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
10struct 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
19struct 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
29BOOST_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
37BOOST_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
48BOOST_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
57template<class... Ts>
58constexpr auto find_positive_max(Ts... xs) BOOST_HOF_RETURNS
59(
60 boost::hof::reverse_fold(max_f(), 0)(xs...)
61);
62
63BOOST_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
72BOOST_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
79BOOST_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
90BOOST_HOF_TEST_CASE()
91{
92 BOOST_HOF_TEST_CHECK(boost::hof::reverse_fold(sum_f(), std::string())("hello", "-", "world") == "world-hello");
93}
94

source code of boost/libs/hof/test/reverse_fold.cpp