Function nom::combinator::map_parser

pub fn map_parser<I: Clone, O1, O2, E: ParseError<I>, F, G>(
    first: F, 
    second: G
) -> impl Fn(I) -> IResult<I, O2, E> where
    F: Fn(I) -> IResult<I, O1, E>,
    G: Fn(O1) -> IResult<O1, O2, E>,
    O1: InputLength, 

applies a parser over the result of another one

use nom::character::complete::digit1;
use nom::bytes::complete::take;
use nom::combinator::map_parser;

let parse = map_parser(take(5u8), digit1);

assert_eq!(parse("12345"), Ok(("", "12345")));
assert_eq!(parse("123ab"), Ok(("", "123")));
assert_eq!(parse("123"), Err(Err::Error(("123", ErrorKind::Eof))));