How to convert LR(1) to LL(k) ?

Hi


I am a new user of PCCTS and am trying to write a translator with it.
However I found the following productions which goes well with
yacc/bison have generated ambiguities with the PCCTS:


/* the dangling else problem */
stmt : matched_stmt
| unmatched_stmt
;


matched_stmt: IF EXPR THEN matched_stmt ELSE matched_stmt
| OTHER_STMT
;


unmatched_stmt: IF EXPR THEN stmt
| IF EXPR THEN matched_stmt ELSE unmatched_stmt
;


ANTLR gives me the following Warring message


for stmt : Warning warning: alts 1 and 2 of the rule itself ambiguous
upon {IF }, { EXPR }, { THEN }, { IF OTHER_STMT }
for unmatched_stmt : Warning warning: alts 1 and 2 of the rule itself
ambiguous upon {IF }, { EXPR }, { THEN }, { IF OTHER_STMT }


How can I change the grammer and/or add predicate to avoid the warning
message!?


Is there any guideline that can be used to change the LR(1) grammar to
LL(k)?


Many thanks


Patrick Lee
--

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