102 lines
2.5 KiB
C++
102 lines
2.5 KiB
C++
/*=============================================================================
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Copyright (c) 2015 Paul Fultz II
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rotate.h
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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==============================================================================*/
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#ifndef BOOST_HOF_GUARD_ROTATE_H
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#define BOOST_HOF_GUARD_ROTATE_H
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/// rotate
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/// ====
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///
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/// Description
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/// -----------
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///
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/// The `rotate` function adaptor moves the first parameter to the last
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/// parameter.
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///
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/// Synopsis
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/// --------
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///
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/// template<class F>
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/// rotate_adaptor<F> rotate(F f);
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///
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/// Semantics
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/// ---------
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///
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/// assert(rotate(f)(x, xs...) == f(xs..., x));
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///
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/// Requirements
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/// ------------
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///
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/// F must be:
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///
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/// * [ConstInvocable](ConstInvocable)
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/// * MoveConstructible
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///
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/// Example
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/// -------
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///
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/// #include <boost/hof.hpp>
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/// #include <cassert>
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///
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/// int main() {
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/// int r = boost::hof::rotate(boost::hof::_ - boost::hof::_)(2, 5);
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/// assert(r == 3);
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/// }
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///
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#include <boost/hof/detail/result_of.hpp>
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#include <boost/hof/reveal.hpp>
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#include <boost/hof/detail/make.hpp>
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#include <boost/hof/detail/static_const_var.hpp>
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namespace boost { namespace hof {
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template<class F>
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struct rotate_adaptor : detail::callable_base<F>
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{
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typedef rotate_adaptor fit_rewritable1_tag;
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BOOST_HOF_INHERIT_CONSTRUCTOR(rotate_adaptor, detail::callable_base<F>);
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template<class... Ts>
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constexpr const detail::callable_base<F>& base_function(Ts&&... xs) const noexcept
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{
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return boost::hof::always_ref(*this)(xs...);
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}
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struct rotate_failure
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{
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template<class Failure>
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struct apply
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{
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template<class T, class... Ts>
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struct of
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: Failure::template of<Ts..., T>
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{};
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};
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};
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struct failure
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: failure_map<rotate_failure, detail::callable_base<F>>
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{};
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BOOST_HOF_RETURNS_CLASS(rotate_adaptor);
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template<class T, class... Ts>
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constexpr BOOST_HOF_SFINAE_RESULT(const detail::callable_base<F>&, id_<Ts>..., id_<T>)
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operator()(T&& x, Ts&&... xs) const BOOST_HOF_SFINAE_RETURNS
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(
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(BOOST_HOF_MANGLE_CAST(const detail::callable_base<F>&)(BOOST_HOF_CONST_THIS->base_function(xs...)))
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(BOOST_HOF_FORWARD(Ts)(xs)..., BOOST_HOF_FORWARD(T)(x))
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);
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};
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BOOST_HOF_DECLARE_STATIC_VAR(rotate, detail::make<rotate_adaptor>);
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}} // namespace boost::hof
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#endif
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