1 //===- llvm/ADT/ScopeExit.h - Execute code at scope exit --------*- 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 defines the make_scope_exit function, which executes user-defined
11 /// cleanup logic at scope exit.
12 ///
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_ADT_SCOPEEXIT_H
16 #define LLVM_ADT_SCOPEEXIT_H
17 
18 #include "llvm/Support/Compiler.h"
19 
20 #include <type_traits>
21 #include <utility>
22 
23 namespace llvm {
24 namespace detail {
25 
26 template <typename Callable> class scope_exit {
27   Callable ExitFunction;
28   bool Engaged = true; // False once moved-from or release()d.
29 
30 public:
31   template <typename Fp>
32   explicit scope_exit(Fp &&F) : ExitFunction(std::forward<Fp>(F)) {}
33 
34   scope_exit(scope_exit &&Rhs)
35       : ExitFunction(std::move(Rhs.ExitFunction)), Engaged(Rhs.Engaged) {
36     Rhs.release();
37   }
38   scope_exit(const scope_exit &) = delete;
39   scope_exit &operator=(scope_exit &&) = delete;
40   scope_exit &operator=(const scope_exit &) = delete;
41 
42   void release() { Engaged = false; }
43 
44   ~scope_exit() {
45     if (Engaged)
46       ExitFunction();
47   }
48 };
49 
50 } // end namespace detail
51 
52 // Keeps the callable object that is passed in, and execute it at the
53 // destruction of the returned object (usually at the scope exit where the
54 // returned object is kept).
55 //
56 // Interface is specified by p0052r2.
57 template <typename Callable>
58 LLVM_NODISCARD detail::scope_exit<typename std::decay<Callable>::type>
59 make_scope_exit(Callable &&F) {
60   return detail::scope_exit<typename std::decay<Callable>::type>(
61       std::forward<Callable>(F));
62 }
63 
64 } // end namespace llvm
65 
66 #endif
67