/* -*- 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 js_public_Object_h #define js_public_Object_h #include "js/shadow/Object.h" // JS::shadow::Object #include "mozilla/Assertions.h" // MOZ_ASSERT #include // size_t #include // uint32_t #include "jstypes.h" // JS_PUBLIC_API #include "js/Class.h" // js::ESClass, JSCLASS_RESERVED_SLOTS #include "js/Realm.h" // JS::GetCompartmentForRealm #include "js/RootingAPI.h" // JS::{,Mutable}Handle #include "js/Value.h" // JS::Value struct JS_PUBLIC_API JSContext; class JS_PUBLIC_API JSObject; namespace JS { class JS_PUBLIC_API Compartment; /** * Determine the ECMAScript "class" -- Date, String, RegExp, and all the other * builtin object types (described in ECMAScript in terms of an objecting having * "an [[ArrayBufferData]] internal slot" or similar language for other kinds of * object -- of the provided object. * * If this function is passed a wrapper that can be unwrapped, the determination * is performed on that object. If the wrapper can't be unwrapped, and it's not * a wrapper that prefers to treat this operation as a failure, this function * will indicate that the object is |js::ESClass::Other|. */ extern JS_PUBLIC_API bool GetBuiltinClass(JSContext* cx, Handle obj, js::ESClass* cls); /** Get the |JSClass| of an object. */ inline const JSClass* GetClass(const JSObject* obj) { return reinterpret_cast(obj)->shape->base->clasp; } /** * Get the |JS::Compartment*| of an object. * * Note that the compartment of an object in this realm, that is a * cross-compartment wrapper around an object from another realm, is the * compartment of this realm. */ static MOZ_ALWAYS_INLINE Compartment* GetCompartment(JSObject* obj) { Realm* realm = reinterpret_cast(obj)->shape->base->realm; return GetCompartmentForRealm(realm); } /** * Get the value stored in a reserved slot in an object. * * If |obj| is known to be a proxy and you're willing to use friend APIs, * |js::GetProxyReservedSlot| in "js/Proxy.h" is very slightly more efficient. */ inline const Value& GetReservedSlot(JSObject* obj, size_t slot) { MOZ_ASSERT(slot < JSCLASS_RESERVED_SLOTS(GetClass(obj))); return reinterpret_cast(obj)->slotRef(slot); } namespace detail { extern JS_PUBLIC_API void SetReservedSlotWithBarrier(JSObject* obj, size_t slot, const Value& value); } // namespace detail /** * Store a value in an object's reserved slot. * * This can be used with both native objects and proxies. However, if |obj| is * known to be a proxy, |js::SetProxyReservedSlot| in "js/Proxy.h" is very * slightly more efficient. */ inline void SetReservedSlot(JSObject* obj, size_t slot, const Value& value) { MOZ_ASSERT(slot < JSCLASS_RESERVED_SLOTS(GetClass(obj))); auto* sobj = reinterpret_cast(obj); if (sobj->slotRef(slot).isGCThing() || value.isGCThing()) { detail::SetReservedSlotWithBarrier(obj, slot, value); } else { sobj->slotRef(slot) = value; } } /** * Helper function to get the pointer value (or nullptr if not set) from an * object's reserved slot. The slot must contain either a PrivateValue(T*) or * UndefinedValue. */ template inline T* GetMaybePtrFromReservedSlot(JSObject* obj, size_t slot) { Value v = GetReservedSlot(obj, slot); return v.isUndefined() ? nullptr : static_cast(v.toPrivate()); } /** * Helper function to get the pointer value (or nullptr if not set) from the * object's first reserved slot. Must only be used for objects with a JSClass * that has the JSCLASS_SLOT0_IS_NSISUPPORTS flag. */ template inline T* GetObjectISupports(JSObject* obj) { MOZ_ASSERT(GetClass(obj)->slot0IsISupports()); return GetMaybePtrFromReservedSlot(obj, 0); } /** * Helper function to store |PrivateValue(nsISupportsValue)| in the object's * first reserved slot. Must only be used for objects with a JSClass that has * the JSCLASS_SLOT0_IS_NSISUPPORTS flag. * * Note: the pointer is opaque to the JS engine (including the GC) so it's the * embedding's responsibility to trace or free this value. */ inline void SetObjectISupports(JSObject* obj, void* nsISupportsValue) { MOZ_ASSERT(GetClass(obj)->slot0IsISupports()); SetReservedSlot(obj, 0, PrivateValue(nsISupportsValue)); } } // namespace JS #endif // js_public_Object_h