1 files changed, 37 insertions, 0 deletions
diff --git a/dom/bindings/XrayExpandoClass.h b/dom/bindings/XrayExpandoClass.h
new file mode 100644
index 0000000000..a18a7125ca
--- /dev/null
+++ b/dom/bindings/XrayExpandoClass.h
@@ -0,0 +1,37 @@
+/* -*- 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/. */
+
+/**
+ * This file declares a macro for defining Xray expando classes and declares the
+ * default Xray expando class.  The actual definition of that default class
+ * lives elsewhere.
+ */
+#ifndef mozilla_dom_XrayExpandoClass_h
+#define mozilla_dom_XrayExpandoClass_h
+
+/*
+ * maybeStatic_ Should be either `static` or nothing (because some Xray expando
+ * classes are not static).
+ *
+ * name_ should be the name of the variable.
+ *
+ * extraSlots_ should be how many extra slots to give the class, in addition to
+ * the ones Xray expandos want.
+ */
+#define DEFINE_XRAY_EXPANDO_CLASS(maybeStatic_, name_, extraSlots_)           \
+  maybeStatic_ const JSClass name_ = {                                        \
+      "XrayExpandoObject",                                                    \
+      JSCLASS_HAS_RESERVED_SLOTS(xpc::JSSLOT_EXPANDO_COUNT + (extraSlots_)) | \
+          JSCLASS_FOREGROUND_FINALIZE,                                        \
+      &xpc::XrayExpandoObjectClassOps}
+
+namespace mozilla::dom {
+
+extern const JSClass DefaultXrayExpandoObjectClass;
+
+}  // namespace mozilla::dom
+
+#endif /* mozilla_dom_XrayExpandoClass_h */