include/llvm/ADT/ScopeExit.h

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