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- /*!
- @file
- Forward declares `boost::hana::intersperse`.
- @copyright Louis Dionne 2013-2017
- Distributed under the Boost Software License, Version 1.0.
- (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
- */
- #ifndef BOOST_HANA_FWD_INTERSPERSE_HPP
- #define BOOST_HANA_FWD_INTERSPERSE_HPP
- #include <boost/hana/config.hpp>
- #include <boost/hana/core/when.hpp>
- BOOST_HANA_NAMESPACE_BEGIN
- //! Insert a value between each pair of elements in a finite sequence.
- //! @ingroup group-Sequence
- //!
- //! Given a finite `Sequence` `xs` with a linearization of
- //! `[x1, x2, ..., xn]`, `intersperse(xs, z)` is a new sequence with a
- //! linearization of `[x1, z, x2, z, x3, ..., xn-1, z, xn]`. In other
- //! words, it inserts the `z` element between every pair of elements of
- //! the original sequence. If the sequence is empty or has a single
- //! element, `intersperse` returns the sequence as-is. In all cases,
- //! the sequence must be finite.
- //!
- //!
- //! @param xs
- //! The sequence in which a value is interspersed.
- //!
- //! @param z
- //! The value to be inserted between every pair of elements of the sequence.
- //!
- //!
- //! Example
- //! -------
- //! @include example/intersperse.cpp
- #ifdef BOOST_HANA_DOXYGEN_INVOKED
- constexpr auto intersperse = [](auto&& xs, auto&& z) {
- return tag-dispatched;
- };
- #else
- template <typename S, typename = void>
- struct intersperse_impl : intersperse_impl<S, when<true>> { };
- struct intersperse_t {
- template <typename Xs, typename Z>
- constexpr auto operator()(Xs&& xs, Z&& z) const;
- };
- constexpr intersperse_t intersperse{};
- #endif
- BOOST_HANA_NAMESPACE_END
- #endif // !BOOST_HANA_FWD_INTERSPERSE_HPP
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