@Override
	public String getText(Interval interval) {
		int start = interval.a;
		int stop = interval.b;
		if ( stop >= n ) stop = n-1;
		int count = stop - start + 1;
		if ( start >= n ) return "";
//		System.err.println("data: "+Arrays.toString(data)+", n="+n+
//						   ", start="+start+
//						   ", stop="+stop);
		return new String(data, start, count);
	}
consume() ahead until p==index; can't just set p=index as we must
 update line and charPositionInLine. If we seek backwards, just set p
runtime/Java/src/org/antlr/v4/runtime/ANTLRInputStream.java