Function tag

pub fn tag<T, I, Error>(tag: T) -> impl Parser<I, Output = I, Error = Error>
where
    Error: ParseError<I>,
    I: Input + Compare<T>,
    T: Input + Clone,

Recognizes a pattern.

The input data will be compared to the tag combinator’s argument and will return the part of the input that matches the argument.

Example

use nom::bytes::streaming::tag;

fn parser(s: &str) -> IResult<&str, &str> {
  tag("Hello")(s)
}

assert_eq!(parser("Hello, World!"), Ok((", World!", "Hello")));
assert_eq!(parser("Something"), Err(Err::Error(Error::new("Something", ErrorKind::Tag))));
assert_eq!(parser("S"), Err(Err::Error(Error::new("S", ErrorKind::Tag))));
assert_eq!(parser("H"), Err(Err::Incomplete(Needed::new(4))));