content: /*
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
   *
   * Copyright (c) 1997-2010 Oracle and/or its affiliates. All rights reserved.
   *
   * The contents of this file are subject to the terms of either the GNU
   * General Public License Version 2 only ("GPL") or the Common Development
   * and Distribution License("CDDL") (collectively, the "License").  You
   * may not use this file except in compliance with the License.  You can
   * obtain a copy of the License at
   * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
   * or packager/legal/LICENSE.txt.  See the License for the specific
   * language governing permissions and limitations under the License.
   *
   * When distributing the software, include this License Header Notice in each
   * file and include the License file at packager/legal/LICENSE.txt.
   *
   * GPL Classpath Exception:
   * Oracle designates this particular file as subject to the "Classpath"
   * exception as provided by Oracle in the GPL Version 2 section of the License
   * file that accompanied this code.
   *
   * Modifications:
   * If applicable, add the following below the License Header, with the fields
   * enclosed by brackets [] replaced by your own identifying information:
   * "Portions Copyright [year] [name of copyright owner]"
   *
   * Contributor(s):
   * If you wish your version of this file to be governed by only the CDDL or
   * only the GPL Version 2, indicate your decision by adding "[Contributor]
   * elects to include this software in this distribution under the [CDDL or GPL
   * Version 2] license."  If you don't indicate a single choice of license, a
   * recipient has the option to distribute your version of this file under
   * either the CDDL, the GPL Version 2 or to extend the choice of license to
   * its licensees as provided above.  However, if you add GPL Version 2 code
   * and therefore, elected the GPL Version 2 license, then the option applies
   * only if the new code is made subject to such option by the copyright
   * holder.
   */
  
  /*
   * $Id: XPathFactory.java,v 1.7 2010-11-01 04:36:14 joehw Exp $
   * %W% %E%
   */
  package mf.javax.xml.xpath;
  
  /**
   * <p>An <code>XPathFactory</code> instance can be used to create
   * {@link javax.xml.xpath.XPath} objects.</p>
   * <p/>
   * <p>See {@link #newInstance(String uri)} for lookup mechanism.</p>
   * <p/>
   * <p>The {@link XPathFactory} class is not thread-safe. In other words,
   * it is the application's responsibility to ensure that at most
   * one thread is using a {@link XPathFactory} object at any
   * given moment. Implementations are encouraged to mark methods
   * as <code>synchronized</code> to protect themselves from broken clients.
   * <p/>
   * <p>{@link XPathFactory} is not re-entrant. While one of the
   * <code>newInstance</code> methods is being invoked, applications
   * may not attempt to recursively invoke a <code>newInstance</code> method,
   * even from the same thread.
   *
   * @author <a href="mailto:Norman.Walsh@Sun.com">Norman Walsh</a>
   * @author <a href="mailto:Jeff.Suttor@Sun.com">Jeff Suttor</a>
   * @version $Revision: 1.7 $, $Date: 2010-11-01 04:36:14 $
   * @since 1.5
   */
  public abstract class XPathFactory {
  
  
      /**
       * <p>The default property name according to the JAXP spec.</p>
       */
      public static final String DEFAULT_PROPERTY_NAME = "mf.javax.xml.xpath.XPathFactory";
  
      /**
       * <p>Default Object Model URI.</p>
       */
      public static final String DEFAULT_OBJECT_MODEL_URI = "http://java.sun.com/jaxp/xpath/dom";
  
      /**
       * <p> Take care of restrictions imposed by java security model </p>
       */
      private static SecuritySupport ss = new SecuritySupport();
  
      /**
       * <p>Protected constructor as {@link #newInstance()} or {@link #newInstance(String uri)}
       * or {@link #newInstance(String uri, String factoryClassName, ClassLoader classLoader)}
       * should be used to create a new instance of an <code>XPathFactory</code>.</p>
       */
      protected XPathFactory() {
      }
  
