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
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
use std::u8;
use crate::json::{self, JSONError};
#[derive(Clone, Debug, PartialEq)]
pub enum Token {
OpenBrace,
CloseBrace,
OpenBracket,
CloseBracket,
Colon,
Comma,
StringLiteral(String),
NumericLiteral(String),
True,
False,
Null,
Unknown(String),
}
#[derive(Clone, Debug)]
pub struct TokenPos(pub Token, pub usize, pub usize);
pub struct Lexer {
buffer: Vec<u8>,
pos: usize,
marker: usize,
line: usize,
column: usize,
}
impl Lexer {
pub fn new(buffer: Vec<u8>) -> Lexer {
Lexer {
buffer,
pos: 0,
marker: 0,
line: 1,
column: 1,
}
}
#[inline]
fn curr(&self) -> u8 {
self.buffer[self.pos]
}
#[inline]
fn mark(&self) -> u8 {
self.buffer[self.marker]
}
/// Advance lexer by `len` bytes, adjusting column and line positions as necessary
fn advance(&mut self, len: usize) -> json::Result<()> {
// err if out of bounds
if self.pos + len > self.buffer.len() {
return Err(JSONError::LexerError(
format!(
"new position {} out of bounds for buffer length {}",
self.pos + len,
self.buffer.len(),
)
));
}
// find locations of all the line breaks
let mut line_breaks: Vec<usize> = vec![];
for i in self.pos..self.pos + len {
if self.buffer[i] == b'\n' {
line_breaks.push(i);
}
}
// advance raw character position
self.pos += len;
self.marker = self.pos;
// if line breaks were found...
if line_breaks.len() > 0 {
// increment line count by number of '\n' chars found
self.line += line_breaks.len();
// set column pos to the offset from the last line break
self.column = self.pos - line_breaks.pop().unwrap();
} else {
// advance column position
self.column += len;
}
Ok(())
}
// may use later idk
#[allow(dead_code)]
fn seek(&mut self, codepoint: u8) -> json::Result<()> {
// this ensures that we don't select the current position
self.marker = self.pos + 1;
while self.mark() != codepoint {
self.marker += 1;
if self.marker >= self.buffer.len() {
return Err(JSONError::LexerError(
format!(
"codepoint {} never found",
codepoint as char,
)
));
}
}
// to include seeked-for character
self.marker += 1;
Ok(())
}
fn seek_in(&mut self, low: u8, high: u8) {
while self.marker < self.buffer.len() && self.mark() >= low && self.mark() <= high {
self.marker += 1;
}
}
fn seek_all(&mut self, values: &[u8]) {
while self.marker < self.buffer.len() {
if values.iter().any(|&val| val == self.mark()) {
self.marker += 1;
} else {
break;
}
}
}
fn highlighted(&self) -> &str {
core::str::from_utf8(&self.buffer[self.pos..self.marker]).unwrap()
}
pub fn tokenify(&mut self) -> json::Result<Vec<TokenPos>> {
// quick and dirty; will switch to better system later
const ALPHABET: [u8; 52] = [
b'a', b'b', b'c', b'd', b'e', b'f', b'g',
b'h', b'i', b'j', b'k', b'l', b'm', b'n',
b'o', b'p', b'q', b'r', b's', b't', b'u',
b'v', b'w', b'x', b'y', b'z',
b'A', b'B', b'C', b'D', b'E', b'F', b'G',
b'H', b'I', b'J', b'K', b'L', b'M', b'N',
b'O', b'P', b'Q', b'R', b'S', b'T', b'U',
b'V', b'W', b'X', b'Y', b'Z',
];
self.pos = 0;
let mut tokens: Vec<TokenPos> = vec![];
loop {
if self.pos == self.buffer.len() {
break Ok(tokens);
}
match self.curr() {
b'{' => {
tokens.push(TokenPos(Token::OpenBrace, self.line, self.column));
self.advance(1)?;
},
b'}' => {
tokens.push(TokenPos(Token::CloseBrace, self.line, self.column));
self.advance(1)?;
},
b'[' => {
tokens.push(TokenPos(Token::OpenBracket, self.line, self.column));
self.advance(1)?;
},
b']' => {
tokens.push(TokenPos(Token::CloseBracket, self.line, self.column));
self.advance(1)?;
},
b':' => {
tokens.push(TokenPos(Token::Colon, self.line, self.column));
self.advance(1)?;
},
b',' => {
tokens.push(TokenPos(Token::Comma, self.line, self.column));
self.advance(1)?;
},
b' ' => {
self.advance(1)?;
},
b'\n' => {
self.advance(1)?;
},
b'"' => {
// this ensures that we don't select the current position
self.marker = self.pos + 1;
loop {
self.marker += 1;
if self.mark() == b'"' {
if self.buffer[self.marker - 1] != b'\\' {
break;
}
}
if self.marker >= self.buffer.len() {
return Err(JSONError::LexerError(
format!(
"ending \" never found"
)
));
}
}
// to include seeked-for character
self.marker += 1;
tokens.push(TokenPos(
Token::StringLiteral(self.highlighted().to_owned()),
self.line,
self.column,
));
self.advance(self.marker - self.pos)?;
},
b't' => {
self.seek_all(&ALPHABET);
if self.highlighted() == "true" {
tokens.push(TokenPos(Token::True, self.line, self.column));
} else {
tokens.push(TokenPos(
Token::Unknown(self.highlighted().to_owned()),
self.line,
self.column,
));
}
self.advance(self.marker - self.pos)?;
},
b'f' => {
self.seek_all(&ALPHABET);
if self.highlighted() == "false" {
tokens.push(TokenPos(Token::False, self.line, self.column));
} else {
tokens.push(TokenPos(
Token::Unknown(self.highlighted().to_owned()),
self.line,
self.column,
));
}
self.advance(self.marker - self.pos)?;
},
b'n' => {
self.seek_all(&ALPHABET);
if self.highlighted() == "null" {
tokens.push(TokenPos(Token::Null, self.line, self.column));
} else {
tokens.push(TokenPos(
Token::Unknown(self.highlighted().to_owned()),
self.line,
self.column,
));
}
self.advance(self.marker - self.pos)?;
},
b'A'..=b'z' => {
self.seek_in(b'A', b'z');
tokens.push(TokenPos(
Token::Unknown(self.highlighted().to_owned()),
self.line,
self.column,
));
self.advance(self.marker - self.pos)?;
},
b'0'..=b'9' | b'-' | b'+' | b'.' => {
const NUM_CHARS: [u8; 15] = [
b'0', b'1', b'2', b'3',
b'4', b'5', b'6', b'7',
b'8', b'9', b'.', b'e',
b'E', b'+', b'-',
];
self.seek_all(&NUM_CHARS);
tokens.push(TokenPos(
Token::NumericLiteral(self.highlighted().to_owned()),
self.line,
self.column,
));
self.advance(self.marker - self.pos)?;
},
_ => {
break Err(JSONError::LexerError(
format!(
"invalid character '{}' at line {}, column {}",
self.curr() as char,
self.line,
self.column,
)
));
}
}
}
}
}