And by the way - you should have ALL your rules return a StringTemplate ($st = ) for consistency. I suspect that you are no doing this in your statement rule and that is why your stats parameter is being set to a collection of null, as $s.st is null. Don't use $text at all when referencing the rules, create a template for the return of every rule and cascade them back up the chain.
Jim From: [email protected] [mailto:[email protected]] On Behalf Of Jim Idle Sent: Tuesday, December 01, 2009 9:49 AM To: antlr-interest Subject: Re: [antlr-interest] Help with a tree grammar: losing a list of statements $s is the correct reference, but it is a collection of whatever the statement rule returns, so you may need to use an iterator in your string template. , or it might just be that your statement rule isn't setting up its st properly. stats={$s} then ..., stats) ::= << ... <stats:{<it>}; separator="\n"> Your reference to $text is the text for the whole node, and so you get the while keyword too. So, check your statement rule generates a good st, then use $s=statement and just pass in $s.st to check that just one statement works, then go to s+= and see if that works, then add an iterator in the template and see if that works. Use small incremental changes to see where your problem lies, rather than just stabbing in the dark ;-) Also do not forget that you do not HAVE to use rewrite rules, you can create the template in an action, then repeatedly set the stats attribute in your loop, which will create a collection of StringTemplate. Jim From: [email protected] [mailto:[email protected]] On Behalf Of Pauba, Kevin L Sent: Tuesday, December 01, 2009 8:54 AM To: antlr-interest Subject: Re: [antlr-interest] Help with a tree grammar: losing a list of statements Sorry to respond to my own post but I've made some (limited) progress. I changed the rewriting tree grammar rule from: | ^(KW_while ^(EXPR l=string condition=string r=string) ^(SLIST s+=statement+)) -> template(lhs={$l.text}, operator={$condition.text}, rhs={$r.text}, stats={$s}) << ... >> to: | ^(KW_while ^(EXPR l=string condition=string r=string) ^(SLIST s+=statement+)) -> template(lhs={$l.text}, operator={$condition.text}, rhs={$r.text}, stats={$text}) << ... >> and now get more substituted for <stats> than I expected: L: ; while $99 > 0 test $99 > 0 L_END: while $99 > 0 LET $99 - 1 LET $98 + 1 endwhile goto L: L_END: I don't want the "while $99 > 0" or "endwhile" in there, just the text of the tokens for the statements in SLIST. Reading TDAR a little more, I discovered (again) "Deriving imaginary Nodes from Real Tokens" (pg 175) and modified the parser grammar from: | KW_while l=string condition=string r=string statement+ KW_endwhile -> ^(KW_while ^(EXPR $l $condition $r) ^(SLIST statement+)) to: | KW_while l=string condition=string r=string statement+ KW_endwhile -> ^(KW_while ^(EXPR $l $condition $r) ^(SLIST[$l,"statements"] statement+)) but I get the following error: error(117): JCC.g:0:0: missing attribute access on rule scope: l (that l is a lower case L). I welcome any hints or pointers to TDAR sections for a solution. Thanks! From: [email protected] [mailto:[email protected]] On Behalf Of Pauba, Kevin L Sent: Monday, November 30, 2009 11:31 AM To: antlr-interest Subject: [antlr-interest] Help with a tree grammar: losing a list of statements I have a parser and tree grammar written to add better flow control constructs to an assembly language-like DSL. Here's the parser grammar rule of interest: | KW_while l=string condition=string r=string statement+ KW_endwhile -> ^(KW_while ^(EXPR $l $condition $r) ^(SLIST statement+)) In ANTLRWorks it shows what I expect for an AST using the following text: while $99 > 0 let $99 - 1 let $98 + 1 endwhile The expected AST includes a tree with a root of KW_while and two children (the EXPR and the SLIST (the list of two statement trees). I hope that makes sense. I have a tree-walking grammar that uses "output=template" and "rewrite = true" with the following rule: | ^(KW_while ^(EXPR l=string condition=string r=string) ^(SLIST s+=statement+)) -> template(lhs={$l.text}, operator={$condition.text}, rhs={$r.text}, stats={$s}) << L: ; while <lhs> <operator> <rhs> test <lhs> <operator> <rhs> L_END: <stats> goto L: L_END: >> I'm doing something wrong as the "<stats>" ends up being null and I get the following output: L: ; while $99 > 0 test $99 > 0 L_END: goto L: L_END: What is wrong with my rewrite grammar? -- You received this message because you are subscribed to the Google Groups "il-antlr-interest" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/il-antlr-interest?hl=en.
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