GraalVM/Polyglot: how to get SourceLocation programmatically

Question

Is there a way to get the current source location (SourceSection) from java?

e.g. a js script executed via context.eval() calls a java method, the java method logs the current js script name+line

PolyglotException has a getSourceLocation() that provide this information. also stack traces from polyglot seems to contains information about the source location e.g. at :program(Unnamed:2:23-53)

Answer 1

I know you asked this a long time ago, but I have just seen it for the first time.

Here is a way to get to the current location easily:

static StackFrame getCurrentLocation() {
    PolyglotException e = Context.getCurrent().asValue(new RuntimeException()).as(PolyglotException.class);
    for (StackFrame frame: e.getPolyglotStackTrace()) {
        if (frame.isGuestFrame()) {
            return frame;
        }
    }
    return null;
}

Here is a full runnable example:

public class Test {

    public static void main(String[] args) {
        try (Context context = Context.newBuilder().allowHostAccess(HostAccess.ALL).build()) {
            context.getBindings("js").putMember("test", new Test());
            
            Source source = Source.newBuilder("js", "test.callback()", "mysource.js").buildLiteral();
            context.eval(source);
        }
    }
    
    public void callback() {
        System.out.println(getCurrentLocation());
    }
    
    
    static StackFrame getCurrentLocation() {
        PolyglotException e = Context.getCurrent().asValue(new RuntimeException()).as(PolyglotException.class);
        for (StackFrame frame: e.getPolyglotStackTrace()) {
            if (frame.isGuestFrame()) {
                return frame;
            }
        }
        return null;
    }
}

This prints:

<js> :program(mysource.js:1:0-14)