[cedet-semantic] A few questions about the semantic API

[Toby 'q. C. <ts...@ca...>]

Hi,

I'm trying to make use of semantic information in the
intellisense-like completion package I maintain (predictive completion
mode). It stores possible completions in "dictionary" data structures
optimised for fast lookup (fast enough to return completions from a
40,000 word English dictionary quicker than I can type on my old
Pentium2 450). It also learns word usage frequencies as you type, and
can prioritise completions using this information.

I know semantic's completion speed has been discussed now and again on
this list, so I'm hoping using my package on top of semantic might be
of interest to some people. And prioritising completions by how often
they've been used might be a nice feature for intellisense-like
tools.

So much for the propaganda and vapour-ware announcements ;-)


I've read the manual and some of the code in semantic-ia.el,
semantic-ctxt.el and semantic-analyze.el, but there are a few things
I'm still not sure about, probably because I know next to nothing
about parser/lexers. Sorry if the questions are vague, trivial, show I
misunderstood something fundamental about semantic, or are answered in
the manual (I hope I've done my best to avoid 2 and 4...!)

1) As I understand it, I'll basically need to write an alternative
version of `semantic-analyze-possible-completions' that looks up
completions in my dictionary structures instead of directly in the tag
tables. I'll also need code to automatically generate those
dictionaries, and keep them synced with the tag tables. (The
dictionaries then basically serve as a structured cache of the
completion candidates.) Does this sound reasonable from the
perspective of someone who understands semantic better than me?

2) Obviously, caching completion candidates is a waste of time,
however clever the data structure, if you have to regenerate the cache
every time you look up a completion. I was hoping to use the
information from `semantic-after-partial/toplevel-cache-change-hook'
to tell me which tags have been created/removed/modified. But from
playing with it a bit, I get the impression that the argument passed
to hook functions only contains new tags, not removed/modified
ones. Is that right? Is there some way to get at that information? Or
is it simply not available because of the way the (incremental) parser
works?

3) You define dictionaries for predictive mode that are local to
certain buffer regions using overlays. I think I'll at least need to
set up an overlay for each scope, possibly more. I've written a
package that can automatically create overlays as you type, defined by
regexps (again designed to work fast enough not to get in the way of
typing). But I know semantic sets up overlays all over the place for
the tags found by the parser. Does semantic already create overlays I
could use? E.g. are there overlays covering the text between {...} in
c-mode, or covering the symbol after a "->" dereference? If so, can I
get semantic to add extra properties to them?

4) It would be useful for me to be able to get a list of
functions/variables/arguments that are local to the current scope.
I.e. not all variables available in the current scope, but all
variables only available in the innermost scope. I think
`semantic-get-local-variables' and related return the former. Are
there functions that return the latter? If not, is it safe to use
`semantic-up-context', as `semantic-get-local-variables-default' does,
or will this only work with some languages?


Ok, I think that'll do for now ;)

Thanks a lot for any help. Hope I'll be able to contribute back some
useful code eventually.

Toby
-- 
PhD Student
Quantum Information Theory group
Max Planck Institute for Quantum Optics
Garching, Germany

email: to...@dr...
web: www.dr-qubit.org