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3rdparty/boost_1_81_0/boost/hof/mutable.hpp 1.94 KB
598bfd3f   Hu Chunming   提交_GLIBCXX_USE_CX...
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  /*=============================================================================
      Copyright (c) 2014 Paul Fultz II
      mutable.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_FUNCTION_MUTABLE_H
  #define BOOST_HOF_GUARD_FUNCTION_MUTABLE_H
  
  /// mutable
  /// =======
  /// 
  /// Description
  /// -----------
  /// 
  /// The `mutable` function adaptor allows using a non-const function object
  /// inside of a const-function object. In Fit, all the function adaptors use
  /// `const` call overloads, so if there is a function that has a non-const
  /// call operator, it couldn't be used directly. So, `mutable_` allows the
  /// function to be used inside of the call operator.
  /// 
  /// NOTE: This function should be used with caution since many functions are
  /// copied, so relying on some internal shared state can be error-prone.
  /// 
  /// Synopsis
  /// --------
  /// 
  ///     template<class F>
  ///     mutable_adaptor<F> mutable_(F f)
  /// 
  /// Requirements
  /// ------------
  /// 
  /// F must be:
  /// 
  /// * [MutableFunctionObject](MutableFunctionObject)
  /// * MoveConstructible
  /// 
  
  #include <boost/hof/detail/result_of.hpp>
  #include <boost/hof/detail/delegate.hpp>
  #include <boost/hof/detail/move.hpp>
  #include <boost/hof/detail/make.hpp>
  #include <boost/hof/detail/static_const_var.hpp>
  
  namespace boost { namespace hof {
  
  template<class F>
  struct mutable_adaptor
  {
      mutable F f;
  
      BOOST_HOF_DELEGATE_CONSTRUCTOR(mutable_adaptor, F, f);
  
      BOOST_HOF_RETURNS_CLASS(mutable_adaptor);
  
      template<class... Ts>
      BOOST_HOF_SFINAE_RESULT(F, id_<Ts>...) 
      operator()(Ts&&... xs) const BOOST_HOF_SFINAE_RETURNS(BOOST_HOF_CONST_THIS->f(BOOST_HOF_FORWARD(Ts)(xs)...));
  };
  
  BOOST_HOF_DECLARE_STATIC_VAR(mutable_, detail::make<mutable_adaptor>);
  
  }} // namespace boost::hof
  
  
  #endif