(1) Lack of good documentation which makes it hard to and time consuming to learn javacc and make changes to Pig grammar <== ANTLR is very very well documented. http://www.pragprog.com/titles/tpantlr/the-definitive-antlr-reference http://media.pragprog.com/titles/tpantlr/toc.pdf http://www.antlr.org/wiki/display/ANTLR3/ANTLR+3+Wiki+Home
(2) No easy way to customize error handling and error messages <== ANTLR has very extensive error handling support http://media.pragprog.com/titles/tpantlr/errors.pdf (3) Single path that performs both tokenizing and parsing <== What is the advantage of decoupling tokenizer and parsing ? In addition, "Composite Grammar" is very useful for keeping the parser modular. Things that can be treated as sub-languages such as bag schema definition can be done and unit tested separately. ANTLRWorks http://www.antlr.org/works/index.html <http://www.antlr.org/works/index.html>also makes grammar development very efficient. Think about IDE that helps you debug your code (which is grammar). One question, is there any use case for branching and loops? The current Pig is more like a query (declarative) language. I don't really see how loop constructs would fit. I think what Ted mentioned is more embedding Pig in other languages and use those languages to do loops. We should think about how the logical plan layer can be made simpler for external use so don't have to introduce a new layer. Is there any major active development on it? Currently I have more spare time and should be able to help out. (BTW, I'm slow because this is just my hobby. I don't want to drag you guys) Pi Song On Tue, Feb 24, 2009 at 6:23 AM, nitesh bhatia <niteshbhatia...@gmail.com>wrote: > Hi > I got this info from javacc mailing lists. This may prove helpful: > > > ---------------------------------------------------------------------------------------------------------------------------------------------------------------- > -----Original Message----- From: Ken Beesley > [mailto:ken....@xrce.xerox.com] Sent: Wednesday, August 18, 2004 2:56 > PM To: javacc Subject: [JavaCC] Alternatives to JavaCC (was Hello All) > > Vicas wrote: > > Hello All > > Kindly let me know other parsers available which does the same job as > javacc. > > It would be very nice of you if you can send me some documentation > related to this. > > Thanks Vikas > > (Correction and clarifications to the following would be _very_ > welcome. I'm very likely out of date.) > > Of course, no two software tools are likely to do _exactly_ the same > job. Someone already pointed you to ANTLR, which is probably the > best-known alternative to JavaCC. Another possibility is SableCC. > http://sablecc.org > > The criteria include stability, documentation, language of the parser > generated, and abstract-syntax-tree building. > > When I last looked (a couple of years ago) at ANTLR, SableCC and > JavaCC, I chose JavaCC for the following reasons: > > 1. ANTLR could not handle Unicode input. Things change, of course, so > ANTLR might now be more Unicode-friendly. Unicode was important to me, > so this was a big factor in my decision. > > On the plus side for ANTLR, it has better abstract-syntax-tree > building capabilities (in my opinion) than JJTree/JavaCC. You can > learn to use JJTree commands, but it's not easy for most people. > > And ANTLR can generate either a Java or a C++ parser. JavaCC generates > only Java parsers. > > Another concern about ANTLR was that it was reputed to change a lot as > the guru, Terence Parr, experimented with new syntax and > functionality. JavaCC, at least at the time, was reputed to be more > stable, perhaps stable to a fault. I wanted stability and reliability. > > 2. SableCC is much like JavaCC; it generates a Java parser from a > grammar description; but it had, in my opinion, less flexible > abstract-syntax-tree building than JJTree/JavaCC. In SableCC (when I > looked at it), the AST it built was always a direct reflection of your > grammar, generating one tree node for each grammar expansion involved > in a parse, much like using JavaCC with Java Tree Builder (JTB > http://www.cs.purdue.edu/jtb/). When using JavaCC, JTB is the > alternative to using JJTree. > > Using SableCC, or the combination JavaCC/JTB, should be _very_ similar > indeed. > > In my opinion, SableCC and JavaCC/JTB have made a conscious choice to > simplify AST building--you get trees that reflect the expansions in > your grammar. Period. But often these default trees will be big, full > of extraneous nodes that reflect precedence hierarchies in the > recursive-descent parsing. If you want to have more control over AST > building, to get more compact and tailored ASTs, you need to pay the > price of learning JJTree. > > Assuming that you need to build ASTs, with JavaCC you have the choice > between JJTree and JTB. With SableCC, when I last looked at it, you > only get the JTB-like option. > > ******* > > (Again, corrections and expansions would be much appreciated.) > > Ken Beesley > > > > > > --------------------------------------------------------------------------------------------------------------------------------------------------- > > > Of course, no two software tools are likely to do _exactly_ the same > job. Someone already pointed you to ANTLR, which is probably the > best-known alternative to JavaCC. Another possibility is SableCC. > http://sablecc.org > > The criteria include stability, documentation, language of the parser > generated, and abstract-syntax-tree building. > > When I last looked (a couple of years ago) at ANTLR, SableCC and > JavaCC, I chose JavaCC for the following reasons: > > 1. ANTLR could not handle Unicode input. Things change, of course, so > ANTLR might now be more Unicode-friendly. Unicode was important to me, > so this was a big factor in my decision. > > On the plus side for ANTLR, it has better abstract-syntax-tree > building capabilities (in my opinion) than JJTree/JavaCC. You can > learn to use JJTree commands, but it's not easy for most people. > > And ANTLR can generate either a Java or a C++ parser. JavaCC generates > only Java parsers. > > Another concern about ANTLR was that it was reputed to change a lot as > the guru, Terence Parr, experimented with new syntax and > functionality. JavaCC, at least at the time, was reputed to be more > stable, perhaps stable to a fault. I wanted stability and reliability. > > 2. SableCC is much like JavaCC; it generates a Java parser from a > grammar description; but it had, in my opinion, less flexible > abstract-syntax-tree building than JJTree/JavaCC. In SableCC (when I > looked at it), the AST it built was always a direct reflection of your > grammar, generating one tree node for each grammar expansion involved > in a parse, much like using JavaCC with Java Tree Builder (JTB > http://www.cs.purdue.edu/jtb/). When using JavaCC, JTB is the > alternative to using JJTree. > > Using SableCC, or the combination JavaCC/JTB, should be _very_ similar > indeed. > > In my opinion, SableCC and JavaCC/JTB have made a conscious choice to > simplify AST building--you get trees that reflect the expansions in > your grammar. Period. But often these default trees will be big, full > of extraneous nodes that reflect precedence hierarchies in the > recursive-descent parsing. If you want to have more control over AST > building, to get more compact and tailored ASTs, you need to pay the > price of learning JJTree. > > Assuming that you need to build ASTs, with JavaCC you have the choice > between JJTree and JTB. With SableCC, when I last looked at it, you > only get the JTB-like option. > > ---------- > > > > > > On Mon, Feb 23, 2009 at 10:06 PM, Alan Gates <ga...@yahoo-inc.com> wrote: > > We looked into antlr. It appears to be very similar to javacc, with the > > added feature that the java code it generates is humanly readable. That > > isn't why we want to switch off of javacc. Olga listed the 3 things we > want > > out of a parser that javacc isn't giving us (lack of docs, no easy > > customization of error handle, decoupling of scanning and parsing). So > > antlr doesn't look viable. > > > > In response to Pi's suggestion that we could use the logical plan, I hope > we > > could use something close to it. Whatever we choose we want it to be > > flexible enough to represent richer language constructs (like branch and > > loop). I'm not sure our current logical plan can do that. At the same > > time, we don't need another layer of translation (we already have logical > -> > > physical -> mapreduce). I would like to find a representation that could > > handle expressing the syntax and what is currently the logical plan. > > > > Alan. > > > > On Feb 20, 2009, at 5:15 PM, pi song wrote: > > > >> Should be pretty close but we may need to cleanup the interface a bit. > >> Then > >> the new parser module can be switched in easily. > >> BTW, have we already got the solution for the new parser generator? > >> > >> Pi > >> > >> > >> On Fri, Feb 20, 2009 at 9:03 PM, Ted Dunning <ted.dunn...@gmail.com> > >> wrote: > >> > >>> > >>> Probably nearly the same effect as you suggest. Are the concepts at > the > >>> logical plan layer similar to those expressed in pig latin? Or has a > >>> significant transformation occurred by then? > >>> > >>> > >>> On Fri, Feb 20, 2009 at 1:59 AM, pi song <pi.so...@gmail.com> wrote: > >>> > >>>> Sounds good but how about exposing the logical plan layer instead? > >>>> Wouldn't > >>>> that yield the same effect? From python for example you still can > >>>> construct > >>>> a logical plan and give to Pig to execute. > >>>> > >>> > >>> > >>> > >>> -- > >>> Ted Dunning, CTO > >>> DeepDyve > >>> > >>> > > > > > > > > -- > Nitesh Bhatia > Dhirubhai Ambani Institute of Information & Communication Technology > Gandhinagar > Gujarat > > "Life is never perfect. It just depends where you draw the line." > > visit: > http://www.awaaaz.com - connecting through music > http://www.volstreet.com - lets volunteer for better tomorrow > http://www.instibuzz.com - Voice opinions, Transact easily, Have fun >
