rustybuzz/hb/
text_parser.rs

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1use super::hb_tag_t;
2
3pub struct TextParser<'a> {
4    pos: usize,
5    text: &'a str,
6}
7
8impl<'a> TextParser<'a> {
9    #[inline]
10    pub fn new(text: &'a str) -> Self {
11        TextParser { pos: 0, text }
12    }
13
14    #[inline]
15    pub fn at_end(&self) -> bool {
16        self.pos >= self.text.len()
17    }
18
19    #[inline]
20    pub fn curr_byte(&self) -> Option<u8> {
21        if !self.at_end() {
22            Some(self.curr_byte_unchecked())
23        } else {
24            None
25        }
26    }
27
28    #[inline]
29    fn curr_byte_unchecked(&self) -> u8 {
30        self.text.as_bytes()[self.pos]
31    }
32
33    #[inline]
34    pub fn advance(&mut self, n: usize) {
35        debug_assert!(self.pos + n <= self.text.len());
36        self.pos += n;
37    }
38
39    pub fn consume_byte(&mut self, c: u8) -> Option<()> {
40        let curr = self.curr_byte()?;
41        if curr != c {
42            return None;
43        }
44
45        self.advance(1);
46        Some(())
47    }
48
49    #[inline]
50    pub fn skip_spaces(&mut self) {
51        // Unlike harfbuzz::ISSPACE, is_ascii_whitespace doesn't includes `\v`, but whatever.
52        while !self.at_end() && self.curr_byte_unchecked().is_ascii_whitespace() {
53            self.advance(1);
54        }
55    }
56
57    pub fn consume_quote(&mut self) -> Option<u8> {
58        let c = self.curr_byte()?;
59        if matches!(c, b'\'' | b'"') {
60            self.advance(1);
61            Some(c)
62        } else {
63            None
64        }
65    }
66
67    #[inline]
68    pub fn consume_bytes<F>(&mut self, f: F) -> &'a str
69    where
70        F: Fn(u8) -> bool,
71    {
72        let start = self.pos;
73        self.skip_bytes(f);
74        &self.text[start..self.pos]
75    }
76
77    pub fn skip_bytes<F>(&mut self, f: F)
78    where
79        F: Fn(u8) -> bool,
80    {
81        while !self.at_end() && f(self.curr_byte_unchecked()) {
82            self.advance(1);
83        }
84    }
85
86    pub fn consume_tag(&mut self) -> Option<hb_tag_t> {
87        let tag = self.consume_bytes(|c| c.is_ascii_alphanumeric() || c == b'_');
88        if tag.len() > 4 {
89            return None;
90        }
91
92        Some(hb_tag_t::from_bytes_lossy(tag.as_bytes()))
93    }
94
95    pub fn consume_i32(&mut self) -> Option<i32> {
96        let start = self.pos;
97
98        if matches!(self.curr_byte(), Some(b'-') | Some(b'+')) {
99            self.advance(1);
100        }
101
102        self.skip_bytes(|c| c.is_ascii_digit());
103        self.text[start..self.pos].parse::<i32>().ok()
104    }
105
106    pub fn consume_f32(&mut self) -> Option<f32> {
107        let start = self.pos;
108
109        // TODO: does number like 1-e2 required?
110
111        if matches!(self.curr_byte(), Some(b'-') | Some(b'+')) {
112            self.advance(1);
113        }
114
115        self.skip_bytes(|c| c.is_ascii_digit());
116
117        if self.consume_byte(b'.').is_some() {
118            self.skip_bytes(|c| c.is_ascii_digit());
119        }
120
121        self.text[start..self.pos].parse::<f32>().ok()
122    }
123
124    pub fn consume_bool(&mut self) -> Option<bool> {
125        self.skip_spaces();
126
127        let value = self.consume_bytes(|c| c.is_ascii_alphabetic()).as_bytes();
128        if value.len() == 2 {
129            if value[0].to_ascii_lowercase() == b'o' && value[1].to_ascii_lowercase() == b'n' {
130                return Some(true);
131            }
132        } else if value.len() == 3 {
133            if value[0].to_ascii_lowercase() == b'o'
134                && value[1].to_ascii_lowercase() == b'f'
135                && value[2].to_ascii_lowercase() == b'f'
136            {
137                return Some(false);
138            }
139        }
140
141        None
142    }
143}
rustybuzz/hb/text_parser.rs

rustybuzz/hb/
text_parser.rs
