227 lines
7 KiB
Java
227 lines
7 KiB
Java
/* XPathFactory.java --
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Copyright (C) 2004, 2005 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package javax.xml.xpath;
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import java.io.BufferedReader;
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import java.io.File;
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import java.io.FileInputStream;
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import java.io.InputStream;
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import java.io.InputStreamReader;
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import java.io.IOException;
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import java.util.Properties;
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/**
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* Factory for creating XPath environments.
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*
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* @author (a href='mailto:dog@gnu.org'>Chris Burdess</a)
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* @since 1.3
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*/
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public abstract class XPathFactory
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{
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/**
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* The default property name according to the JAXP specification.
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*/
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public static final String DEFAULT_PROPERTY_NAME =
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"javax.xml.xpath.XPathFactory";
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/**
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* The default object model URI.
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*/
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public static final String DEFAULT_OBJECT_MODEL_URI =
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XPathConstants.DOM_OBJECT_MODEL;
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protected XPathFactory()
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{
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}
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/**
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* Returns a new factory for the default (DOM) object model.
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*/
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public static final XPathFactory newInstance()
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{
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try
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{
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return newInstance(DEFAULT_OBJECT_MODEL_URI);
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}
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catch (XPathFactoryConfigurationException e)
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{
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throw new RuntimeException(e.getMessage());
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}
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}
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/**
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* Returns a new factory for the given object model URI.
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* The implementation class to load is the first found in the following
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* locations that advertises support for the given model URI:
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* <ol>
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* <li>the <code>javax.xml.xpath.XPathFactory</code> system property</li>
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* <li>the above named property value in the
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* <code><i>$JAVA_HOME</i>/lib/jaxp.properties</code> file</li>
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* <li>the class name specified in the
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* <code>META-INF/services/javax.xml.xpath.XPathFactory</code> system
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* resource</li>
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* <li>the default factory class</li>
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* </ol>
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* @param uri the object model URI
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*/
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public static final XPathFactory newInstance(String uri)
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throws XPathFactoryConfigurationException
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{
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ClassLoader loader = Thread.currentThread().getContextClassLoader();
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if (loader == null)
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{
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loader = XPathFactory.class.getClassLoader();
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}
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String className = null;
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int count = 0;
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do
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{
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className = getFactoryClassName(loader, count++);
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if (className != null)
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{
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try
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{
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Class t = (loader != null) ? loader.loadClass(className) :
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Class.forName(className);
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XPathFactory ret = (XPathFactory) t.newInstance();
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if (ret.isObjectModelSupported(uri))
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{
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return ret;
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}
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className = null;
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}
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catch (ClassNotFoundException e)
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{
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className = null;
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}
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catch (Exception e)
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{
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throw new XPathFactoryConfigurationException(e);
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}
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}
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}
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while (className == null && count < 4);
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String msg = "no factories with support for " + uri;
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throw new XPathFactoryConfigurationException(msg);
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}
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private static String getFactoryClassName(ClassLoader loader, int attempt)
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{
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final String propertyName = DEFAULT_PROPERTY_NAME;
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switch (attempt)
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{
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case 0:
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return System.getProperty(propertyName);
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case 1:
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try
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{
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File file = new File(System.getProperty("java.home"));
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file = new File(file, "lib");
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file = new File(file, "jaxp.properties");
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InputStream in = new FileInputStream(file);
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Properties props = new Properties();
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props.load(in);
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in.close();
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return props.getProperty(propertyName);
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}
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catch (IOException e)
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{
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return null;
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}
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case 2:
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try
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{
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String serviceKey = "/META-INF/services/" + propertyName;
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InputStream in = (loader != null) ?
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loader.getResourceAsStream(serviceKey) :
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XPathFactory.class.getResourceAsStream(serviceKey);
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if (in != null)
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{
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BufferedReader r =
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new BufferedReader(new InputStreamReader(in));
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String ret = r.readLine();
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r.close();
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return ret;
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}
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}
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catch (IOException e)
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{
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}
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return null;
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case 3:
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return "gnu.xml.xpath.XPathFactoryImpl";
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default:
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return null;
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}
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}
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/**
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* Indicates whether the specified object model URI is supported by
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* this factory.
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*/
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public abstract boolean isObjectModelSupported(String objectModel);
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/**
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* Sets the state of the named feature.
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*/
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public abstract void setFeature(String name, boolean value)
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throws XPathFactoryConfigurationException;
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/**
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* Returns the state of the named feature.
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*/
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public abstract boolean getFeature(String name)
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throws XPathFactoryConfigurationException;
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/**
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* Sets the XPath variable resolver calback.
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*/
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public abstract void setXPathVariableResolver(XPathVariableResolver resolver);
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/**
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* Sets the XPath extension function resolver calback.
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*/
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public abstract void setXPathFunctionResolver(XPathFunctionResolver resolver);
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/**
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* Returns a new XPath evaluation environment.
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*/
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public abstract XPath newXPath();
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}
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