On 07/07/2012 12:37 PM, Roman D. Boiko wrote:
On Saturday, 7 July 2012 at 16:27:00 UTC, Philippe Sigaud wrote:
Note that PEG does not impose to use packrat parsing, even though it
was developed to use it. I think it's a historical 'accident' that put
the two together: Bryan Ford thesis used the two together.
Note that many PEG parsers do not rely on packrat (Pegged does not).
There are a bunch of articles on Bryan Ford's website by a guy
writting a PEG parser for Java, and who found that storing the last
rules was enought to get a slight speed improvement, buth that doing
anymore sotrage was detrimental to the parser's overall efficiency.
That's great! Anyway I want to understand the advantages and limitations
of both Pegged and ANTLR, and probably study some more techniques. Such
research consumes a lot of time but can be done incrementally along with
development.
Yeah, it's good to hear this notion reinforced. I had this suspicion
that the packrat parser is not necessarily the best/fastest solution,
mostly because of the large allocation that has to happen before you get
O(n) performance. Thus I figured that pegged might eventually use
different parsing strategies underneath it all, possibly with a lot of
special-casing and clever hand-tuned and profiled optimizations. At
least that's what makes sense to me.
