simdcsv 0.1.0

A CSV parser
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

pub const COMMA_CLASS: u8 = 1;
pub const NEW_LINE_CLASS: u8 = 2;

pub const QUOTATION_CLASS: u8 = 3;

pub const LO_LOOKUP: [u8; 16] = [
    0,
    0,
    QUOTATION_CLASS,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    NEW_LINE_CLASS,
    0,
    COMMA_CLASS,
    NEW_LINE_CLASS,
    0,
    0,
];
pub const HI_LOOKUP: [u8; 16] = [
    NEW_LINE_CLASS,
    0,
    COMMA_CLASS | QUOTATION_CLASS,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
];

use crate::u8x16::u8x16;

#[derive(Debug)]
pub struct CsvClassifier<'a> {
    cursor: usize,
    data: &'a [u8],
}

impl<'a> CsvClassifier<'a> {
    pub const fn new(data: &'a [u8]) -> Self {
        Self { cursor: 0, data }
    }

    pub fn classify(&mut self) -> Vec<u8x16> {
        let mut bitsets = Vec::new();

        let high_nibble_lookup = u8x16::from_slice_unchecked(&HI_LOOKUP);
        let low_nibble_lookup = u8x16::from_slice_unchecked(&LO_LOOKUP);

        while self.cursor < self.data.len() {
            let (lanes, _aligned) = self.load_u8x16();

            let (hi_lanes, lo_lanes) = lanes.nibbles();
            let res = high_nibble_lookup.classify(hi_lanes) & low_nibble_lookup.classify(lo_lanes);

            bitsets.push(res);
        }

        bitsets
    }

    fn load_u8x16(&mut self) -> (u8x16, bool) {
        if self.cursor + u8x16::LANE_COUNT < self.data.len() {
            let slice = &self.data[self.cursor..self.cursor + u8x16::LANE_COUNT];
            self.cursor += u8x16::LANE_COUNT;

            return (u8x16::from_slice_unchecked(slice), true);
        }

        let slice = &self.data[self.cursor..];
        self.cursor = self.data.len();

        let mut temp = [0u8; 16];
        temp[..slice.len()].copy_from_slice(slice);

        let last = self.data[self.data.len() - 1];

        if last != 0x0A && last != 0x0D {
            temp[slice.len()] = 0x0A;
        }

        (u8x16::from_slice_unchecked(&temp), false)
    }
}

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

    #[test]
    fn test_basic_classify() {
        let mut classifier = CsvClassifier::new(b"a,b,c\nf,\"g\"");
        let bitsets = classifier.classify();

        assert_eq!(bitsets.len(), 1);
        let res: [u8; 16] = bitsets[0].into();

        assert_eq!(
            res,
            [
                0,
                COMMA_CLASS,
                0,
                COMMA_CLASS,
                0,
                NEW_LINE_CLASS,
                0,
                COMMA_CLASS,
                QUOTATION_CLASS,
                0,
                QUOTATION_CLASS,
                NEW_LINE_CLASS, // we always add a \n at the end
                0,
                0,
                0,
                0,
            ]
        );
    }
}