Hi,
I have a simple grammar - which includes a '+' or '-' operation on a
variable (ID) or constant (INT).
The "add" rule is obviously: "mult" (+/- "mult").
However, the way I need the "add" rule defined throws the
MismatchedTokenException:
----------------------------------------------------------------------------
add : mult
(
('+' mult)
|
('-' mult)
)*
;
while this way to define "add" rule works just fine:
----------------------------------------------------------------------------
add : mult ( ( '+' | '-' ) mult)* ;
Can you please give some insights white Antlr 3.0 does not like the first
way to define "add" rule?
The reason I need it this way is to use tree rewrites.
I tried using syntactic predicates but they error out. I have consulted
Anltr reference book as well - however nothing obvious jumped at me.
Full grammar below.
Thanks a lot for your help!
grammar Dummy;
expr : add ';' ;
add : mult
(
('+' mult)
|
('-' mult)
)*
;
//add : mult ( ( '+' | '-' ) mult)* ;
mult : constant
| variable
| '(' expr ')'
;
variable : ID;
constant : INT;
ID : ('a'..'z'|'A'..'Z') ('a'..'z'|'A'..'Z'|'0'..'9'|'_')* ;
INT : '0'..'9'+;
WS : ( ' ' | '\t' | '\r' | '\n' ) { $channel=HIDDEN; } ;
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