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tdutils/td/utils/Observer.h

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+/*
+    This file is part of TON Blockchain Library.
+
+    TON Blockchain Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    TON Blockchain Library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with TON Blockchain Library.  If not, see <http://www.gnu.org/licenses/>.
+
+    Copyright 2017-2019 Telegram Systems LLP
+*/
+#pragma once
+
+#include "td/utils/common.h"
+
+namespace td {
+
+class ObserverBase {
+ public:
+  ObserverBase() = default;
+  ObserverBase(const ObserverBase &) = delete;
+  ObserverBase &operator=(const ObserverBase &) = delete;
+  ObserverBase(ObserverBase &&) = delete;
+  ObserverBase &operator=(ObserverBase &&) = delete;
+  virtual ~ObserverBase() = default;
+
+  virtual void notify() = 0;
+};
+
+class Observer : ObserverBase {
+ public:
+  Observer() = default;
+  explicit Observer(unique_ptr<ObserverBase> &&ptr) : observer_ptr_(std::move(ptr)) {
+  }
+
+  void notify() override {
+    if (observer_ptr_) {
+      observer_ptr_->notify();
+    }
+  }
+
+ private:
+  unique_ptr<ObserverBase> observer_ptr_;
+};
+
+}  // namespace td