Support weak references for bookmark / history / result observers. Bug 319324, r=darin.

This file was copied in CVS from the following location:
mozilla/browser/components/places/src/nsMaybeWeakPtr.cpp
Original committer: bryner%brianryner.com
Original revision: 1.1
Original date: 2005/12/08 22:23:52

toolkit/components/places/src/nsMaybeWeakPtr.cpp

@@ -0,0 +1,114 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is Places code.
+ *
+ * The Initial Developer of the Original Code is
+ * Google Inc.
+ * Portions created by the Initial Developer are Copyright (C) 2005
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   Brian Ryner <bryner@brianryner.com> (original author)
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+#include "nsMaybeWeakPtr.h"
+
+void*
+nsMaybeWeakPtr_base::GetValueAs(const nsIID &iid) const
+{
+  nsresult rv;
+  void *ref;
+  if (mPtr) {
+    rv = mPtr->QueryInterface(iid, &ref);
+    if (NS_SUCCEEDED(rv)) {
+      return ref;
+    }
+  }
+
+  nsCOMPtr<nsIWeakReference> weakRef = do_QueryInterface(mPtr);
+  if (weakRef) {
+    rv = weakRef->QueryReferent(iid, &ref);
+    if (NS_FAILED(rv)) {
+      ref = nsnull;
+    }
+  }
+  return ref;
+}
+
+/* static */ nsresult
+nsMaybeWeakPtrArray_base::AppendWeakElementBase(nsTArray_base *aArray,
+                                                nsISupports *aElement,
+                                                PRBool aOwnsWeak)
+{
+  nsCOMPtr<nsISupports> ref;
+  if (aOwnsWeak) {
+    nsCOMPtr<nsIWeakReference> weakRef;
+    weakRef = do_GetWeakReference(aElement);
+    NS_REINTERPRET_CAST(nsCOMPtr<nsISupports>*, &weakRef)->swap(ref);
+  } else {
+    ref = aElement;
+  }
+
+  isupports_type *array = NS_STATIC_CAST(isupports_type*, aArray);
+  if (array->IndexOf(ref) != isupports_type::NoIndex) {
+    return NS_ERROR_INVALID_ARG; // already present
+  }
+  if (!array->AppendElement(ref)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  return NS_OK;
+}
+
+/* static */ nsresult
+nsMaybeWeakPtrArray_base::RemoveWeakElementBase(nsTArray_base *aArray,
+                                                nsISupports *aElement)
+{
+  isupports_type *array = NS_STATIC_CAST(isupports_type*, aArray);
+  PRUint32 index = array->IndexOf(aElement);
+  if (index != isupports_type::NoIndex) {
+    array->RemoveElementAt(index);
+    return NS_OK;
+  }
+
+  // Don't use do_GetWeakReference; it should only be called if we know
+  // the object supports weak references.
+  nsCOMPtr<nsISupportsWeakReference> supWeakRef = do_QueryInterface(aElement);
+  NS_ENSURE_TRUE(supWeakRef, NS_ERROR_INVALID_ARG);
+
+  nsCOMPtr<nsIWeakReference> weakRef;
+  nsresult rv = supWeakRef->GetWeakReference(getter_AddRefs(weakRef));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  index = array->IndexOf(weakRef);
+  if (index == isupports_type::NoIndex) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  array->RemoveElementAt(index);
+  return NS_OK;
+}