Hi, Vincent. Vincent Massol wrote: >> I would like to discuss about the new xwiki query language. >> http://dev.xwiki.org/xwiki/bin/view/Design/XWikiQueryLanguage >> >> We need to choose a syntax and data model of the query language >> >> There are some examples in >> http://dev.xwiki.org/xwiki/bin/view/Design/XWiki+Query+Language+Specification >> >> I already have a prototype based on my JPQL parser (SableCC based > > Is that a good parser generator? I know JavaCC and Antlr but have > never used SableCC. I'm just worried about us having different parser > generators so if we choose one we should try to continue using it > across our modules as much as possible. Right now my preference would > go to javacc or antlr since they're more well known. Ideally antlr is > by far the most powerful but I think it may also be the most complex > to use unfortunately.
I'd say it perfect for tasks like this (language preprocessors). Look at http://svn.xwiki.org/svnroot/xwiki/sandbox/xwiki-query/jpql-parser/src/main/sablecc/JPQL.grammar It contain no code, only EBNF with name labels. And it generates a good AST and visitors for hook and rewrite some interesting places with save all remain input. This is hard to do in other parser generators. It also have CST to AST feature for generate some custom AST, like other parsers do. According to use different parsers, SableCC and xwql has no affect on other modules. SableCC has no runtime dependency (in contrast of antlr). So I think it is ok for use SableCC for xwql. I agree that antlr is most powerful. But it requires much more hand work. (create and generate AST) PS: Also, SableCC is LALR(k) parser, means it is more powerful in grammar sense than LL(k) without lookahead. >> example: >> "select doc.fullName >> from Document as doc, doc.XWiki.XWikiUsers as user >> where user.email like '%xwiki.com' and doc.author=:username" >> >> "select doc.fullName from Document as doc" may be omitted. It will be >> added if there is no Document in query statement. So "from >> doc.XWiki.XWikiUsers as user" is correct query statement. > > I don't like the mix of semantics between doc.fullName for example > (which represents a property of a document - a field in the DB) and > doc.XWiki.XWikiUsers which represents an object of a document. I don't > think they should be at the same level and the usage of "." in the > object name is confusing (and may also confuse the parser). > > I'd prefer something like: doc.objects(XWiki.XWikiUsers) or > doc.objects("XWiki.XWikiUsers"). > > Then we can add: doc.attachment(attachmentName) and doc.class later on. > > WDYT? "doc.XWiki.Class as obj" has the same sense as "object.list as listitem" in JPQL. 'XWiki.Class' is a part of document. It is not a single field, but a virtual collection. But I agree, there is conflict possible with objects and other parts of document (attachments, class) so we need some prefix. And you variant is quite good. It eliminates the problems with special chars in document names. so +1 to doc.objects(XWiki.Class). "" is not needed IMO. Parser can take care of special chars in this case too, i think. WDOT? PS: another variant: from Document as doc, doc.objects as obj where obj.class='XWiki.Class' more universal, but less readable and hierarchical. >> ... -- Artem Melentyev _______________________________________________ devs mailing list [email protected] http://lists.xwiki.org/mailman/listinfo/devs
