ceph/src/boost/libs/hof/test/reverse_fold.cpp

   1 /*=============================================================================
   2     Copyright (c) 2017 Paul Fultz II
   3     reverse_fold.cpp
   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 #include <boost/hof/reverse_fold.hpp>
   8 #include "test.hpp"
   9
  10 struct max_f
  11 {
  12     template<class T, class U>
  13     constexpr T operator()(T x, U y) const noexcept
  14     {
  15         return x > y ? x : y;
  16     }
  17 };
  18
  19 struct sum_f
  20 {
  21     template<class T, class U>
  22     constexpr T operator()(T x, U y) const BOOST_HOF_RETURNS_DEDUCE_NOEXCEPT(x+y)
  23     {
  24         return x + y;
  25     }
  26 };
  27
  28 #if BOOST_HOF_HAS_NOEXCEPT_DEDUCTION
  29 BOOST_HOF_TEST_CASE()
  30 {
  31     static_assert(noexcept(boost::hof::reverse_fold(max_f(), 0)(2, 3, 4, 5)), "noexcept reverse_fold");
  32     static_assert(noexcept(boost::hof::reverse_fold(sum_f(), 0)(2, 3, 4, 5)), "noexcept reverse_fold");
  33     static_assert(!noexcept(boost::hof::reverse_fold(sum_f(), std::string())("hello", "-", "world")), "noexcept reverse_fold");
  34 }
  35 #endif
  36
  37 BOOST_HOF_TEST_CASE()
  38 {
  39     BOOST_HOF_TEST_CHECK(boost::hof::reverse_fold(max_f(), 0)(2, 3, 4, 5) == 5);
  40     BOOST_HOF_TEST_CHECK(boost::hof::reverse_fold(max_f(), 0)(5, 4, 3, 2) == 5);
  41     BOOST_HOF_TEST_CHECK(boost::hof::reverse_fold(max_f(), 0)(2, 3, 5, 4) == 5);
  42
  43     BOOST_HOF_STATIC_TEST_CHECK(boost::hof::reverse_fold(max_f(), 0)(2, 3, 4, 5) == 5);
  44     BOOST_HOF_STATIC_TEST_CHECK(boost::hof::reverse_fold(max_f(), 0)(5, 4, 3, 2) == 5);
  45     BOOST_HOF_STATIC_TEST_CHECK(boost::hof::reverse_fold(max_f(), 0)(2, 3, 5, 4) == 5);
  46 }
  47
  48 BOOST_HOF_TEST_CASE()
  49 {
  50     BOOST_HOF_TEST_CHECK(boost::hof::reverse_fold(max_f(), 0)() == 0);
  51     BOOST_HOF_TEST_CHECK(boost::hof::reverse_fold(max_f(), 0)(5) == 5);
  52
  53     BOOST_HOF_STATIC_TEST_CHECK(boost::hof::reverse_fold(max_f(), 0)() == 0);
  54     BOOST_HOF_STATIC_TEST_CHECK(boost::hof::reverse_fold(max_f(), 0)(5) == 5);
  55 }
  56
  57 template<class... Ts>
  58 constexpr auto find_positive_max(Ts... xs) BOOST_HOF_RETURNS
  59 (
  60     boost::hof::reverse_fold(max_f(), 0)(xs...)
  61 );
  62
  63 BOOST_HOF_TEST_CASE()
  64 {
  65     BOOST_HOF_TEST_CHECK(find_positive_max() == 0);
  66     BOOST_HOF_TEST_CHECK(find_positive_max(5) == 5);
  67
  68     BOOST_HOF_STATIC_TEST_CHECK(find_positive_max() == 0);
  69     BOOST_HOF_STATIC_TEST_CHECK(find_positive_max(5) == 5);
  70 }
  71
  72 BOOST_HOF_TEST_CASE()
  73 {
  74     BOOST_HOF_TEST_CHECK(boost::hof::reverse_fold(max_f())(5) == 5);
  75
  76     BOOST_HOF_STATIC_TEST_CHECK(boost::hof::reverse_fold(max_f())(5) == 5);
  77 }
  78
  79 BOOST_HOF_TEST_CASE()
  80 {
  81     BOOST_HOF_TEST_CHECK(boost::hof::reverse_fold(max_f())(2, 3, 4, 5) == 5);
  82     BOOST_HOF_TEST_CHECK(boost::hof::reverse_fold(max_f())(5, 4, 3, 2) == 5);
  83     BOOST_HOF_TEST_CHECK(boost::hof::reverse_fold(max_f())(2, 3, 5, 4) == 5);
  84
  85     BOOST_HOF_STATIC_TEST_CHECK(boost::hof::reverse_fold(max_f())(2, 3, 4, 5) == 5);
  86     BOOST_HOF_STATIC_TEST_CHECK(boost::hof::reverse_fold(max_f())(5, 4, 3, 2) == 5);
  87     BOOST_HOF_STATIC_TEST_CHECK(boost::hof::reverse_fold(max_f())(2, 3, 5, 4) == 5);
  88 }
  89
  90 BOOST_HOF_TEST_CASE()
  91 {
  92     BOOST_HOF_TEST_CHECK(boost::hof::reverse_fold(sum_f(), std::string())("hello", "-", "world") == "world-hello");
  93 }