* Peter da Silva <pe...@taronga.com> [2007-08-02 21:45]: > > Please have the length of strings upfront. > > Length encoding isn't self-syncing,
Synching the length is O(1). Not doing it makes *everything* O(n) and leaves you to deal with the semi-predicate problem, source of lots of 'sploits and other fun for the whole family. Pick your poison; I know which one I prefer. > and it also limits the length of individual parameters by the > size of the length. So what? Just make sure the counter is wide enough for any string you can keep in memory. Wasteful? So use a variable-width encoding for the length. It can be brutally stupid as it only needs to be competitive with NUL termination on very short strings. Using a single byte for strings < 128 bytes and a machine word for anything longer will do just fine. If you use the lowest bit as a flag to signify the type, then massaging the counter takes under 2 cycles on average with optimal machine code: ridiculously fast -- a common theme with operations on length-prefixed strings. That C and UNIX immortalised zero-terminated strings amounts to a crime if you consider the amount of CPU cycles that have since been wasted scanning for NULs. Regards, -- Aristotle Pagaltzis // <http://plasmasturm.org/>
