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-rw-r--r--js/xpconnect/src/XPCJSWeakReference.cpp89
1 files changed, 89 insertions, 0 deletions
diff --git a/js/xpconnect/src/XPCJSWeakReference.cpp b/js/xpconnect/src/XPCJSWeakReference.cpp
new file mode 100644
index 0000000000..fbf2e22441
--- /dev/null
+++ b/js/xpconnect/src/XPCJSWeakReference.cpp
@@ -0,0 +1,89 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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() = default;
+
+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::ReflectorToISupportsDynamic(obj, cx);
+ 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(cx, 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;
+}