1 files changed, 54 insertions, 0 deletions
diff --git a/dom/base/MozQueryInterface.h b/dom/base/MozQueryInterface.h
new file mode 100644
index 0000000000..1dd3d9bfff
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+++ b/dom/base/MozQueryInterface.h
@@ -0,0 +1,54 @@
+/* -*- 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/. */
+
+#ifndef mozilla_dom_MozQueryInterface
+#define mozilla_dom_MozQueryInterface
+
+/**
+ * This class implements an optimized QueryInterface method for
+ * XPConnect-wrapped JS objects.
+ *
+ * For JavaScript callers, it behaves as an ordinary QueryInterface method,
+ * returning its `this` object or throwing depending on the interface it was
+ * passed.
+ *
+ * For native XPConnect callers, we bypass JSAPI entirely, and directly check
+ * whether the queried interface is in the interfaces list.
+ */
+
+#include "mozilla/dom/BindingDeclarations.h"
+#include "mozilla/dom/NonRefcountedDOMObject.h"
+#include "nsID.h"
+
+namespace mozilla {
+class ErrorResult;
+
+namespace dom {
+
+class MozQueryInterface final : public NonRefcountedDOMObject {
+ public:
+  explicit MozQueryInterface(nsTArray<nsIID>&& aInterfaces)
+      : mInterfaces(std::move(aInterfaces)) {}
+
+  bool QueriesTo(const nsIID& aIID) const;
+
+  void LegacyCall(JSContext* cx, JS::Handle<JS::Value> thisv,
+                  JS::Handle<JS::Value> aIID,
+                  JS::MutableHandle<JS::Value> aResult, ErrorResult& aRv) const;
+
+  nsISupports* GetParentObject() const { return nullptr; }
+
+  bool WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto,
+                  JS::MutableHandle<JSObject*> aReflector);
+
+ private:
+  nsTArray<nsIID> mInterfaces;
+};
+
+}  // namespace dom
+}  // namespace mozilla
+
+#endif  // mozilla_dom_MozQueryInterface