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X-definition 4.2 (Open Source Software)
package org.xdef.xml;
import java.lang.reflect.InvocationTargetException;
import java.util.Iterator;
import javax.xml.namespace.NamespaceContext;
import javax.xml.namespace.QName;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import javax.xml.xpath.XPathFunction;
import javax.xml.xpath.XPathFunctionResolver;
import javax.xml.xpath.XPathVariableResolver;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.xdef.impl.xml.KNodeList;
import org.xdef.msg.XML;
import org.xdef.sys.SRuntimeException;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xdef.sys.StringParser;
/** XPath expression.
* @author Vaclav Trojan
*/
public class KXpathExpr {
private static final XPathFactory XPF;
private static final boolean XP2;
/** Source string with XPath expression. */
private String _source;
private XPathExpression _value;
private XPath _xp;
private XPathFunctionResolver _fr;
private XPathVariableResolver _vr;
private NamespaceContext _nc;
static {
XPathFactory x;
try {
Class cls = Class.forName("net.sf.saxon.xpath.XPathFactoryImpl");
x = (XPathFactory) cls.getConstructor().newInstance();
} catch (ClassNotFoundException | IllegalAccessException
| IllegalArgumentException | InstantiationException
| NoSuchMethodException | SecurityException
| InvocationTargetException | Error ex) {
x = null;
}
XPF = (x == null) ? XPathFactory.newInstance() : x;
XP2 = x != null;
}
/** Creates a new instance of KXpathExpr without NameSpace context,
* variables and functions.
* @param expr String with XPath expression.
*/
public KXpathExpr(final String expr) {this(expr, null, null, null);}
/** Creates a new instance of KXpathExpr
* @param expr String with XPath expression.
* @param nc NameSpace context or null.
*/
public KXpathExpr(final String expr, final NamespaceContext nc) {
this(expr, nc, null, null);
}
/** Creates a new instance of KXpathExpr
* @param expr String with XPath expression.
* @param nc NameSpace context or null.
* @param fr Function resolver or null.
* @param vr Variable resolver or null.
*/
public KXpathExpr(final String expr,
final NamespaceContext nc,
final XPathFunctionResolver fr,
final XPathVariableResolver vr) {
_source = expr.trim();
try {//return compiled XPath as XPathExpressionImpl object
if (chkSimpleExpr() >= 0) {
return;
}
_xp = XPF.newXPath();
_xp.setNamespaceContext(nc!=null? nc : new KNsContext());
_xp.setXPathFunctionResolver(fr!=null ? fr : new KFunResolver());
_xp.setXPathVariableResolver(vr!=null ? vr : new KVarResolver());
_value = _xp.compile(expr);
} catch (XPathExpressionException ex) {
String s = ex.getMessage();
s = (s != null && !s.trim().isEmpty()
? ": " + s.trim() : "XPathExpressionException");
throw new SRuntimeException(XML.XML505, s);
}
}
/** Check if expression can be converted to w3c.dom operations (optimize).
* @return -1 .. not simple, 0 .. element name, 1 .. attr, 6 .. self::.
*/
private int chkSimpleExpr() {
String s;
if (_source == null || (s =_source.trim()).isEmpty()) {
return -1;
}
int ndx = s.charAt(0) == '@' ? 1 : s.startsWith("self::") ? 6 : 0;
s = s.substring(ndx);
return !s.contains("::")
&& StringParser.chkXMLName(s, StringParser.XMLVER1_0) ? ndx : -1;
}
/** Get variable resolver.
* @return variable resolver.
*/
public XPathVariableResolver getVariableResolver() {
return _xp == null ? null : _xp.getXPathVariableResolver();
}
/** Get function resolver.
* @return function resolver.
*/
public XPathFunctionResolver getFunctionResolver() {
return _xp == null ? null : _xp.getXPathFunctionResolver();
}
/** Get namespace context.
* @return namespace context.
*/
public NamespaceContext getNamespaceContext() {
return _xp == null ? null : _xp.getNamespaceContext();
}
/** Set namespace context.
