[antlr-interest] Change node content in AST tree generated with ANTLRWorks

[Bart Kiers]

Note that it doesn't matter if you use ANTLRWorks or the org.antlr.Tool on
the command line to generate the lexer/parser: they do the same thing.

   1. Did you define your custom tree in the options section of your
   grammar?
   2. Did you "attach" a custom TreeAdaptor to your parser?

Here's a little demo that demonstrates the 2 points I mentioned above:

grammar T;

options {
  output=AST;
  ASTLabelType=MyTree;
}

@parser::members {

  static class MyTree extends CommonTree {

    public MyTree(Token t) {
      super(t);
    }

    @Override
    public String toString() {
      return "MyTree=" + super.toString();
    }
  }

  public static void main(String[] args) throws Exception {
    String source = "abc";
    TLexer lexer = new TLexer(new ANTLRStringStream(source));
    TParser parser = new TParser(new CommonTokenStream(lexer));
    parser.setTreeAdaptor(new CommonTreeAdaptor(){
      @Override
      public Object create(Token t) {
        return new MyTree(t);
      }
    });
    parser.parse();
  }
}

parse
  :  (ANY {System.out.println($ANY.tree);})+ EOF
  ;

ANY
  :  .
  ;


which, after generating the lexer/parser, compiling all .java files and
running the class with the main method:

$ java -cp antlr-3.2.jar org.antlr.Tool T.g
$ javac -cp antlr-3.2.jar *.java
$ java -cp .:antlr-3.2.jar TParser


 produces:

MyTree=a
MyTree=b
MyTree=c


Regards,

Bart.



On Sun, May 1, 2011 at 2:47 AM, Fernando Sanchez <fernando at rti.com> wrote:

> Hi,
>
> Is there a way to customize the text associated with the nodes of the AST
> tree generated with ANTLRWorks?. I tried to overwrite the toString method in
> my Tree node (inherit from CommonTree) without success.
>
> Regards,
>    Fernando
>
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