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construct/include/ircd/util/closure.h

120 lines
3.2 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_CLOSURE_H
namespace ircd {
inline namespace util
{
template<template<class, class...>
class F,
class R,
class... A>
struct closure;
template<template<class, class...>
class F,
class... A>
struct closure<F, bool, A...>;
/// Template for creating callback-based iterations allowing closures of
/// either `void (...)` or `bool (...)` to be passed to the same overload.
///
/// This reduces/deduplicates interfaces which offer an overload for each
/// and thus two library symbols, usually just calling each other...
///
template<template<class, class...>
class F,
class... A>
using closure_bool = closure<F, bool, A...>;
template<class... A>
using function_bool = closure_bool<std::function, A...>;
}}
template<template<class, class...>
class F,
class R,
class... A>
struct ircd::util::closure
:F<R (A...)>
{
using proto_type = R (A...);
using func_type = F<proto_type>;
using func_type::func_type;
using func_type::operator=;
};
template<template<class, class...>
class F,
class... A>
struct ircd::util::closure<F, bool, A...>
:F<bool (A...)>
{
using proto_bool_type = bool (A...);
using proto_void_type = void (A...);
using func_bool_type = F<proto_bool_type>;
using func_void_type = F<proto_void_type>;
template<class lambda>
closure(lambda &&o,
typename std::enable_if<!std::is_constructible<func_bool_type, lambda>::value, int>::type = 0)
noexcept(std::is_nothrow_invocable<lambda, void, A...>());
template<class lambda>
closure(lambda &&o,
typename std::enable_if<std::is_constructible<func_bool_type, lambda>::value, int>::type = 0)
noexcept(std::is_nothrow_invocable<lambda, bool, A...>());
closure() = default;
};
template<template<class, class...>
class F,
class... A>
template<class lambda>
[[gnu::always_inline]]
inline
ircd::util::closure<F, bool, A...>::closure(lambda &&o,
typename std::enable_if<!std::is_constructible<func_bool_type, lambda>::value, int>::type)
noexcept(std::is_nothrow_invocable<lambda, void, A...>())
:F<bool (A...)>
{
[o(std::move(o))](A&&... a)
noexcept(std::is_nothrow_invocable<lambda, void, A...>())
{
static_assert
(
std::is_same<void, decltype(o(std::forward<A>(a)...))>()
);
o(std::forward<A>(a)...);
return true;
}
}
{}
template<template<class, class...>
class F,
class... A>
template<class lambda>
[[gnu::always_inline]]
inline
ircd::util::closure<F, bool, A...>::closure(lambda &&o,
typename std::enable_if<std::is_constructible<func_bool_type, lambda>::value, int>::type)
noexcept(std::is_nothrow_invocable<lambda, bool, A...>())
:F<bool (A...)>
{
std::forward<lambda>(o)
}
{}