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2c86ba2390
- Rename fold{l,r,l1,r1} to fold.{right,left} with overloads.
- Rename foldlM/foldrM to monadic_fold.{left,right}
- Add no-state variants of the monadic folds
- Improve the fold's documentation
- Deprecate the previous folds; they'll be removed soon
Fixes #18.
59 lines
1.5 KiB
C++
59 lines
1.5 KiB
C++
/*
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@copyright Louis Dionne 2015
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
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*/
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#include <boost/hana/assert.hpp>
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#include <boost/hana/config.hpp>
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#include <boost/hana/ext/boost/mpl/vector.hpp>
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#include <boost/hana/ext/std/integral_constant.hpp>
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#include <boost/hana/integral_constant.hpp>
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#include <boost/hana/tuple.hpp>
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#include <boost/mpl/fold.hpp>
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#include <boost/mpl/if.hpp>
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#include <boost/mpl/int.hpp>
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#include <boost/mpl/next.hpp>
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#include <boost/mpl/placeholders.hpp>
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#include <boost/mpl/vector.hpp>
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#include <type_traits>
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namespace hana = boost::hana;
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namespace mpl = boost::mpl;
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namespace with_mpl {
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//! [mpl]
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using types = mpl::vector<long, float, short, float, long, long double>;
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using number_of_floats = mpl::fold<
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types,
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mpl::int_<0>,
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mpl::if_<std::is_floating_point<mpl::_2>,
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mpl::next<mpl::_1>,
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mpl::_1
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>
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>::type;
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static_assert(number_of_floats::value == 3, "");
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//! [mpl]
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}
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namespace with_hana {
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//! [hana]
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constexpr auto types = hana::tuple_t<long, float, short, float, long, long double>;
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BOOST_HANA_CONSTEXPR_LAMBDA auto number_of_floats = hana::fold.left(
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types,
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hana::int_<0>,
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[](auto count, auto t) {
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return hana::if_(hana::trait<std::is_floating_point>(t),
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count + hana::int_<1>,
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count
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);
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}
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);
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BOOST_HANA_CONSTANT_CHECK(number_of_floats == hana::int_<3>);
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//! [hana]
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}
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int main() { }
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