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