1// Copyright Louis Dionne 2013-2022
2// Distributed under the Boost Software License, Version 1.0.
3// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
4
5#include <boost/hana/functional/overload_linearly.hpp>
6
7#include <boost/hana/assert.hpp>
8#include <boost/hana/equal.hpp>
9
10#include <laws/base.hpp>
11namespace hana = boost::hana;
12using hana::test::ct_eq;
13
14
15struct A { };
16struct AA : A { };
17struct B { };
18struct C { };
19
20int main() {
21 // 2 functions without overlap
22 {
23 auto f = hana::overload_linearly(
24 [](A) { return ct_eq<0>{}; },
25 [](B) { return ct_eq<1>{}; }
26 );
27
28 BOOST_HANA_CONSTANT_CHECK(hana::equal(
29 f(A{}),
30 ct_eq<0>{}
31 ));
32
33 BOOST_HANA_CONSTANT_CHECK(hana::equal(
34 f(AA{}),
35 f(A{})
36 ));
37
38 BOOST_HANA_CONSTANT_CHECK(hana::equal(
39 f(B{}),
40 ct_eq<1>{}
41 ));
42 }
43
44 // 2 functions with overlap
45 {
46 auto f = hana::overload_linearly(
47 [](A) { return ct_eq<0>{}; },
48 [](A) { return ct_eq<1>{}; }
49 );
50
51 auto g = hana::overload_linearly(
52 [](A) { return ct_eq<0>{}; },
53 [](AA) { return ct_eq<1>{}; }
54 );
55
56 BOOST_HANA_CONSTANT_CHECK(hana::equal(
57 f(A{}),
58 ct_eq<0>{}
59 ));
60
61 BOOST_HANA_CONSTANT_CHECK(hana::equal(
62 f(AA{}),
63 f(A{})
64 ));
65
66 BOOST_HANA_CONSTANT_CHECK(hana::equal(
67 g(A{}),
68 ct_eq<0>{}
69 ));
70
71 BOOST_HANA_CONSTANT_CHECK(hana::equal(
72 g(AA{}),
73 g(A{})
74 ));
75 }
76
77 // 3 functions
78 {
79 auto f = hana::overload_linearly(
80 [](A) { return ct_eq<0>{}; },
81 [](B) { return ct_eq<1>{}; },
82 [](C) { return ct_eq<2>{}; }
83 );
84
85 BOOST_HANA_CONSTANT_CHECK(hana::equal(
86 f(A{}),
87 ct_eq<0>{}
88 ));
89
90 BOOST_HANA_CONSTANT_CHECK(hana::equal(
91 f(AA{}),
92 f(A{})
93 ));
94
95 BOOST_HANA_CONSTANT_CHECK(hana::equal(
96 f(B{}),
97 ct_eq<1>{}
98 ));
99
100 BOOST_HANA_CONSTANT_CHECK(hana::equal(
101 f(C{}),
102 ct_eq<2>{}
103 ));
104 }
105
106 // 1 function (github issue #280)
107 {
108 auto f = hana::overload_linearly(
109 [](A) { return ct_eq<0>{}; }
110 );
111
112 BOOST_HANA_CONSTANT_CHECK(hana::equal(
113 f(A{}),
114 ct_eq<0>{}
115 ));
116
117 BOOST_HANA_CONSTANT_CHECK(hana::equal(
118 f(AA{}),
119 f(A{})
120 ));
121 }
122}
123

source code of boost/libs/hana/test/functional/overload_linearly.cpp