-
Notifications
You must be signed in to change notification settings - Fork 54
/
file.rs
78 lines (69 loc) · 1.69 KB
/
file.rs
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
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
use crate::error::Error;
use std::mem::transmute;
use std::str::FromStr;
/// Describe a file (column) on a chess board
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Debug, Hash)]
pub enum File {
A,
B,
C,
D,
E,
F,
G,
H,
}
/// How many files are there?
pub const NUM_FILES: usize = 8;
/// Enumerate all files
pub const ALL_FILES: [File; NUM_FILES] = [
File::A,
File::B,
File::C,
File::D,
File::E,
File::F,
File::G,
File::H,
];
impl File {
/// Convert a `usize` into a `File` (the inverse of to_index). If i > 7, wrap around.
#[inline]
pub fn from_index(i: usize) -> File {
unsafe { transmute((i as u8) & 7) }
}
/// Go one file to the left. If impossible, wrap around.
#[inline]
pub fn left(&self) -> File {
File::from_index(self.to_index().wrapping_sub(1))
}
/// Go one file to the right. If impossible, wrap around.
#[inline]
pub fn right(&self) -> File {
File::from_index(self.to_index() + 1)
}
/// Convert this `File` into a `usize` from 0 to 7 inclusive.
#[inline]
pub fn to_index(&self) -> usize {
*self as usize
}
}
impl FromStr for File {
type Err = Error;
fn from_str(s: &str) -> Result<Self, Self::Err> {
if s.len() < 1 {
return Err(Error::InvalidFile);
}
match s.chars().next().unwrap() {
'a' => Ok(File::A),
'b' => Ok(File::B),
'c' => Ok(File::C),
'd' => Ok(File::D),
'e' => Ok(File::E),
'f' => Ok(File::F),
'g' => Ok(File::G),
'h' => Ok(File::H),
_ => Err(Error::InvalidFile),
}
}
}