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100 lines
2.2 KiB
C++
100 lines
2.2 KiB
C++
/*=============================================================================
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Copyright (c) 2015 Paul Fultz II
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repeat.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_REPEAT_H
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#define FIT_GUARD_REPEAT_H
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/// repeat
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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 `repeat` function decorator will repeatedly apply a function a given
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/// number of times.
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///
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///
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/// Synopsis
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/// --------
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///
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/// template<class IntegralConstant>
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/// constexpr repeat_adaptor<IntegralConstant> repeat(IntegralConstant);
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///
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/// Requirements
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/// ------------
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///
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/// IntegralConstant must be:
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///
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/// * IntegralConstant
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///
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/// Example
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/// -------
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///
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/// struct increment
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/// {
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/// template<class T>
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/// constexpr T operator()(T x) const
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/// {
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/// return x + 1;
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/// }
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/// };
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///
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/// constexpr auto increment_by_5 = fit::repeat(std::integral_constant<int, 5>())(increment());
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/// assert(increment_by_5(1) == 6);
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///
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#include <fit/always.h>
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#include <fit/detail/delegate.h>
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#include <fit/detail/result_of.h>
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#include <fit/detail/move.h>
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#include <fit/detail/sfinae.h>
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#include <fit/detail/static_const_var.h>
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#include <fit/decorate.h>
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namespace fit { namespace detail {
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template<int N>
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struct repeater
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{
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template<class F, class... Ts>
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constexpr FIT_SFINAE_RESULT(repeater<N-1>, id_<const F&>, result_of<const F&, id_<Ts>...>)
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operator()(const F& f, Ts&&... xs) const FIT_SFINAE_RETURNS
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(
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repeater<N-1>()(f, f(fit::forward<Ts>(xs)...))
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);
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};
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template<>
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struct repeater<0>
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{
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template<class F, class T>
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constexpr T operator()(const F&, T&& x) const
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{
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return x;
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}
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};
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struct repeat_decorator
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{
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template<class T, class F, class... Ts>
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constexpr auto operator()(T, const F& f, Ts&&... xs) const FIT_RETURNS
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(
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detail::repeater<T::value>()
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(
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f,
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fit::forward<Ts>(xs)...
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)
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);
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};
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}
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FIT_DECLARE_STATIC_VAR(repeat, decorate_adaptor<detail::repeat_decorator>);
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}
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#endif |