Initial import of the Chrome Frame codebase. Integration in chrome.gyp coming...

chrome_frame/scoped_ns_ptr_win.h

+// Copyright (c) 2009 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 CHROME_FRAME_SCOPED_NS_PTR_WIN_H_
+#define CHROME_FRAME_SCOPED_NS_PTR_WIN_H_
+
+#include "base/logging.h"
+#include "base/ref_counted.h"
+
+#include "third_party/xulrunner-sdk/win/include/xpcom/nsISupports.h"
+
+
+// Utility template to prevent users of ScopedNsPtr from calling AddRef and/or
+// Release() without going through the ScopedNsPtr class.
+template <class nsInterface>
+class BlocknsISupportsMethods : public nsInterface {
+ private:
+  NS_IMETHOD QueryInterface(REFNSIID iid, void** object) = 0;
+  NS_IMETHOD_(nsrefcnt) AddRef() = 0;
+  NS_IMETHOD_(nsrefcnt) Release() = 0;
+};
+
+// A smart pointer class for nsISupports.
+// Based on ScopedComPtr.
+// We have our own class instead of nsCOMPtr.  nsCOMPtr has parts of its
+// implementation in the xpcomglue lib which we can't use since that lib
+// is built with incompatible build flags to ours.
+template <class nsInterface,
+          const nsIID* interface_id =
+              reinterpret_cast<const nsIID*>(&__uuidof(nsInterface))>
+class ScopedNsPtr : public scoped_refptr<nsInterface> {
+ public:
+  typedef scoped_refptr<nsInterface> ParentClass;
+
+  ScopedNsPtr() {
+  }
+
+  explicit ScopedNsPtr(nsInterface* p) : ParentClass(p) {
+  }
+
+  explicit ScopedNsPtr(const ScopedNsPtr<nsInterface, interface_id>& p)
+      : ParentClass(p) {
+  }
+
+  ~ScopedNsPtr() {
+    // We don't want the smart pointer class to be bigger than the pointer
+    // it wraps.
+    COMPILE_ASSERT(sizeof(ScopedNsPtr<nsInterface, interface_id>) ==
+                   sizeof(nsInterface*), ScopedNsPtrSize);
+  }
+
+  // Explicit Release() of the held object.  Useful for reuse of the
+  // ScopedNsPtr instance.
+  // Note that this function equates to nsISupports::Release and should not
+  // be confused with e.g. scoped_ptr::release().
+  void Release() {
+    if (ptr_ != NULL) {
+      ptr_->Release();
+      ptr_ = NULL;
+    }
+  }
+
+  // Sets the internal pointer to NULL and returns the held object without
+  // releasing the reference.
+  nsInterface* Detach() {
+    nsInterface* p = ptr_;
+    ptr_ = NULL;
+    return p;
+  }
+
+  // Accepts an interface pointer that has already been addref-ed.
+  void Attach(nsInterface* p) {
+    DCHECK(ptr_ == NULL);
+    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());
+  nsInterface** Receive() {
+    DCHECK(ptr_ == NULL) << "Object leak. Pointer must be NULL";
+    return &ptr_;
+  }
+
+  template <class Query>
+  nsresult QueryInterface(Query** p) {
+    DCHECK(p != NULL);
+    DCHECK(ptr_ != NULL);
+    return ptr_->QueryInterface(Query::GetIID(), reinterpret_cast<void**>(p));
+  }
+
+  template <class Query>
+  nsresult QueryInterface(const nsIID& iid, Query** p) {
+    DCHECK(p != NULL);
+    DCHECK(ptr_ != NULL);
+    return ptr_->QueryInterface(iid, reinterpret_cast<void**>(p));
+  }
+
+  // Queries |other| for the interface this object wraps and returns the
+  // error code from the other->QueryInterface operation.
+  nsresult QueryFrom(nsISupports* other) {
+    DCHECK(other != NULL);
+    return other->QueryInterface(iid(), reinterpret_cast<void**>(Receive()));
+  }
+
+  // Checks if the identity of |other| and this object is the same.
+  bool IsSameObject(nsISupports* other) {
+    if (!other && !ptr_)
+      return true;
+
+    if (!other || !ptr_)
+      return false;
+
+    nsIID iid = NS_ISUPPORTS_IID;
+    ScopedNsPtr<nsISupports, iid> my_identity;
+    QueryInterface(my_identity.Receive());
+
+    ScopedNsPtr<nsISupports, iid> other_identity;
+    other->QueryInterface(other_identity.Receive());
+
+    return static_cast<nsISupports*>(my_identity) ==
+           static_cast<nsISupports*>(other_identity);
+  }
+
+  // Provides direct access to the interface.
+  // Here we use a well known trick to make sure we block access to
+  // IUknown methods so that something bad like this doesn't happen:
+  //    ScopedNsPtr<nsISupports> 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 ScopedNsPtr instance to the wrapped interface
+  // and then making the call... but generally that shouldn't be necessary.
+  BlocknsISupportsMethods<nsInterface>* operator->() const {
+    DCHECK(ptr_ != NULL);
+    return reinterpret_cast<BlocknsISupportsMethods<nsInterface>*>(ptr_);
+  }
+
+  // static methods
+
+  static const nsIID& iid() {
+    return *interface_id;
+  }
+};
+
+#endif  // CHROME_FRAME_SCOPED_NS_PTR_WIN_H_