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107 lines
2.6 KiB
107 lines
2.6 KiB
/*============================================================================= |
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Copyright (c) 2015 Paul Fultz II |
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flip.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_FLIP_H |
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#define BOOST_HOF_GUARD_FLIP_H |
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/// flip |
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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 `flip` function adaptor swaps the first two parameters. |
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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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/// flip_adaptor<F> flip(F f); |
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/// |
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/// Semantics |
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/// --------- |
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/// |
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/// assert(flip(f)(x, y, xs...) == f(y, x, xs...)); |
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/// |
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/// Requirements |
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/// ------------ |
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/// |
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/// F must be at least: |
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/// |
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/// * [BinaryInvocable](BinaryInvocable) |
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/// |
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/// Or: |
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/// |
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/// * [Invocable](Invocable) with more than two argurments |
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/// |
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/// And: |
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/// |
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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::flip(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/callable_base.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 flip_adaptor : detail::callable_base<F> |
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{ |
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typedef flip_adaptor fit_rewritable1_tag; |
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BOOST_HOF_INHERIT_CONSTRUCTOR(flip_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 |
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{ |
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return boost::hof::always_ref(*this)(xs...); |
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} |
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struct flip_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 U, class... Ts> |
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struct of |
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: Failure::template of<U, T, Ts...> |
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{}; |
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}; |
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}; |
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struct failure |
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: failure_map<flip_failure, detail::callable_base<F>> |
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{}; |
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BOOST_HOF_RETURNS_CLASS(flip_adaptor); |
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template<class T, class U, class... Ts> |
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constexpr BOOST_HOF_SFINAE_RESULT(const detail::callable_base<F>&, id_<U>, id_<T>, id_<Ts>...) |
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operator()(T&& x, U&& y, 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(U)(y), BOOST_HOF_FORWARD(T)(x), BOOST_HOF_FORWARD(Ts)(xs)...) |
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); |
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}; |
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BOOST_HOF_DECLARE_STATIC_VAR(flip, detail::make<flip_adaptor>); |
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}} // namespace boost::hof |
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#endif
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