Function nom::bytes::streaming::take_while

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, 

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)

Streaming Specific

Streaming version will return a Err::Incomplete(Needed::Size(1)) if the pattern reaches the end of the input

Example

use nom::bytes::streaming::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"), Err(Err::Incomplete(Needed::Size(1))));
assert_eq!(alpha(b""), Err(Err::Incomplete(Needed::Size(1))));