See also the Document Object Model (DOM) Level 3 XPath Specification.
* *The XPathResult interface represents the result of the
* evaluation of an XPath expression within the context of a particular
* node. Since evaluation of an XPath expression can result in various
* result types, this object makes it possible to discover and manipulate
* the type and value of the result.
This implementation wraps an XObject.
*
* @see com.sun.org.apache.xpath.internal.objects.XObject
* @see org.w3c.dom.xpath.XPathResult
*
* @xsl.usage internal
*/
class XPathResultImpl implements XPathResult, EventListener {
/**
* The wrapped XObject
*/
final private XObject m_resultObj;
/**
* The xpath object that wraps the expression used for this result.
*/
final private XPath m_xpath;
/**
* This the type specified by the user during construction. Typically
* the constructor will be called by com.sun.org.apache.xpath.internal.XPath.evaluate().
*/
final private short m_resultType;
private boolean m_isInvalidIteratorState = false;
/**
* Only used to attach a mutation event handler when specified
* type is an iterator type.
*/
final private Node m_contextNode;
/**
* The iterator, if this is an iterator type.
*/
private NodeIterator m_iterator = null;;
/**
* The list, if this is a snapshot type.
*/
private NodeList m_list = null;
/**
* Constructor for XPathResultImpl.
*
* For internal use only.
*/
XPathResultImpl(short type, XObject result, Node contextNode, XPath xpath) {
// Check that the type is valid
if (!isValidType(type)) {
String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_INVALID_XPATH_TYPE, new Object[] {new Integer(type)});
throw new XPathException(XPathException.TYPE_ERR,fmsg); // Invalid XPath type argument: {0}
}
// Result object should never be null!
if (null == result) {
String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_EMPTY_XPATH_RESULT, null);
throw new XPathException(XPathException.INVALID_EXPRESSION_ERR,fmsg); // Empty XPath result object
}
this.m_resultObj = result;
this.m_contextNode = contextNode;
this.m_xpath = xpath;
// If specified result was ANY_TYPE, determine XObject type
if (type == ANY_TYPE) {
this.m_resultType = getTypeFromXObject(result);
} else {
this.m_resultType = type;
}
// If the context node supports DOM Events and the type is one of the iterator
// types register this result as an event listener
if (((m_resultType == XPathResult.ORDERED_NODE_ITERATOR_TYPE) ||
(m_resultType == XPathResult.UNORDERED_NODE_ITERATOR_TYPE))) {
addEventListener();
}// else can we handle iterator types if contextNode doesn't support EventTarget??
// If this is an iterator type get the iterator
if ((m_resultType == ORDERED_NODE_ITERATOR_TYPE) ||
(m_resultType == UNORDERED_NODE_ITERATOR_TYPE) ||
(m_resultType == ANY_UNORDERED_NODE_TYPE) ||
(m_resultType == FIRST_ORDERED_NODE_TYPE)) {
try {
m_iterator = m_resultObj.nodeset();
} catch (TransformerException te) {
// probably not a node type
String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_INCOMPATIBLE_TYPES, new Object[] {m_xpath.getPatternString(), getTypeString(getTypeFromXObject(m_resultObj)),getTypeString(m_resultType)});
throw new XPathException(XPathException.TYPE_ERR, fmsg); // "The XPathResult of XPath expression {0} has an XPathResultType of {1} which cannot be coerced into the specified XPathResultType of {2}."},
}
// If user requested ordered nodeset and result is unordered
// need to sort...TODO
// if ((m_resultType == ORDERED_NODE_ITERATOR_TYPE) &&
// (!(((DTMNodeIterator)m_iterator).getDTMIterator().isDocOrdered()))) {
//
// }
// If it's a snapshot type, get the nodelist
} else if ((m_resultType == UNORDERED_NODE_SNAPSHOT_TYPE) ||
(m_resultType == ORDERED_NODE_SNAPSHOT_TYPE)) {
try {
m_list = m_resultObj.nodelist();
} catch (TransformerException te) {
// probably not a node type
String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_INCOMPATIBLE_TYPES, new Object[] {m_xpath.getPatternString(), getTypeString(getTypeFromXObject(m_resultObj)),getTypeString(m_resultType)});
throw new XPathException(XPathException.TYPE_ERR, fmsg); // "The XPathResult of XPath expression {0} has an XPathResultType of {1} which cannot be coerced into the specified XPathResultType of {2}."},
}
}
}
/**
* @see org.w3c.dom.xpath.XPathResult#getResultType()
*/
public short getResultType() {
return m_resultType;
}
/**
* The value of this number result.
