[antlr-interest] automated completion - choosing matching productions and the next token
Terence Parr
parrt at cs.usfca.edu
Sat Jun 14 00:19:05 PDT 2008
I'm supposed to be working on book while traveling but spent a few
hours yesterday thinking about how useful NFAs of the grammar would
be at runtime. As we parse, I could update a ptr into the NFA and
keep a stack of rulenames etc... At any moment, one could ask the
NFA for the set of next valid tokens. This would make the generated
code simpler as well since I wouldn't have to precompute all those
damn bitsets for FOLLOWs (error handling sets).
Would be great for autocompletion and other stuff.
if i could do some lookahead prediction with it, i could also avoid
generating synpreds as separate classes etc...
I'll try to put this together for 3.2
Ter
On Jun 14, 2008, at 12:57 AM, Doucette, Charles wrote:
> I am working on an editor for a language.
> I have a grammar definition for a parser that builds a custom AST
> tree (not a standard Antlr AST tree).
> The editor already uses the parser to automatically flag syntax
> errors.
>
> Is there any way to automatically determine
> a) the current production
> b) the current token based on the production
> c) semantically choose the appropriate completions based on a) & b)
> above
>
> The Eclipse Java editor and JDT do this all already, so I know the
> technology exists.
> What I don't know is if it is based on fully automated parser
> technology (like from Antlr) or if it is based on simple heuristics
> (like looking for an identifier after a "." or "=").
>
> Thanks,
> Chuck
>
> Charles E. Doucette · 617-399-1122 · Vaultus Mobile Technologies,
> 263 Summer St., Boston, MA 02210 · http://www.vaultus.com
>
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