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/* -*- 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<T>. 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<typename T>
struct GCPolicy<mozilla::OwningNonNull<T>>
{
typedef mozilla::OwningNonNull<T> 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<OwningNonNull> 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<typename T, typename Wrapper>
struct WrappedPtrOperations<mozilla::OwningNonNull<T>, Wrapper>
{
operator T& () const
{
return static_cast<const Wrapper*>(this)->get();
}
};
} // namespace js
#endif /* mozilla_RootedOwningNonNull_h__ */
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