Function nom::multi::fold_many_m_n

pub fn fold_many_m_n<I, O, E, F, G, H, R>(
    min: usize, 
    max: usize, 
    parse: F, 
    init: H, 
    fold: G
) -> impl FnMut(I) -> IResult<I, R, E> where
    I: Clone + InputLength,
    F: Parser<I, O, E>,
    G: FnMut(R, O) -> R,
    H: FnMut() -> R,
    E: ParseError<I>, 

Applies a parser n times or until it fails and accumulates the results using a given function and initial value. Fails if the embedded parser does not succeed at least m times.

Arguments

• m The minimum number of iterations.
• n The maximum number of iterations.
• f The parser to apply.
• init A function returning the initial value.
• g The function that combines a result of f with the current accumulator.

use nom::multi::fold_many_m_n;
use nom::bytes::complete::tag;

fn parser(s: &str) -> IResult<&str, Vec<&str>> {
  fold_many_m_n(
    0,
    2,
    tag("abc"),
    Vec::new,
    |mut acc: Vec<_>, item| {
      acc.push(item);
      acc
    }
  )(s)
}

assert_eq!(parser("abcabc"), Ok(("", vec!["abc", "abc"])));
assert_eq!(parser("abc123"), Ok(("123", vec!["abc"])));
assert_eq!(parser("123123"), Ok(("123123", vec![])));
assert_eq!(parser(""), Ok(("", vec![])));
assert_eq!(parser("abcabcabc"), Ok(("abc", vec!["abc", "abc"])));