• Rob Pike's avatar
    bufio: fix scanning with a final empty token. · ec127547
    Rob Pike authored
    The Scan function's interface to the split function was not sufficient
    to handle an empty final token in a pure function; state was required.
    This was ugly.
    
    We introduce a special error value that a split function can return
    that signals that this token is OK, but is the last one and scanning
    should stop immediately _after_ this token.
    
    The same effect could be achieved using the same trick (a special
    error value) and checking for that error after Scan finishes, but it's
    a little clumsy. Providing a published sentinel value in bufio is
    cleaner and means everyone can use the same trick. The result
    is an error-free scan.
    
    Rewrite the test (that was only barely working) to use the value
    and be more robust.
    
    Also write a new example showing how to do it.
    
    Fixes #11836
    
    Change-Id: Iaae77d0f95b4a2efa0175ced94d93c66353079e8
    Reviewed-on: https://go-review.googlesource.com/14924Reviewed-by: 's avatarIan Lance Taylor <iant@golang.org>
    ec127547
scan_test.go 12.9 KB