I have written over the weekend a replacement for lib/fields.c and most of lib/parse.c, which uses flex (and flex start conditions) to generate a table-driven scanner-cum-parser. I haven't tested this fully for correctness yet, but I have done basic functionality tests and some performance tests.
Upsides: * It runs 35% faster than the existing hand-coded *p++-style parser. * It's about 25% smaller in source code, and I think much clearer. * It should also fix any top-bit-set character handling bugs which remain in the current codebase. * It will make it easier in the future to decouple the parsing functionality from dpkg's internal data structures so that the parser can be made available through a library interface. The downside is that it's 100K longer in code size. This is a particular problem because copies of it are distributed amongst several tools. There are three copies of it in dpkg.deb (in Ubuntu gutsy), for example. It's tempting to say that we should merge dpkg and dpkg-query and dpkg-trigger back into a single executable. This would probably save 150K or so in the current Ubuntu dpkg, and make the flex-based triggers-supporting dpkg package 50-70K smaller than the current sid dpkg. So I ask: why does dpkg-query exist as a separate executable ? Anyway, I think we should deploy the flex-based scanner in sid (after I've tested it a bit more) and then think at our leisure about how to improve the shared code situation. The branch with this code on can be found at http://www.chiark.greenend.org.uk/~ian/git/dpkg/dpkg.speedup/ but note that that's a fork from my Ubuntu triggers branch so it probably ought not to go into sid just yet, at least until the triggers are stabilised in Ubuntu (which I think will be quite soon). (People who were at the Debian UK BBQ may have heard me say that my new parser was no faster. That was before I spent this afternoon removing all of the backtracking from it.) Ian. (FAOD this message is from my personal DD hat, not my Ubuntu hat) -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
