rocket::mtls::x509::der_parser::asn1_rs::nom::combinator

Function cond

Source 
pub fn cond<I, O, E, F>(b: bool, f: F) -> impl FnMut(I)
where
    E: ParseError<I>,
    F: Parser<I, O, E>,
Available on crate feature mtls only.
Expand description

Calls the parser if the condition is met.

use nom::combinator::cond;
use nom::character::complete::alpha1;

fn parser(b: bool, i: &str) -> IResult<&str, Option<&str>> {
  cond(b, alpha1)(i)
}

assert_eq!(parser(true, "abcd;"), Ok((";", Some("abcd"))));
assert_eq!(parser(false, "abcd;"), Ok(("abcd;", None)));
assert_eq!(parser(true, "123;"), Err(Err::Error(Error::new("123;", ErrorKind::Alpha))));
assert_eq!(parser(false, "123;"), Ok(("123;", None)));