[antlr-interest] New article on StringTemplates and Treewalkers

[shmuel siegel]

Terence Parr wrote:
> Hi.  My impression from reading his article was that Andy was  
> interpreting tree walker to be the simple visitor pattern where all  you 
> can see is "I'm at node function definition" as opposed to the  more 
> powerful grammar-based tree pattern matching:
> 
> funcdef
>     : ^(FUNCDEF ID args body)
>     ;
> 
> Specifically he asked where one would worry about whether or not a  
> return statement was present in the body.  Seems straightforward to  
> have an action after the body rule reference that checked a boolean  set 
> by body.  You might do this (using the new dynamic scope stuff):
> 
> funcdef
> scope {
>   boolean hasReturn;
> }
> @init {
>   hasReturn = false;
> }
>     : ^(FUNCDEF ID args body) {if ($hasReturn) ...}
>     ;
> 
> body : stat+ ;
> 
> stat : ... | ^(RETURN expr) {$funcdef::hasReturn=true;} | ... ;
> 
> Andy, is this easier or harder than you imagined?  Does it address  your 
> point?
> 
> Ter
> 
> 
I think that Andy was more bothered by how to translate something like

int func(int x)
{
     if(x=5)
	return 3;
}

since even though it looks like java, it is not valid java.

Shmuel


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