Function `fold_many_m_n`

fn fold_many_m_n<I, E, F, G, H, R>(min: usize, max: usize, parser: F, init: H, g: G) -> impl Parser<I, Output = R, Error = E>
where
    I: Clone + Input,
    F: Parser<I, Error = E>,
    G: FnMut(R, <F as Parser<I>>::Output) -> R,
    H: FnMut() -> R,
    E: ParseError<I>

Repeats the embedded parser m..=n times, calling g to gather the results

This stops before n when the parser returns Err::Error. To instead chain an error up, see [cut][crate::combinator::cut].

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.

Note: If the parser passed to many1 accepts empty inputs (like alpha0 or digit0), many1 will return an error, to prevent going into an infinite loop.

# use nom::{Err, error::ErrorKind, Needed, IResult, Parser};
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
    }
  ).parse(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"])));