1 files changed, 65 insertions, 0 deletions
diff --git a/js/public/shadow/Shape.h b/js/public/shadow/Shape.h
new file mode 100644
index 0000000000..c83d320bf2
--- /dev/null
+++ b/js/public/shadow/Shape.h
@@ -0,0 +1,65 @@
+/* -*- 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/. */
+
+/*
+ * Shadow definition of |js::BaseShape| and |js::Shape| innards.  Do not use
+ * this directly!
+ */
+
+#ifndef js_shadow_Shape_h
+#define js_shadow_Shape_h
+
+#include <stdint.h>  // uint32_t
+
+#include "jstypes.h"  // JS_PUBLIC_API
+
+#include "js/Id.h"  // JS::PropertyKey
+
+struct JSClass;
+class JS_PUBLIC_API JSObject;
+
+namespace JS {
+
+namespace shadow {
+
+struct BaseShape {
+  const JSClass* clasp;
+  JS::Realm* realm;
+};
+
+class Shape {
+ public:
+  shadow::BaseShape* base;
+  uint32_t immutableFlags;
+
+  enum class Kind : uint8_t {
+    // SharedShape or DictionaryShape for NativeObject.
+    // (Only) these two kinds must have the low bit set, to allow for fast
+    // is-native checking.
+    Shared = 1,
+    Dictionary = 3,
+    // ProxyShape for ProxyObject.
+    Proxy = 0,
+    // WasmGCShape for WasmGCObject.
+    WasmGC = 2,
+  };
+
+  static constexpr uint32_t KIND_SHIFT = 4;
+  static constexpr uint32_t KIND_MASK = 0b11;
+
+  static constexpr uint32_t FIXED_SLOTS_SHIFT = 6;
+  static constexpr uint32_t FIXED_SLOTS_MASK = 0x1f << FIXED_SLOTS_SHIFT;
+
+  bool isProxy() const {
+    return Kind((immutableFlags >> KIND_SHIFT) & KIND_MASK) == Kind::Proxy;
+  }
+};
+
+}  // namespace shadow
+
+}  // namespace JS
+
+#endif  // js_shadow_Shape_h