* @exception XPathException
* TYPE_ERR: raised if resultType is not
* NUMBER_TYPE.
* @see org.w3c.dom.xpath.XPathResult#getNumberValue()
*/
public double getNumberValue() throws XPathException {
if (getResultType() != NUMBER_TYPE) {
String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_CANT_CONVERT_XPATHRESULTTYPE_TO_NUMBER, new Object[] {m_xpath.getPatternString(), getTypeString(m_resultType)});
throw new XPathException(XPathException.TYPE_ERR,fmsg);
// "The XPathResult of XPath expression {0} has an XPathResultType of {1} which cannot be converted to a number"
} else {
try {
return m_resultObj.num();
} catch (Exception e) {
// Type check above should prevent this exception from occurring.
throw new XPathException(XPathException.TYPE_ERR,e.getMessage());
}
}
}
/**
* The value of this string result.
* @exception XPathException
* TYPE_ERR: raised if resultType is not
* STRING_TYPE.
*
* @see org.w3c.dom.xpath.XPathResult#getStringValue()
*/
public String getStringValue() throws XPathException {
if (getResultType() != STRING_TYPE) {
String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_CANT_CONVERT_TO_STRING, new Object[] {m_xpath.getPatternString(), m_resultObj.getTypeString()});
throw new XPathException(XPathException.TYPE_ERR,fmsg);
// "The XPathResult of XPath expression {0} has an XPathResultType of {1} which cannot be converted to a string."
} else {
try {
return m_resultObj.str();
} catch (Exception e) {
// Type check above should prevent this exception from occurring.
throw new XPathException(XPathException.TYPE_ERR,e.getMessage());
}
}
}
/**
* @see org.w3c.dom.xpath.XPathResult#getBooleanValue()
*/
public boolean getBooleanValue() throws XPathException {
if (getResultType() != BOOLEAN_TYPE) {
String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_CANT_CONVERT_TO_BOOLEAN, new Object[] {m_xpath.getPatternString(), getTypeString(m_resultType)});
throw new XPathException(XPathException.TYPE_ERR,fmsg);
// "The XPathResult of XPath expression {0} has an XPathResultType of {1} which cannot be converted to a boolean."
} else {
try {
return m_resultObj.bool();
} catch (TransformerException e) {
// Type check above should prevent this exception from occurring.
throw new XPathException(XPathException.TYPE_ERR,e.getMessage());
}
}
}
/**
* The value of this single node result, which may be null.
* @exception XPathException
* TYPE_ERR: raised if resultType is not
* ANY_UNORDERED_NODE_TYPE or
* FIRST_ORDERED_NODE_TYPE.
*
* @see org.w3c.dom.xpath.XPathResult#getSingleNodeValue()
*/
public Node getSingleNodeValue() throws XPathException {
if ((m_resultType != ANY_UNORDERED_NODE_TYPE) &&
(m_resultType != FIRST_ORDERED_NODE_TYPE)) {
String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_CANT_CONVERT_TO_SINGLENODE, new Object[] {m_xpath.getPatternString(), getTypeString(m_resultType)});
throw new XPathException(XPathException.TYPE_ERR,fmsg);
// "The XPathResult of XPath expression {0} has an XPathResultType of {1} which cannot be converted to a single node.
// This method applies only to types ANY_UNORDERED_NODE_TYPE and FIRST_ORDERED_NODE_TYPE."
}
NodeIterator result = null;
try {
result = m_resultObj.nodeset();
} catch (TransformerException te) {
throw new XPathException(XPathException.TYPE_ERR,te.getMessage());
}
if (null == result) return null;
Node node = result.nextNode();
// Wrap "namespace node" in an XPathNamespace
if (isNamespaceNode(node)) {
return new XPathNamespaceImpl(node);
} else {
return node;
}
}
/**
* @see org.w3c.dom.xpath.XPathResult#getInvalidIteratorState()
*/
public boolean getInvalidIteratorState() {
return m_isInvalidIteratorState;
}
/**
* The number of nodes in the result snapshot. Valid values for
* snapshotItem indices are 0 to
* snapshotLength-1 inclusive.
