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pub use nom::Err;
use nom::{
bytes::streaming::{tag, take_until, take_while},
character::{
is_alphanumeric,
streaming::{u16, u8},
},
combinator::{map, verify},
error::{context, ContextError, ParseError},
multi::length_data,
sequence::{delimited, separated_pair, terminated, tuple},
IResult,
};
use crate::fields::FixStr;
pub fn generic_field<'a, E: ParseError<&'a [u8]> + ContextError<&'a [u8]>>(
i: &'a [u8],
) -> IResult<&'a [u8], (u16, &[u8]), E> {
terminated(
separated_pair(u16, tag("="), take_until("\x01")),
tag("\x01"),
)(i)
}
fn verify_fix_str(bytes: &[u8]) -> bool {
for b in bytes {
if let 0x00..=0x1f | 0x80..=0xff = b {
return false;
}
}
true
}
fn begin_string<'a, E: ParseError<&'a [u8]> + ContextError<&'a [u8]>>(
i: &'a [u8],
) -> IResult<&'a [u8], &[u8], E> {
context(
"begin_string",
delimited(
tag("8="),
verify(take_until("\x01"), verify_fix_str),
tag("\x01"),
),
)(i)
}
fn checksum<'a, E: ParseError<&'a [u8]> + ContextError<&'a [u8]>>(
i: &'a [u8],
) -> IResult<&[u8], u8, E> {
context("checksum", delimited(tag("10="), u8, tag("\x01")))(i)
}
fn body_length<'a, E: ParseError<&'a [u8]> + ContextError<&'a [u8]>>(
i: &'a [u8],
) -> IResult<&[u8], u16, E> {
delimited(tag("9="), u16, tag("\x01"))(i)
}
fn _message_type<'a, E: ParseError<&'a [u8]> + ContextError<&'a [u8]>>(
i: &'a [u8],
) -> IResult<&[u8], &[u8], E> {
context(
"message_type",
delimited(tag("35="), take_while(is_alphanumeric), tag("\x01")),
)(i)
}
#[derive(Debug)]
pub struct RawMessage<'a> {
pub begin_string: &'a FixStr,
pub body: &'a [u8],
pub checksum: u8,
}
pub fn raw_message(i: &'_ [u8]) -> IResult<&'_ [u8], RawMessage<'_>> {
map(
tuple((begin_string, length_data(body_length), checksum)),
|(begin_string, body, checksum)| RawMessage {
begin_string: unsafe { FixStr::from_ascii_unchecked(begin_string) },
body,
checksum,
},
)(i)
}
#[cfg(test)]
mod tests {
use nom::Err::Incomplete;
use super::raw_message;
#[test]
fn parse_complete_ok() {
let input = b"8=MSG_BODY\x019=19\x01<lots of tags here>10=015\x01";
assert!(raw_message(input).is_ok());
}
#[test]
fn parse_from_chunks_ok() {
let input = &[
b"8=MSG_BOD".as_slice(),
b"Y\x019=19\x01<lots".as_slice(),
b" of tags here>10=015\x01".as_slice(),
b"leftover".as_slice(),
];
let mut buf = Vec::new();
let mut i = input.iter();
{
buf.extend_from_slice(i.next().unwrap());
assert!(matches!(raw_message(&buf), Err(Incomplete(_))));
}
{
buf.extend_from_slice(i.next().unwrap());
assert!(matches!(raw_message(&buf), Err(Incomplete(_))));
}
{
buf.extend_from_slice(i.next().unwrap());
assert!(matches!(raw_message(&buf), Ok(([], _))));
}
{
buf.extend_from_slice(i.next().unwrap());
assert!(matches!(raw_message(&buf), Ok((b"leftover", _))));
}
}
}