// itlib-sentry v1.01

//

// A sentry which invokes a function object when destroyed

//

// SPDX-License-Identifier: MIT

// MIT License:

// Copyright(c) 2020-2022 Borislav Stanimirov

//

// Permission is hereby granted, free of charge, to any person obtaining

// a copy of this software and associated documentation files(the

// "Software"), to deal in the Software without restriction, including

// without limitation the rights to use, copy, modify, merge, publish,

// distribute, sublicense, and / or sell copies of the Software, and to

// permit persons to whom the Software is furnished to do so, subject to

// the following conditions :

//

// The above copyright notice and this permission notice shall be

// included in all copies or substantial portions of the Software.

//

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

// NONINFRINGEMENT.IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE

// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION

// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION

// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

//

//

// VERSION HISTORY

//

// 1.01 (2022-01-13) [[nodicard]] of type if compiled with C++17

// 1.00 (2020-10-15) Initial release

//

//

// DOCUMENTATION

//

// Simply include this file wherever you need.

// It defines the class itlib::sentry. The sentry invokes a provided function

// object (lambda, free function, object with operator()) when destroyed. It's

// useful when you want to invoke some code when exiting a scope, which has

// many exit points.

//

// To create a sentry with C++11, you can use itlib::make_sentry(func), which

// will properly construct the sentry.

//

// With C++17 and template argument deduction you can just create a local

// sentry object with the given function

//

// C++11 example:

//

// void foo(int n);

// {

// itlib::sentry at_exit = itlib::make_sentry([]() { cout << "exiting foo"; });

// if (n==0) return;

// for (int i=0; i<n; ++i) bar();

// }

//

// C++17 example:

//

// void foo(int n);

// {

// itlib::sentry at_exit([]() { cout << "exiting foo"; });

// if (n==0) return;

// for (int i=0; i<n; ++i) bar();

// }

//

//

// TESTS

//

// You can find unit tests in the official repo:

// https://github.com/iboB/itlib/blob/master/test/

//

#pragma once

#include <utility>

#if !defined(ITLIB_NODISCARD)

# if __cplusplus >= 201700

# define ITLIB_NODISCARD [[nodiscard]]

# else

# define ITLIB_NODISCARD

# endif

#endif

namespace itlib

{

template <typename Func>

class ITLIB_NODISCARD sentry

{

public:

explicit sentry(Func&& atexit) : m_func(std::forward<Func>(atexit)) {}

sentry(const sentry&) = delete;

sentry& operator=(const sentry&) = delete;

sentry& operator=(sentry&&) = delete;

private:

Func m_func;

public:

#if __cplusplus >= 201700

// c++ 17 has guaranteed copy-elision, so we can afford to do this

sentry(sentry&&) = delete;

~sentry() { m_func(); }

#else

sentry(sentry&& other) noexcept

: m_func(std::move(other.m_func))

, m_has_func(other.m_has_func)

{

other.m_has_func = false;

}

~sentry() { if (m_has_func) m_func(); }

private:

bool m_has_func = true;

#endif

};

template <typename Func>

sentry<Func> make_sentry(Func&& func)

{

return sentry<Func>(std::forward<Func>(func));

}

}