Function `tag`

fn tag<T, I, Error: ParseError<I>>(tag: T) -> impl Fn(I) -> crate::internal::IResult<I, I, Error>
where
    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

It will return Err(Err::Error((_, ErrorKind::Tag))) if the input doesn't match the pattern

Example

# use nom::{Err, error::{Error, ErrorKind}, Needed, IResult};
use nom::bytes::complete::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(""), Err(Err::Error(Error::new("", ErrorKind::Tag))));