cached = result; cachedDocs = ds;
	public Sequence eval(		Sequence contextSequence,		Item contextItem) {		DocumentSet ds = context.getStaticallyKnownDocuments();		if(ds == null || ds.getLength() == 0)			return Sequence.EMPTY_SEQUENCE;		//NodeSet result = new ExtArrayNodeSet(ds.getLength(), 1);		NodeSet result = new ArraySet(ds.getLength());		for (Iterator i = ds.iterator(); i.hasNext();) {			result.add(new NodeProxy((DocumentImpl) i.next(), -1));		}		return result;	}