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#pragma once
/* Copyright (c) 2017 Stanislaw Halik
*
* 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 appear in all copies.
*/
namespace meta::detail {
template<typename... xs>
struct tuple;
template<typename... xs>
struct reverse_;
template<typename x0, typename... xs, template<typename...> class x, typename... ys>
struct reverse_<x<x0, xs...>, x<ys...>>
{
using type = typename reverse_<x<xs...>, x<x0, ys...>>::type;
};
template<template<typename...> class x, typename... ys>
struct reverse_<x<>, x<ys...>>
{
using type = x<ys...>;
};
template<template<typename...> class, typename, typename...> struct lift_;
template<template<typename...> class to, template<typename...> class from, typename... xs>
struct lift_<to, from<xs...>>
{
using type = to<xs...>;
};
template<typename> struct append_helper;
template<typename, typename> struct cons_;
template<template<typename...> class t, typename x, typename... xs>
struct cons_<x, t<xs...>>
{
using type = t<x, xs...>;
};
template<typename> struct append2;
template<template<typename...> class t, typename... xs>
struct append2<t<xs...>>
{
template<typename> struct append1;
template<template<typename...> class u, typename... ys>
struct append1<u<ys...>>
{
using type = t<xs..., ys...>;
};
};
template<typename, typename...> struct list__;
template<typename rest, typename... first>
struct list__
{
template<typename> struct list1;
template<template<typename...> class t, typename... xs>
struct list1<t<xs...>>
{
using type = t<first..., xs...>;
};
using type = typename list1<rest>::type;
};
template<typename xs, typename ys>
struct append_
{
using t1 = append2<xs>;
using type = typename t1::template append1<ys>::type;
};
} // ns meta::detail
namespace meta {
template<typename... xs>
using tuple_ = detail::tuple<xs...>;
template<typename... xs>
using reverse = typename detail::reverse_<detail::tuple<xs...>, detail::tuple<>>::type;
// the to/from order is awkward but mimics function composition
template<template<typename...> class to, typename from>
using lift = typename detail::lift_<to, from>::type;
template<typename x, typename... xs>
using first = x;
template<typename x, typename... xs>
using rest = detail::tuple<xs...>;
template<typename... xs>
using butlast = reverse<rest<reverse<xs...>>>;
template<typename... xs>
using last = lift<first, reverse<xs...>>;
template<typename x, typename rest>
using cons = typename detail::cons_<x, rest>::type;
template<typename xs, typename ys>
using append = typename detail::append_<xs, ys>;
template<typename rest, typename... xs>
using list_ = typename detail::list__<rest, xs...>;
} // ns meta
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