Function recognize

pub fn recognize<I, E, F>(parser: F) -> impl Parser<I, Output = I, Error = E>
where
    I: Clone + Offset + Input,
    E: ParseError<I>,
    F: Parser<I, Error = E>,

If the child parser was successful, return the consumed input as produced value.

use nom::combinator::recognize;
use nom::character::complete::{char, alpha1};
use nom::sequence::separated_pair;

let mut parser = recognize(separated_pair(alpha1, char(','), alpha1));

assert_eq!(parser.parse("abcd,efgh"), Ok(("", "abcd,efgh")));
assert_eq!(parser.parse("abcd;"),Err(Err::Error((";", ErrorKind::Char))));