[antlr-interest] invoke subtemplates on multivalue attribute

[Michael]

Am Thursday 30 April 2009 11:25:28 schrieb Florian Barth:
> I try to map the conditional statement to StringTemplate with the  
> following rule:
> cond    :       ^(IF
>                         ^(CONDITION conds+=condExpression)
>                         ^(THEN thens+=expression)
>                         ^(ELSEIF
>                                 ^(conds+=CONDITION condExpression)
>                                 ^(thens+=THEN expression)
>                         )*
>                         ^(ELSE else=expression)?
>                 )
>                 ->      
> conditional(conditions={$conds.st},thens={$thens.st},else={$else.st})
>                 ;
>
> The second problem is the application of the StringTemplates in the  
> Rewrite rule. The forwarding to the expression StringTemplate works  
> perfect. However applying the conds.st and thens.st to the multi-
> valued attributes leads to compiler errors as the templates do not  
> accept a multi-valued attribute and so does not descend into the rules  
> responsible for rendering the expressions.

I think antlr is smart in generating multivalue nodes, you can in the parser 
say something like:

if: IF c=cond THEN b=block (ELSEIF c+=cond THEN b+=block)* else? -> ^IF(cond+, 
block*, else) 

to generate a tree which allready has the conds and elseif nodes collected.
Your tree is then like:
^(IF cond+ block+ else?)

 Michael