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 | #include <utility> |
19 | |
20 | namespace llvm { |
21 | |
22 | /// A utility class that uses RAII to save and restore the value of a variable. |
23 | template <typename T> struct SaveAndRestore { |
24 | SaveAndRestore(T &X) : X(X), OldValue(X) {} |
25 | SaveAndRestore(T &X, const T &NewValue) : X(X), OldValue(X) { X = NewValue; } |
26 | SaveAndRestore(T &X, T &&NewValue) : X(X), OldValue(std::move(X)) { |
27 | X = std::move(NewValue); |
28 | } |
29 | ~SaveAndRestore() { X = std::move(OldValue); } |
30 | const T &get() { return OldValue; } |
31 | |
32 | private: |
33 | T &X; |
34 | T OldValue; |
35 | }; |
36 | |
37 | // User-defined CTAD guides. |
38 | template <typename T> SaveAndRestore(T &) -> SaveAndRestore<T>; |
39 | template <typename T> SaveAndRestore(T &, const T &) -> SaveAndRestore<T>; |
40 | template <typename T> SaveAndRestore(T &, T &&) -> SaveAndRestore<T>; |
41 | |
42 | } // namespace llvm |
43 | |
44 | #endif |
45 | |