Function nom::multi::fold_many_m_n

pub fn fold_many_m_n<I, O, E, F, G, R>(
    m: usize, 
    n: usize, 
    f: F, 
    init: R, 
    g: G
) -> impl Fn(I) -> IResult<I, R, E> where
    I: Clone + PartialEq,
    F: Fn(I) -> IResult<I, O, E>,
    G: Fn(R, O) -> R,
    E: ParseError<I>,
    R: Clone, 

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 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"])));