[antlr-interest] if-then-else rule design question
Gavin Lambert
antlr at mirality.co.nz
Mon Jun 16 05:35:05 PDT 2008
At 21:07 16/06/2008, Fridi wrote:
>How can I create a tree parser that conditionally runs into
>specific leaves of the tree only? I have studied the great
>ANTLR book, but I did not find a similar example right now.
I haven't actually used this myself, but from what I remember of a
discussion a while back, something like this ought to work:
ifelse
: ^(IFELSE condition
( { $condition.value }? => statement . { do($statement); }
| . statement { do($statement); }
)
)
;
(You can adapt the idea for other tree structures. The main point
is the use of '.' to indicate "don't care".)
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