Re: LR(1) Parser Generator

Tim Josling wrote:
> I am looking for the source for an LR(1) compiler, preferably
> written in C, and with open source licencing. Google cannot help.
> Is anyone aware of anything. I do have a pascal implementation
> but I do not like pascal (for no good reason I'm sure) and P2C
> core dumps on the program.
>
> LALR implementations are available but it has to be LR(1).


I am currently working on an LR(1) parser generator for Java (which is
also written in Java), which generates parsers from YACC input grammars.
I have the generator "engine" already working, but as of yet I have not
completed the parser or code generator portions.


I plan to release it as open source. Would this be of interest to you?




> Everyone says LR(1) implementations are too slow or too big but
> those books were written when mainframes has 1mb of 'core'.


I agree. I actually use a modified LR(1) parser generator, which
attempts to merge as many item sets as it can, a la LALR(1) parsers,
so the resulting state tables are not that much bigger than LALR(1)
tables (and will, in fact, be exactly the same size if the input
grammar is LALR(1) or SLR(1)). I call this method "Merged LR(k)", or
"MLR(k)" for short.


-- David R. Tribble, mailto:david@tribble.com --

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