Function winnow::bytes::tag

pub fn tag<T, I, Error: ParseError<I>>(
    tag: T
) -> impl FnMut(I) -> IResult<I, <I as Stream>::Slice, Error>where
    I: StreamIsPartial + Stream + Compare<T>,
    T: SliceLen + Clone,

Recognizes a literal

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(ErrMode::Backtrack(Error::new(_, ErrorKind::Tag))) if the input doesn’t match the pattern

Note: Parser is implemented for strings and byte strings as a convenience (complete only)

Example

use winnow::bytes::tag;

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

assert_eq!(parser("Hello, World!"), Ok((", World!", "Hello")));
assert_eq!(parser("Something"), Err(ErrMode::Backtrack(Error::new("Something", ErrorKind::Tag))));
assert_eq!(parser(""), Err(ErrMode::Backtrack(Error::new("", ErrorKind::Tag))));

use winnow::bytes::tag;

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

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