ladybird/AK/Tuple.h
Nico Weber 4409b33145 AK: Make IndexSequence use size_t
This makes it possible to use MakeIndexSequqnce in functions like:

    template<typename T, size_t N>
    constexpr auto foo(T (&a)[N])

This means AK/StdLibExtraDetails.h must now include AK/Types.h
for size_t, which means AK/Types.h can no longer include
AK/StdLibExtras.h (which arguably it shouldn't do anyways),
which requires rejiggering some things.

(IMHO Types.h shouldn't use AK::Details metaprogramming at all.
FlatPtr doesn't necessarily have to use Conditional<> and ssize_t could
maybe be in its own header or something. But since it's tangential to
this PR, going with the tried and true "lift things that cause the
cycle up to the top" approach.)
2024-02-11 18:53:00 +01:00

227 lines
4.6 KiB
C++

/*
* Copyright (c) 2021, Ali Mohammad Pur <mpfard@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/StdLibExtras.h>
#include <AK/TypeList.h>
namespace AK::Detail {
template<typename... Ts>
struct Tuple {
};
template<typename T>
struct Tuple<T> {
Tuple(T&& value)
requires(!IsSame < T &&, T const& >)
: value(forward<T>(value))
{
}
Tuple(T const& value)
: value(value)
{
}
template<typename U>
U& get()
{
static_assert(IsSame<T, U>, "Invalid tuple access");
return value;
}
template<typename U>
U const& get() const
{
return const_cast<Tuple<T>&>(*this).get<U>();
}
template<typename U, size_t index>
U& get_with_index()
{
static_assert(IsSame<T, U> && index == 0, "Invalid tuple access");
return value;
}
template<typename U, size_t index>
U const& get_with_index() const
{
return const_cast<Tuple<T>&>(*this).get_with_index<U, index>();
}
private:
T value;
};
template<typename T, typename... TRest>
struct Tuple<T, TRest...> : Tuple<TRest...> {
template<typename FirstT, typename... RestT>
Tuple(FirstT&& first, RestT&&... rest)
: Tuple<TRest...>(forward<RestT>(rest)...)
, value(forward<FirstT>(first))
{
}
Tuple(T&& first, TRest&&... rest)
: Tuple<TRest...>(move(rest)...)
, value(move(first))
{
}
template<typename U>
U& get()
{
if constexpr (IsSame<T, U>)
return value;
else
return Tuple<TRest...>::template get<U>();
}
template<typename U>
U const& get() const
{
return const_cast<Tuple<T, TRest...>&>(*this).get<U>();
}
template<typename U, size_t index>
U& get_with_index()
{
if constexpr (IsSame<T, U> && index == 0)
return value;
else
return Tuple<TRest...>::template get_with_index<U, index - 1>();
}
template<typename U, size_t index>
U const& get_with_index() const
{
return const_cast<Tuple<T, TRest...>&>(*this).get_with_index<U, index>();
}
private:
T value;
};
}
namespace AK {
template<typename... Ts>
struct Tuple : Detail::Tuple<Ts...> {
using Types = TypeList<Ts...>;
using Detail::Tuple<Ts...>::Tuple;
using Indices = MakeIndexSequence<sizeof...(Ts)>;
Tuple(Tuple&& other)
: Tuple(move(other), Indices())
{
}
Tuple(Tuple const& other)
: Tuple(other, Indices())
{
}
Tuple& operator=(Tuple&& other)
{
set(move(other), Indices());
return *this;
}
Tuple& operator=(Tuple const& other)
{
set(other, Indices());
return *this;
}
template<typename T>
auto& get()
{
return Detail::Tuple<Ts...>::template get<T>();
}
template<size_t index>
auto& get()
{
return Detail::Tuple<Ts...>::template get_with_index<typename Types::template Type<index>, index>();
}
template<typename T>
auto& get() const
{
return Detail::Tuple<Ts...>::template get<T>();
}
template<size_t index>
auto& get() const
{
return Detail::Tuple<Ts...>::template get_with_index<typename Types::template Type<index>, index>();
}
template<typename F>
auto apply_as_args(F&& f)
{
return apply_as_args(forward<F>(f), Indices());
}
template<typename F>
auto apply_as_args(F&& f) const
{
return apply_as_args(forward<F>(f), Indices());
}
static constexpr auto size() { return sizeof...(Ts); }
private:
template<size_t... Is>
Tuple(Tuple&& other, IndexSequence<Is...>)
: Detail::Tuple<Ts...>(move(other.get<Is>())...)
{
}
template<size_t... Is>
Tuple(Tuple const& other, IndexSequence<Is...>)
: Detail::Tuple<Ts...>(other.get<Is>()...)
{
}
template<size_t... Is>
void set(Tuple&& other, IndexSequence<Is...>)
{
((get<Is>() = move(other.get<Is>())), ...);
}
template<size_t... Is>
void set(Tuple const& other, IndexSequence<Is...>)
{
((get<Is>() = other.get<Is>()), ...);
}
template<typename F, size_t... Is>
auto apply_as_args(F&& f, IndexSequence<Is...>)
{
return forward<F>(f)(get<Is>()...);
}
template<typename F, size_t... Is>
auto apply_as_args(F&& f, IndexSequence<Is...>) const
{
return forward<F>(f)(get<Is>()...);
}
};
template<class... Args>
Tuple(Args... args) -> Tuple<Args...>;
}
#if USING_AK_GLOBALLY
using AK::Tuple;
#endif