Christopher, thanks for your comments. You are right, I should have been more careful in my wording. What I meant to say is that, to my knowledge, there is nothing comparable for Java. I'm sure there are lots of really clever PEG solutions for other languages, especially the ones with language features like operator overloading, closures or scala-like implicits, not to speak of the truly dynamic (Ruby, Groovy, etc.) or functional languages (like Haskell).
However, Java with its rather rigid syntax does seem to make the design of an internal DSL for rule specification a bit hard, which is probably why I found the landscape for PEG support in Java surprisingly barren. Cheers, Mathias --- math...@parboiled.org http://www.parboiled.org On 12.11.2009, at 17:51, Christopher Diggins wrote: > Thanks for sharing the library with the community. It looks like a lot > of work has been put into it, and the documentation is excellent. > > My only quibble, is that I wouldn't call the approach unique. While I > am unaware of what is available in Java there are many similar > libraries in other languages. For example I used a similar technique > in C# in the Heron language > (http://code.google.com/p/heron-language/source/browse/trunk/HeronEngine/HeronGrammar.cs > > ). > The only difference is that I used operator overloading for sequence > and priortized choice operators. > > - Christopher Diggins > > On Thu, Nov 12, 2009 at 11:10 AM, Mathias <math...@parboiled.org> > wrote: >> Hello everyone, >> >> I thought the Java guys among you might be interested in a new, open >> source Java 1.5+ library supporting PEG parsing in a pretty unique >> way. >> http://www.parboiled.org was born out of frustration over existing >> parser generators with their external grammar files that lack IDE >> support and are often just a little bit too hard to integrate in >> real- >> world projects. >> >> parboiled let's you specify your PEG grammar rules right in Java >> source. >> >> Small example: >> Consider the following grammar (a classical calculator example): >> >> Expression ← Term ((‘+’ / ‘-’) Term)* >> Term ← Factor ((‘*’ / ‘/’) Factor)* >> Factor ← Number / ‘(’ Expression ‘)’ >> Number ← [0-9]+ >> >> >> A parboiled parser definition, complete and in ready-to-compile Java >> code would look like this: >> >> >> public class CalculatorParser extends BaseParser<Object, >> Actions<Object>> { >> >> public Rule expression() { >> return sequence( >> term(), >> zeroOrMore( >> sequence( >> firstOf('+', '-'), >> term() >> ) >> ) >> ); >> } >> >> public Rule term() { >> return sequence( >> factor(), >> zeroOrMore( >> sequence( >> firstOf('*', '/'), >> factor() >> ) >> ) >> ); >> } >> >> public Rule factor() { >> return firstOf( >> number(), >> sequence('(', expression(), ')') >> ); >> } >> >> public Rule number() { >> return oneOrMore(charRange('0', '9')); >> } >> } >> >> Your rule definitions can also include direct calls to action methods >> which will behave as expected, they are called at the right time >> during the parsing run. >> parboiled supports AST construction in a very flexible way and has a >> few other, quite neat features (like proper parse error recovery, >> white space gobbling and so on). It currently implements a recursive >> descent parser, but could be extended to support packrat parsing as >> well without too much trouble. >> >> The source and a rather full-blown documentation currently lives at >> github, which you are forwarded to from http://parboiled.org. >> >> Maybe you like the approach and are willing to provide feedback... >> I'd >> be happy to receive any. >> >> Cheers, >> Mathias >> >> --- >> math...@parboiled.org >> http://www.parboiled.org >> >> >> _______________________________________________ >> PEG mailing list >> PEG@lists.csail.mit.edu >> https://lists.csail.mit.edu/mailman/listinfo/peg >> --- math...@parboiled.org http://www.parboiled.org _______________________________________________ PEG mailing list PEG@lists.csail.mit.edu https://lists.csail.mit.edu/mailman/listinfo/peg
