chromium/base/observer_list_internal.h

// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_OBSERVER_LIST_INTERNAL_H_
#define BASE_OBSERVER_LIST_INTERNAL_H_

#include <string>

#include "base/base_export.h"
#include "base/check.h"
#include "base/containers/linked_list.h"
#include "base/dcheck_is_on.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/raw_ptr_exclusion.h"
#include "base/memory/weak_ptr.h"
#include "base/observer_list_types.h"

#if DCHECK_IS_ON()
#include "base/debug/stack_trace.h"
#endif

namespace base {
namespace internal {

// Adapter for putting raw pointers into an ObserverList<Foo>::Unchecked.
template <base::RawPtrTraits ptr_traits = RawPtrTraits::kEmpty,
          bool use_raw_pointer = false>
class BASE_EXPORT UncheckedObserverAdapter { … };

// Adapter for CheckedObserver types so that they can use the same syntax as a
// raw pointer when stored in the std::vector of observers in an ObserverList.
// It wraps a WeakPtr<CheckedObserver> and allows a "null" pointer via
// destruction to be distinguished from an observer marked for deferred removal
// whilst an iteration is in progress.
class BASE_EXPORT CheckedObserverAdapter { … };

// Wraps a pointer in a stack-allocated, base::LinkNode. The node is
// automatically removed from the linked list upon destruction (of the node, not
// the pointer). Nodes are detached from the list via Invalidate() in the
// destructor of ObserverList. This invalidates all WeakLinkNodes. There is no
// threading support.
template <class ObserverList>
class WeakLinkNode : public base::LinkNode<WeakLinkNode<ObserverList>> { … };

}  // namespace internal
}  // namespace base

#endif  // BASE_OBSERVER_LIST_INTERNAL_H_