* @exception XPathException
* TYPE_ERR: raised if resultType is not
* UNORDERED_NODE_SNAPSHOT_TYPE or
* ORDERED_NODE_SNAPSHOT_TYPE.
*
* @see org.w3c.dom.xpath.XPathResult#getSnapshotLength()
*/
public int getSnapshotLength() throws XPathException {
if ((m_resultType != UNORDERED_NODE_SNAPSHOT_TYPE) &&
(m_resultType != ORDERED_NODE_SNAPSHOT_TYPE)) {
String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_CANT_GET_SNAPSHOT_LENGTH, new Object[] {m_xpath.getPatternString(), getTypeString(m_resultType)});
throw new XPathException(XPathException.TYPE_ERR,fmsg);
// "The method getSnapshotLength cannot be called on the XPathResult of XPath expression {0} because its XPathResultType is {1}.
}
return m_list.getLength();
}
/**
* Iterates and returns the next node from the node set or
* nullif there are no more nodes.
* @return Returns the next node.
* @exception XPathException
* TYPE_ERR: raised if resultType is not
* UNORDERED_NODE_ITERATOR_TYPE or
* ORDERED_NODE_ITERATOR_TYPE.
* @exception DOMException
* INVALID_STATE_ERR: The document has been mutated since the result was
* returned.
* @see org.w3c.dom.xpath.XPathResult#iterateNext()
*/
public Node iterateNext() throws XPathException, DOMException {
if ((m_resultType != UNORDERED_NODE_ITERATOR_TYPE) &&
(m_resultType != ORDERED_NODE_ITERATOR_TYPE)) {
String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_NON_ITERATOR_TYPE, new Object[] {m_xpath.getPatternString(), getTypeString(m_resultType)});
throw new XPathException(XPathException.TYPE_ERR, fmsg);
// "The method iterateNext cannot be called on the XPathResult of XPath expression {0} because its XPathResultType is {1}.
// This method applies only to types UNORDERED_NODE_ITERATOR_TYPE and ORDERED_NODE_ITERATOR_TYPE."},
}
if (getInvalidIteratorState()) {
String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_DOC_MUTATED, null);
throw new DOMException(DOMException.INVALID_STATE_ERR,fmsg); // Document mutated since result was returned. Iterator is invalid.
}
Node node = m_iterator.nextNode();
if(null == node)
removeEventListener(); // JIRA 1673
// Wrap "namespace node" in an XPathNamespace
if (isNamespaceNode(node)) {
return new XPathNamespaceImpl(node);
} else {
return node;
}
}
/**
* Returns the indexth item in the snapshot collection. If
* index is greater than or equal to the number of nodes in
* the list, this method returns null. Unlike the iterator
* result, the snapshot does not become invalid, but may not correspond
* to the current document if it is mutated.
* @param index Index into the snapshot collection.
* @return The node at the indexth position in the
* NodeList, or null if that is not a valid
* index.
* @exception XPathException
* TYPE_ERR: raised if resultType is not
* UNORDERED_NODE_SNAPSHOT_TYPE or
* ORDERED_NODE_SNAPSHOT_TYPE.
*
* @see org.w3c.dom.xpath.XPathResult#snapshotItem(int)
*/
public Node snapshotItem(int index) throws XPathException {
if ((m_resultType != UNORDERED_NODE_SNAPSHOT_TYPE) &&
(m_resultType != ORDERED_NODE_SNAPSHOT_TYPE)) {
String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_NON_SNAPSHOT_TYPE, new Object[] {m_xpath.getPatternString(), getTypeString(m_resultType)});
throw new XPathException(XPathException.TYPE_ERR, fmsg);
// "The method snapshotItem cannot be called on the XPathResult of XPath expression {0} because its XPathResultType is {1}.
// This method applies only to types UNORDERED_NODE_SNAPSHOT_TYPE and ORDERED_NODE_SNAPSHOT_TYPE."},
}
Node node = m_list.item(index);
// Wrap "namespace node" in an XPathNamespace
if (isNamespaceNode(node)) {
return new XPathNamespaceImpl(node);
} else {
return node;
}
}
/**
* Check if the specified type is one of the supported types.
* @param type The specified type
*
* @return true If the specified type is supported; otherwise, returns false.
