Function winnow::ascii::digit1

pub fn digit1<I, E: ParserError<I>>(
    input: &mut I,
) -> PResult<<I as Stream>::Slice, E>
where
    I: StreamIsPartial + Stream,
    <I as Stream>::Token: AsChar,

Recognizes one or more ASCII numerical characters: '0'..='9'

Complete version: Will return an error if there’s not enough input data, or the whole input if no terminating token is found (a non digit character).

Partial version: Will return Err(winnow::error::ErrMode::Incomplete(_)) if there’s not enough input data, or if no terminating token is found (a non digit character).

Example

fn parser<'s>(input: &mut &'s str) -> PResult<&'s str, InputError<&'s str>> {
    digit1.parse_next(input)
}

assert_eq!(parser.parse_peek("21c"), Ok(("c", "21")));
assert_eq!(parser.parse_peek("c1"), Err(ErrMode::Backtrack(InputError::new("c1", ErrorKind::Slice))));
assert_eq!(parser.parse_peek(""), Err(ErrMode::Backtrack(InputError::new("", ErrorKind::Slice))));

assert_eq!(digit1::<_, InputError<_>>.parse_peek(Partial::new("21c")), Ok((Partial::new("c"), "21")));
assert_eq!(digit1::<_, InputError<_>>.parse_peek(Partial::new("c1")), Err(ErrMode::Backtrack(InputError::new(Partial::new("c1"), ErrorKind::Slice))));
assert_eq!(digit1::<_, InputError<_>>.parse_peek(Partial::new("")), Err(ErrMode::Incomplete(Needed::new(1))));

Parsing an integer

You can use digit1 in combination with Parser::try_map to parse an integer:

fn parser<'s>(input: &mut &'s str) -> PResult<u32, InputError<&'s str>> {
  digit1.try_map(str::parse).parse_next(input)
}

assert_eq!(parser.parse_peek("416"), Ok(("", 416)));
assert_eq!(parser.parse_peek("12b"), Ok(("b", 12)));
assert!(parser.parse_peek("b").is_err());