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3rdparty/boost_1_81_0/boost/hof/rotate.hpp 2.52 KB
598bfd3f   Hu Chunming   提交_GLIBCXX_USE_CX...
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  /*=============================================================================
      Copyright (c) 2015 Paul Fultz II
      rotate.h
      Distributed under the Boost Software License, Version 1.0. (See accompanying
      file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  ==============================================================================*/
  
  #ifndef BOOST_HOF_GUARD_ROTATE_H
  #define BOOST_HOF_GUARD_ROTATE_H
  
  /// rotate
  /// ====
  /// 
  /// Description
  /// -----------
  /// 
  /// The `rotate` function adaptor moves the first parameter to the last
  /// parameter.
  /// 
  /// Synopsis
  /// --------
  /// 
  ///     template<class F>
  ///     rotate_adaptor<F> rotate(F f);
  /// 
  /// Semantics
  /// ---------
  /// 
  ///     assert(rotate(f)(x, xs...) == f(xs..., x));
  /// 
  /// Requirements
  /// ------------
  /// 
  /// F must be:
  /// 
  /// * [ConstInvocable](ConstInvocable)
  /// * MoveConstructible
  /// 
  /// Example
  /// -------
  /// 
  ///     #include <boost/hof.hpp>
  ///     #include <cassert>
  /// 
  ///     int main() {
  ///         int r = boost::hof::rotate(boost::hof::_ - boost::hof::_)(2, 5);
  ///         assert(r == 3);
  ///     }
  /// 
  
  #include <boost/hof/detail/result_of.hpp>
  #include <boost/hof/reveal.hpp>
  #include <boost/hof/detail/make.hpp>
  #include <boost/hof/detail/static_const_var.hpp>
  
  namespace boost { namespace hof {
  
  template<class F>
  struct rotate_adaptor : detail::callable_base<F>
  {
      typedef rotate_adaptor fit_rewritable1_tag;
      BOOST_HOF_INHERIT_CONSTRUCTOR(rotate_adaptor, detail::callable_base<F>);
  
      template<class... Ts>
      constexpr const detail::callable_base<F>& base_function(Ts&&... xs) const noexcept
      {
          return boost::hof::always_ref(*this)(xs...);
      }
  
      struct rotate_failure
      {
          template<class Failure>
          struct apply
          {
              template<class T, class... Ts>
              struct of
              : Failure::template of<Ts..., T>
              {};
          };
      };
  
      struct failure
      : failure_map<rotate_failure, detail::callable_base<F>>
      {};
  
      BOOST_HOF_RETURNS_CLASS(rotate_adaptor);
  
      template<class T, class... Ts>
      constexpr BOOST_HOF_SFINAE_RESULT(const detail::callable_base<F>&, id_<Ts>..., id_<T>) 
      operator()(T&& x, Ts&&... xs) const BOOST_HOF_SFINAE_RETURNS
      (
          (BOOST_HOF_MANGLE_CAST(const detail::callable_base<F>&)(BOOST_HOF_CONST_THIS->base_function(xs...)))
              (BOOST_HOF_FORWARD(Ts)(xs)..., BOOST_HOF_FORWARD(T)(x))
      );
  };
  
  BOOST_HOF_DECLARE_STATIC_VAR(rotate, detail::make<rotate_adaptor>);
  
  }} // namespace boost::hof
  
  #endif