grammarsmith 0.4.0

Common helpers for handwriting lexers and parsers.
Documentation 
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
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141

#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};

use std::ops::{Add, AddAssign, Sub, SubAssign};

/// A position in a file.
///
/// # Examples
/// ```
/// use grammarsmith::position::BytePos;
/// let pos = BytePos(0);
/// assert_eq!(pos.shift('a'), BytePos(1));
/// ```
#[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Eq, Ord, Hash, Default)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct BytePos(pub usize);

impl BytePos {
    pub fn shift(self, ch: char) -> Self {
        BytePos(self.0 + ch.len_utf8())
    }
}

impl From<usize> for BytePos {
    fn from(value: usize) -> Self {
        BytePos(value)
    }
}

impl From<BytePos> for usize {
    fn from(value: BytePos) -> Self {
        value.0
    }
}

impl Add<BytePos> for BytePos {
    type Output = Self;

    fn add(self, rhs: BytePos) -> Self::Output {
        BytePos(self.0 + rhs.0)
    }
}

impl Add<usize> for BytePos {
    type Output = Self;

    fn add(self, rhs: usize) -> Self::Output {
        BytePos(self.0 + rhs)
    }
}

impl AddAssign<usize> for BytePos {
    fn add_assign(&mut self, rhs: usize) {
        self.0 += rhs;
    }
}

impl AddAssign<BytePos> for BytePos {
    fn add_assign(&mut self, rhs: BytePos) {
        self.0 += rhs.0;
    }
}

impl Sub<BytePos> for BytePos {
    type Output = Self;

    fn sub(self, rhs: BytePos) -> Self::Output {
        BytePos(self.0 - rhs.0)
    }
}

impl Sub<usize> for BytePos {
    type Output = Self;

    fn sub(self, rhs: usize) -> Self::Output {
        BytePos(self.0 - rhs)
    }
}

impl SubAssign<usize> for BytePos {
    fn sub_assign(&mut self, rhs: usize) {
        self.0 -= rhs;
    }
}

impl SubAssign<BytePos> for BytePos {
    fn sub_assign(&mut self, rhs: BytePos) {
        self.0 -= rhs.0;
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_addition_operations() {
        let mut pos = BytePos(5);

        // Test Add
        assert_eq!(pos + 3, BytePos(8));

        // Test AddAssign
        pos += 3;
        assert_eq!(pos, BytePos(8));
    }

    #[test]
    fn test_subtraction_operations() {
        let mut pos = BytePos(5);

        // Test Sub
        assert_eq!(pos - 3, BytePos(2));

        // Test SubAssign
        pos -= 3;
        assert_eq!(pos, BytePos(2));
    }

    #[test]
    fn test_shift_with_different_chars() {
        let pos = BytePos(0);

        // ASCII character (1 byte)
        assert_eq!(pos.shift('a'), BytePos(1));

        // 2-byte character
        assert_eq!(pos.shift('é'), BytePos(2));

        // 3-byte character
        assert_eq!(pos.shift('€'), BytePos(3));

        // 4-byte character
        assert_eq!(pos.shift('🦀'), BytePos(4));

        // Test consecutive shifts
        let pos2 = BytePos(0);
        let final_pos = pos2.shift('a').shift('€').shift('🦀');
        assert_eq!(final_pos, BytePos(8)); // 1 + 3 + 4 bytes
    }
}