On 07/07/2012 12:05, Dmitry Olshansky wrote:
On 07-Jul-12 13:06, Roman D. Boiko wrote:
On Saturday, 7 July 2012 at 00:45:36 UTC, David Piepgrass wrote:
This work on parsers might be a good place for me to dive in. I have
an interest in parsers and familiarity with LL, LALR, PEGs, and even
Pratt parsers (fun!), but I am still inexperienced.
...
One thing that has always concerned me about PEGs is that they always
say PEGs are slower than traditional two-phase LALR(1) or LL(k)
parsers. However, I have never seen any benchmarks. Does anyone know
exactly how much performance you lose in an (optimized) PEG compared
to an (optimized) LALR/LL parser + LL/regex lexer?
I decided to ask a question about this:
http://stackoverflow.com/questions/11373644/performance-of-parsers-peg-vs-lalr1-or-llk
Don't hesitate to edit it if you would like to clarify some aspect.
I can tell you that they are not slower then one another in principle.
Quality of implementations trumps every theoretical aspect here. LALR is
usually fast even if implemented by book but they are hard to optimize
futher and quite restrictive on "semantic extensions".
Proper CFG parsers all are liner-time anyway.
D isn't 100% CFG. But it is close.