      /**
       * <p>Get a new <code>XPathFactory</code> instance using the default object model,
       * {@link #DEFAULT_OBJECT_MODEL_URI},
       * the W3C DOM.</p>
       * <p/>
       * <p>This method is functionally equivalent to:</p>
       * <pre>
       *   newInstance(DEFAULT_OBJECT_MODEL_URI)
       * </pre>
       * <p/>
       * <p>Since the implementation for the W3C DOM is always available, this method will never fail.</p>
       *
       * @return Instance of an <code>XPathFactory</code>.
       * @throws RuntimeException When there is a failure in creating an
       *                          <code>XPathFactory</code> for the default object model.
       */
      public static final XPathFactory newInstance() {
  
          try {
              return newInstance(DEFAULT_OBJECT_MODEL_URI);
          } catch (XPathFactoryConfigurationException xpathFactoryConfigurationException) {
              throw new RuntimeException(
                      "XPathFactory#newInstance() failed to create an XPathFactory for the default object model: "
                              + DEFAULT_OBJECT_MODEL_URI
                              + " with the XPathFactoryConfigurationException: "
                              + xpathFactoryConfigurationException.toString()
              );
          }
      }
  
      /**
       * <p>Get a new <code>XPathFactory</code> instance using the specified object model.</p>
       * <p/>
       * <p>To find a <code>XPathFactory</code> object,
       * this method looks the following places in the following order where "the class loader" refers to the context class loader:</p>
       * <ol>
       * <li>
       * If the system property {@link #DEFAULT_PROPERTY_NAME} + ":uri" is present,
       * where uri is the parameter to this method, then its value is read as a class name.
       * The method will try to create a new instance of this class by using the class loader,
       * and returns it if it is successfully created.
       * </li>
       * <li>
       * ${java.home}/lib/jaxp.properties is read and the value associated with the key being the system property above is looked for.
       * If present, the value is processed just like above.
       * </li>
       * <li>
       * The class loader is asked for service provider provider-configuration files matching <code>javax.xml.xpath.XPathFactory</code>
       * in the resource directory META-INF/services.
       * See the JAR File Specification for file format and parsing rules.
       * Each potential service provider is required to implement the method:
       * <pre>
       *       {@link #isObjectModelSupported(String objectModel)}
       *     </pre>
       * The first service provider found in class loader order that supports the specified object model is returned.
       * </li>
       * <li>
       * Platform default <code>XPathFactory</code> is located in a platform specific way.
       * There must be a platform default XPathFactory for the W3C DOM, i.e. {@link #DEFAULT_OBJECT_MODEL_URI}.
       * </li>
       * </ol>
       * <p>If everything fails, an <code>XPathFactoryConfigurationException</code> will be thrown.</p>
       *
       * <p>Tip for Trouble-shooting:</p>
       * <p>See {@link java.util.Properties#load(java.io.InputStream)} for exactly how a property file is parsed.
       * In particular, colons ':' need to be escaped in a property file, so make sure the URIs are properly escaped in it.
       * For example:</p>
       * <pre>
       *   http\://java.sun.com/jaxp/xpath/dom=org.acme.DomXPathFactory
       * </pre>
       *
       * @param uri Identifies the underlying object model.
       *            The specification only defines the URI {@link #DEFAULT_OBJECT_MODEL_URI},
       *            <code>http://java.sun.com/jaxp/xpath/dom</code> for the W3C DOM,
       *            the org.w3c.dom package, and implementations are free to introduce other URIs for other object models.
       * @return Instance of an <code>XPathFactory</code>.
       * @throws XPathFactoryConfigurationException If the specified object model is unavailable.
       * @throws NullPointerException               If <code>uri</code> is <code>null</code>.
       * @throws IllegalArgumentException           If <code>uri</code> is <code>null</code>
       *                                            or <code>uri.length() == 0</code>.
       */
      public static final XPathFactory newInstance(final String uri)
              throws XPathFactoryConfigurationException {
  
          if (uri == null) {
              throw new NullPointerException(
                      "XPathFactory#newInstance(String uri) cannot be called with uri == null"
              );
          }
  
          if (uri.length() == 0) {
              throw new IllegalArgumentException(
                      "XPathFactory#newInstance(String uri) cannot be called with uri == \"\""
              );
          }
  
