ceph/src/boost/boost/hof/rotate.hpp

   1 /*=============================================================================
   2     Copyright (c) 2015 Paul Fultz II
   3     rotate.h
   4     Distributed under the Boost Software License, Version 1.0. (See accompanying
   5     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6 ==============================================================================*/
   7
   8 #ifndef BOOST_HOF_GUARD_ROTATE_H
   9 #define BOOST_HOF_GUARD_ROTATE_H
  10
  11 /// rotate
  12 /// ====
  13 ///
  14 /// Description
  15 /// -----------
  16 ///
  17 /// The `rotate` function adaptor moves the first parameter to the last
  18 /// parameter.
  19 ///
  20 /// Synopsis
  21 /// --------
  22 ///
  23 ///     template<class F>
  24 ///     rotate_adaptor<F> rotate(F f);
  25 ///
  26 /// Semantics
  27 /// ---------
  28 ///
  29 ///     assert(rotate(f)(x, xs...) == f(xs..., x));
  30 ///
  31 /// Requirements
  32 /// ------------
  33 ///
  34 /// F must be:
  35 ///
  36 /// * [ConstInvocable](ConstInvocable)
  37 /// * MoveConstructible
  38 ///
  39 /// Example
  40 /// -------
  41 ///
  42 ///     #include <boost/hof.hpp>
  43 ///     #include <cassert>
  44 ///
  45 ///     int main() {
  46 ///         int r = boost::hof::rotate(boost::hof::_ - boost::hof::_)(2, 5);
  47 ///         assert(r == 3);
  48 ///     }
  49 ///
  50
  51 #include <boost/hof/detail/result_of.hpp>
  52 #include <boost/hof/reveal.hpp>
  53 #include <boost/hof/detail/make.hpp>
  54 #include <boost/hof/detail/static_const_var.hpp>
  55
  56 namespace boost { namespace hof {
  57
  58 template<class F>
  59 struct rotate_adaptor : detail::callable_base<F>
  60 {
  61     typedef rotate_adaptor fit_rewritable1_tag;
  62     BOOST_HOF_INHERIT_CONSTRUCTOR(rotate_adaptor, detail::callable_base<F>);
  63
  64     template<class... Ts>
  65     constexpr const detail::callable_base<F>& base_function(Ts&&... xs) const noexcept
  66     {
  67         return boost::hof::always_ref(*this)(xs...);
  68     }
  69
  70     struct rotate_failure
  71     {
  72         template<class Failure>
  73         struct apply
  74         {
  75             template<class T, class... Ts>
  76             struct of
  77             : Failure::template of<Ts..., T>
  78             {};
  79         };
  80     };
  81
  82     struct failure
  83     : failure_map<rotate_failure, detail::callable_base<F>>
  84     {};
  85
  86     BOOST_HOF_RETURNS_CLASS(rotate_adaptor);
  87
  88     template<class T, class... Ts>
  89     constexpr BOOST_HOF_SFINAE_RESULT(const detail::callable_base<F>&, id_<Ts>..., id_<T>)
  90     operator()(T&& x, Ts&&... xs) const BOOST_HOF_SFINAE_RETURNS
  91     (
  92         (BOOST_HOF_MANGLE_CAST(const detail::callable_base<F>&)(BOOST_HOF_CONST_THIS->base_function(xs...)))
  93             (BOOST_HOF_FORWARD(Ts)(xs)..., BOOST_HOF_FORWARD(T)(x))
  94     );
  95 };
  96
  97 BOOST_HOF_DECLARE_STATIC_VAR(rotate, detail::make<rotate_adaptor>);
  98
  99 }} // namespace boost::hof
 100
 101 #endif