1 /*=============================================================================
2 Copyright (c) 2017 Paul Fultz II
3 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/fold.hpp>
8 #include "test.hpp"
9
10 struct max_f
11 {
12 template<class T, class U>
operator ()max_f13 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>
operator ()sum_f22 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
BOOST_HOF_TEST_CASE()29 BOOST_HOF_TEST_CASE()
30 {
31 static_assert(noexcept(boost::hof::fold(max_f(), 0)(2, 3, 4, 5)), "noexcept fold");
32 static_assert(noexcept(boost::hof::fold(sum_f(), 0)(2, 3, 4, 5)), "noexcept fold");
33 static_assert(!noexcept(boost::hof::fold(sum_f(), std::string())("hello", "-", "world")), "noexcept fold");
34 }
35 #endif
36
BOOST_HOF_TEST_CASE()37 BOOST_HOF_TEST_CASE()
38 {
39 BOOST_HOF_TEST_CHECK(boost::hof::fold(max_f(), 0)(2, 3, 4, 5) == 5);
40 BOOST_HOF_TEST_CHECK(boost::hof::fold(max_f(), 0)(5, 4, 3, 2) == 5);
41 BOOST_HOF_TEST_CHECK(boost::hof::fold(max_f(), 0)(2, 3, 5, 4) == 5);
42
43 BOOST_HOF_STATIC_TEST_CHECK(boost::hof::fold(max_f(), 0)(2, 3, 4, 5) == 5);
44 BOOST_HOF_STATIC_TEST_CHECK(boost::hof::fold(max_f(), 0)(5, 4, 3, 2) == 5);
45 BOOST_HOF_STATIC_TEST_CHECK(boost::hof::fold(max_f(), 0)(2, 3, 5, 4) == 5);
46 }
47
BOOST_HOF_TEST_CASE()48 BOOST_HOF_TEST_CASE()
49 {
50 BOOST_HOF_TEST_CHECK(boost::hof::fold(max_f(), 0)() == 0);
51 BOOST_HOF_TEST_CHECK(boost::hof::fold(max_f(), 0)(5) == 5);
52
53 BOOST_HOF_STATIC_TEST_CHECK(boost::hof::fold(max_f(), 0)() == 0);
54 BOOST_HOF_STATIC_TEST_CHECK(boost::hof::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::fold(max_f(), 0)(xs...)
61 );
62
BOOST_HOF_TEST_CASE()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
BOOST_HOF_TEST_CASE()72 BOOST_HOF_TEST_CASE()
73 {
74 BOOST_HOF_TEST_CHECK(boost::hof::fold(max_f())(5) == 5);
75
76 BOOST_HOF_STATIC_TEST_CHECK(boost::hof::fold(max_f())(5) == 5);
77 }
78
BOOST_HOF_TEST_CASE()79 BOOST_HOF_TEST_CASE()
80 {
81 BOOST_HOF_TEST_CHECK(boost::hof::fold(max_f())(2, 3, 4, 5) == 5);
82 BOOST_HOF_TEST_CHECK(boost::hof::fold(max_f())(5, 4, 3, 2) == 5);
83 BOOST_HOF_TEST_CHECK(boost::hof::fold(max_f())(2, 3, 5, 4) == 5);
84
85 BOOST_HOF_STATIC_TEST_CHECK(boost::hof::fold(max_f())(2, 3, 4, 5) == 5);
86 BOOST_HOF_STATIC_TEST_CHECK(boost::hof::fold(max_f())(5, 4, 3, 2) == 5);
87 BOOST_HOF_STATIC_TEST_CHECK(boost::hof::fold(max_f())(2, 3, 5, 4) == 5);
88 }
89
BOOST_HOF_TEST_CASE()90 BOOST_HOF_TEST_CASE()
91 {
92 BOOST_HOF_TEST_CHECK(boost::hof::fold(sum_f(), std::string())("hello", "-", "world") == "hello-world");
93 }
94