          ClassLoader classLoader = ss.getContextClassLoader();
  
          if (classLoader == null) {
              //use the current class loader
              classLoader = XPathFactory.class.getClassLoader();
          }
  
          XPathFactory xpathFactory = new XPathFactoryFinder(classLoader).newFactory(uri);
  
          if (xpathFactory == null) {
              throw new XPathFactoryConfigurationException(
                      "No XPathFactory implementation found for the object model: "
                              + uri
              );
          }
  
          return xpathFactory;
      }
  
      /**
       * <p>Obtain a new instance of a <code>XPathFactory</code> from a factory class name. <code>XPathFactory</code>
       * is returned if specified factory class supports the specified object model.
       * This function is useful when there are multiple providers in the classpath.
       * It gives more control to the application as it can specify which provider
       * should be loaded.</p>
       * <p/>
       * <p/>
       * <h2>Tip for Trouble-shooting</h2>
       * <p>Setting the <code>jaxp.debug</code> system property will cause
       * this method to print a lot of debug messages
       * to <code>System.err</code> about what it is doing and where it is looking at.</p>
       * <p/>
       * <p> If you have problems try:</p>
       * <pre>
       * java -Djaxp.debug=1 YourProgram ....
       * </pre>
       *
       * @param uri              Identifies the underlying object model. The specification only defines the URI
       *                         {@link #DEFAULT_OBJECT_MODEL_URI},<code>http://java.sun.com/jaxp/xpath/dom</code>
       *                         for the W3C DOM, the org.w3c.dom package, and implementations are free to introduce
       *                         other URIs for other object models.
       * @param factoryClassName fully qualified factory class name that provides implementation of <code>javax.xml.xpath.XPathFactory</code>.
       * @param classLoader      <code>ClassLoader</code> used to load the factory class. If <code>null</code>
       *                         current <code>Thread</code>'s context classLoader is used to load the factory class.
       * @return New instance of a <code>XPathFactory</code>
       * @throws XPathFactoryConfigurationException if <code>factoryClassName</code> is <code>null</code>, or
       *                                            the factory class cannot be loaded, instantiated
       *                                            or the factory class does not support the object model specified
       *                                            in the <code>uri</code> parameter.
       * @throws NullPointerException               If <code>uri</code> is <code>null</code>.
       * @throws IllegalArgumentException           If <code>uri</code> is <code>null</code>
       *                                            or <code>uri.length() == 0</code>.
       * @see #newInstance()
       * @see #newInstance(String uri)
       * @since 1.6
       */
      public static XPathFactory newInstance(String uri, String factoryClassName, ClassLoader classLoader)
              throws XPathFactoryConfigurationException {
          ClassLoader cl = classLoader;
  
          if (uri == null) {
              throw new NullPointerException(
                      "XPathFactory#newInstance(String uri) cannot be called with uri == null"
              );
          }
  
          if (uri.length() == 0) {
              throw new IllegalArgumentException(
                      "XPathFactory#newInstance(String uri) cannot be called with uri == \"\""
              );
          }
  
          if (cl == null) {
              cl = ss.getContextClassLoader();
          }
  
          XPathFactory f = new XPathFactoryFinder(cl).createInstance(factoryClassName);
  
          if (f == null) {
              throw new XPathFactoryConfigurationException(
                      "No XPathFactory implementation found for the object model: "
                              + uri
              );
          }
          //if this factory supports the given schemalanguage return this factory else thrown exception
          if (f.isObjectModelSupported(uri)) {
              return f;
          } else {
              throw new XPathFactoryConfigurationException("Factory " + factoryClassName + " doesn't support given " + uri + " object model");
          }
  
