Reporting progress of parser

Question

I have a large file that I am trying to parse with Antlr in Java, and I would like to show the progress.

It looked like could do the following:

CommonTokenStream tokens = new CommonTokenStream(lexer);
int maxTokenIndex = tokens.size();

and then use maxTokenIndex in a ParseTreeListener as such:

public void exitMyRule(MyRuleContext context) {
    int tokenIndex = context.start.getTokenIndex();
    myReportProgress(tokenIndex, maxTokenIndex);
}

The second half of that appears to work. I get ever increasing values for tokenIndex. However, tokens.size() is returning 0. This makes it impossible to gauge how much progress I have made.

Is there a good way to get an estimate of how far along I am?

Answer 1

The following appears to work.

File file = getFile();
ANTLRInputStream input = new ANTLRInputStream(new FileReader(file));
ProgressMonitor progress = new ProgressMonitor(null,
                                               "Loading " + file.getName(),
                                               null,
                                               0,
                                               input.size());

Then extend MyGrammarBaseListener with

@Override 
public void exitMyRule(MyRuleContext context) {
    progress.setProgress(context.stop.getStopIndex());
}