parsy 0.5.6

An easy-to-use, efficient parser combinators library
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

use std::marker::PhantomData;

use perfect_derive::perfect_derive;

use crate::{container::Container, Eaten, PResult, Parser, ParserInput};

#[perfect_derive(Clone, Copy)]
pub struct Repeated<T, P: Parser<T>, C: Container<T>> {
    parser: P,
    min: Option<usize>,
    max: Option<usize>,
    exactly: Option<usize>,
    _p: PhantomData<T>,
    _c: PhantomData<C>,
}

impl<T, P: Parser<T>, C: Container<T>> Repeated<T, P, C> {
    pub fn new(parser: P) -> Self {
        Self {
            parser,
            min: None,
            max: None,
            exactly: None,
            _p: PhantomData,
            _c: PhantomData,
        }
    }

    pub fn at_least(mut self, min: usize) -> Self {
        assert!(
            self.exactly.is_none(),
            "Cannot specify both a minimum and an exact number of repetitions"
        );

        if let Some(max) = self.max {
            assert!(min <= max, "Minimum number of repetitions ({min}) cannot be higher than the maximum ({max}) number of repetitoins");
        }

        self.min = Some(min);
        self
    }

    pub fn at_most(mut self, max: usize) -> Self {
        assert!(
            self.exactly.is_none(),
            "Cannot specify both a maximum and an exact number of repetitions"
        );

        if let Some(min) = self.min {
            assert!(min <= max, "Minimum number of repetitions ({min}) cannot be higher than the maximum ({max}) number of repetitoins");
        }

        self.max = Some(max);
        self
    }

    pub fn exactly(mut self, exactly: usize) -> Self {
        assert!(
            self.min.is_none(),
            "Cannot specify both a minimum and an exact number of repetitions"
        );

        assert!(
            self.max.is_none(),
            "Cannot specify both a maximum and an exact number of repetitions"
        );

        self.exactly = Some(exactly);
        self
    }
}

impl<T, P: Parser<T>, C: Container<T>> Parser<C> for Repeated<T, P, C> {
    fn parse_inner(&self, input: &mut ParserInput) -> PResult<C> {
        let start = input.at();
        let mut ate = 0;

        let mut out = C::create();
        let mut count = 0;

        let err = loop {
            match self.parser.parse(input) {
                Err(err) if err.is_critical() => return Err(err),
                Err(err) => break Some(err),
                Ok(eaten) => {
                    ate += eaten.at.len;
                    count += 1;

                    out.add(eaten.data);

                    if let Some(max) = self.max {
                        if count > max {
                            break None;
                        }
                    }

                    if let Some(exactly) = self.exactly {
                        if count == exactly {
                            break None;
                        }
                    }
                }
            }
        };

        if let Some(min) = self.min {
            if count < min {
                return Err(err
                    .filter(|_| count == 0)
                    .unwrap_or_else(|| input.at().custom_err("Not enough repetitions", ate)));
            }
        }

        Ok(Eaten::ate(start.range(ate), out))
    }
}