[antlr-interest] "type cannot be resolved or is not a field"

[The Researcher]

Hi Phil,

Try doing it this way from the command line for the first version of the
grammar, but read the explanations in the 5-minute introduction.

Create these four files and run the highlighted commands. I showed you a
full run show you could see what to expect.

Also, notice that CLASSPAH only references antlr-3.4-complete.jar

SimpleCalc.g

grammar SimpleCalc;

tokens {
      PLUS = '+' ;
      MINUS = '-' ;
      MULT  = '*' ;
      DIV   = '/' ;
}

/*------------------------------------------------------------------
* PARSER RULES
*------------------------------------------------------------------*/
expr  : term ( ( PLUS | MINUS ) term )* ;
term  : factor ( ( MULT | DIV ) factor )* ;
factor      : NUMBER ;

/*------------------------------------------------------------------
* LEXER RULES
*------------------------------------------------------------------*/
NUMBER      : (DIGIT)+ ;
WHITESPACE : ( '\t' | ' ' | '\r' | '\n'| '\u000C' )+ { $channel = HIDDEN; }
;
fragment DIGIT    : '0'..'9' ;



Main.java

import org.antlr.runtime.*;

public class Main
{
public static void main(String[] args) throws Exception {
SimpleCalcLexer lex = new SimpleCalcLexer(new ANTLRFileStream(args[0]));
      CommonTokenStream tokens = new CommonTokenStream(lex);
SimpleCalcParser parser = new SimpleCalcParser(tokens);
try {
parser.expr();
} catch (RecognitionException e) {
e.printStackTrace();
}
}
}


bad.dat

6/2+(3*4)-1


good.dat

6/2+3*4-1


student at antlr:~/projects/antlr/mail/mail002$ echo $CLASSPATH

/home/student/antlr-3.4-complete.jar:

student at antlr:~/projects/antlr/mail/mail002$ ls -l

total 16

-rw-r--r-- 1 student student 12 Sep 12 18:40 bad.dat

-rw-r--r-- 1 student student 10 Sep 12 18:40 good.dat

-rw-r--r-- 1 student student 460 Sep 12 18:38 Main.java

-rw-r--r-- 1 student student 640 Sep 12 18:47 SimpleCalc.g

student at antlr:~/projects/antlr/mail/mail002$ java org.antlr.Tool
SimpleCalc.g

student at antlr:~/projects/antlr/mail/mail002$ ls -l

total 40

-rw-r--r-- 1 student student 12 Sep 12 18:40 bad.dat

-rw-r--r-- 1 student student 10 Sep 12 18:40 good.dat

-rw-r--r-- 1 student student 460 Sep 12 18:38 Main.java

-rw-r--r-- 1 student student 640 Sep 12 18:47 SimpleCalc.g

-rw-r--r-- 1 student student 8962 Sep 12 18:48 SimpleCalcLexer.java

-rw-r--r-- 1 student student 5852 Sep 12 18:48 SimpleCalcParser.java

-rw-r--r-- 1 student student 83 Sep 12 18:48 SimpleCalc.tokens

student at antlr:~/projects/antlr/mail/mail002$ javac *.java

student at antlr:~/projects/antlr/mail/mail002$ ls -l

total 52

-rw-r--r-- 1 student student 12 Sep 12 18:40 bad.dat

-rw-r--r-- 1 student student 10 Sep 12 18:40 good.dat

-rw-r--r-- 1 student student 857 Sep 12 18:49 Main.class

-rw-r--r-- 1 student student 460 Sep 12 18:38 Main.java

-rw-r--r-- 1 student student 640 Sep 12 18:47 SimpleCalc.g

-rw-r--r-- 1 student student 3905 Sep 12 18:49 SimpleCalcLexer.class

-rw-r--r-- 1 student student 8962 Sep 12 18:48 SimpleCalcLexer.java

-rw-r--r-- 1 student student 3609 Sep 12 18:49 SimpleCalcParser.class

-rw-r--r-- 1 student student 5852 Sep 12 18:48 SimpleCalcParser.java

-rw-r--r-- 1 student student 83 Sep 12 18:48 SimpleCalc.tokens

student at antlr:~/projects/antlr/mail/mail002$ java Main bad.dat

bad.dat line 1:4 no viable alternative at character '('

bad.dat line 1:8 no viable alternative at character ')'

student at antlr:~/projects/antlr/mail/mail002$ java Main good.dat

student at antlr:~/projects/antlr/mail/mail002$


Notice that using good.dat is valid data so no errors will be presented.


Hope that helps,


Eric



On Mon, Sep 12, 2011 at 6:28 PM, phil jones <interstar at gmail.com> wrote:
>
> Hi everyone,
>
> I don't know if this is a support list, so forgive me if I shouldn't
> be asking this here. (If not here, where?)
>
> I just downloaded and am trying to learn Antlr, starting with the
> calculator example in the five minute guide. I've generated the Java
> lexer / parser, but when I try to compile these I'm getting the error
> :
>
> "type cannot be resolved or is not a field"
>
> The error occurs in the line " this.type = _type;"
>
> in a generated block :
>
>    // $ANTLR start PLUS
>    public final void mPLUS() throws RecognitionException {
>        try {
>            int _type = PLUS;
>            // SimpleCalc.g:3:6: ( '+' )
>            // SimpleCalc.g:3:8: '+'
>            {
>            match('+');
>
>            }
>
>            this.type = _type;
>        }
>        finally {
>        }
>    }
>    // $ANTLR end PLUS
>
> That's in the class SimpleCalcLexer which extends Lexer. So can it be
> that Lexer doesn't have a "type" attribute? Should it have one?
>
> I generated the lexer code from the command line, but am now trying to
> compile it in Processing. (I put the antlr3.3 jar in the Processing
> libraries directory.)
>
> cheers
>
> phil jones
>
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