73 lines
2.1 KiB
C++
73 lines
2.1 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at http://mozilla.org/MPL/2.0/. */
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/**
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* An implementation of Rooted for OwningNonNull<T>. This works by assuming
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* that T has a Trace() method defined on it which will trace whatever things
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* inside the T instance need tracing.
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*
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* This implementation has one serious drawback: operator= doesn't work right
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* because it's declared on Rooted directly and expects the type Rooted is
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* templated over.
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*/
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#ifndef mozilla_RootedOwningNonNull_h__
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#define mozilla_RootedOwningNonNull_h__
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#include "mozilla/OwningNonNull.h"
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#include "js/GCPolicyAPI.h"
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#include "js/RootingAPI.h"
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namespace JS {
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template<typename T>
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struct GCPolicy<mozilla::OwningNonNull<T>>
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{
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typedef mozilla::OwningNonNull<T> SmartPtrType;
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static SmartPtrType initial()
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{
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return SmartPtrType();
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}
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static void trace(JSTracer* trc, SmartPtrType* tp,
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const char* name)
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{
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// We have to be very careful here. Normally, OwningNonNull can't be null.
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// But binding code can end up in a situation where it sets up a
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// Rooted<OwningNonNull> and then before it gets a chance to assign to it
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// (e.g. from the constructor of the thing being assigned) a GC happens. So
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// we can land here when *tp stores a null pointer because it's not
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// initialized.
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//
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// So we need to check for that before jumping.
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if ((*tp).isInitialized()) {
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(*tp)->Trace(trc);
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}
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}
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};
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} // namespace JS
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namespace js {
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template<typename T>
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struct RootedBase<mozilla::OwningNonNull<T>>
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{
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typedef mozilla::OwningNonNull<T> SmartPtrType;
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operator SmartPtrType& () const
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{
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auto& self = *static_cast<const JS::Rooted<SmartPtrType>*>(this);
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return self.get();
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}
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operator T& () const
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{
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auto& self = *static_cast<const JS::Rooted<SmartPtrType>*>(this);
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return self.get();
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}
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};
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} // namespace js
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#endif /* mozilla_RootedOwningNonNull_h__ */
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