]>
Commit | Line | Data |
---|---|---|
b32b8144 | 1 | // Copyright Louis Dionne 2013-2017 |
7c673cae FG |
2 | // Distributed under the Boost Software License, Version 1.0. |
3 | // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt) | |
4 | ||
5 | #include <boost/hana/functional/fix.hpp> | |
6 | ||
7 | #include <boost/hana/assert.hpp> | |
8 | #include <boost/hana/config.hpp> | |
9 | #include <boost/hana/equal.hpp> | |
10 | #include <boost/hana/eval_if.hpp> | |
11 | #include <boost/hana/functional/always.hpp> | |
12 | #include <boost/hana/integral_constant.hpp> | |
13 | #include <boost/hana/minus.hpp> | |
14 | #include <boost/hana/mult.hpp> | |
15 | namespace hana = boost::hana; | |
16 | ||
17 | ||
18 | BOOST_HANA_CONSTEXPR_LAMBDA auto fact = hana::fix([](auto fact, auto n) { | |
19 | return hana::eval_if(hana::equal(n, hana::ullong_c<0>), | |
20 | hana::always(hana::ullong_c<1>), | |
21 | [=](auto _) { return hana::mult(n, fact(_(n) - hana::ullong_c<1>)); } | |
22 | ); | |
23 | }); | |
24 | ||
25 | constexpr unsigned long long reference(unsigned long long n) | |
26 | { return n == 0 ? 1 : n * reference(n - 1); } | |
27 | ||
28 | template <int n> | |
29 | void test() { | |
30 | BOOST_HANA_CONSTANT_CHECK(hana::equal( | |
31 | fact(hana::ullong_c<n>), | |
32 | hana::ullong_c<reference(n)> | |
33 | )); | |
34 | test<n - 1>(); | |
35 | } | |
36 | ||
37 | template <> void test<-1>() { } | |
38 | ||
39 | int main() { | |
40 | test<15>(); | |
41 | } |