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Diffstat (limited to 'boost/hana/fwd/for_each.hpp')
| -rw-r--r-- | boost/hana/fwd/for_each.hpp | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/boost/hana/fwd/for_each.hpp b/boost/hana/fwd/for_each.hpp new file mode 100644 index 0000000000..35c0bd45ce --- /dev/null +++ b/boost/hana/fwd/for_each.hpp @@ -0,0 +1,55 @@ +/*! +@file +Forward declares `boost::hana::for_each`. + +@copyright Louis Dionne 2013-2016 +Distributed under the Boost Software License, Version 1.0. +(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt) + */ + +#ifndef BOOST_HANA_FWD_FOR_EACH_HPP +#define BOOST_HANA_FWD_FOR_EACH_HPP + +#include <boost/hana/config.hpp> +#include <boost/hana/core/when.hpp> + + +BOOST_HANA_NAMESPACE_BEGIN + //! Perform an action on each element of a foldable, discarding + //! the result each time. + //! @ingroup group-Foldable + //! + //! Iteration is done from left to right, i.e. in the same order as when + //! using `fold_left`. If the structure is not finite, this method will + //! not terminate. + //! + //! + //! @param xs + //! The structure to iterate over. + //! + //! @param f + //! A function called as `f(x)` for each element `x` of the structure. + //! The result of `f(x)`, whatever it is, is ignored. + //! + //! + //! Example + //! ------- + //! @include example/for_each.cpp +#ifdef BOOST_HANA_DOXYGEN_INVOKED + constexpr auto for_each = [](auto&& xs, auto&& f) -> void { + tag-dispatched; + }; +#else + template <typename T, typename = void> + struct for_each_impl : for_each_impl<T, when<true>> { }; + + struct for_each_t { + template <typename Xs, typename F> + constexpr void operator()(Xs&& xs, F&& f) const; + }; + + constexpr for_each_t for_each{}; +#endif +BOOST_HANA_NAMESPACE_END + +#endif // !BOOST_HANA_FWD_FOR_EACH_HPP |