1 files changed, 114 insertions, 0 deletions
diff --git a/dom/bindings/SpiderMonkeyInterface.h b/dom/bindings/SpiderMonkeyInterface.h
new file mode 100644
index 0000000000..92cdd3090b
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+++ b/dom/bindings/SpiderMonkeyInterface.h
@@ -0,0 +1,114 @@
+/* -*- 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_SpiderMonkeyInterface_h
+#define mozilla_dom_SpiderMonkeyInterface_h
+
+#include "jsapi.h"
+#include "js/RootingAPI.h"
+#include "js/TracingAPI.h"
+
+namespace mozilla::dom {
+
+/*
+ * Class that just handles the JSObject storage and tracing for spidermonkey
+ * interfaces
+ */
+struct SpiderMonkeyInterfaceObjectStorage {
+ protected:
+  JSObject* mImplObj;
+  JSObject* mWrappedObj;
+
+  SpiderMonkeyInterfaceObjectStorage()
+      : mImplObj(nullptr), mWrappedObj(nullptr) {}
+
+  SpiderMonkeyInterfaceObjectStorage(
+      SpiderMonkeyInterfaceObjectStorage&& aOther)
+      : mImplObj(aOther.mImplObj), mWrappedObj(aOther.mWrappedObj) {
+    aOther.mImplObj = nullptr;
+    aOther.mWrappedObj = nullptr;
+  }
+
+ public:
+  inline void TraceSelf(JSTracer* trc) {
+    JS::TraceRoot(trc, &mImplObj,
+                  "SpiderMonkeyInterfaceObjectStorage.mImplObj");
+    JS::TraceRoot(trc, &mWrappedObj,
+                  "SpiderMonkeyInterfaceObjectStorage.mWrappedObj");
+  }
+
+  inline bool inited() const { return !!mImplObj; }
+
+  inline bool WrapIntoNewCompartment(JSContext* cx) {
+    return JS_WrapObject(
+        cx, JS::MutableHandle<JSObject*>::fromMarkedLocation(&mWrappedObj));
+  }
+
+  inline JSObject* Obj() const {
+    MOZ_ASSERT(inited());
+    return mWrappedObj;
+  }
+
+ private:
+  SpiderMonkeyInterfaceObjectStorage(
+      const SpiderMonkeyInterfaceObjectStorage&) = delete;
+};
+
+// A class for rooting an existing SpiderMonkey Interface struct
+template <typename InterfaceType>
+class MOZ_RAII SpiderMonkeyInterfaceRooter : private JS::CustomAutoRooter {
+ public:
+  template <typename CX>
+  SpiderMonkeyInterfaceRooter(const CX& cx, InterfaceType* aInterface)
+      : JS::CustomAutoRooter(cx), mInterface(aInterface) {}
+
+  virtual void trace(JSTracer* trc) override { mInterface->TraceSelf(trc); }
+
+ private:
+  SpiderMonkeyInterfaceObjectStorage* const mInterface;
+};
+
+// And a specialization for dealing with nullable SpiderMonkey interfaces
+template <typename Inner>
+struct Nullable;
+template <typename InterfaceType>
+class MOZ_RAII SpiderMonkeyInterfaceRooter<Nullable<InterfaceType>>
+    : private JS::CustomAutoRooter {
+ public:
+  template <typename CX>
+  SpiderMonkeyInterfaceRooter(const CX& cx, Nullable<InterfaceType>* aInterface)
+      : JS::CustomAutoRooter(cx), mInterface(aInterface) {}
+
+  virtual void trace(JSTracer* trc) override {
+    if (!mInterface->IsNull()) {
+      mInterface->Value().TraceSelf(trc);
+    }
+  }
+
+ private:
+  Nullable<InterfaceType>* const mInterface;
+};
+
+// Class for easily setting up a rooted SpiderMonkey interface object on the
+// stack
+template <typename InterfaceType>
+class MOZ_RAII RootedSpiderMonkeyInterface final
+    : public InterfaceType,
+      private SpiderMonkeyInterfaceRooter<InterfaceType> {
+ public:
+  template <typename CX>
+  explicit RootedSpiderMonkeyInterface(const CX& cx)
+      : InterfaceType(), SpiderMonkeyInterfaceRooter<InterfaceType>(cx, this) {}
+
+  template <typename CX>
+  RootedSpiderMonkeyInterface(const CX& cx, JSObject* obj)
+      : InterfaceType(obj),
+        SpiderMonkeyInterfaceRooter<InterfaceType>(cx, this) {}
+};
+
+}  // namespace mozilla::dom
+
+#endif /* mozilla_dom_SpiderMonkeyInterface_h */