/**
* Convert an XPath value to an object in this object model. If the supplied value can be
* converted to an object in this model, of the specified class, then the conversion should be
* done and the resulting object returned. If the value cannot be converted, the method should
* return null. Note that the supplied class might be a List, in which case the method should
* inspect the contents of the Value to see whether they belong to this object model.
*
* @throws XPathException if the target class is explicitly associated with this object model, but
* the supplied value cannot be converted to the appropriate class
*/
public Object convertXPathValueToObject(Value value, Class target, XPathContext context)
throws XPathException {
// We accept the object if (a) the target class is Node, Node[], or NodeList,
// or (b) the supplied object is a node, or sequence of nodes, that wrap DOM nodes,
// provided that the target class is Object or a collection class
boolean requireDOM =
(Node.class.isAssignableFrom(target)
|| (target == NodeList.class)
|| (target.isArray() && Node.class.isAssignableFrom(target.getComponentType())));
// Note: we allow the declared type of the method argument to be a subclass of Node. If the
// actual
// node supplied is the wrong kind of node, this will result in a Java exception.
boolean allowDOM =
(target == Object.class
|| target.isAssignableFrom(ArrayList.class)
|| target.isAssignableFrom(HashSet.class)
|| (target.isArray() && target.getComponentType() == Object.class));
if (!(requireDOM || allowDOM)) {
return null;
}
List nodes = new ArrayList(20);
SequenceIterator iter = value.iterate(context);
while (true) {
Item item = iter.next();
if (item == null) {
break;
}
if (item instanceof VirtualNode) {
Object o = ((VirtualNode) item).getUnderlyingNode();
if (o instanceof Node) {
nodes.add(o);
} else {
if (requireDOM) {
DynamicError err =
new DynamicError(
"Extension function required class "
+ target.getName()
+ "; supplied value of class "
+ item.getClass().getName()
+ " could not be converted");
throw err;
}
;
}
} else if (requireDOM) {
if (item instanceof NodeInfo) {
nodes.add(NodeOverNodeInfo.wrap((NodeInfo) item));
} else {
DynamicError err =
new DynamicError(
"Extension function required class "
+ target.getName()
+ "; supplied value of class "
+ item.getClass().getName()
+ " could not be converted");
throw err;
}
} else {
return null; // DOM Nodes are not actually required; let someone else try the conversion
}
}
if (nodes.size() == 0 && !requireDOM) {
return null; // empty sequence supplied - try a different mapping
}
if (Node.class.isAssignableFrom(target)) {
if (nodes.size() != 1) {
DynamicError err =
new DynamicError(
"Extension function requires a single DOM Node"
+ "; supplied value contains "
+ nodes.size()
+ " nodes");
throw err;
}
return nodes.get(0);
// could fail if the node is of the wrong kind
} else if (target == NodeList.class) {
return new DOMNodeList(nodes);
} else if (target.isArray() && target.getComponentType() == Node.class) {
Node[] array = new Node[nodes.size()];
nodes.toArray(array);
return array;
} else if (target.isAssignableFrom(ArrayList.class)) {
return nodes;
} else if (target.isAssignableFrom(HashSet.class)) {
return new HashSet(nodes);
} else {
// after all this work, give up
return null;
}
}
