[antlr-interest] HI, i have a simple problem

[Cesar Arrieta]

Hi..here a post my MyCalc.g3 file..it is working fine..my problem is that i
dont know how to make my program tell if an error ocurrs..for example i want
that parser.expr() throw an exception or return a boolean telling if the
parse went fine or not?? no just sending messages to the console.
I hope you could help me, Thanks.
well this is the file MyCalc.g3:
and valids inputs are 8*b1*9+5*B2
and wrong inputs are 8*v*b1+da*b1b

grammar MiCalc;

tokens {

PLUS = '+' ;

MINUS = '-' ;

MULT = '*' ;

DIV = '/' ;

PUNTO = '.';

}

@header {

package lib;

import Jama.Matrix;

}

@lexer::header {

package lib;

}



@members {

public static void main(String[] args) throws Exception {

//This is a file for the input

//valid input 8 * b1

//wrong input 8dsa*b1b

String texto="texto";

MiCalcLexer lex = new MiCalcLexer(new ANTLRFileStream(texto));

CommonTokenStream tokens = new CommonTokenStream(lex);

MiCalcParser parser = new MiCalcParser(tokens);

parser.expr();



}

}

/*------------------------------------------------------------------

* PARSER RULES

*------------------------------------------------------------------*/



expr : term ( ( PLUS | MINUS ) term )* ;



term : factorN (((MULT | DIV) factorN) | ((MULT | DIV) factorBi) )*

| factorBi (((MULT) factorBi) | ((MULT | DIV) factorN))*;

factorN : (NUMBER | FLOAT);

factorBi: BINDEX NUMBER;



/*------------------------------------------------------------------

* LEXER RULES

*------------------------------------------------------------------*/

NUMBER : (DIGIT)+ ;

FLOAT : (NUMBER (PUNTO) NUMBER)+;

/*

WHITESPACE : ( '\t' | ' ' | '\r' | '\n'| '\u000C' )+ { $channel = HIDDEN; }
;

*/

fragment DIGIT : '0'..'9' ;

BINDEX : ('b' | 'B');
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