Move "clang/Analysis/Support/SaveAndRestore.h" to "llvm/ADT/SaveAndRestore.h"

to make it more widely available.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151564 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ADT/SaveAndRestore.h

@@ -0,0 +1,47 @@
+//===-- SaveAndRestore.h - Utility  -------------------------------*- C++ -*-=//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file provides utility classes that uses RAII to save and restore
+//  values.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_SAVERESTORE
+#define LLVM_ADT_SAVERESTORE
+
+namespace llvm {
+
+// SaveAndRestore - A utility class that uses RAII to save and restore
+//  the value of a variable.
+template<typename T>
+struct SaveAndRestore {
+  SaveAndRestore(T& x) : X(x), old_value(x) {}
+  SaveAndRestore(T& x, const T &new_value) : X(x), old_value(x) {
+    X = new_value;
+  }
+  ~SaveAndRestore() { X = old_value; }
+  T get() { return old_value; }
+private:
+  T& X;
+  T old_value;
+};
+
+// SaveOr - Similar to SaveAndRestore.  Operates only on bools; the old
+//  value of a variable is saved, and during the dstor the old value is
+//  or'ed with the new value.
+struct SaveOr {
+  SaveOr(bool& x) : X(x), old_value(x) { x = false; }
+  ~SaveOr() { X |= old_value; }
+private:
+  bool& X;
+  const bool old_value;
+};
+
+}
+#endif