include/llvm/Support/SaveAndRestore.h

   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