1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
|
// Check that we expand multiple or-patterns from left to right.
// run-pass
fn search(target: (bool, bool, bool)) -> u32 {
let x = ((false, true), (false, true), (false, true));
let mut guard_count = 0;
match x {
((a, _) | (_, a), (b @ _, _) | (_, b @ _), (c @ false, _) | (_, c @ true))
if {
guard_count += 1;
(a, b, c) == target
} =>
{
guard_count
}
_ => unreachable!(),
}
}
// Equivalent to the above code, but hopefully easier to understand.
fn search_old_style(target: (bool, bool, bool)) -> u32 {
let x = ((false, true), (false, true), (false, true));
let mut guard_count = 0;
match x {
((a, _), (b @ _, _), (c @ false, _))
| ((a, _), (b @ _, _), (_, c @ true))
| ((a, _), (_, b @ _), (c @ false, _))
| ((a, _), (_, b @ _), (_, c @ true))
| ((_, a), (b @ _, _), (c @ false, _))
| ((_, a), (b @ _, _), (_, c @ true))
| ((_, a), (_, b @ _), (c @ false, _))
| ((_, a), (_, b @ _), (_, c @ true))
if {
guard_count += 1;
(a, b, c) == target
} =>
{
guard_count
}
_ => unreachable!(),
}
}
fn main() {
assert_eq!(search((false, false, false)), 1);
assert_eq!(search((false, false, true)), 2);
assert_eq!(search((false, true, false)), 3);
assert_eq!(search((false, true, true)), 4);
assert_eq!(search((true, false, false)), 5);
assert_eq!(search((true, false, true)), 6);
assert_eq!(search((true, true, false)), 7);
assert_eq!(search((true, true, true)), 8);
assert_eq!(search_old_style((false, false, false)), 1);
assert_eq!(search_old_style((false, false, true)), 2);
assert_eq!(search_old_style((false, true, false)), 3);
assert_eq!(search_old_style((false, true, true)), 4);
assert_eq!(search_old_style((true, false, false)), 5);
assert_eq!(search_old_style((true, false, true)), 6);
assert_eq!(search_old_style((true, true, false)), 7);
assert_eq!(search_old_style((true, true, true)), 8);
}
|
