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
pub type Result<T> = std::result::Result<T, RError>;
pub struct RedisProtocolParser;
#[derive(Debug, PartialEq)]
pub enum RESP<'a> {
String(&'a [u8]),
Error(&'a [u8]),
Integer(&'a [u8]),
BulkString(&'a [u8]),
Array(Vec<RESP<'a>>),
}
#[derive(Debug)]
pub enum RError {
UnknownSymbol(char),
EmptyInput,
NoCrlf,
IncorrectFormat,
}
impl std::fmt::Display for RError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "{}", self)
}
}
impl<'a> std::error::Error for RError {}
impl RedisProtocolParser {
pub fn parse_resp(input: &[u8]) -> Result<(RESP, &[u8])> {
let mut iterator = input.iter();
if let Some(first) = iterator.next() {
let first = *first as char;
let (resp, left) = match first {
'+' => RedisProtocolParser::parse_simple_string(input)?,
':' => RedisProtocolParser::parse_integers(input)?,
'$' => RedisProtocolParser::parse_bulk_strings(input)?,
'*' => RedisProtocolParser::parse_arrays(input)?,
'-' => RedisProtocolParser::parse_errors(input)?,
symbol => return Err(RError::UnknownSymbol(symbol)),
};
Ok((resp, left))
} else {
Err(RError::EmptyInput)
}
}
fn get_everything_until_crlf(input: &[u8]) -> Result<(&[u8], &[u8])> {
for index in 1..input.len() {
if input[index] as char == '\r' && input[index + 1] as char == '\n' {
return Ok((&input[1..index], &input[index + 2..]));
}
}
Err(RError::NoCrlf)
}
pub fn parse_simple_string(input: &[u8]) -> Result<(RESP, &[u8])> {
RedisProtocolParser::get_everything_until_crlf(input).map(|(x, y)| (RESP::String(x), y))
}
pub fn parse_errors(input: &[u8]) -> Result<(RESP, &[u8])> {
RedisProtocolParser::get_everything_until_crlf(input).map(|(x, y)| (RESP::Error(x), y))
}
pub fn parse_integers(input: &[u8]) -> Result<(RESP, &[u8])> {
RedisProtocolParser::get_everything_until_crlf(input).map(|(x, y)| (RESP::Integer(x), y))
}
pub fn parse_bulk_strings(input: &[u8]) -> Result<(RESP, &[u8])> {
let (size_str, input) = RedisProtocolParser::get_everything_until_crlf(input)?;
let size = std::str::from_utf8(size_str)
.unwrap()
.parse::<u64>()
.unwrap();
let sizes = size as usize;
if sizes > input.len() {
return Err(RError::IncorrectFormat);
} else {
return Ok((RESP::BulkString(&input[..sizes]), &input[sizes + 2..]));
}
}
pub fn parse_arrays(input: &[u8]) -> Result<(RESP, &[u8])> {
let (size_str, input) = RedisProtocolParser::get_everything_until_crlf(input)?;
let size = std::str::from_utf8(size_str)
.unwrap()
.parse::<u64>()
.unwrap();
let sizes = size as usize;
let mut left = input;
let mut result = Vec::with_capacity(sizes);
for _ in 0..sizes {
let (element, tmp) = RedisProtocolParser::parse_resp(left)?;
result.push(element);
left = tmp;
}
Ok((RESP::Array(result), left))
}
}
#[cfg(test)]
mod test {
use super::*;
type Result = super::Result<()>;
#[test]
pub fn test_simple_string() -> Result {
let input = "+hello\r\n".as_bytes();
let (resp, left) = RedisProtocolParser::parse_resp(input)?;
assert_eq!(resp, RESP::String("hello".as_bytes()));
assert!(left.is_empty());
Ok(())
}
#[test]
pub fn test_bulk_string() -> Result {
let input = "$6\r\nfoobar\r\n".as_bytes();
let (resp, left) = RedisProtocolParser::parse_resp(input)?;
assert_eq!(resp, RESP::BulkString("foobar".as_bytes()));
assert!(left.is_empty());
let input = "$0\r\n\r\n".as_bytes();
let (resp, left) = RedisProtocolParser::parse_resp(input)?;
assert_eq!(resp, RESP::BulkString("".as_bytes()));
assert!(left.is_empty());
Ok(())
}
#[test]
pub fn test_arrays() -> Result {
let input = "*2\r\n$3\r\nfoo\r\n$3\r\nbar\r\n".as_bytes();
let (resp, left) = RedisProtocolParser::parse_resp(input)?;
assert_eq!(
resp,
RESP::Array(vec![
RESP::BulkString("foo".as_bytes()),
RESP::BulkString("bar".as_bytes())
])
);
assert!(left.is_empty());
let input = "*5\r\n:1\r\n:2\r\n:3\r\n:4\r\n$6\r\nfoobar\r\n".as_bytes();
let (resp, left) = RedisProtocolParser::parse_resp(input)?;
assert_eq!(
resp,
RESP::Array(vec![
RESP::Integer("1".as_bytes()),
RESP::Integer("2".as_bytes()),
RESP::Integer("3".as_bytes()),
RESP::Integer("4".as_bytes()),
RESP::BulkString("foobar".as_bytes()),
])
);
assert!(left.is_empty());
Ok(())
}
#[test]
pub fn test_array_of_arrays() -> Result {
let input = "*2\r\n*3\r\n:1\r\n:2\r\n:3\r\n*2\r\n+Foo\r\n-Bar\r\n".as_bytes();
let (resp, left) = RedisProtocolParser::parse_resp(input)?;
assert_eq!(
resp,
RESP::Array(vec![
RESP::Array(vec![
RESP::Integer("1".as_bytes()),
RESP::Integer("2".as_bytes()),
RESP::Integer("3".as_bytes()),
]),
RESP::Array(vec![
RESP::String("Foo".as_bytes()),
RESP::Error("Bar".as_bytes()),
]),
])
);
assert!(left.is_empty());
Ok(())
}
}