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use nom::branch::alt;
use nom::multi::many_m_n;
use nom::{bytes::streaming::tag, IResult};
use crate::utils::{parse_bytes_with_length, parse_integer_with_prefix, parse_str_with_prefix};
#[derive(Debug, PartialEq)]
pub enum Resp2Type<'a> {
String(&'a str),
Error(&'a str),
Integer(usize),
BulkString(&'a [u8]),
Null,
Array(Vec<Resp2Type<'a>>),
}
fn parse_simple_string(input: &[u8]) -> IResult<&[u8], Resp2Type> {
let (input, string) = parse_str_with_prefix(input, '+')?;
Ok((input, Resp2Type::String(string)))
}
fn parse_error(input: &[u8]) -> IResult<&[u8], Resp2Type> {
let (input, string) = parse_str_with_prefix(input, '-')?;
Ok((input, Resp2Type::Error(string)))
}
fn parse_integer(input: &[u8]) -> IResult<&[u8], Resp2Type> {
let (input, int) = parse_integer_with_prefix(input, ':')?;
Ok((input, Resp2Type::Integer(int)))
}
fn parse_bulk_string(input: &[u8]) -> IResult<&[u8], Resp2Type> {
let (input, length) = parse_integer_with_prefix(input, '$')?;
let (input, bytes) = parse_bytes_with_length(input, length)?;
Ok((input, Resp2Type::BulkString(bytes)))
}
fn parse_null_string(input: &[u8]) -> IResult<&[u8], Resp2Type> {
let (input, _) = tag("$-1\r\n")(input)?;
Ok((input, Resp2Type::Null))
}
fn parse_array(input: &[u8]) -> IResult<&[u8], Resp2Type> {
let (input, length) = parse_integer_with_prefix(input, '*')?;
let (input, result) = many_m_n(length, length, parse)(input)?;
Ok((input, Resp2Type::Array(result)))
}
pub fn parse(input: &[u8]) -> IResult<&[u8], Resp2Type> {
alt((
parse_simple_string,
parse_error,
parse_integer,
parse_bulk_string,
parse_null_string,
parse_array,
))(input)
}
#[cfg(test)]
mod tests {
use crate::resp2::{parse, Resp2Type};
#[test]
fn test_parse_simple_string() {
assert_eq!(
parse(&b"+OK\r\n"[..]),
Ok((&b""[..], Resp2Type::String("OK")))
);
}
#[test]
fn test_parse_error() {
assert_eq!(
parse(&b"-Error message\r\n"[..]),
Ok((&b""[..], Resp2Type::Error("Error message")))
);
}
#[test]
fn test_parse_integer() {
assert_eq!(
parse(&b":100\r\n"[..]),
Ok((&b""[..], Resp2Type::Integer(100)))
);
}
#[test]
fn test_parse_bulk_string() {
assert_eq!(
parse(&b"$10\r\n1234567890\r\n"[..]),
Ok((&b""[..], Resp2Type::BulkString(&b"1234567890"[..])))
);
}
#[test]
fn test_parse_null_string() {
assert_eq!(parse(&b"$-1\r\n"[..]), Ok((&b""[..], Resp2Type::Null)));
}
#[test]
fn test_parse_array_empty() {
assert_eq!(
parse(&b"*0\r\n"[..]),
Ok((&b""[..], Resp2Type::Array(vec![])))
);
}
#[test]
fn test_parse_array_mixed_objecs() {
assert_eq!(
parse(&b"*3\r\n:1\r\n:2\r\n$3\r\nfoo\r\n"[..]),
Ok((
&b""[..],
Resp2Type::Array(vec![
Resp2Type::Integer(1),
Resp2Type::Integer(2),
Resp2Type::BulkString(&b"foo"[..])
])
))
);
}
}