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
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
|
use super::{Cursor, OtherHighlights, Parse, ParseError, Result};
use crate::regex::{GreedyBehavior, Pattern, LookDirection, LookPolarity};
const SYMBOLS: &[u8] = b"{}[]()*+-?|.\\ ";
fn is_symbol(x: u8) -> bool {
SYMBOLS.contains(&x)
}
impl Parse for Pattern {
fn parse(b: &mut Cursor<'_>) -> super::Result<Self> {
let begin = b.loc();
let result = parse0(b);
if result.is_ok() {
b.highlight_from(begin, OtherHighlights::Regex);
}
result
}
}
fn parse0(s: &mut Cursor<'_>) -> Result<Pattern> {
parse_alt(s)
}
fn parse_alt(s: &mut Cursor<'_>) -> Result<Pattern> {
let mut seqs = vec![];
loop {
let seq = parse_seq(s)?;
seqs.push(seq);
let begin = s.loc();
if s.has() && s.peek() == b'|' {
s.adv();
s.highlight_from(begin, OtherHighlights::RegexSymbol);
} else {
break;
}
}
Ok(match seqs.len() {
0 => Pattern::Nothing,
1 => seqs.into_iter().next().unwrap(),
_ => Pattern::Alt(seqs),
})
}
fn parse_seq(s: &mut Cursor<'_>) -> Result<Pattern> {
let mut reps = vec![];
loop {
let rep = parse_rep(s)?;
if rep != Pattern::Nothing {
reps.push(rep);
} else {
break;
}
}
Ok(match reps.len() {
0 => Pattern::Nothing,
1 => reps.into_iter().next().unwrap(),
_ => Pattern::Concat(reps),
})
}
fn parse_rep(s: &mut Cursor<'_>) -> Result<Pattern> {
let atom = parse_atom(s)?;
if atom == Pattern::Nothing {
return Ok(atom);
}
if !s.has() {
return Ok(atom);
}
let begin = s.loc();
let rep = match s.peek() {
b'*' => Some((0, None)),
b'+' => Some((1, None)),
b'?' => Some((0, Some(1))),
_ => None,
};
if let Some((min_rep, max_rep)) = rep {
s.adv();
s.highlight_from(begin, OtherHighlights::RegexSymbol);
let greed = if s.has() && s.peek() == b'?' {
s.adv();
GreedyBehavior::NonGreedy
} else {
GreedyBehavior::Greedy
};
Ok(Pattern::Rep(Box::new(atom), min_rep, max_rep, greed))
} else {
Ok(atom)
}
}
fn parse_atom(s: &mut super::Cursor<'_>) -> Result<Pattern> {
if !s.has() {
return Ok(Pattern::Nothing);
}
let begin = s.loc();
match s.peek() {
b'[' => {
s.adv();
s.highlight_from(begin, OtherHighlights::RegexSymbol);
let mut ranges = Vec::new();
loop {
if !s.has() {
return Err(ParseError::Eof);
}
let begin = s.loc();
let tok = s.adv();
if tok == b']' {
if ranges.is_empty() {
todo!("error handling for empty alternative list");
}
s.highlight_from(begin, OtherHighlights::RegexSymbol);
return Ok(Pattern::Alt(ranges));
}
let begin = s.loc();
if s.has() && s.peek() == b'-' {
s.adv();
s.highlight_from(begin, OtherHighlights::RegexSymbol);
if !s.has() {
return Err(ParseError::Eof);
}
let tok2 = s.peek();
if tok2 == b']' {
ranges.push(Pattern::Byte(tok));
ranges.push(Pattern::Byte(b'-'));
} else if is_symbol(tok2) {
return Err(ParseError::Unknown(tok2));
} else {
s.adv();
ranges.push(Pattern::Range(tok, tok2));
}
} else {
ranges.push(Pattern::Byte(tok));
}
}
}
b'(' => {
s.adv();
let mut assertion = None;
if s.buf.starts_with(b"?=") {
s.advance(2);
assertion = Some((LookDirection::Ahead, LookPolarity::Positive));
} else if s.buf.starts_with(b"?!") {
s.advance(2);
assertion = Some((LookDirection::Ahead, LookPolarity::Negative));
} else if s.buf.starts_with(b"?<=") {
s.advance(3);
assertion = Some((LookDirection::Behind, LookPolarity::Positive));
} else if s.buf.starts_with(b"?<!") {
s.advance(3);
assertion = Some((LookDirection::Behind, LookPolarity::Negative));
}
s.highlight_from(begin, OtherHighlights::RegexSymbol);
let inner = parse0(s)?;
if !s.has() {
return Err(ParseError::Eof);
}
let begin = s.loc();
if s.adv() != b')' {
return Err(ParseError::Expected(')'));
}
s.highlight_from(begin, OtherHighlights::RegexSymbol);
if let Some((dir, pol)) = assertion {
Ok(Pattern::Assertion(dir, pol, Box::new(inner)))
} else {
Ok(Pattern::Submatch(Box::new(inner)))
}
}
b'.' => {
s.adv();
s.highlight_from(begin, OtherHighlights::RegexSymbol);
Ok(Pattern::Range(0, 127))
}
b'\\' => {
s.adv();
if s.has() {
let escaped = s.adv();
s.highlight_from(begin, OtherHighlights::RegexSymbol);
if is_symbol(escaped) {
Ok(Pattern::Byte(escaped))
} else {
// TODO interpret \w and others
Err(ParseError::Unknown(escaped))
}
} else {
Err(ParseError::Eof)
}
}
x if is_symbol(x) => Ok(Pattern::Nothing),
ch => {
s.adv();
Ok(Pattern::Byte(ch))
}
}
}
|
