Use AutoReset (formerly ScopedBool) where possible.

This frequently saves a tiny bit of code, but even when it doesn't I think it's more future-proof (less error-prone).

BUG=none
TEST=none
Review URL: http://codereview.chromium.org/399096

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@32708 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 35 insertions, 0 deletions

diff --git a/base/auto_reset.h b/base/auto_reset.h
new file mode 100644
index 0000000..dd968ef
--- /dev/null
+++ b/base/auto_reset.h
@@ -0,0 +1,35 @@
+// Copyright (c) 2009 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 "base/basictypes.h"
+
+// AutoReset is useful for setting a variable to some value only during a
+// particular scope.  If you have code that has to add "var = false;" or
+// "var = old_var;" at all the exit points of a block, for example, you would
+// benefit from using this instead.
+//
+// NOTE: Right now this is hardcoded to work on bools, since that covers all the
+// cases where we've used it.  It would be reasonable to turn it into a template
+// class in the future.
+
+class AutoReset {
+ public:
+  explicit AutoReset(bool* scoped_variable, bool new_value)
+      : scoped_variable_(scoped_variable),
+        original_value_(*scoped_variable) {
+    *scoped_variable_ = new_value;
+  }
+  ~AutoReset() { *scoped_variable_ = original_value_; }
+
+ private:
+  bool* scoped_variable_;
+  bool original_value_;
+
+  DISALLOW_COPY_AND_ASSIGN(AutoReset);
+};
+
+#endif  // BASE_AUTO_RESET_H_