* @param nc namespace context.
*/
public void setNamespaceContext(final NamespaceContext nc) {_nc = nc;}
/** Get function resolver.
* @param fr function resolver.
*/
public void setFunctionResolver(final XPathFunctionResolver fr) {_fr = fr;}
/** Set variable resolver.
* @param vr variable resolver.
*/
public void setVariableResolver(final XPathVariableResolver vr) {_vr = vr;}
/** Execute XPath expression and return result.
* If result type is null then result types are checked in
* following sequence:
* 1) NODESET, 2) STRING, 3) NODE.
* @param node node or null.
* @param type QName with result type.
* @return object with result of XPath expression.
*/
public Object evaluate(Node node, final QName type) {
if (_value == null) {
Element el = node.getNodeType() == Node.DOCUMENT_NODE ?
((Document) node).getDocumentElement()
: node.getNodeType()==Node.ELEMENT_NODE ? (Element) node : null;
if (el == null) {
return null;
}
int i = chkSimpleExpr();
if (i == 1) {
//attributes
int ndx =_source.indexOf(':');
Node x;
if (ndx<0 || _xp == null || _xp.getNamespaceContext() == null) {
x = el.getAttributeNode(_source.substring(1));
} else {
String prefix = _source.substring(1, ndx);
String localName = _source.substring(ndx+1);
String uri =
_xp.getNamespaceContext().getNamespaceURI(prefix);
x = el.getAttributeNodeNS(uri, localName);
}
if (type == null) {
return x == null ? null : new KNodeList(x);
}
if (type.equals(XPathConstants.STRING)) {
return x == null ? null : x.getNodeValue();
}
if (type.equals(XPathConstants.NODE))
return x;
if (type.equals(XPathConstants.NODESET))
return new KNodeList(x);
if (type.equals(XPathConstants.NUMBER))
return x==null ? 0 : 1;
if (type.equals(XPathConstants.BOOLEAN))
return x!=null;
return x!=null;
}
//elements
NodeList nl;
if (_xp == null) {
if (i == 6) { // self
return el.getNodeName().equals(_source.substring(6)) ?
new KNodeList(el) : new KNodeList();
}
nl = KXmlUtils.getChildElements(node, _source);
} else { //element or attribute
String name = i < 0 ? _source : _source.substring(i);
int ndx = name.indexOf(':');
String prefix = ndx > 0 ? name.substring(0, ndx): "";
String localName = ndx > 0 ? name.substring(ndx+1) : name;
String uri = _xp == null ? null :
_xp.getNamespaceContext() == null ? null
:_xp.getNamespaceContext().getNamespaceURI(prefix);
if (i == 6) { // self
String lName = el.getLocalName();
if (lName == null) {
lName = el.getNodeName();
}
if (lName.equals(localName)) {
if (uri == null) {
return el.getNamespaceURI() == null ?
new KNodeList(el) : new KNodeList();
}
return uri.equals(el.getNamespaceURI()) ?
new KNodeList(el) : new KNodeList();
}
return new KNodeList();
}
if (uri == null) {
nl = KXmlUtils.getChildElements(node, _source);
} else {
nl = KXmlUtils.getChildElementsNS(node, uri, localName);
}
}
if (type == null || type.equals(XPathConstants.NODESET)) {
return nl;
}
if (type.equals(XPathConstants.NUMBER)) return nl.getLength();
if (type.equals(XPathConstants.BOOLEAN)) return nl.getLength() > 0;
return nl.getLength() > 0 ? nl.item(0) : null;
}
if (type == null || type.equals(XPathConstants.NODESET)) {
try {
return (NodeList) _value.evaluate(node, XPathConstants.NODESET);
} catch (XPathExpressionException ex) {
// !!!!!!!!!!!!!!!!!! This is very nasty code !!!!!!!!!!!!!!!!!!