*/
static boolean isValidType( short type ) {
switch (type) {
case ANY_TYPE:
case NUMBER_TYPE:
case STRING_TYPE:
case BOOLEAN_TYPE:
case UNORDERED_NODE_ITERATOR_TYPE:
case ORDERED_NODE_ITERATOR_TYPE:
case UNORDERED_NODE_SNAPSHOT_TYPE:
case ORDERED_NODE_SNAPSHOT_TYPE:
case ANY_UNORDERED_NODE_TYPE:
case FIRST_ORDERED_NODE_TYPE: return true;
default: return false;
}
}
/**
* @see org.w3c.dom.events.EventListener#handleEvent(Event)
*/
public void handleEvent(Event event) {
if (event.getType().equals("DOMSubtreeModified")) {
// invalidate the iterator
m_isInvalidIteratorState = true;
// deregister as a listener to reduce computational load
removeEventListener();
}
}
/**
* Given a request type, return the equivalent string.
* For diagnostic purposes.
*
* @return type string
*/
private String getTypeString(int type)
{
switch (type) {
case ANY_TYPE: return "ANY_TYPE";
case ANY_UNORDERED_NODE_TYPE: return "ANY_UNORDERED_NODE_TYPE";
case BOOLEAN_TYPE: return "BOOLEAN";
case FIRST_ORDERED_NODE_TYPE: return "FIRST_ORDERED_NODE_TYPE";
case NUMBER_TYPE: return "NUMBER_TYPE";
case ORDERED_NODE_ITERATOR_TYPE: return "ORDERED_NODE_ITERATOR_TYPE";
case ORDERED_NODE_SNAPSHOT_TYPE: return "ORDERED_NODE_SNAPSHOT_TYPE";
case STRING_TYPE: return "STRING_TYPE";
case UNORDERED_NODE_ITERATOR_TYPE: return "UNORDERED_NODE_ITERATOR_TYPE";
case UNORDERED_NODE_SNAPSHOT_TYPE: return "UNORDERED_NODE_SNAPSHOT_TYPE";
default: return "#UNKNOWN";
}
}
/**
* Given an XObject, determine the corresponding DOM XPath type
*
* @return type string
*/
private short getTypeFromXObject(XObject object) {
switch (object.getType()) {
case XObject.CLASS_BOOLEAN: return BOOLEAN_TYPE;
case XObject.CLASS_NODESET: return UNORDERED_NODE_ITERATOR_TYPE;
case XObject.CLASS_NUMBER: return NUMBER_TYPE;
case XObject.CLASS_STRING: return STRING_TYPE;
// XPath 2.0 types
// case XObject.CLASS_DATE:
// case XObject.CLASS_DATETIME:
// case XObject.CLASS_DTDURATION:
// case XObject.CLASS_GDAY:
// case XObject.CLASS_GMONTH:
// case XObject.CLASS_GMONTHDAY:
// case XObject.CLASS_GYEAR:
// case XObject.CLASS_GYEARMONTH:
// case XObject.CLASS_TIME:
// case XObject.CLASS_YMDURATION: return STRING_TYPE; // treat all date types as strings?
case XObject.CLASS_RTREEFRAG: return UNORDERED_NODE_ITERATOR_TYPE;
case XObject.CLASS_NULL: return ANY_TYPE; // throw exception ?
default: return ANY_TYPE; // throw exception ?
}
}
/**
* Given a node, determine if it is a namespace node.
*
* @param node
*
* @return boolean Returns true if this is a namespace node; otherwise, returns false.
*/
private boolean isNamespaceNode(Node node) {
if ((null != node) &&
(node.getNodeType() == Node.ATTRIBUTE_NODE) &&
(node.getNodeName().startsWith("xmlns:") || node.getNodeName().equals("xmlns"))) {
return true;
} else {
return false;
}
}
/**
* Add m_contextNode to Event Listner to listen for Mutations Events
*
*/
private void addEventListener(){
if(m_contextNode instanceof EventTarget)
((EventTarget)m_contextNode).addEventListener("DOMSubtreeModified",this,true);
}
/**
* Remove m_contextNode to Event Listner to listen for Mutations Events
*
*/
private void removeEventListener(){
if(m_contextNode instanceof EventTarget)
((EventTarget)m_contextNode).removeEventListener("DOMSubtreeModified",this,true);
}
}