# Function nom::bytes::complete::tag

source · [−]

    pub fn tag<T, Input, Error: ParseError<Input>>(
        tag: T
    ) -> impl Fn(Input) -> IResult<Input, Input, Error> where
        Input: InputTake + Compare<T>,
        T: InputLength + Clone,

Expand description

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::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))));