Function lines::linemapper::map_lines

pub fn map_lines<R, F>(r: R, f: F) -> Result<()> where
    R: BufRead,
    F: FnMut(&[u8]) -> bool, 

Maps the given function f over lines read from r until either the function returns false, the end of stream is encountered, or the underlying reader returns an error.

Examples

Count the number of lines with more than 80 bytes:

   let r: BufRead = ...;
   let mut nl = 0usize;
   map_lines(r, |line| {
       if line.len() > 80 {
           nl += 1;
       }
       true
   });
   println!("long lines: {}", nl);