# Function nom::bytes::complete::take_while

source · [−]

    pub fn take_while<F, Input, Error: ParseError<Input>>(
        cond: F
    ) -> impl Fn(Input) -> IResult<Input, Input, Error> where
        Input: InputTakeAtPosition,
        F: Fn(<Input as InputTakeAtPosition>::Item) -> bool,

Expand description

Returns the longest input slice (if any) that matches the predicate.

The parser will return the longest slice that matches the given predicate (a function that takes the input and returns a bool).

## Example

    use nom::bytes::complete::take_while;
    use nom::character::is_alphabetic;

    fn alpha(s: &[u8]) -> IResult<&[u8], &[u8]> {
      take_while(is_alphabetic)(s)
    }

    assert_eq!(alpha(b"latin123"), Ok((&b"123"[..], &b"latin"[..])));
    assert_eq!(alpha(b"12345"), Ok((&b"12345"[..], &b""[..])));
    assert_eq!(alpha(b"latin"), Ok((&b""[..], &b"latin"[..])));
    assert_eq!(alpha(b""), Ok((&b""[..], &b""[..])));