1// Copyright Louis Dionne 2013-2022
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/assert.hpp>
6#include <boost/hana/core/to.hpp>
7#include <boost/hana/equal.hpp>
8#include <boost/hana/filter.hpp>
9#include <boost/hana/integral_constant.hpp>
10#include <boost/hana/length.hpp>
11#include <boost/hana/mod.hpp>
12#include <boost/hana/range.hpp>
13#include <boost/hana/slice.hpp>
14#include <boost/hana/tuple.hpp>
15#include <boost/hana/type.hpp>
16namespace hana = boost::hana;
17using namespace hana::literals;
18
19
20// Slice a contiguous range
21constexpr auto xs = hana::make_tuple(0, '1', 2.2, 3_c, hana::type_c<float>);
22
23static_assert(
24 hana::slice(xs, hana::tuple_c<std::size_t, 1, 2, 3>) ==
25 hana::make_tuple('1', 2.2, 3_c)
26, "");
27
28
29// A more complex example with a non-contiguous range
30constexpr auto letters = hana::to_tuple(hana::range_c<char, 'a', 'z'>);
31constexpr auto indices = hana::to_tuple(hana::make_range(hana::size_c<0>, hana::length(letters)));
32
33auto even_indices = hana::filter(indices, [](auto n) {
34 return n % hana::size_c<2> == hana::size_c<0>;
35});
36
37BOOST_HANA_CONSTANT_CHECK(
38 hana::slice(letters, even_indices) == hana::tuple_c<char,
39 'a', 'c', 'e', 'g', 'i', 'k', 'm', 'o', 'q', 's', 'u', 'w', 'y'
40 >
41);
42
43int main() { }
44

source code of boost/libs/hana/example/slice.cpp