@Override
    public Source visitSource(@NotNull SiddhiQLParser.SourceContext ctx) {

        Source source = new Source();
        source.streamId = (String) visit(ctx.stream_id());
        source.isInnerStream = ctx.inner != null;
        source.isFaultStream = ctx.fault != null;
        if (source.isFaultStream && source.isInnerStream) {
            throw newSiddhiParserException(ctx, "Found '" + ctx.getText() + "', but only inner or fault " +
                    "can be supported at one!");
        }
        activeStreams.add(ctx.getText());

        return source;
    }
{@inheritDoc}
<p>The default implementation returns the result of calling
{@link #visitChildren} on {@code ctx}.</p>

@param ctx
modules/siddhi-query-compiler/src/main/java/io/siddhi/query/compiler/internal/SiddhiQLBaseVisitorImpl.java