Function patternscan::scan_first_match

pub fn scan_first_match(
    reader: impl Read, 
    pattern: &str
) -> Result<Option<usize>, Error>

Scan for the first instance of pattern in the bytes read by reader.

This function should be used instead of scan if you just want to test whether a byte string contains a given pattern, or just find the first instance, as it returns as soon as the first match is found, and will therefore be more efficient for these purposes in long strings where the pattern occurs early.

Returns a Result containing an Option. This Option will contain Some(index) if the pattern was found, where index is the index of the first match, and None if the pattern was not found. Returns an Error if an error was encountered while scanning, which could occur if the pattern is invalid (i.e: contains something other than 8-bit hex values and wildcards), or if the reader encounters an error.