dart_weak_persistent_value.h

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// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#ifndef LIB_TONIC_DART_WEAK_PERSISTENT_VALUE_H_
#define LIB_TONIC_DART_WEAK_PERSISTENT_VALUE_H_
 
#include <memory>
 
#include "third_party/dart/runtime/include/dart_api.h"
#include "tonic/common/macros.h"
 
namespace tonic {
class DartState;
 
// DartWeakPersistentValue is a bookkeeping class to help pair calls to
// Dart_NewWeakPersistentHandle with Dart_DeleteWeakPersistentHandle even in
// the case if IsolateGroup shutdown. Consider using this class instead of
// holding a Dart_PersistentHandle directly so that you don't leak the
// Dart_WeakPersistentHandle.
class DartWeakPersistentValue {
 public:
  DartWeakPersistentValue();
  ~DartWeakPersistentValue();
 
  Dart_WeakPersistentHandle value() const { return handle_; }
  bool is_empty() const { return handle_ == nullptr; }
 
  void Set(DartState* dart_state,
           Dart_Handle object,
           void* peer,
           intptr_t external_allocation_size,
           Dart_HandleFinalizer callback);
  void Clear();
  Dart_Handle Get();
 
  const std::weak_ptr<DartState>& dart_state() const { return dart_state_; }
 
 private:
  std::weak_ptr<DartState> dart_state_;
  Dart_WeakPersistentHandle handle_;
 
  TONIC_DISALLOW_COPY_AND_ASSIGN(DartWeakPersistentValue);
};
 
}  // namespace tonic
 
#endif  // LIB_TONIC_DART_WEAK_PERSISTENT_VALUE_H_