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   *  AndroidIDE is distributed in the hope that it will be useful,
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   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *  GNU General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License
   *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
   */
  
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   * DO NOT REMOVE OR ALTER!
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  /*
   * Copyright 1999-2004 The Apache Software Foundation.
   *
   * Licensed under the Apache 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
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  /*
   * $Id: CachedXPathAPI.java,v 1.2.4.1 2005/09/10 03:47:42 jeffsuttor Exp $
   */
  package jaxp.sun.org.apache.xpath.internal;
  
  import jaxp.xml.transform.TransformerException;
  
  import jaxp.sun.org.apache.xml.internal.dtm.DTM;
  import jaxp.sun.org.apache.xml.internal.dtm.DTMManager;
  import jaxp.sun.org.apache.xml.internal.utils.PrefixResolver;
  import jaxp.sun.org.apache.xml.internal.utils.PrefixResolverDefault;
  import jaxp.sun.org.apache.xpath.internal.objects.XObject;
  
  import jaxp.sun.org.apache.xpath.internal.objects.XBoolean;
  import jaxp.sun.org.apache.xpath.internal.objects.XNull;
  import jaxp.sun.org.apache.xpath.internal.objects.XNumber;
  import jaxp.sun.org.apache.xpath.internal.objects.XRTreeFrag;
  import jaxp.sun.org.apache.xpath.internal.objects.XString;
  import org.w3c.dom.Document;
  import org.w3c.dom.Node;
  import org.w3c.dom.NodeList;
  import org.w3c.dom.traversal.NodeIterator;
  
  /**
   * The methods in this class are convenience methods into the
   * low-level XPath API.
   *
   * These functions tend to be a little slow, since a number of objects must be
   * created for each evaluation.  A faster way is to precompile the
   * XPaths using the low-level API, and then just use the XPaths
   * over and over.
   *
   * This is an alternative for the old XPathAPI class, which provided
   * static methods for the purpose but had the drawback of
   * instantiating a new XPathContext (and thus building a new DTMManager,
   * and new DTMs) each time it was called. XPathAPIObject instead retains
   * its context as long as the object persists, reusing the DTMs. This
   * does have a downside: if you've changed your source document, you should
   * obtain a new XPathAPIObject to continue searching it, since trying to use
   * the old DTMs will probably yield bad results or malfunction outright... and
   * the cached DTMs may consume memory until this object and its context are
   * returned to the heap. Essentially, it's the caller's responsibility to
   * decide when to discard the cache.
   *
   * @see <a href="http://www.w3.org/TR/xpath">XPath Specification</a>
   * */
  public class CachedXPathAPI
  {
    /** XPathContext, and thus the document model system (DTMs), persists through multiple
        calls to this object. This is set in the constructor.
    */
    protected XPathContext xpathSupport;
  
    /**
     * <p>Default constructor. Establishes its own {@link XPathContext}, and hence
     * its own {@link DTMManager}.
     * Good choice for simple uses.</p>
     * <p>Note that any particular instance of {@link CachedXPathAPI} must not be
     * operated upon by multiple threads without synchronization; we do
     * not currently support multithreaded access to a single
     * {@link DTM}.</p>
     */
    public CachedXPathAPI()
    {
      xpathSupport = new XPathContext();
    }
  
    /**
     * <p>This constructor shares its {@link XPathContext} with a pre-existing
     * {@link CachedXPathAPI}.  That allows sharing document models
     * ({@link DTM}) and previously established location
     * state.</p>
     * <p>Note that the original {@link CachedXPathAPI} and the new one should
     * not be operated upon concurrently; we do not support multithreaded access
     * to a single {@link DTM} at this time.  Similarly,
     * any particular instance of {@link CachedXPathAPI} must not be operated
     * upon by multiple threads without synchronization.</p>
     * <p>%REVIEW% Should this instead do a clone-and-reset on the XPathSupport object?</p>
     *
     */
    public CachedXPathAPI(CachedXPathAPI priorXPathAPI)
    {
      xpathSupport = priorXPathAPI.xpathSupport;
    }
  
