54 lines
1.3 KiB
C++
54 lines
1.3 KiB
C++
// Copyright Louis Dionne 2013-2017
|
|
// Distributed under the Boost Software License, Version 1.0.
|
|
// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
|
|
|
|
template <typename ...xs>
|
|
struct list { };
|
|
|
|
template <typename T>
|
|
struct basic_type { using type = T; };
|
|
|
|
template <typename T>
|
|
constexpr basic_type<T> type{};
|
|
|
|
|
|
template <typename x, typename ...xs>
|
|
constexpr auto head(list<x, xs...>)
|
|
{ return type<x>; }
|
|
|
|
template <typename x, typename ...xs>
|
|
constexpr auto tail(list<x, xs...>)
|
|
{ return list<xs...>{}; }
|
|
|
|
template <typename F, typename State, typename X, typename ...Xs>
|
|
constexpr auto foldl(F f, State s, list<X, Xs...> xs)
|
|
{ return foldl(f, f(s, head(xs)), tail(xs)); }
|
|
|
|
template <typename F, typename State>
|
|
constexpr auto foldl(F, State s, list<>)
|
|
{ return s; }
|
|
|
|
//////////////////////////////////////////////////////////////////////////////
|
|
|
|
|
|
struct f {
|
|
template <typename ...>
|
|
struct result { };
|
|
|
|
template <typename X, typename Y>
|
|
constexpr auto operator()(X, Y) const
|
|
{ return result<X, Y>{}; }
|
|
};
|
|
|
|
template <int> struct x { };
|
|
struct state { };
|
|
|
|
int main() {
|
|
constexpr auto xs = list<
|
|
<%= (1..input_size).map { |i| "x<#{i}>" }.join(', ') %>
|
|
>{};
|
|
|
|
constexpr auto result = foldl(f{}, state{}, xs);
|
|
(void)result;
|
|
}
|