      }
  
      /**
       * <p>Is specified object model supported by this <code>XPathFactory</code>?</p>
       *
       * @param objectModel Specifies the object model which the returned <code>XPathFactory</code> will understand.
       * @return <code>true</code> if <code>XPathFactory</code> supports <code>objectModel</code>, else <code>false</code>.
       * @throws NullPointerException     If <code>objectModel</code> is <code>null</code>.
       * @throws IllegalArgumentException If <code>objectModel.length() == 0</code>.
       */
      public abstract boolean isObjectModelSupported(String objectModel);
  
      /**
       * <p>Set a feature for this <code>XPathFactory</code> and
       * <code>XPath</code>s created by this factory.</p>
       * <p/>
       * <p>
       * Feature names are fully qualified {@link java.net.URI}s.
       * Implementations may define their own features.
       * An {@link XPathFactoryConfigurationException} is thrown if this
       * <code>XPathFactory</code> or the <code>XPath</code>s
       * it creates cannot support the feature.
       * It is possible for an <code>XPathFactory</code> to expose a feature value
       * but be unable to change its state.
       * </p>
       * <p/>
       * <p>
       * All implementations are required to support the {@link javax.xml.XMLConstants#FEATURE_SECURE_PROCESSING} feature.
       * When the feature is <code>true</code>, any reference to  an external function is an error.
       * Under these conditions, the implementation must not call the {@link XPathFunctionResolver}
       * and must throw an {@link XPathFunctionException}.
       * </p>
       *
       * @param name  Feature name.
       * @param value Is feature state <code>true</code> or <code>false</code>.
       * @throws XPathFactoryConfigurationException if this <code>XPathFactory</code> or the <code>XPath</code>s
       *                                            it creates cannot support this feature.
       * @throws NullPointerException               if <code>name</code> is <code>null</code>.
       */
      public abstract void setFeature(String name, boolean value)
              throws XPathFactoryConfigurationException;
  
      /**
       * <p>Get the state of the named feature.</p>
       * <p/>
       * <p>
       * Feature names are fully qualified {@link java.net.URI}s.
       * Implementations may define their own features.
       * An {@link XPathFactoryConfigurationException} is thrown if this
       * <code>XPathFactory</code> or the <code>XPath</code>s
       * it creates cannot support the feature.
       * It is possible for an <code>XPathFactory</code> to expose a feature value
       * but be unable to change its state.
       * </p>
       *
       * @param name Feature name.
       * @return State of the named feature.
       * @throws XPathFactoryConfigurationException if this
       *                                            <code>XPathFactory</code> or the <code>XPath</code>s
       *                                            it creates cannot support this feature.
       * @throws NullPointerException               if <code>name</code> is <code>null</code>.
       */
      public abstract boolean getFeature(String name)
              throws XPathFactoryConfigurationException;
  
      /**
       * <p>Establish a default variable resolver.</p>
       * <p/>
       * <p>Any <code>XPath</code> objects constructed from this factory will use
       * the specified resolver by default.</p>
       * <p/>
       * <p>A <code>NullPointerException</code> is thrown if <code>resolver</code>
       * is <code>null</code>.</p>
       *
       * @param resolver Variable resolver.
       * @throws NullPointerException If <code>resolver</code> is
       *                              <code>null</code>.
       */
      public abstract void setXPathVariableResolver(XPathVariableResolver resolver);
  
      /**
       * <p>Establish a default function resolver.</p>
       * <p/>
       * <p>Any <code>XPath</code> objects constructed from this factory will
       * use the specified resolver by default.</p>
       * <p/>
       * <p>A <code>NullPointerException</code> is thrown if
       * <code>resolver</code> is <code>null</code>.</p>
       *
       * @param resolver XPath function resolver.
       * @throws NullPointerException If <code>resolver</code> is
       *                              <code>null</code>.
       */
      public abstract void setXPathFunctionResolver(XPathFunctionResolver resolver);
  
      /**
       * <p>Return a new <code>XPath</code> using the underlying object
       * model determined when the <code>XPathFactory</code> was instantiated.</p>
       *
       * @return New instance of an <code>XPath</code>.
       */
      public abstract XPath newXPath();
  }
  