[antlr-interest] Lexer question

[Dominik Holenstein]

Tomy,
I have played around with your Lexer and Parser code and have found
this solution:


-------------------------------------------------------
ANTLR Grammar (file n.g):

class NumParser extends Parser;

startRule : (line)* ;

line 	  : (
         	  d:DOUBLE
         	  {System.out.println("Double: "+d.getText());}
         	  |
                   i:INTEGER
                  {System.out.println("Integer: "+i.getText());}	
                   )
                   ;


class NumLexer extends Lexer;

DOUBLE          : (('-')? ('0'..'9')+ '.' ('0'..'9')* )=> ('-')?
('0'..'9')+ '.' ('0'..'9')* | ('0'..'9')+ {$setType(INTEGER);} ;

INTEGER         : ('0'..'9')+ ;

SEMICOLON    : ';' { $setType(Token.SKIP); } ;

NEWLINE	       : (('\r''\n')=> '\r''\n'         		
	       | '\r'
       	       | '\n'
       	       ) { $setType(Token.SKIP); }
      			;
WS                  : (' '|'\t') { $setType(Token.SKIP); } ;

---------------------------------------------------

The Java test code (Main.java):

import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;

public class Main {
	public static void main (String[] args) {
		try {
			// Make sure you change the path for your input file
			DataInputStream input = new DataInputStream(new
FileInputStream("E:\\ANTLR\\Examples\\Numbers\\input.txt"));
			NumLexer lexer = new NumLexer(input);
	    	NumParser parser = new NumParser(lexer);
	    	try {
	    		parser.startRule();
	    	} catch(Exception e) {}
        } catch (FileNotFoundException e) {
        	System.out.println("Error: Cannot open file for reading");
        }
	}
}

--------------------------------------------------------------
Data in the input file (input.txt):
10;
1500;
0.50;
35;
7.25;
3000;

---------------------------------------------------------------

I have added all files as attachments to this e-mail.

You can set k=1 because of the semantic predicate what makes the
parser a bit faster.
The System.out... messages are for testing purposes. I can see then in
the console the output of the parser. I am working with Eclipse 3.2
and ANTLR Studio. I am not sure whether this is 'good' programming
style but it works ;-) . Inputs, feedbacks and better solutions are
welcomed.

I hope it helps!

Regards,
Dominik





On 7/27/06, dotnet fr <dotnetfr at gmail.com> wrote:
> Hi Dominik,
>
> I'm happy to meet a person like me!
> I'm a beginner with antlr and codeworker too ;)
> I'm each minute I'm learning new key. Antlr seems very powerful yeah.
> My project is to create first a class generator, structure generator
> and in final a structure (or class loader). It means I use parsing and
> generation code.
> What do you do with antlr, what is your interest in informatics ?
>
> Cheers
> Tomy
>
> 2006/7/27, Dominik Holenstein <dholenstein at gmail.com>:
> > Hi Tomy,
> > I don't know codeworker but will have a look at it.
> > ANTLR is very powerful and with v3 coming in fall it will get much better.
> > I am a beginner with Java and ANTLR so everything is 'difficult' at
> > the moment. But I am progressing and learning every day!
> > I will look at your issue this afternoon.
> >
> > Regards,
> > Dominik
> >
> >
> >
> > On 7/27/06, dotnet fr <dotnetfr at gmail.com> wrote:
> > > Hi Dominik,
> > >
> > > I have seen in the Predicated LL(k) Lexing in the ANTLR documentation
> > > witch treats about this kind of problem. It works but it's not the
> > > best solution I think ;)
> > > I thought that the antlr lexer try the first token and if it doesn't
> > > match, it go to
> > > the second etc..
> > >
> > > My parser grammar :
> > >
> > > startRule
> > >        :
> > >                nbp_debug
> > >        ;
> > >
> > > protected
> > > debug    :
> > >        (
> > >                DATE
> > >        |       DOUBLE
> > >        |       INTEGER
> > >        |       SEMICOLON
> > >        )*
> > >        ;
> > >
> > > What do you think about Antlr ? I have to do the same project with
> > > codeworker and antlr. Antlr seems more difficult to manipulate.
> > >
> > > Cheers,
> > >
> > > Tomy
> > >
> > > 2006/7/27, Dominik Holenstein <dholenstein at gmail.com>:
> > > > Tomy,
> > > >
> > > > What is you grammar in the parser?
> > > > Thanks.
> > > >
> > > > Dominik
> > > >
> > > >
> > > > On 7/27/06, dotnet fr <dotnetfr at gmail.com> wrote:
> > > > > Hi Everyone,
> > > > >
> > > > > I have a problem about the antlr lexer.
> > > > >
> > > > > In input I have :
> > > > > 10;
> > > > > 1500;
> > > > > 0.50;
> > > > >
> > > > > In my lexer I have :
> > > > > DOUBLE          : ('-')? ('0'..'9')+ '.' ('0'..'9')* ;
> > > > > INTEGER         : ('0'..'9')+ ;
> > > > > SEMICOLON       : ';' ;
> > > > >
> > > > > In my parser and lexer I have k=5.
> > > > >
> > > > > But I've got an error, the lexer seems to get his TOKENS in the order.
> > > > > It gets the 10 like a double (the first in the list) and send an
> > > > > exception
> > > > > (exception: expecting ''.'', found '';'')
> > > > >
> > > > > I want the lexer to skip and try the next TOKEN and send an exception
> > > > > only if there isn't any solutions.
> > > > >
> > > > > Is anyone got this problem too ?
> > > > >
> > > > > Cheers,
> > > > >
> > > > > Tomy
> > > > >
> > > >
> > >
> > >
> > > --
> > > dotnet
> > >
> >
>
>
> --
> dotnet
>
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import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;

public class Main {
	public static void main (String[] args) {
		try {
			// Make sure you change the path of the file 
			DataInputStream input = new DataInputStream(new FileInputStream("E:\\ANTLR\\Examples\\Numbers\\input.txt"));
			NumLexer lexer = new NumLexer(input);
	    		NumParser parser = new NumParser(lexer);
	    		try {
	    			parser.startRule();
	    		} catch(Exception e) {}
        		} catch (FileNotFoundException e) {
        			System.out.println("Error: Cannot open file for reading");
        		  }
             } // publix static...
} // public class Main...
-------------- next part --------------
10;
1500;
0.50;
35;
7.25;
3000;