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
142
143
144
145
146

use crate::pre_tokenizers::unicode_scripts::scripts::{get_script, Script};
use crate::tokenizer::{normalizer::Range, PreTokenizedString, PreTokenizer, Result};
use crate::utils::macro_rules_attribute;

#[derive(Clone, Debug, PartialEq, Eq)]
#[macro_rules_attribute(impl_serde_type!)]
pub struct UnicodeScripts;

impl UnicodeScripts {
    pub fn new() -> Self {
        Self {}
    }
}

impl Default for UnicodeScripts {
    fn default() -> Self {
        Self::new()
    }
}

// This code exists in the Unigram default IsValidSentencePiece.
// It could be integrated directly within `get_script` but I
// think it's kind of tricky to see those modifications later
// I am guessing release mode will optimize this away anyway.
fn fixed_script(c: char) -> Script {
    let raw_script = get_script(c);
    if c as u32 == 0x30FC {
        Script::Han
    } else if c == ' ' {
        Script::Any
    } else {
        match raw_script {
            Script::Hiragana => Script::Han,
            Script::Katakana => Script::Han,
            script => script,
        }
    }
}

impl PreTokenizer for UnicodeScripts {
    fn pre_tokenize(&self, pretokenized: &mut PreTokenizedString) -> Result<()> {
        pretokenized.split(|_, normalized| {
            let mut last_script = None;
            let mut offset = 0;
            let mut ranges: Vec<_> = normalized
                .get()
                .chars()
                .filter_map(|c| {
                    let script = Some(fixed_script(c));
                    let result = if script != Some(Script::Any)
                        && last_script != Some(Script::Any)
                        && last_script != script
                    {
                        Some(offset)
                    } else {
                        None
                    };
                    offset += c.len_utf8();
                    if script != Some(Script::Any) {
                        last_script = script;
                    }

                    result
                })
                .collect();
            ranges.push(normalized.get().len());
            Ok(ranges
                .windows(2)
                .map(|item| {
                    normalized
                        .slice(Range::Normalized(item[0]..item[1]))
                        .expect("NormalizedString bad split")
                })
                .collect::<Vec<_>>())
        })
    }
}

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

    #[test]
    fn basic() {
        let pretok = UnicodeScripts {};
        let mut pretokenized = PreTokenizedString::from("どこで生れ。Yes");
        pretok.pre_tokenize(&mut pretokenized).unwrap();
        assert_eq!(
            pretokenized
                .get_splits(OffsetReferential::Normalized, OffsetType::Byte)
                .into_iter()
                .map(|(s, o, _)| (s, o))
                .collect::<Vec<_>>(),
            vec![("どこで生れ", (0, 15)), ("。", (15, 18)), ("Yes", (18, 21))]
        );
        assert_eq!(
            pretokenized
                .get_splits(OffsetReferential::Original, OffsetType::Byte)
                .into_iter()
                .map(|(s, o, _)| (s, o))
                .collect::<Vec<_>>(),
            vec![("どこで生れ", (0, 15)), ("。", (15, 18)), ("Yes", (18, 21))]
        );
    }

    #[test]
    fn spaces_are_included_in_every_script() {
        let pretok = UnicodeScripts {};
        let mut pretokenized = PreTokenizedString::from("Apples are りんご 林檎");
        pretok.pre_tokenize(&mut pretokenized).unwrap();
        assert_eq!(
            pretokenized
                .get_splits(OffsetReferential::Normalized, OffsetType::Byte)
                .into_iter()
                .map(|(s, o, _)| (s, o))
                .collect::<Vec<_>>(),
            vec![("Apples are ", (0, 11)), ("りんご 林檎", (11, 27))]
        );
        assert_eq!(
            pretokenized
                .get_splits(OffsetReferential::Original, OffsetType::Byte)
                .into_iter()
                .map(|(s, o, _)| (s, o))
                .collect::<Vec<_>>(),
            vec![("Apples are ", (0, 11)), ("りんご 林檎", (11, 27))]
        );
    }

    #[test]
    fn test_unicode_script() {
        assert_eq!(Script::Han, fixed_script('京'));
        assert_eq!(Script::Han, fixed_script('太'));
        assert_eq!(Script::Han, fixed_script('い'));
        assert_eq!(Script::Han, fixed_script('グ'));
        assert_eq!(Script::Han, fixed_script('ー'));
        assert_eq!(Script::Latin, fixed_script('a'));
        assert_eq!(Script::Latin, fixed_script('A'));
        assert_eq!(Script::Common, fixed_script('0'));
        assert_eq!(Script::Common, fixed_script('$'));
        assert_eq!(Script::Common, fixed_script('@'));
        assert_eq!(Script::Common, fixed_script('-'));
        assert_eq!(Script::Any, fixed_script(' '));
    }
}