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      1 //===-- SaveAndRestore.h - Utility  -------------------------------*- C++ -*-=//
      2 //
      3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
      4 // See https://llvm.org/LICENSE.txt for license information.
      5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
      6 //
      7 //===----------------------------------------------------------------------===//
      8 ///
      9 /// \file
     10 /// This file provides utility classes that use RAII to save and restore
     11 /// values.
     12 ///
     13 //===----------------------------------------------------------------------===//
     14 
     15 #ifndef LLVM_SUPPORT_SAVEANDRESTORE_H
     16 #define LLVM_SUPPORT_SAVEANDRESTORE_H
     17 
     18 namespace llvm {
     19 
     20 /// A utility class that uses RAII to save and restore the value of a variable.
     21 template <typename T> struct SaveAndRestore {
     22   SaveAndRestore(T &X) : X(X), OldValue(X) {}
     23   SaveAndRestore(T &X, const T &NewValue) : X(X), OldValue(X) {
     24     X = NewValue;
     25   }
     26   ~SaveAndRestore() { X = OldValue; }
     27   T get() { return OldValue; }
     28 
     29 private:
     30   T &X;
     31   T OldValue;
     32 };
     33 
     34 } // namespace llvm
     35 
     36 #endif
     37