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
use nom::error::{ErrorKind, ParseError};
use nom_locate::LocatedSpanEx;
#[derive(Clone, Debug, PartialEq)]
pub struct GreedyError<I> {
pub errors: Vec<(I, GreedyErrorKind)>,
}
#[derive(Clone, Debug, PartialEq)]
pub enum GreedyErrorKind {
Context(&'static str),
Char(char),
Nom(ErrorKind),
}
impl<I> ParseError<I> for GreedyError<I>
where
I: Position,
{
fn from_error_kind(input: I, kind: ErrorKind) -> Self {
GreedyError {
errors: vec![(input, GreedyErrorKind::Nom(kind))],
}
}
fn append(input: I, kind: ErrorKind, mut other: Self) -> Self {
other.errors.push((input, GreedyErrorKind::Nom(kind)));
other
}
fn from_char(input: I, c: char) -> Self {
GreedyError {
errors: vec![(input, GreedyErrorKind::Char(c))],
}
}
fn add_context(input: I, ctx: &'static str, mut other: Self) -> Self {
other.errors.push((input, GreedyErrorKind::Context(ctx)));
other
}
fn or(self, other: Self) -> Self {
let pos_self = if let Some(x) = self.errors.first() {
x.0.position()
} else {
0
};
let pos_other = if let Some(x) = other.errors.first() {
x.0.position()
} else {
0
};
if pos_other > pos_self {
other
} else {
self
}
}
}
pub fn error_position<T: Position>(e: &GreedyError<T>) -> Option<usize> {
e.errors.first().map(|x| x.0.position())
}
pub trait Position {
fn position(&self) -> usize;
}
impl<T, U> Position for LocatedSpanEx<T, U> {
fn position(&self) -> usize {
self.offset
}
}
#[cfg(test)]
mod tests {
use super::*;
use nom::branch::alt;
use nom::character::complete::{alpha1, digit1};
use nom::error::{ParseError, VerboseError};
use nom::sequence::tuple;
use nom::IResult;
use nom_locate::LocatedSpan;
type Span<'a> = LocatedSpan<&'a str>;
fn parser<'a, E: ParseError<Span<'a>>>(
input: Span<'a>,
) -> IResult<Span<'a>, (Span<'a>, Span<'a>, Span<'a>), E> {
alt((
tuple((alpha1, digit1, alpha1)),
tuple((digit1, alpha1, digit1)),
))(input)
}
#[test]
fn test() {
let error = parser::<VerboseError<Span>>(Span::new("abc012:::"));
match error {
Err(nom::Err::Error(e)) => {
assert_eq!(e.errors.first().map(|x| x.0.position()), Some(0))
}
_ => (),
};
let error = parser::<GreedyError<Span>>(Span::new("abc012:::"));
match error {
Err(nom::Err::Error(e)) => assert_eq!(error_position(&e), Some(6)),
_ => (),
};
}
}