pub fn take_while_m_n<F, Input, Error>(
    m: usize,
    n: usize,
    cond: F
) -> impl Fn(Input)
where Error: ParseError<Input>, Input: InputTake + InputIter + InputLength + Slice<RangeFrom<usize>>, F: Fn(<Input as InputIter>::Item) -> bool,
Available on crate feature mtls only.
Expand description

Returns the longest (m <= len <= n) input slice that matches the predicate.

The parser will return the longest slice that matches the given predicate (a function that takes the input and returns a bool).

It will return an Err::Error((_, ErrorKind::TakeWhileMN)) if the pattern wasn’t met or is out of range (m <= len <= n).


use nom::bytes::complete::take_while_m_n;
use nom::character::is_alphabetic;

fn short_alpha(s: &[u8]) -> IResult<&[u8], &[u8]> {
  take_while_m_n(3, 6, is_alphabetic)(s)

assert_eq!(short_alpha(b"latin123"), Ok((&b"123"[..], &b"latin"[..])));
assert_eq!(short_alpha(b"lengthy"), Ok((&b"y"[..], &b"length"[..])));
assert_eq!(short_alpha(b"latin"), Ok((&b""[..], &b"latin"[..])));
assert_eq!(short_alpha(b"ed"), Err(Err::Error(Error::new(&b"ed"[..], ErrorKind::TakeWhileMN))));
assert_eq!(short_alpha(b"12345"), Err(Err::Error(Error::new(&b"12345"[..], ErrorKind::TakeWhileMN))));