1 //===-- SaveAndRestore.h - Utility -------------------------------*- C++ -*-=// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 /// 10 /// \file 11 /// This file provides utility classes that use RAII to save and restore 12 /// values. 13 /// 14 //===----------------------------------------------------------------------===// 15 16 #ifndef LLVM_SUPPORT_SAVEANDRESTORE_H 17 #define LLVM_SUPPORT_SAVEANDRESTORE_H 18 19 namespace llvm { 20 21 /// A utility class that uses RAII to save and restore the value of a variable. 22 template <typename T> struct SaveAndRestore { 23 SaveAndRestore(T &X) : X(X), OldValue(X) {} 24 SaveAndRestore(T &X, const T &NewValue) : X(X), OldValue(X) { 25 X = NewValue; 26 } 27 ~SaveAndRestore() { X = OldValue; } 28 T get() { return OldValue; } 29 30 private: 31 T &X; 32 T OldValue; 33 }; 34 35 /// Similar to \c SaveAndRestore. Operates only on bools; the old value of a 36 /// variable is saved, and during the dstor the old value is or'ed with the new 37 /// value. 38 struct SaveOr { 39 SaveOr(bool &X) : X(X), OldValue(X) { X = false; } 40 ~SaveOr() { X |= OldValue; } 41 42 private: 43 bool &X; 44 const bool OldValue; 45 }; 46 47 } // namespace llvm 48 49 #endif 50
