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
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
use crate::syntax::ast::{
position::Position,
token::{Token, TokenKind},
Node,
};
use std::fmt;
pub type ParseResult = Result<Node, ParseError>;
pub(crate) trait ErrorContext {
fn context(self, context: &'static str) -> Self;
}
impl<T> ErrorContext for Result<T, ParseError> {
fn context(self, context: &'static str) -> Self {
self.map_err(|e| e.context(context))
}
}
#[derive(Debug, Clone)]
pub enum ParseError {
Expected {
expected: Box<[TokenKind]>,
found: Token,
context: &'static str,
},
Unexpected {
found: Token,
message: Option<&'static str>,
},
AbruptEnd,
General {
message: &'static str,
position: Position,
},
}
impl ParseError {
fn context(self, new_context: &'static str) -> Self {
match self {
Self::Expected {
expected, found, ..
} => Self::expected(expected, found, new_context),
e => e,
}
}
pub(super) fn expected<E>(expected: E, found: Token, context: &'static str) -> Self
where
E: Into<Box<[TokenKind]>>,
{
Self::Expected {
expected: expected.into(),
found,
context,
}
}
pub(super) fn unexpected<C>(found: Token, message: C) -> Self
where
C: Into<Option<&'static str>>,
{
Self::Unexpected {
found,
message: message.into(),
}
}
pub(super) fn general(message: &'static str, position: Position) -> Self {
Self::General { message, position }
}
}
impl fmt::Display for ParseError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::Expected {
expected,
found,
context,
} => write!(
f,
"expected {}, got '{}' in {} at line {}, col {}",
if expected.len() == 1 {
format!(
"token '{}'",
expected.first().map(TokenKind::to_string).unwrap()
)
} else {
format!(
"one of {}",
expected
.iter()
.enumerate()
.map(|(i, t)| {
format!(
"{}'{}'",
if i == 0 {
""
} else if i == expected.len() - 1 {
" or "
} else {
", "
},
t
)
})
.collect::<String>()
)
},
found,
context,
found.span().start().line_number(),
found.span().start().column_number()
),
Self::Unexpected { found, message } => write!(
f,
"unexpected token '{}'{} at line {}, col {}",
found,
if let Some(m) = message {
format!(", {}", m)
} else {
String::new()
},
found.span().start().line_number(),
found.span().start().column_number()
),
Self::AbruptEnd => write!(f, "Abrupt End"),
Self::General { message, position } => write!(
f,
"{} at line {}, col {}",
message,
position.line_number(),
position.column_number()
),
}
}
}