  
    /** Returns the XPathSupport object used in this CachedXPathAPI
     *
     * %REVIEW% I'm somewhat concerned about the loss of encapsulation
     * this causes, but the xml-security folks say they need it.
     * */
    public XPathContext getXPathContext()
    {
      return this.xpathSupport;
    }
  
  
    /**
     * Use an XPath string to select a single node. XPath namespace
     * prefixes are resolved from the context node, which may not
     * be what you want (see the next method).
     *
     * @param contextNode The node to start searching from.
     * @param str A valid XPath string.
     * @return The first node found that matches the XPath, or null.
     *
     * @throws TransformerException
     */
    public  Node selectSingleNode(Node contextNode, String str)
            throws TransformerException
    {
      return selectSingleNode(contextNode, str, contextNode);
    }
  
    /**
     * Use an XPath string to select a single node.
     * XPath namespace prefixes are resolved from the namespaceNode.
     *
     * @param contextNode The node to start searching from.
     * @param str A valid XPath string.
     * @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces.
     * @return The first node found that matches the XPath, or null.
     *
     * @throws TransformerException
     */
    public  Node selectSingleNode(
            Node contextNode, String str, Node namespaceNode)
              throws TransformerException
    {
  
      // Have the XObject return its result as a NodeSetDTM.
      NodeIterator nl = selectNodeIterator(contextNode, str, namespaceNode);
  
      // Return the first node, or null
      return nl.nextNode();
    }
  
    /**
     *  Use an XPath string to select a nodelist.
     *  XPath namespace prefixes are resolved from the contextNode.
     *
     *  @param contextNode The node to start searching from.
     *  @param str A valid XPath string.
     *  @return A NodeIterator, should never be null.
     *
     * @throws TransformerException
     */
    public  NodeIterator selectNodeIterator(Node contextNode, String str)
            throws TransformerException
    {
      return selectNodeIterator(contextNode, str, contextNode);
    }
  
    /**
     *  Use an XPath string to select a nodelist.
     *  XPath namespace prefixes are resolved from the namespaceNode.
     *
     *  @param contextNode The node to start searching from.
     *  @param str A valid XPath string.
     *  @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces.
     *  @return A NodeIterator, should never be null.
     *
     * @throws TransformerException
     */
    public  NodeIterator selectNodeIterator(
            Node contextNode, String str, Node namespaceNode)
              throws TransformerException
    {
  
      // Execute the XPath, and have it return the result
      XObject list = eval(contextNode, str, namespaceNode);
  
      // Have the XObject return its result as a NodeSetDTM.
      return list.nodeset();
    }
  
    /**
     *  Use an XPath string to select a nodelist.
     *  XPath namespace prefixes are resolved from the contextNode.
     *
     *  @param contextNode The node to start searching from.
     *  @param str A valid XPath string.
     *  @return A NodeIterator, should never be null.
     *
     * @throws TransformerException
     */
    public  NodeList selectNodeList(Node contextNode, String str)
            throws TransformerException
    {
      return selectNodeList(contextNode, str, contextNode);
    }
  
    /**
     *  Use an XPath string to select a nodelist.
     *  XPath namespace prefixes are resolved from the namespaceNode.
     *
     *  @param contextNode The node to start searching from.
     *  @param str A valid XPath string.
     *  @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces.
     *  @return A NodeIterator, should never be null.
     *
     * @throws TransformerException
     */
    public  NodeList selectNodeList(
            Node contextNode, String str, Node namespaceNode)
              throws TransformerException
    {
  
      // Execute the XPath, and have it return the result
      XObject list = eval(contextNode, str, namespaceNode);
  
