[antlr-interest] Duplicate nodes on a parse tree?

[Vadim Tropashko]

Here is another way to approach the problem. When
running the antlrworks interpreter, the parse tree
don't have any duplicates. How does the interpreter
constructs the tree? 


--- Vadim Tropashko <vadimtro at yahoo.com> wrote:

> I'm leveraging debugger parse tree generation as
> described in
>
http://www.antlr.org/wiki/pages/viewpage.action?pageId=1760
> 
> Everything works as advertised, although I'm getting
> duplicate nodes. For example given the rule:
> 
> boolean_primary options { backtrack=true; }
> :         sim_expr
> |
>  member_predicate
> |                          comparison_predicate
> ;
> 
> I'm getting the tree branch like this
> 
> boolean_primary
>     sim_expr
>         ....
>     sim_expr
>         ....
> 
> Is the duplicate "sim_expr" branch occurrence due to
> backtracking?  Then what would be the right way to
> filter out those ghost nodes? 
> 
> 
>  
>
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