Repo created

TMessagesProj/jni/voip/webrtc/base/auto_reset.h

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+// Copyright (c) 2011 The Chromium 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 BASE_AUTO_RESET_H_
+#define BASE_AUTO_RESET_H_
+
+#include <utility>
+
+// base::AutoReset<> is useful for setting a variable to a new value only within
+// a particular scope. An base::AutoReset<> object resets a variable to its
+// original value upon destruction, making it an alternative to writing
+// "var = false;" or "var = old_val;" at all of a block's exit points.
+//
+// This should be obvious, but note that an base::AutoReset<> instance should
+// have a shorter lifetime than its scoped_variable, to prevent invalid memory
+// writes when the base::AutoReset<> object is destroyed.
+
+namespace base {
+
+template <typename T>
+class AutoReset {
+ public:
+  template <typename U>
+  AutoReset(T* scoped_variable, U&& new_value)
+      : scoped_variable_(scoped_variable),
+        original_value_(
+            std::exchange(*scoped_variable_, std::forward<U>(new_value))) {}
+
+  AutoReset(AutoReset&& other)
+      : scoped_variable_(std::exchange(other.scoped_variable_, nullptr)),
+        original_value_(std::move(other.original_value_)) {}
+
+  AutoReset& operator=(AutoReset&& rhs) {
+    scoped_variable_ = std::exchange(rhs.scoped_variable_, nullptr);
+    original_value_ = std::move(rhs.original_value_);
+    return *this;
+  }
+
+  ~AutoReset() {
+    if (scoped_variable_)
+      *scoped_variable_ = std::move(original_value_);
+  }
+
+ private:
+  T* scoped_variable_;
+  T original_value_;
+};
+
+}  // namespace base
+
+#endif  // BASE_AUTO_RESET_H_