1/*=============================================================================
2 Copyright (c) 2017 Paul Fultz II
3 fix.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/fix.hpp>
8#include <boost/hof/static.hpp>
9#include <boost/hof/reveal.hpp>
10#include <boost/hof/result.hpp>
11#include "test.hpp"
12
13#include <memory>
14
15struct factorial_t
16{
17 template<class Self, class T>
18 T operator()(Self s, T x) const noexcept
19 {
20 return x == 0 ? 1 : x * s(x-1);
21 }
22};
23
24struct factorial_constexpr_t
25{
26 template<class Self, class T>
27 constexpr T operator()(Self s, T x) const noexcept
28 {
29 return x == 0 ? 1 : x * s(x-1);
30 }
31};
32
33struct factorial_move_t
34{
35 std::unique_ptr<int> i;
36 factorial_move_t() : i(new int(1))
37 {}
38 template<class Self, class T>
39 T operator()(const Self& s, T x) const
40 {
41 return x == 0 ? *i : x * s(x-1);
42 }
43};
44
45static constexpr boost::hof::fix_adaptor<factorial_t> factorial = {};
46static constexpr boost::hof::fix_adaptor<factorial_constexpr_t> factorial_constexpr = {};
47static constexpr boost::hof::static_<boost::hof::fix_adaptor<factorial_move_t> > factorial_move = {};
48
49#if BOOST_HOF_HAS_NOEXCEPT_DEDUCTION
50BOOST_HOF_TEST_CASE()
51{
52 static_assert(noexcept(factorial(5)), "noexcept fix");
53}
54#endif
55
56BOOST_HOF_TEST_CASE()
57{
58 const int r = factorial(5);
59 BOOST_HOF_TEST_CHECK(r == 5*4*3*2*1);
60}
61
62BOOST_HOF_TEST_CASE()
63{
64 const int r = boost::hof::reveal(factorial)(5);
65 BOOST_HOF_TEST_CHECK(r == 5*4*3*2*1);
66}
67
68#if !BOOST_HOF_NO_EXPRESSION_SFINAE
69BOOST_HOF_TEST_CASE()
70{
71 const int r = boost::hof::fix(boost::hof::result<int>(factorial_constexpr_t()))(5);
72 BOOST_HOF_TEST_CHECK(r == 5*4*3*2*1);
73}
74
75BOOST_HOF_TEST_CASE()
76{
77 const int r = boost::hof::result<int>(factorial_constexpr)(5);
78 BOOST_HOF_TEST_CHECK(r == 5*4*3*2*1);
79}
80BOOST_HOF_TEST_CASE()
81{
82 BOOST_HOF_STATIC_TEST_CHECK(boost::hof::fix(boost::hof::result<int>(factorial_constexpr_t()))(5) == 5*4*3*2*1);
83 BOOST_HOF_STATIC_TEST_CHECK(boost::hof::result<int>(factorial_constexpr)(5) == 5*4*3*2*1);
84}
85#endif
86BOOST_HOF_TEST_CASE()
87{
88#if BOOST_HOF_HAS_GENERIC_LAMBDA
89 auto factorial_ = boost::hof::fix([](auto s, auto x) -> decltype(x) { return x == 0 ? 1 : x * s(x-1); });
90 int r = boost::hof::result<int>(factorial_)(5);
91 BOOST_HOF_TEST_CHECK(r == 5*4*3*2*1);
92#endif
93}
94
95BOOST_HOF_TEST_CASE()
96{
97 const int r = factorial_move(5);
98 BOOST_HOF_TEST_CHECK(r == 5*4*3*2*1);
99 BOOST_HOF_TEST_CHECK(boost::hof::fix(factorial_move_t())(5) == 5*4*3*2*1);
100}
101

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