Function scan_pattern_to_printer 

pub fn scan_pattern_to_printer<R: Read, P: Printer>(
    reader: R,
    pattern: &str,
    printer: P,
) -> Result<(), Error>

scan_pattern_to_printer will print a Read’s contents to the given Printer, while also scanning its contents for a regular expression. Lines that match this pattern will be highlighted in the output.

Note that this pattern is not anchored at the start of the line by default, and therefore a match anywhere in the line will force the entire line to be considered a match. For instance, the pattern [a-z] will match 123abc456.

Errors

There are four general error cases

• An invalid regular expression
• An error produced by the underlying grep library during the search
• I/O errors in scanning from the Read (these will be manifested as search errors, as the search process is what performs the reading).
• A failure to print to the given printer

See Error for more details.