Parametrized parsers for nom

main.rs

use nom::IResult;

// Hard-coded
named!(pub balanced1<()>, do_parse!(take!(1) >> tag!("~") >> take!(1) >> ()));
named!(pub balanced2<()>, do_parse!(take!(2) >> tag!("~") >> take!(2) >> ()));
named!(pub balanced3<()>, do_parse!(take!(3) >> tag!("~") >> take!(3) >> ()));
// Parametrized (function)
fn balanced_fn(input: &[u8], n: usize) -> IResult<&[u8], ()> {
  do_parse!(input, take!(n) >> tag!("~") >> take!(n) >> ())
}
// Parametrized (macro)
named_args!(balanced_macro(n: usize) <()>,
  do_parse!(take!(n) >> tag!("~") >> take!(n) >> ())
);
// Combined (function)
named!(pub balanced5_fn<()>, apply!(balanced_macro, 5));
// Combined (macro)
named!(pub balanced5_macro<()>, call!(balanced_macro, 5));

#[cfg(test)]
mod tests {
  use nom;
  use super::*;

  #[test]
  fn test_balanced() {
    assert_eq!(balanced1(&b"a~a"[..]), nom::IResult::Done(&[][..], ()));
    assert_eq!(balanced2(&b"aa~aa"[..]), nom::IResult::Done(&[][..], ()));
    assert_eq!(balanced3(&b"aaa~aaa"[..]), nom::IResult::Done(&[][..], ()));
    assert_eq!(balanced_fn(&b"aaaaa~aaaaa"[..], 5), nom::IResult::Done(&[][..], ()));
    assert_eq!(balanced_macro(&b"aaaaa~aaaaa"[..], 5), nom::IResult::Done(&[][..], ()));
    assert_eq!(balanced5_fn(&b"aaaaa~aaaaa"[..]), nom::IResult::Done(&[][..], ()));
    assert_eq!(balanced5_macro(&b"aaaaa~aaaaa"[..]), nom::IResult::Done(&[][..], ()));
  }
}