if (type == null || type.equals(XPathConstants.NODESET)
&& ex instanceof XPathExpressionException) {
String s = ex.getMessage();
Throwable x = ex;
while (s == null && (x = x.getCause()) != null) {
s = x.getMessage();
}
if (s != null) {
try {
if (s.toUpperCase().contains("BOOLEAN"))
return _value.evaluate(node,
XPathConstants.BOOLEAN);
if (s.toUpperCase().contains("NUMBER"))
return _value.evaluate(node,
XPathConstants.NUMBER);
} catch (XPathExpressionException exx) {}
}
}
try {
return _value.evaluate(node, XPathConstants.STRING);
} catch (XPathExpressionException ex1) {
try {
return _value.evaluate(node, XPathConstants.NODE);
} catch (XPathExpressionException ex2) {
if (node == null) {
return null;
}
//XPath error&{0}{: }
throw new SRuntimeException(XML.XML505,
ex.toString() + ",\n" + ex1.toString()
+ ",\n" + ex2.toString());
}
}
}
} else {
try {
return _value.evaluate(node, type);
} catch (XPathExpressionException ex) {
if (node == null) {
return null;
}
//XPath error&{0}{: }
throw new SRuntimeException(XML.XML505, ex.toString());
}
}
}
/** Execute XPath expression and return result.
/* If result type is null then result types are checked in
* following sequence:
* 1) NODESET, 2) STRING, 3) NODE.
* @param node node or null.
* @param type QName with result type or null.
* @param expr String with XPath expression.
* @param nc NameSpace context.
* @param fr Function resolver or null.
* @param vr Variable resolver or null.
* @return object with result of XPath expression.
*/
public static Object evaluate(final Node node,
final QName type,
final String expr,
final NamespaceContext nc,
final XPathFunctionResolver fr,
final XPathVariableResolver vr) {
return new KXpathExpr(expr, nc, fr, vr).evaluate(node, type);
}
/** Execute XPath expression (no NameSpace context, no variables,
* no functions) and return result.
* Result types are checked in following sequence:
* 1) NODESET, 2) STRING, 3) NODE.
* @param node node or null.
* @param expr String with XPath expression.
* @return object with result of XPath expression.
*/
public static Object evaluate(final Node node, final String expr) {
return new KXpathExpr(expr).evaluate(node, (QName) null);
}
/** Execute XPath expression (no NameSpace context, no variables,
* no functions) and return result.
* Result types are checked in following sequence:
* 1) NODESET, 2) STRING, 3) NODE.
* @param node node or null.
* @param expr String with XPath expression.
* @param nc NameSpace context.
* @return object with result of XPath expression.
*/
public static Object evaluate(final Node node,
final String expr,
final NamespaceContext nc) {
return new KXpathExpr(expr, nc).evaluate(node, (QName) null);
}
@Override
/** Get string with XPath source,
* @return string with XPath source.
*/
public String toString() {return _source;}
/** Check if XPath2 implementation is available.
* @return true if XPath2 implementation is available.
*/
public static final boolean isXPath2() {return XP2;}
private final class KFunResolver implements XPathFunctionResolver {
@Override
public final XPathFunction resolveFunction(final QName functionName,
final int arity) {
return _fr!=null ? _fr.resolveFunction(functionName, arity) : null;
}
}
private final class KVarResolver implements XPathVariableResolver{
@Override
public final Object resolveVariable(final QName variableName) {
return _vr!=null ? _vr.resolveVariable(variableName) : null;
}
}
private final class KNsContext implements NamespaceContext {
@Override
public final String getNamespaceURI(final String prefix) {
return _nc!=null ? _nc.getNamespaceURI(prefix) : null;
}
@Override
public final String getPrefix(final String namespaceURI) {
return _nc!=null ? _nc.getPrefix(namespaceURI) : null;
}
@Override
@SuppressWarnings("unchecked")
public final Iterator getPrefixes(final String namespaceURI) {
return _nc!=null ? _nc.getPrefixes(namespaceURI) : null;
}
}
}