marser 0.1.2

Parser combinator toolkit with matcher-level backtracking and rich error reporting.
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

//! Exact single-token parsers: a literal value or a [`char`] literal.

use std::fmt::Debug;

use crate::{
    context::ParserContext,
    error::{MatcherRunError, error_handler::ErrorHandler},
    input::{Input, InputStream},
    parser::ParserCombinator,
};

/// Matches `token` and advances by one on success.
#[derive(Clone, Debug)]
pub struct SingleTokenParser<Token> {
    token: Token,
}

impl<Token> SingleTokenParser<Token> {
    /// Parser for one occurrence of `token`.
    pub fn new(token: Token) -> Self {
        Self { token }
    }
}

impl<Token> ParserCombinator for SingleTokenParser<Token> {}

impl<'src, Inp: Input<'src, Token = Token>, Token: PartialEq + Clone + Debug>
    super::internal::ParserImpl<'src, Inp> for SingleTokenParser<Token>
{
    type Output = Token;
    const CAN_FAIL: bool = true;
    #[inline]
    fn parse(
        &self,
        _context: &mut ParserContext<'src>,
        _error_handler: &mut impl ErrorHandler,
        input: &mut InputStream<'src, Inp>,
    ) -> Result<Option<Self::Output>, MatcherRunError> {
        let start = input.get_pos();
        if let Some(token) = input.next()
            && token == self.token
        {
            return Ok(Some(self.token.clone()));
        }
        input.set_pos(start);
        Ok(None)
    }
}

// impl<Token, Label> MaybeLabel<Label> for SingleTokenParser<Token> {}
impl ParserCombinator for char {}

impl<'src, Inp: Input<'src, Token = char>> super::internal::ParserImpl<'src, Inp> for char {
    type Output = char;
    const CAN_FAIL: bool = true;

    #[inline]
    fn parse(
        &self,
        _context: &mut ParserContext<'src>,
        _error_handler: &mut impl ErrorHandler,
        input: &mut InputStream<'src, Inp>,
    ) -> Result<Option<Self::Output>, MatcherRunError> {
        let start = input.get_pos();
        if let Some(token) = input.next()
            && token == *self
        {
            return Ok(Some(*self));
        }
        input.set_pos(start);
        Ok(None)
    }
}

impl ParserCombinator for u8 {}

impl<'src> super::internal::ParserImpl<'src, &'src [u8]> for u8 {
    type Output = u8;
    const CAN_FAIL: bool = true;

    #[inline]
    fn parse(
        &self,
        _context: &mut ParserContext<'src>,
        _error_handler: &mut impl ErrorHandler,
        input: &mut InputStream<'src, &'src [u8]>,
    ) -> Result<Option<Self::Output>, MatcherRunError> {
        let start = input.get_pos();
        if let Some(tok) = input.next()
            && *tok == *self
        {
            return Ok(Some(*self));
        }
        input.set_pos(start);
        Ok(None)
    }
}