Macro nom::length_count

macro_rules! length_count {
    ($i : expr, $submac : ident! ($($args : tt) *), $submac2 : ident!
 ($($args2 : tt) *)) => { ... };
    ($i : expr, $submac : ident! ($($args : tt) *), $g : expr) => { ... };
    ($i : expr, $f : expr, $submac : ident! ($($args : tt) *)) => { ... };
    ($i : expr, $f : expr, $g : expr) => { ... };
}

length_count!(I -> IResult<I, nb>, I -> IResult<I,O>) => I -> IResult<I, Vec<O>> gets a number from the first parser, then applies the second parser that many times

use nom::number::complete::be_u8;
named!(parser<Vec<&[u8]>>, length_count!(be_u8, tag!("abc")));

assert_eq!(parser(&b"\x02abcabcabc"[..]), Ok(((&b"abc"[..], vec![&b"abc"[..], &b"abc"[..]]))));
assert_eq!(parser(&b"\x04abcabcabc"[..]), Err(Err::Incomplete(Needed::Size(3))));