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3rdparty/boost_1_81_0/libs/hof/test/fix.cpp 2.67 KB
73ef4ff3   Hu Chunming   提交三方库
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  /*=============================================================================
      Copyright (c) 2017 Paul Fultz II
      fix.cpp
      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)
  ==============================================================================*/
  #include <boost/hof/fix.hpp>
  #include <boost/hof/static.hpp>
  #include <boost/hof/reveal.hpp>
  #include <boost/hof/result.hpp>
  #include "test.hpp"
  
  #include <memory>
  
  struct factorial_t
  {
      template<class Self, class T>
      T operator()(Self s, T x) const noexcept
      {
          return x == 0 ? 1 : x * s(x-1);
      }
  };
  
  struct factorial_constexpr_t
  {
      template<class Self, class T>
      constexpr T operator()(Self s, T x) const noexcept
      {
          return x == 0 ? 1 : x * s(x-1);
      }
  };
  
  struct factorial_move_t
  {
      std::unique_ptr<int> i;
      factorial_move_t() : i(new int(1))
      {}
      template<class Self, class T>
      T operator()(const Self& s, T x) const
      {
          return x == 0 ? *i : x * s(x-1);
      }
  };
  
  static constexpr boost::hof::fix_adaptor<factorial_t> factorial = {};
  static constexpr boost::hof::fix_adaptor<factorial_constexpr_t> factorial_constexpr = {};
  static constexpr boost::hof::static_<boost::hof::fix_adaptor<factorial_move_t> > factorial_move = {};
  
  #if BOOST_HOF_HAS_NOEXCEPT_DEDUCTION
  BOOST_HOF_TEST_CASE()
  {
      static_assert(noexcept(factorial(5)), "noexcept fix");
  }
  #endif
  
  BOOST_HOF_TEST_CASE()
  {
      const int r = factorial(5);
      BOOST_HOF_TEST_CHECK(r == 5*4*3*2*1);
  }
  
  BOOST_HOF_TEST_CASE()
  {
      const int r = boost::hof::reveal(factorial)(5);
      BOOST_HOF_TEST_CHECK(r == 5*4*3*2*1);
  }
  
  #if !BOOST_HOF_NO_EXPRESSION_SFINAE
  BOOST_HOF_TEST_CASE()
  {
      const int r = boost::hof::fix(boost::hof::result<int>(factorial_constexpr_t()))(5);
      BOOST_HOF_TEST_CHECK(r == 5*4*3*2*1);
  }
  
  BOOST_HOF_TEST_CASE()
  {
      const int r = boost::hof::result<int>(factorial_constexpr)(5);
      BOOST_HOF_TEST_CHECK(r == 5*4*3*2*1);
  }
  BOOST_HOF_TEST_CASE()
  {
      BOOST_HOF_STATIC_TEST_CHECK(boost::hof::fix(boost::hof::result<int>(factorial_constexpr_t()))(5) == 5*4*3*2*1);
      BOOST_HOF_STATIC_TEST_CHECK(boost::hof::result<int>(factorial_constexpr)(5) == 5*4*3*2*1);
  }
  #endif
  BOOST_HOF_TEST_CASE()
  {
  #if BOOST_HOF_HAS_GENERIC_LAMBDA
      auto factorial_ = boost::hof::fix([](auto s, auto x) -> decltype(x) { return x == 0 ? 1 : x * s(x-1); });
      int r = boost::hof::result<int>(factorial_)(5);
      BOOST_HOF_TEST_CHECK(r == 5*4*3*2*1);
  #endif
  }
  
  BOOST_HOF_TEST_CASE()
  {
      const int r = factorial_move(5);
      BOOST_HOF_TEST_CHECK(r == 5*4*3*2*1);
      BOOST_HOF_TEST_CHECK(boost::hof::fix(factorial_move_t())(5) == 5*4*3*2*1);
  }