1 | // Copyright 2013 The Flutter Authors. All rights reserved. |
2 | // Use of this source code is governed by a BSD-style license that can be |
3 | // found in the LICENSE file. |
4 | |
5 | #ifndef FLUTTER_FML_MEMORY_WEAK_PTR_INTERNAL_H_ |
6 | #define FLUTTER_FML_MEMORY_WEAK_PTR_INTERNAL_H_ |
7 | |
8 | #include "flutter/fml/macros.h" |
9 | #include "flutter/fml/memory/ref_counted.h" |
10 | |
11 | namespace fml { |
12 | namespace internal { |
13 | |
14 | // |WeakPtr<T>|s have a reference to a |WeakPtrFlag| to determine whether they |
15 | // are valid (non-null) or not. We do not store a |T*| in this object since |
16 | // there may also be |WeakPtr<U>|s to the same object, where |U| is a superclass |
17 | // of |T|. |
18 | // |
19 | // This class in not thread-safe, though references may be released on any |
20 | // thread (allowing weak pointers to be destroyed/reset/reassigned on any |
21 | // thread). |
22 | class WeakPtrFlag : public fml::RefCountedThreadSafe<WeakPtrFlag> { |
23 | public: |
24 | WeakPtrFlag(); |
25 | |
26 | ~WeakPtrFlag(); |
27 | |
28 | bool is_valid() const { return is_valid_; } |
29 | |
30 | void Invalidate(); |
31 | |
32 | private: |
33 | bool is_valid_; |
34 | |
35 | FML_DISALLOW_COPY_AND_ASSIGN(WeakPtrFlag); |
36 | }; |
37 | |
38 | } // namespace internal |
39 | } // namespace fml |
40 | |
41 | #endif // FLUTTER_FML_MEMORY_WEAK_PTR_INTERNAL_H_ |
42 | |