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3rdparty/boost_1_81_0/boost/hana/fwd/replace.hpp 1.84 KB
63e88f80   Hu Chunming   提交三方库
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  /*!
  @file
  Forward declares `boost::hana::replace`.
  
  Copyright Louis Dionne 2013-2022
  Distributed under the Boost Software License, Version 1.0.
  (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
   */
  
  #ifndef BOOST_HANA_FWD_REPLACE_HPP
  #define BOOST_HANA_FWD_REPLACE_HPP
  
  #include <boost/hana/config.hpp>
  #include <boost/hana/core/when.hpp>
  
  
  namespace boost { namespace hana {
      //! Replace all the elements of a structure that compare equal
      //! to some `value` with some new fixed value.
      //! @ingroup group-Functor
      //!
      //!
      //! Signature
      //! ---------
      //! Given `F` a Functor and `U` a type that can be compared with `T`,
      //! the signature is
      //! \f$
      //!     \mathtt{replace} : F(T) \times U \times T \to F(T)
      //! \f$
      //!
      //! @param xs
      //! The structure to replace elements of.
      //!
      //! @param oldval
      //! An object compared with each element of the structure. Elements
      //! of the structure that compare equal to `oldval` are replaced
      //! by `newval` in the new structure.
      //!
      //! @param newval
      //! A value by which every element `x` of the structure that compares
      //! equal to `oldval` is replaced.
      //!
      //!
      //! Example
      //! -------
      //! @include example/replace.cpp
  #ifdef BOOST_HANA_DOXYGEN_INVOKED
      constexpr auto replace = [](auto&& xs, auto&& oldval, auto&& newval) {
          return tag-dispatched;
      };
  #else
      template <typename Xs, typename = void>
      struct replace_impl : replace_impl<Xs, when<true>> { };
  
      struct replace_t {
          template <typename Xs, typename OldVal, typename NewVal>
          constexpr auto operator()(Xs&& xs, OldVal&& oldval, NewVal&& newval) const;
      };
  
      BOOST_HANA_INLINE_VARIABLE constexpr replace_t replace{};
  #endif
  }} // end namespace boost::hana
  
  #endif // !BOOST_HANA_FWD_REPLACE_HPP