[antlr-interest] Duplicate nodes on a parse tree?
Terence Parr
parrt at cs.usfca.edu
Wed Mar 14 12:53:11 PDT 2007
THat is a result of backtracking. If parser.backtracking>0 don't add
a node.
Default is to show during debugging.
Ter
On Feb 28, 2007, at 2:51 PM, Vadim Tropashko 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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