[antlr-interest] Fw: a newbie question

[william yuan]

i am right here waitting for an answer ,thanks

----- Original Message ----- 
From: "william yuan" <ordinarybackstreetmoldywilliam at gmail.com>
To: <antlr-interest at antlr.org>
Sent: Wednesday, March 25, 2009 11:23 PM
Subject: a newbie question


> Hi ALL,
> I have met another problem when i am tring to understand the antlr tree. 
> here is my example
> Cozily.g
>
> grammar Cozily;
> options {
>    output=AST;
>    ASTLabelType=CommonTree; // type of $stat.tree ref etc...
> }
>
> expr:    INT '+'^ INT
> | INT '-'^ INT
> |  INT '*'^ INT
> |   INT '%'^ INT
>    ;
> INT :   '0'..'9'+ ;
> WS  :   (' '|'\t'|'\n'|'\r')+ {skip();} ;
> // END:tokens
>
> and the tree here CozilyTree.g
>
> tree grammar CozilyTree;
>
> options {
>    tokenVocab=Expr;
>    ASTLabelType=CommonTree;
> }
> prog:   expr{System.out.println($expr.value);} ;
>
> expr returns [int value]
>    :   ^('+' a=INT b=INT) {$value = 
> Integer.parseInt($a.text)+Integer.parseInt($a.text);}
>    |   ^('-' a=INT b=INT) {$value = 
> Integer.parseInt($a.text)-Integer.parseInt($a.text);;}
>    |   ^('*' a=INT b=INT) {$value = 
> Integer.parseInt($a.text)*Integer.parseInt($a.text);;}
>    | ^('%' a=INT b=INT) {$value = 
> Integer.parseInt($a.text)/Integer.parseInt($a.text);;}
>    ;
>
> // END:expr
>
> I wanna make a calculator, only to get evaluate the expressions like '1+1' 
> or '2*3' and of this sort,
> but output is here
> .....\CozilyTree.g: node from line 1:1 no viable alternative at input '+' 
> when i inputted 1+1
>
> so what is the root cause ?
>
> Thanks  in adv .
>
> Best Regards,
> Bill Yuan
>