hana/example/index_if.cpp
Jason Rice 6d086796a3 [index_if] New index_if function
- Adds index_if
    - Rewrites detail::index_if to use recursive alias stuff
      optimized for tuple and basic_tuple
    - find_if now uses index_if for Iterables
    - at_key now uses index_if for Sequence
    - Removes duplicate code and unnecessary special case implementations
        - detail::advance_until
        - at_key::advance_until
        - tuple_tag implementation of find_if
    - Uses Foldable instead of Sequence for cases where length is known.
      (find_if had a specialization when Iterable and not Sequence)
    - Adds test.*.auto.index_if for Sequences
    - Adds test support/counter for testing infinite iterables
2017-04-07 16:19:52 -07:00

23 lines
879 B
C++

// Copyright Louis Dionne 2013-2017
// Copyright Jason Rice 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)
#include <boost/hana/core/is_a.hpp>
#include <boost/hana/equal.hpp>
#include <boost/hana/index_if.hpp>
#include <boost/hana/integral_constant.hpp>
#include <boost/hana/optional.hpp>
#include <boost/hana/tuple.hpp>
namespace hana = boost::hana;
constexpr auto xs = hana::make_tuple(0, '1', 2.0);
static_assert(hana::index_if(xs, hana::is_an<int>) == hana::just(hana::size_c<0>), "");
static_assert(hana::index_if(xs, hana::is_a<char>) == hana::just(hana::size_c<1>), "");
static_assert(hana::index_if(xs, hana::is_a<double>) == hana::just(hana::size_c<2>), "");
static_assert(hana::index_if(xs, hana::is_a<hana::tuple_tag>) == hana::nothing, "");
int main() { }