
+    if (rhs)
+      rhs->AddRef();
+    Interface* old_ptr = ptr_;
+    ptr_ = rhs;
+    if (old_ptr)
+      old_ptr->Release();
+    return *this;
+  }
+
+  ScopedComPtr<Interface, interface_id>& operator=(
+      const ScopedComPtr<Interface, interface_id>& rhs) {
+    return *this = rhs.ptr_;
+  }
+
+  Interface& operator*() const {
+    DCHECK(ptr_);
+    return *ptr_;
+  }
+
+  bool operator==(const ScopedComPtr<Interface, interface_id>& rhs) const {
+    return ptr_ == rhs.get();
+  }
+
+  template <typename U>
+  bool operator==(const ScopedComPtr<U>& rhs) const {
+    return ptr_ == rhs.get();
+  }
+
+  template <typename U>
+  bool operator==(const U* rhs) const {
+    return ptr_ == rhs;
+  }
+
+  bool operator!=(const ScopedComPtr<Interface, interface_id>& rhs) const {
+    return ptr_ != rhs.get();
+  }
+
+  template <typename U>
+  bool operator!=(const ScopedComPtr<U>& rhs) const {
+    return ptr_ != rhs.get();
+  }
+
+  template <typename U>
+  bool operator!=(const U* rhs) const {
+    return ptr_ != rhs;
+  }
+
+  void swap(ScopedComPtr<Interface, interface_id>& r) {
+    Interface* tmp = ptr_;
+    ptr_ = r.ptr_;
+    r.ptr_ = tmp;
+  }
 
   // static methods
-
   static const IID& iid() {
     return *interface_id;
   }
+
+ private:
+  Interface* ptr_ = nullptr;
 };
 
+template <typename T, typename U>
+bool operator==(const T* lhs, const ScopedComPtr<U>& rhs) {
+  return lhs == rhs.get();
+}
+
+template <typename T>
+bool operator==(const ScopedComPtr<T>& lhs, std::nullptr_t null) {
+  return !static_cast<bool>(lhs);
+}
+
+template <typename T>
+bool operator==(std::nullptr_t null, const ScopedComPtr<T>& rhs) {
+  return !static_cast<bool>(rhs);
+}
+
+template <typename T, typename U>
+bool operator!=(const T* lhs, const ScopedComPtr<U>& rhs) {
+  return !operator==(lhs, rhs);
+}
+
+template <typename T>
+bool operator!=(const ScopedComPtr<T>& lhs, std::nullptr_t null) {
+  return !operator==(lhs, null);
+}
+
+template <typename T>
+bool operator!=(std::nullptr_t null, const ScopedComPtr<T>& rhs) {
+  return !operator==(null, rhs);
+}
+
+template <typename T>
+std::ostream& operator<<(std::ostream& out, const ScopedComPtr<T>& p) {
+  return out << p.get();
+}
+
 }  // namespace win
 }  // namespace base
 
 #endif  // BASE_WIN_SCOPED_COMPTR_H_