package org.teiid.query.xquery.saxon;
import java.util.LinkedList;
import java.util.List;
import net.sf.saxon.event.ProxyReceiver;
import net.sf.saxon.expr.AxisExpression;
import net.sf.saxon.expr.PathMap.PathMapArc;
import net.sf.saxon.expr.PathMap.PathMapNode;
import net.sf.saxon.expr.PathMap.PathMapRoot;
import net.sf.saxon.om.Axis;
import net.sf.saxon.pattern.NodeTest;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.Type;
/**
* A filter that uses the PathMap to determine what should be included in the document
*
* TODO: optimize filtering by not reconstructing the matchcontexts
* TODO: we may still need to do xom/nux style handling of large results, but
* that requires more analysis to determine subtree independence
*/
class PathMapFilter extends ProxyReceiver {
static class MatchContext {
List<PathMapArc> elementArcs;
List<PathMapArc> attributeArcs;
boolean matchedElement;
boolean matchesText;
boolean matchesComment;
void bulidContext(PathMapNode node) {
for (PathMapArc arc : node.getArcs()) {
processArc(arc);
}
}
void processArc(PathMapArc arc) {
AxisExpression ae = arc.getStep();
NodeTest test = ae.getNodeTest();
if (test == null) {
addAnyNodeArc(arc);
} else {
switch (test.getPrimitiveType()) {
case Type.TEXT:
matchesText = true;
case Type.NODE:
addAnyNodeArc(arc);
break;
case Type.COMMENT:
matchesComment = true;
break;
case Type.ELEMENT:
addElementArc(arc);
break;
case Type.ATTRIBUTE:
addAttributeArc(arc);
break;
}
}
}
private void addAnyNodeArc(PathMapArc arc) {
if (arc.getStep().getAxis() == Axis.ATTRIBUTE) {
addAttributeArc(arc);
return;
}
addElementArc(arc);
addAttributeArc(arc);
matchesText = true;
matchesComment = true;
}
private void addAttributeArc(PathMapArc arc) {
if (attributeArcs == null) {
attributeArcs = new LinkedList<PathMapArc>();
}
attributeArcs.add(arc);
}
private void addElementArc(PathMapArc arc) {
if (elementArcs == null) {
elementArcs = new LinkedList<PathMapArc>();
}
elementArcs.add(arc);
}
}
private LinkedList<MatchContext> matchContext = new LinkedList<MatchContext>();
public PathMapFilter(PathMapRoot root) {
MatchContext mc = new MatchContext();
mc.bulidContext(root);
matchContext.add(mc);
}
@Override
public void startElement(int nameCode, int typeCode,
int locationId, int properties)
throws XPathException {
MatchContext mc = matchContext.getLast();
MatchContext newContext = new MatchContext();
if (mc.elementArcs != null) {
for (PathMapArc arc : mc.elementArcs) {
AxisExpression ae = arc.getStep();
NodeTest test = ae.getNodeTest();
if (test == null || test.matches(Type.ELEMENT, nameCode, typeCode)) {
newContext.bulidContext(arc.getTarget());
newContext.matchedElement = true;
}
if (ae.getAxis() == Axis.DESCENDANT || ae.getAxis() == Axis.DESCENDANT_OR_SELF) {
newContext.processArc(arc);
}
}
}
matchContext.add(newContext);
if (newContext.matchedElement) {
super.startElement(nameCode, typeCode, locationId, properties);
}
}
@Override
public void attribute(int nameCode, int typeCode,
CharSequence value, int locationId, int properties)
throws XPathException {
MatchContext mc = matchContext.getLast();
if (!mc.matchedElement) {
return;
}
if (mc.attributeArcs != null) {
for (PathMapArc arc : mc.attributeArcs) {
AxisExpression ae = arc.getStep();
NodeTest test = ae.getNodeTest();
if (test == null || test.matches(Type.ATTRIBUTE, nameCode, typeCode)) {
super.attribute(nameCode, typeCode, value, locationId, properties);
return;
}
}
}
}
@Override
public void characters(CharSequence chars, int locationId,
int properties) throws XPathException {
MatchContext context = matchContext.getLast();
if (context.matchedElement && context.matchesText) {
super.characters(chars, locationId, properties);
}
}
@Override
public void comment(CharSequence chars, int locationId,
int properties) throws XPathException {
MatchContext context = matchContext.getLast();
if (context.matchedElement && context.matchesComment) {
super.comment(chars, locationId, properties);
}
}
@Override
public void processingInstruction(String target,
CharSequence data, int locationId, int properties)
throws XPathException {
MatchContext context = matchContext.getLast();
if (context.matchedElement) {
super.processingInstruction(target, data, locationId, properties);
}
}
@Override
public void namespace(int namespaceCode, int properties)
throws XPathException {
MatchContext context = matchContext.getLast();
if (context.matchedElement) {
super.namespace(namespaceCode, properties);
}
}
@Override
public void endElement() throws XPathException {
MatchContext context = matchContext.removeLast();
if (context.matchedElement) {
super.endElement();
}
}
}