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       1             : /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* vim: set ts=8 sts=2 et sw=2 tw=80: */
       3             : /* This Source Code Form is subject to the terms of the Mozilla Public
       4             :  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
       5             :  * You can obtain one at http://mozilla.org/MPL/2.0/. */
       6             : 
       7             : /**
       8             :  * An implementation of Rooted for OwningNonNull<T>.  This works by assuming
       9             :  * that T has a Trace() method defined on it which will trace whatever things
      10             :  * inside the T instance need tracing.
      11             :  *
      12             :  * This implementation has one serious drawback: operator= doesn't work right
      13             :  * because it's declared on Rooted directly and expects the type Rooted is
      14             :  * templated over.
      15             :  */
      16             : 
      17             : #ifndef mozilla_RootedOwningNonNull_h__
      18             : #define mozilla_RootedOwningNonNull_h__
      19             : 
      20             : #include "mozilla/OwningNonNull.h"
      21             : #include "js/GCPolicyAPI.h"
      22             : #include "js/RootingAPI.h"
      23             : 
      24             : namespace JS {
      25             : template<typename T>
      26             : struct GCPolicy<mozilla::OwningNonNull<T>>
      27             : {
      28             :   typedef mozilla::OwningNonNull<T> SmartPtrType;
      29             : 
      30          19 :   static SmartPtrType initial()
      31             :   {
      32          19 :     return SmartPtrType();
      33             :   }
      34             : 
      35           0 :   static void trace(JSTracer* trc, SmartPtrType* tp,
      36             :                     const char* name)
      37             :   {
      38             :     // We have to be very careful here.  Normally, OwningNonNull can't be null.
      39             :     // But binding code can end up in a situation where it sets up a
      40             :     // Rooted<OwningNonNull> and then before it gets a chance to assign to it
      41             :     // (e.g. from the constructor of the thing being assigned) a GC happens.  So
      42             :     // we can land here when *tp stores a null pointer because it's not
      43             :     // initialized.
      44             :     //
      45             :     // So we need to check for that before jumping.
      46           0 :     if ((*tp).isInitialized()) {
      47           0 :       (*tp)->Trace(trc);
      48             :     }
      49           0 :   }
      50             : };
      51             : } // namespace JS
      52             : 
      53             : namespace js {
      54             : template<typename T, typename Wrapper>
      55          19 : struct WrappedPtrOperations<mozilla::OwningNonNull<T>, Wrapper>
      56             : {
      57          19 :   operator T& () const
      58             :   {
      59          19 :     return static_cast<const Wrapper*>(this)->get();
      60             :   }
      61             : };
      62             : } // namespace js
      63             : 
      64             : #endif /* mozilla_RootedOwningNonNull_h__ */