[antlr-interest] ANTLR 3.0 status: got nongreedy loops going

[Terence Parr]

Howdy,

Spent 3 days thinking this week and one hour coding to get nongreedy 
loops going properly.  ANTLR lexers are much easier to specify now.  
For example, here is a sample grammar I'm working with:

lexer grammar L;

IF : "if" ;
ID : ('a'..'z')+ ;
WS : (' '|'\n')+ ;
CMT : "/*" ( greedy=false : . )* "*/" ;

It properly deals with IF vs ID and it handles the CMT rule properly.  
It stops when reading when it sees "*/".  Here is the test example:

java TestLexer "bbd if /* * / ** foo */ abc"

[bbd/65538,0:0]
[ /65539,0:0]
[if/65536,0:0]
[ /65539,0:0]
[/* * / ** foo *//65540,0:0]
[ /65539,0:0]
[abc/65538,0:0]

TestLexer is just a loop that prints out Token objects.

         IntegerStream charStream = new ANTLRStringStream(args[0]);
         L lexer = new L(charStream);
         Token t = lexer.nextToken();
         while ( t.getType()!= IntegerStream.EOF ) {
                 System.out.println(t.toString());
                 t = lexer.nextToken();
         }

I feel confident that soon I'll be able to handle the Java grammar. :)

BTW, org.antlr.runtime.* is only 370 lines of code so far. :)

runtime/ANTLRStringStream.java
runtime/CommonToken.java
runtime/CommonTokenStream.java
runtime/DFA.java
runtime/IntegerStream.java
runtime/Lexer.java
runtime/Parser.java
runtime/Token.java
runtime/TokenSource.java
runtime/TokenStream.java

L8R,
Ter
--
CS Professor & Grad Director, University of San Francisco
Creator, ANTLR Parser Generator, http://www.antlr.org
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