/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* 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/. */ /** * An implementation of Rooted for OwningNonNull. This works by assuming * that T has a Trace() method defined on it which will trace whatever things * inside the T instance need tracing. * * This implementation has one serious drawback: operator= doesn't work right * because it's declared on Rooted directly and expects the type Rooted is * templated over. */ #ifndef mozilla_RootedOwningNonNull_h__ #define mozilla_RootedOwningNonNull_h__ #include "mozilla/OwningNonNull.h" #include "js/GCPolicyAPI.h" #include "js/RootingAPI.h" namespace JS { template struct GCPolicy> { typedef mozilla::OwningNonNull SmartPtrType; static SmartPtrType initial() { return SmartPtrType(); } static void trace(JSTracer* trc, SmartPtrType* tp, const char* name) { // We have to be very careful here. Normally, OwningNonNull can't be null. // But binding code can end up in a situation where it sets up a // Rooted and then before it gets a chance to assign to it // (e.g. from the constructor of the thing being assigned) a GC happens. So // we can land here when *tp stores a null pointer because it's not // initialized. // // So we need to check for that before jumping. if ((*tp).isInitialized()) { (*tp)->Trace(trc); } } }; } // namespace JS namespace js { template struct RootedBase> { typedef mozilla::OwningNonNull SmartPtrType; operator SmartPtrType& () const { auto& self = *static_cast*>(this); return self.get(); } operator T& () const { auto& self = *static_cast*>(this); return self.get(); } }; } // namespace js #endif /* mozilla_RootedOwningNonNull_h__ */