Function winnow::binary::length_and_then
source · pub fn length_and_then<Input, Output, Count, Error, CountParser, ParseNext>(
count: CountParser,
parser: ParseNext
) -> impl Parser<Input, Output, Error>where
Input: StreamIsPartial + Stream + UpdateSlice + Clone,
Count: ToUsize,
CountParser: Parser<Input, Count, Error>,
ParseNext: Parser<Input, Output, Error>,
Error: ParserError<Input>,
Expand description
Parse a length-prefixed slice (TLV)
Complete version: Returns an error if there is not enough input data.
[Partial version][crate::_topic::partial]: Will return Err(winnow::error::ErrMode::Incomplete(_))
if there is not enough data.
§Example
use winnow::Bytes;
use winnow::binary::be_u16;
use winnow::binary::length_and_then;
type Stream<'i> = Partial<&'i Bytes>;
fn stream(b: &[u8]) -> Stream<'_> {
Partial::new(Bytes::new(b))
}
fn complete_stream(b: &[u8]) -> Stream<'_> {
let mut p = Partial::new(Bytes::new(b));
let _ = p.complete();
p
}
fn parser(s: Stream<'_>) -> IResult<Stream<'_>, &[u8]> {
length_and_then(be_u16, "abc").parse_peek(s)
}
assert_eq!(parser(stream(b"\x00\x03abcefg")), Ok((stream(&b"efg"[..]), &b"abc"[..])));
assert_eq!(parser(stream(b"\x00\x03123123")), Err(ErrMode::Backtrack(InputError::new(complete_stream(&b"123"[..]), ErrorKind::Tag))));
assert_eq!(parser(stream(b"\x00\x03a")), Err(ErrMode::Incomplete(Needed::new(2))));