1 files changed, 94 insertions, 0 deletions
diff --git a/js/xpconnect/src/XPCJSWeakReference.cpp b/js/xpconnect/src/XPCJSWeakReference.cpp
new file mode 100644
index 000000000..bd7c80bc0
--- /dev/null
+++ b/js/xpconnect/src/XPCJSWeakReference.cpp
@@ -0,0 +1,94 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* vim: set ts=8 sts=4 et sw=4 tw=99: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "xpcprivate.h"
+#include "XPCJSWeakReference.h"
+
+#include "nsContentUtils.h"
+
+using namespace JS;
+
+xpcJSWeakReference::xpcJSWeakReference()
+{
+}
+
+NS_IMPL_ISUPPORTS(xpcJSWeakReference, xpcIJSWeakReference)
+
+nsresult xpcJSWeakReference::Init(JSContext* cx, const JS::Value& object)
+{
+    if (!object.isObject())
+        return NS_OK;
+
+    JS::RootedObject obj(cx, &object.toObject());
+
+    XPCCallContext ccx(cx);
+
+    // See if the object is a wrapped native that supports weak references.
+    nsCOMPtr<nsISupports> supports = xpc::UnwrapReflectorToISupports(obj);
+    nsCOMPtr<nsISupportsWeakReference> supportsWeakRef =
+        do_QueryInterface(supports);
+    if (supportsWeakRef) {
+        supportsWeakRef->GetWeakReference(getter_AddRefs(mReferent));
+        if (mReferent) {
+            return NS_OK;
+        }
+    }
+    // If it's not a wrapped native, or it is a wrapped native that does not
+    // support weak references, fall back to getting a weak ref to the object.
+
+    // See if object is a wrapped JSObject.
+    RefPtr<nsXPCWrappedJS> wrapped;
+    nsresult rv = nsXPCWrappedJS::GetNewOrUsed(obj,
+                                               NS_GET_IID(nsISupports),
+                                               getter_AddRefs(wrapped));
+    if (!wrapped) {
+        NS_ERROR("can't get nsISupportsWeakReference wrapper for obj");
+        return rv;
+    }
+
+    return wrapped->GetWeakReference(getter_AddRefs(mReferent));
+}
+
+NS_IMETHODIMP
+xpcJSWeakReference::Get(JSContext* aCx, MutableHandleValue aRetval)
+{
+    aRetval.setNull();
+
+    if (!mReferent) {
+        return NS_OK;
+    }
+
+    nsCOMPtr<nsISupports> supports = do_QueryReferent(mReferent);
+    if (!supports) {
+        return NS_OK;
+    }
+
+    nsCOMPtr<nsIXPConnectWrappedJS> wrappedObj = do_QueryInterface(supports);
+    if (!wrappedObj) {
+        // We have a generic XPCOM object that supports weak references here.
+        // Wrap it and pass it out.
+        return nsContentUtils::WrapNative(aCx, supports,
+                                          &NS_GET_IID(nsISupports),
+                                          aRetval);
+    }
+
+    JS::RootedObject obj(aCx, wrappedObj->GetJSObject());
+    if (!obj) {
+        return NS_OK;
+    }
+
+    // Most users of XPCWrappedJS don't need to worry about
+    // re-wrapping because things are implicitly rewrapped by
+    // xpcconvert. However, because we're doing this directly
+    // through the native call context, we need to call
+    // JS_WrapObject().
+    if (!JS_WrapObject(aCx, &obj)) {
+        return NS_ERROR_FAILURE;
+    }
+
+    aRetval.setObject(*obj);
+    return NS_OK;
+}