lexigram-lib 0.9.2

Full library of the lexigram lexer/parser generator
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

// Copyright (c) 2025 Redglyph (@gmail.com). All Rights Reserved.

#[derive(Clone)]
pub struct TakeUntil<I, P> {
    iter: I,
    end: bool,
    predicate: P
}

impl<I, P> Iterator for TakeUntil<I, P>
    where I: Iterator,
          P: FnMut(&I::Item) -> bool
{
    type Item = I::Item;

    fn next(&mut self) -> Option<Self::Item> {
        if self.end {
            None
        } else {
            let item = self.iter.next();
            if let Some(item) = item {
                self.end = (self.predicate)(&item);
                Some(item)
            } else {
                self.end = true;
                None
            }
        }
    }
}

pub trait TakeUntilIterator<T, P>: Iterator<Item=T>
    where P: FnMut(&T) -> bool
{
    fn take_until(self, predicate: P) -> TakeUntil<Self, P> where Self: Sized {
        TakeUntil { iter: self, end: false, predicate }
    }
}

impl<T, I: Iterator<Item=T>, P: FnMut(&T) -> bool> TakeUntilIterator<T, P> for I {}

// ---------------------------------------------------------------------------------------------

#[derive(Clone)]
pub struct TakeMutUntil<I, P> {
    iter: I,
    end: bool,
    predicate: P
}

impl<I, P> Iterator for TakeMutUntil<I, P>
    where I: Iterator,
          P: FnMut(&mut I::Item) -> bool
{
    type Item = I::Item;

    fn next(&mut self) -> Option<Self::Item> {
        if self.end {
            None
        } else {
            let item = self.iter.next();
            if let Some(mut item) = item {
                self.end = (self.predicate)(&mut item);
                Some(item)
            } else {
                self.end = true;
                None
            }
        }
    }
}

pub trait TakeMutUntilIterator<T, P>: Iterator<Item=T>
    where P: FnMut(&mut T) -> bool
{
    fn take_mut_until(self, predicate: P) -> TakeMutUntil<Self, P> where Self: Sized {
        TakeMutUntil { iter: self, end: false, predicate }
    }
}

impl<T, I: Iterator<Item=T>, P: FnMut(&mut T) -> bool> TakeMutUntilIterator<T, P> for I {}

// ---------------------------------------------------------------------------------------------

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

    #[test]
    fn adapter_take_until() {
        let v = vec![1, 2, 3, 4, 5];
        let result = v.iter().take_until(|&x| *x >= 4).map(|&n| n).collect::<Vec<_>>();
        assert_eq!(result, vec![1, 2, 3, 4]);
    }

    // For comparison:
    //      let v = vec![1, 2, 3, 4, 5];
    //      let result = v.iter().take_while(|&x| *x < 4).map(|&n| n).collect::<Vec<_>>();
    //      assert_eq!(result, vec![1, 2, 3]);

    #[test]
    fn predicate_take_until_empty() {
        let v: Vec<i32> = vec![];
        let result = v.iter().take_until(|&x| *x >= 4).map(|&n| n).collect::<Vec<_>>();
        assert_eq!(result.len(), 0);
    }

    #[test]
    fn predicate_take_until_false() {
        let v = vec![1, 2, 3, 4, 5];
        let result = v.iter().take_until(|&x| *x > 10).map(|&n| n).collect::<Vec<_>>();
        assert_eq!(result, vec![1, 2, 3, 4, 5]);
    }

    #[test]
    fn predicate_take_until_true() {
        let v = vec![1, 2, 3, 4, 5];
        let result = v.iter().take_until(|&x| *x < 10).map(|&n| n).collect::<Vec<_>>();
        assert_eq!(result, vec![1]);
    }

    #[test]
    fn adapter_take_mut_until() {
        let mut v: Vec<i32> = vec![1, 2, 3, 4, 5];
        let result = v.iter_mut().take_mut_until(|x| {
            **x = **x + 1;
            **x >= 4
        }).map(|x| *x).collect::<Vec<_>>();
        assert_eq!(result, vec![2, 3, 4]);
        assert_eq!(v, vec![2, 3, 4, 4, 5]);
    }
}