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construct/include/ircd/util/maybe.h

70 lines
1.5 KiB
C++

// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2019 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.
#pragma once
#define HAVE_IRCD_UTIL_MAYBE_H
namespace ircd { inline namespace util
{
using maybe_void_type = std::tuple<bool, std::exception_ptr>;
template<class function>
using maybe_retval = typename std::invoke_result<function>::type;
template<class function>
using maybe_type = std::tuple<maybe_retval<function>, std::exception_ptr>;
template<class function>
constexpr bool maybe_void();
template<class function>
typename std::enable_if<!maybe_void<function>(), maybe_type<function>>::type
maybe(function&& f)
noexcept try
{
return
{
f(), std::exception_ptr{}
};
}
catch(...)
{
return
{
{}, std::current_exception()
};
}
template<class function>
typename std::enable_if<maybe_void<function>(), maybe_void_type>::type
maybe(function&& f)
noexcept try
{
f();
return
{
true, std::exception_ptr{}
};
}
catch(...)
{
return
{
false, std::current_exception()
};
}
template<class function>
constexpr bool
maybe_void()
{
return std::is_same<maybe_retval<function>, void>();
}
}}