      // Return a NodeList.
      return list.nodelist();
    }
  
    /**
     *  Evaluate XPath string to an XObject.  Using this method,
     *  XPath namespace prefixes will be resolved from the namespaceNode.
     *  @param contextNode The node to start searching from.
     *  @param str A valid XPath string.
     *  @return An XObject, which can be used to obtain a string, number, nodelist, etc, should never be null.
     *  @see XObject
     *  @see XNull
     *  @see XBoolean
     *  @see XNumber
     *  @see XString
     *  @see XRTreeFrag
     *
     * @throws TransformerException
     */
    public  XObject eval(Node contextNode, String str)
            throws TransformerException
    {
      return eval(contextNode, str, contextNode);
    }
  
    /**
     *  Evaluate XPath string to an XObject.
     *  XPath namespace prefixes are resolved from the namespaceNode.
     *  The implementation of this is a little slow, since it creates
     *  a number of objects each time it is called.  This could be optimized
     *  to keep the same objects around, but then thread-safety issues would arise.
     *
     *  @param contextNode The node to start searching from.
     *  @param str A valid XPath string.
     *  @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces.
     *  @return An XObject, which can be used to obtain a string, number, nodelist, etc, should never be null.
     *  @see XObject
     *  @see XNull
     *  @see XBoolean
     *  @see XNumber
     *  @see XString
     *  @see XRTreeFrag
     *
     * @throws TransformerException
     */
    public  XObject eval(Node contextNode, String str, Node namespaceNode)
            throws TransformerException
    {
  
      // Since we don't have a XML Parser involved here, install some default support
      // for things like namespaces, etc.
      // (Changed from: XPathContext xpathSupport = new XPathContext();
      //    because XPathContext is weak in a number of areas... perhaps
      //    XPathContext should be done away with.)
  
      // Create an object to resolve namespace prefixes.
      // XPath namespaces are resolved from the input context node's document element
      // if it is a root node, or else the current context node (for lack of a better
      // resolution space, given the simplicity of this sample code).
      PrefixResolverDefault prefixResolver = new PrefixResolverDefault(
        (namespaceNode.getNodeType() == Node.DOCUMENT_NODE)
        ? ((Document) namespaceNode).getDocumentElement() : namespaceNode);
  
      // Create the XPath object.
      XPath xpath = new XPath(str, null, prefixResolver, XPath.SELECT, null);
  
      // Execute the XPath, and have it return the result
      // return xpath.execute(xpathSupport, contextNode, prefixResolver);
      int ctxtNode = xpathSupport.getDTMHandleFromNode(contextNode);
  
      return xpath.execute(xpathSupport, ctxtNode, prefixResolver);
    }
  
    /**
     *   Evaluate XPath string to an XObject.
     *   XPath namespace prefixes are resolved from the namespaceNode.
     *   The implementation of this is a little slow, since it creates
     *   a number of objects each time it is called.  This could be optimized
     *   to keep the same objects around, but then thread-safety issues would arise.
     *
     *   @param contextNode The node to start searching from.
     *   @param str A valid XPath string.
     *   @param prefixResolver Will be called if the parser encounters namespace
     *                         prefixes, to resolve the prefixes to URLs.
     *   @return An XObject, which can be used to obtain a string, number, nodelist, etc, should never be null.
     *   @see XObject
     *   @see XNull
     *   @see XBoolean
     *   @see XNumber
     *   @see XString
     *   @see XRTreeFrag
     *
     * @throws TransformerException
     */
    public  XObject eval(
            Node contextNode, String str, PrefixResolver prefixResolver)
              throws TransformerException
    {
  
      // Since we don't have a XML Parser involved here, install some default support
      // for things like namespaces, etc.
      // (Changed from: XPathContext xpathSupport = new XPathContext();
      //    because XPathContext is weak in a number of areas... perhaps
      //    XPathContext should be done away with.)
      // Create the XPath object.
      XPath xpath = new XPath(str, null, prefixResolver, XPath.SELECT, null);
  
      // Execute the XPath, and have it return the result
      XPathContext xpathSupport = new XPathContext();
      int ctxtNode = xpathSupport.getDTMHandleFromNode(contextNode);
  
      return xpath.execute(xpathSupport, ctxtNode, prefixResolver);
    }
  }
  