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96 lines
2.3 KiB
C++
96 lines
2.3 KiB
C++
/*=============================================================================
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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 FIT_GUARD_FLIP_H
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#define FIT_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:
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///
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/// * [BinaryCallable](concepts.md#binarycallable)
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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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/// int r = fit::flip(fit::_ - fit::_)(2, 5);
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/// assert(r == 3);
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///
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#include <fit/detail/callable_base.hpp>
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#include <fit/reveal.hpp>
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#include <fit/detail/make.hpp>
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#include <fit/detail/static_const_var.hpp>
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namespace fit {
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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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FIT_INHERIT_CONSTRUCTOR(flip_adaptor, detail::callable_base<F>);
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template<class... Ts>
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constexpr const F& base_function(Ts&&... xs) const
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{
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return 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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FIT_RETURNS_CLASS(flip_adaptor);
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template<class T, class U, class... Ts>
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constexpr FIT_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 FIT_SFINAE_RETURNS
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(
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(FIT_MANGLE_CAST(const detail::callable_base<F>&)(FIT_CONST_THIS->base_function(xs...)))
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(FIT_FORWARD(U)(y), FIT_FORWARD(T)(x), FIT_FORWARD(Ts)(xs)...)
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);
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};
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FIT_DECLARE_STATIC_VAR(flip, detail::make<flip_adaptor>);
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} // namespace fit
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#endif
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