DTMNodeIterator gives us an implementation of the
* DTMNodeIterator which returns DOM nodes.
*
* Please note that this is not necessarily equivlaent to a DOM
* NodeIterator operating over the same document. In particular:
* State: In progress!!
* */ public class DTMNodeIterator implements org.w3c.dom.traversal.NodeIterator { private DTMIterator dtm_iter; private boolean valid=true; //================================================================ // Methods unique to this class /** Public constructor: Wrap a DTMNodeIterator around an existing * and preconfigured DTMIterator * */ public DTMNodeIterator(DTMIterator dtmIterator) { try { dtm_iter=(DTMIterator)dtmIterator.clone(); } catch(CloneNotSupportedException cnse) { throw new org.apache.xml.utils.WrappedRuntimeException(cnse); } } /** Access the wrapped DTMIterator. I'm not sure whether anyone will * need this or not, but let's write it and think about it. * */ public DTMIterator getDTMIterator() { return dtm_iter; } //================================================================ // org.w3c.dom.traversal.NodeFilter API follows /** Detaches the NodeIterator from the set which it iterated over, * releasing any computational resources and placing the iterator in * the INVALID state. * */ public void detach() { // Theoretically, we could release dtm_iter at this point. But // some of the operations may still want to consult it even though // navigation is now invalid. valid=false; } /** The value of this flag determines whether the children * of entity reference nodes are visible to the iterator. * * @return false, always (the DTM model flattens entity references) * */ public boolean getExpandEntityReferences() { return false; } /** Return a handle to the filter used to screen nodes. * * This is ill-defined in Xalan's usage of Nodeiterator, where we have * built stateful XPath-based filtering directly into the traversal * object. We could return something which supports the NodeFilter interface * and allows querying whether a given node would be permitted if it appeared * as our next node, but in the current implementation that would be very * complex -- and just isn't all that useful. * * @throws DOMException -- NOT_SUPPORTED_ERROR because I can't think * of anything more useful to do in this case * */ public NodeFilter getFilter() { throw new DTMDOMException(DOMException.NOT_SUPPORTED_ERR); } /** @return The root node of the NodeIterator, as specified * when it was created. * */ public Node getRoot() { int handle=dtm_iter.getRoot(); return dtm_iter.getDTM(handle).getNode(handle); } /** Return a mask describing which node types are presented via the * iterator. **/ public int getWhatToShow() { return dtm_iter.getWhatToShow(); } /** @return the next node in the set and advance the position of the * iterator in the set. * * @throw DOMException - INVALID_STATE_ERR Raised if this method is * called after the detach method was invoked. * */ public Node nextNode() throws DOMException { if(!valid) throw new DTMDOMException(DOMException.INVALID_STATE_ERR); int handle=dtm_iter.nextNode(); if (handle==-1) return null; return dtm_iter.getDTM(handle).getNode(handle); } /** @return the next previous in the set and advance the position of the * iterator in the set. * * @throw DOMException - INVALID_STATE_ERR Raised if this method is * called after the detach method was invoked. * */ public Node previousNode() { if(!valid) throw new DTMDOMException(DOMException.INVALID_STATE_ERR); int handle=dtm_iter.previousNode(); return dtm_iter.getDTM(handle).getNode(handle); } }