Re: Get line numbers with Antlr parser

On 2006-05-16, Ulrich Hobelmann <u.hobelmann@web.de> wrote:
> Hi, I'm using the Java1.5 parser + tree parser by Mike Studman.
>
> My problem: I need to extract the line numbers from the parser.
You will have to build an AST class to be used by antlr for that,
replacing the standard one
>
> Funny thing: in one part of the parser it works, but in the tree parser
> it doesn't. In java15.g I added some printlns to print getLine() of
> some nodes, and they printed the lines. The very same nodes are also
> put into a tree structure to read by the java-tree parser (obviously).
This is not surprising: theline and colum information is not stored in
the tree being built
>
> What can / do I have to do, to get the line numbers to the high level,
> where I need it?
You can define for instance something like the following


public class MyAST extends CommonAST {
    private int col = 0,line = 0;
    public void initialize(Token tok) {
        super.initialize(tok);
        line = tok.getLine();
        col = tok.getColumn();
    }
    public void initialize (AST ast) {
        super.initialize(ast);
        if (ast instanceof MyAST){
            col = ((MyAST)ast).getColumn();
            line = ((MyAST)ast).getLine();
        }
    }
    public int getLine() { return line; }
    public int getColumn() { return col; }
}


and use it with
parser.setASTNodeClass("MyAST");


That way, antlr will build the tree using MyAST nodes, which store the
line and column information


Have fun,
antoine

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