org.opencastproject.util.Xpath Maven / Gradle / Ivy
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* The Apereo Foundation licenses this file to you under the Educational
* Community License, Version 2.0 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of the License
* at:
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* http://opensource.org/licenses/ecl2.txt
*
* Unless required by applicable law or agreed to in writing, software
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
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package org.opencastproject.util;
import static org.opencastproject.util.data.Option.none;
import static org.opencastproject.util.data.Option.option;
import org.opencastproject.util.data.Option;
import org.w3c.dom.Node;
import javax.xml.namespace.NamespaceContext;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
/** A thin layer around {@link XPath} to evaluate expressions in the context of a {@link Node}. */
public final class Xpath {
private final XPath xpath;
private final Node node;
private Xpath(Node node) {
this.xpath = XPathFactory.newInstance().newXPath();
this.node = node;
}
/** Create a new evaluation context for node respecting the given namespace resolutions. */
public static Xpath mk(Node node, NamespaceContext ns) {
final Xpath xpath = new Xpath(node);
xpath.xpath.setNamespaceContext(ns);
return xpath;
}
/** Evaluate the xpath expression against the contained document. The expression must return a node. */
// todo replace return type with Valid once it is implemented
public Option node(String expr) {
try {
return option((Node) xpath.evaluate(expr, node, XPathConstants.NODE));
} catch (XPathExpressionException e) {
return none();
}
}
}