openMSX
utils
function_ref.hh
Go to the documentation of this file.
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// This is a simplified / stripped-down version of:
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// https://github.com/TartanLlama/function_ref/blob/master/include/tl/function_ref.hpp
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// function_ref - A low-overhead non-owning function
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// Written in 2017 by Simon Brand (@TartanLlama)
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//
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// To the extent possible under law, the author(s) have dedicated all
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// copyright and related and neighboring rights to this software to the
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// public domain worldwide. This software is distributed without any warranty.
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//
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// You should have received a copy of the CC0 Public Domain Dedication
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// along with this software. If not, see
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// <http://creativecommons.org/publicdomain/zero/1.0/>.
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#ifndef FUNCTION_REF_HH
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#define FUNCTION_REF_HH
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#include <functional>
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#include <type_traits>
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#include <utility>
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template
<
typename
F>
class
function_ref
;
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template
<
typename
R,
typename
... Args>
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class
function_ref
<R(Args...)>
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{
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public
:
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constexpr
function_ref
() noexcept = delete;
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template<typename
F
,
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std
::enable_if_t<!
std
::is_same_v<
std
::decay_t<
F
>,
function_ref
> &&
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std
::is_invocable_r_v<R,
F
&&, Args...>>* =
nullptr
>
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constexpr
function_ref
(
F
&& f) noexcept
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: obj(const_cast<
void
*>(static_cast<const
void
*>(
std
::addressof(f))))
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{
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callback = [](
void
* o, Args... args) -> R {
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return
std::invoke(*
static_cast<
std::add_pointer_t<F>
>
(o),
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std::forward<Args>(args)...);
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};
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}
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template
<
typename
F
,
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std::enable_if_t<std::is_invocable_r_v<R,
F
&&, Args...>>* =
nullptr
>
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constexpr
function_ref
&
operator=
(
F
&& f)
noexcept
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{
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obj =
reinterpret_cast<
void
*
>
(std::addressof(f));
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callback = [](
void
* o, Args... args) {
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return
std::invoke(*
reinterpret_cast<
std::add_pointer_t<F>
>
(o),
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std::forward<Args>(args)...);
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};
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return
*
this
;
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}
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constexpr
R
operator()
(Args... args)
const
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{
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return
callback(obj, std::forward<Args>(args)...);
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}
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private
:
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void
* obj =
nullptr
;
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R (*callback)(
void
*, Args...) =
nullptr
;
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};
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template
<
typename
R
,
typename
... Args>
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function_ref
(R(*)(Args...)) ->
function_ref
<R(Args...)>;
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#endif
function_ref< R(Args...)>::operator()
constexpr R operator()(Args... args) const
Definition
function_ref.hh:56
function_ref< R(Args...)>::operator=
constexpr function_ref & operator=(F &&f) noexcept
Definition
function_ref.hh:46
function_ref< R(Args...)>::function_ref
constexpr function_ref() noexcept=delete
function_ref
Definition
function_ref.hh:24
openmsx::R
RegFunction R
Definition
ImGuiVdpRegs.cc:184
std
STL namespace.
F
Definition
view_test.cc:242
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