58 lines
1.8 KiB
C++
58 lines
1.8 KiB
C++
/*!
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@file
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Forward declares `boost::hana::intersperse`.
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@copyright Louis Dionne 2013-2016
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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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#ifndef BOOST_HANA_FWD_INTERSPERSE_HPP
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#define BOOST_HANA_FWD_INTERSPERSE_HPP
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#include <boost/hana/config.hpp>
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#include <boost/hana/core/when.hpp>
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BOOST_HANA_NAMESPACE_BEGIN
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//! Insert a value between each pair of elements in a finite sequence.
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//! @ingroup group-Sequence
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//!
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//! Given a finite `Sequence` `xs` with a linearization of
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//! `[x1, x2, ..., xn]`, `intersperse(xs, z)` is a new sequence with a
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//! linearization of `[x1, z, x2, z, x3, ..., xn-1, z, xn]`. In other
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//! words, it inserts the `z` element between every pair of elements of
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//! the original sequence. If the sequence is empty or has a single
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//! element, `intersperse` returns the sequence as-is. In all cases,
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//! the sequence must be finite.
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//!
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//!
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//! @param xs
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//! The sequence in which a value is interspersed.
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//!
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//! @param z
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//! The value to be inserted between every pair of elements of the sequence.
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//!
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//!
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//! Example
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//! -------
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//! @include example/intersperse.cpp
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#ifdef BOOST_HANA_DOXYGEN_INVOKED
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constexpr auto intersperse = [](auto&& xs, auto&& z) {
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return tag-dispatched;
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};
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#else
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template <typename S, typename = void>
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struct intersperse_impl : intersperse_impl<S, when<true>> { };
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struct intersperse_t {
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template <typename Xs, typename Z>
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constexpr auto operator()(Xs&& xs, Z&& z) const;
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};
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constexpr intersperse_t intersperse{};
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#endif
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_FWD_INTERSPERSE_HPP
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