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 * reserved comment block

 * 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: Extensions.java,v 1.2.4.1 2005/09/10 18:53:32 jeffsuttor Exp $

 */

package com.sun.org.apache.xalan.internal.lib;

import java.util.Hashtable;

import java.util.StringTokenizer;

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.parsers.ParserConfigurationException;

import com.sun.org.apache.xalan.internal.extensions.ExpressionContext;

import com.sun.org.apache.xalan.internal.xslt.EnvironmentCheck;

import com.sun.org.apache.xpath.internal.NodeSet;

import com.sun.org.apache.xpath.internal.objects.XBoolean;

import com.sun.org.apache.xpath.internal.objects.XNumber;

import com.sun.org.apache.xpath.internal.objects.XObject;

import com.sun.org.apache.xalan.internal.utils.ObjectFactory;

import org.w3c.dom.Document;

import org.w3c.dom.DocumentFragment;

import org.w3c.dom.Node;

import org.w3c.dom.NodeList;

import org.w3c.dom.Text;

import org.w3c.dom.traversal.NodeIterator;

import org.xml.sax.SAXNotSupportedException;

/**

 * This class contains many of the Xalan-supplied extensions.

 * It is accessed by specifying a namespace URI as follows:

 * <pre>

 *    xmlns:xalan="http://xml.apache.org/xalan"

 * </pre>

 * @xsl.usage general

 */

public class Extensions

{

  /**

   * Constructor Extensions

   *

   */

  private Extensions(){}  // Make sure class cannot be instantiated

  /**

   * This method is an extension that implements as a Xalan extension

   * the node-set function also found in xt and saxon.

   * If the argument is a Result Tree Fragment, then <code>nodeset</code>

   * returns a node-set consisting of a single root node as described in

   * section 11.1 of the XSLT 1.0 Recommendation.  If the argument is a

   * node-set, <code>nodeset</code> returns a node-set.  If the argument

   * is a string, number, or boolean, then <code>nodeset</code> returns

   * a node-set consisting of a single root node with a single text node

   * child that is the result of calling the XPath string() function on the

   * passed parameter.  If the argument is anything else, then a node-set

   * is returned consisting of a single root node with a single text node

   * child that is the result of calling the java <code>toString()</code>

   * method on the passed argument.

   * Most of the

   * actual work here is done in <code>MethodResolver</code> and

   * <code>XRTreeFrag</code>.

   * @param myProcessor Context passed by the extension processor

   * @param rtf Argument in the stylesheet to the nodeset extension function

   *

   * NEEDSDOC ($objectName$) @return

   */

  public static NodeSet nodeset(ExpressionContext myProcessor, Object rtf)

  {

    String textNodeValue;

    if (rtf instanceof NodeIterator)

    {

      return new NodeSet((NodeIterator) rtf);

    }

    else

    {

      if (rtf instanceof String)

      {

        textNodeValue = (String) rtf;

      }

      else if (rtf instanceof Boolean)

      {

        textNodeValue = new XBoolean(((Boolean) rtf).booleanValue()).str();

      }

      else if (rtf instanceof Double)

      {

        textNodeValue = new XNumber(((Double) rtf).doubleValue()).str();

      }

      else

      {

        textNodeValue = rtf.toString();

      }

      // This no longer will work right since the DTM.

      // Document myDoc = myProcessor.getContextNode().getOwnerDocument();

      try

      {

        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

        DocumentBuilder db = dbf.newDocumentBuilder();

        Document myDoc = db.newDocument();

        Text textNode = myDoc.createTextNode(textNodeValue);

        DocumentFragment docFrag = myDoc.createDocumentFragment();

        docFrag.appendChild(textNode);

        return new NodeSet(docFrag);

      }

      catch(ParserConfigurationException pce)

      {

        throw new com.sun.org.apache.xml.internal.utils.WrappedRuntimeException(pce);

      }

    }

  }

  /**

   * Returns the intersection of two node-sets.

   *

   * @param nl1 NodeList for first node-set

   * @param nl2 NodeList for second node-set

   * @return a NodeList containing the nodes in nl1 that are also in nl2

   *

   * Note: The usage of this extension function in the xalan namespace

   * is deprecated. Please use the same function in the EXSLT sets extension

   * (http://exslt.org/sets).

   */

  public static NodeList intersection(NodeList nl1, NodeList nl2)

  {

    return ExsltSets.intersection(nl1, nl2);

  }

  /**

   * Returns the difference between two node-sets.

   *

   * @param nl1 NodeList for first node-set

   * @param nl2 NodeList for second node-set

   * @return a NodeList containing the nodes in nl1 that are not in nl2

   *

   * Note: The usage of this extension function in the xalan namespace

   * is deprecated. Please use the same function in the EXSLT sets extension

   * (http://exslt.org/sets).

