rustybuzz/hb/
machine_cursor.rs

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1use core::ops::{Add, AddAssign, Sub, SubAssign};
2
3// Similar to machine_index_t in harfbuzz, but Rust specific.
4#[derive(Debug)]
5pub struct MachineCursor<'a, T, F> {
6    data: &'a [T],
7    pred: F,
8    pos: usize,
9}
10
11impl<'a, T, F> MachineCursor<'a, T, F>
12where
13    F: Fn(&[T], usize) -> bool,
14{
15    pub fn new(data: &'a [T], pred: F) -> Self {
16        let pos = (0..data.len())
17            .find(|i| pred(data, *i))
18            .unwrap_or(data.len());
19        Self { data, pred, pos }
20    }
21
22    fn advance1(&mut self) {
23        self.pos = (self.pos + 1..self.data.len())
24            .find(|q| (self.pred)(self.data, *q))
25            .unwrap_or(self.data.len());
26    }
27
28    fn recede1(&mut self) {
29        self.pos = (0..self.pos)
30            .rev()
31            .find(|q| (self.pred)(self.data, *q))
32            .unwrap_or(0);
33    }
34
35    pub fn index(&self) -> usize {
36        self.pos
37    }
38
39    pub fn end(&self) -> Self
40    where
41        F: Clone,
42    {
43        Self {
44            data: self.data,
45            pred: self.pred.clone(),
46            pos: self.data.len(),
47        }
48    }
49}
50
51impl<'a, T, F> Add<usize> for MachineCursor<'a, T, F>
52where
53    F: Fn(&[T], usize) -> bool,
54{
55    type Output = Self;
56
57    fn add(mut self, rhs: usize) -> Self::Output {
58        for _ in 0..rhs {
59            self.advance1();
60        }
61        self
62    }
63}
64
65impl<'a, T, F> Sub<usize> for MachineCursor<'a, T, F>
66where
67    F: Fn(&[T], usize) -> bool,
68{
69    type Output = Self;
70
71    fn sub(mut self, rhs: usize) -> Self::Output {
72        for _ in 0..rhs {
73            self.recede1();
74        }
75        self
76    }
77}
78
79impl<'a, T, F> AddAssign<usize> for MachineCursor<'a, T, F>
80where
81    F: Fn(&[T], usize) -> bool,
82{
83    fn add_assign(&mut self, rhs: usize) {
84        for _ in 0..rhs {
85            self.advance1();
86        }
87    }
88}
89
90impl<'a, T, F> SubAssign<usize> for MachineCursor<'a, T, F>
91where
92    F: Fn(&[T], usize) -> bool,
93{
94    fn sub_assign(&mut self, rhs: usize) {
95        for _ in 0..rhs {
96            self.recede1();
97        }
98    }
99}
100
101impl<'a, T, F> PartialEq for MachineCursor<'a, T, F> {
102    fn eq(&self, other: &Self) -> bool {
103        self.pos == other.pos
104    }
105}
106
107impl<'a, T, F> Clone for MachineCursor<'a, T, F>
108where
109    F: Clone,
110{
111    fn clone(&self) -> Self {
112        Self {
113            data: self.data,
114            pred: self.pred.clone(),
115            pos: self.pos,
116        }
117    }
118}
119
120impl<'a, T, F> Copy for MachineCursor<'a, T, F> where F: Copy {}
rustybuzz/hb/machine_cursor.rs

rustybuzz/hb/
machine_cursor.rs