   */

  public static NodeList difference(NodeList nl1, NodeList nl2)

  {

    return ExsltSets.difference(nl1, nl2);

  }

  /**

   * Returns node-set containing distinct string values.

   *

   * @param nl NodeList for node-set

   * @return a NodeList with nodes from nl containing distinct string values.

   * In other words, if more than one node in nl contains the same string value,

   * only include the first such node found.

   *

   * Note: The usage of this extension function in the xalan namespace

   * is deprecated. Please use the same function in the EXSLT sets extension

   * (http://exslt.org/sets).

   */

  public static NodeList distinct(NodeList nl)

  {

    return ExsltSets.distinct(nl);

  }

  /**

   * Returns true if both node-sets contain the same set of nodes.

   *

   * @param nl1 NodeList for first node-set

   * @param nl2 NodeList for second node-set

   * @return true if nl1 and nl2 contain exactly the same set of nodes.

   */

  public static boolean hasSameNodes(NodeList nl1, NodeList nl2)

  {

    NodeSet ns1 = new NodeSet(nl1);

    NodeSet ns2 = new NodeSet(nl2);

    if (ns1.getLength() != ns2.getLength())

      return false;

    for (int i = 0; i < ns1.getLength(); i++)

    {

      Node n = ns1.elementAt(i);

      if (!ns2.contains(n))

        return false;

    }

    return true;

  }

  /**

   * Returns the result of evaluating the argument as a string containing

   * an XPath expression.  Used where the XPath expression is not known until

   * run-time.  The expression is evaluated as if the run-time value of the

   * argument appeared in place of the evaluate function call at compile time.

   *

   * @param myContext an <code>ExpressionContext</code> passed in by the

   *                  extension mechanism.  This must be an XPathContext.

   * @param xpathExpr The XPath expression to be evaluated.

   * @return the XObject resulting from evaluating the XPath

   *

   * @throws SAXNotSupportedException

   *

   * Note: The usage of this extension function in the xalan namespace

   * is deprecated. Please use the same function in the EXSLT dynamic extension

   * (http://exslt.org/dynamic).

   */

  public static XObject evaluate(ExpressionContext myContext, String xpathExpr)

         throws SAXNotSupportedException

  {

    return ExsltDynamic.evaluate(myContext, xpathExpr);

  }

  /**

   * Returns a NodeSet containing one text node for each token in the first argument.

   * Delimiters are specified in the second argument.

   * Tokens are determined by a call to <code>StringTokenizer</code>.

   * If the first argument is an empty string or contains only delimiters, the result

   * will be an empty NodeSet.

   *

   * Contributed to XalanJ1 by <a href="mailto:benoit.cerrina@writeme.com">Benoit Cerrina</a>.

   *

   * @param toTokenize The string to be split into text tokens.

   * @param delims The delimiters to use.

   * @return a NodeSet as described above.

   */

  public static NodeList tokenize(String toTokenize, String delims)

  {

    Document doc = DocumentHolder.m_doc;

    StringTokenizer lTokenizer = new StringTokenizer(toTokenize, delims);

    NodeSet resultSet = new NodeSet();

    synchronized (doc)

    {

      while (lTokenizer.hasMoreTokens())

      {

        resultSet.addNode(doc.createTextNode(lTokenizer.nextToken()));

      }

    }

    return resultSet;

  }

  /**

   * Returns a NodeSet containing one text node for each token in the first argument.

   * Delimiters are whitespace.  That is, the delimiters that are used are tab (&#x09),

   * linefeed (&#x0A), return (&#x0D), and space (&#x20).

   * Tokens are determined by a call to <code>StringTokenizer</code>.

   * If the first argument is an empty string or contains only delimiters, the result

   * will be an empty NodeSet.

   *

   * Contributed to XalanJ1 by <a href="mailto:benoit.cerrina@writeme.com">Benoit Cerrina</a>.

   *

   * @param toTokenize The string to be split into text tokens.

   * @return a NodeSet as described above.

   */

  public static NodeList tokenize(String toTokenize)

  {

    return tokenize(toTokenize, " \t\n\r");

  }

  /**

   * Return a Node of basic debugging information from the

   * EnvironmentCheck utility about the Java environment.

   *

   * <p>Simply calls the {@link com.sun.org.apache.xalan.internal.xslt.EnvironmentCheck}

   * utility to grab info about the Java environment and CLASSPATH,

   * etc., and then returns the resulting Node.  Stylesheets can

   * then maniuplate this data or simply xsl:copy-of the Node.  Note

   * that we first attempt to load the more advanced

   * org.apache.env.Which utility by reflection; only if that fails

   * to we still use the internal version.  Which is available from

   * <a href="http://xml.apache.org/commons/">http://xml.apache.org/commons/</a>.</p>

   *

   * <p>We throw a WrappedRuntimeException in the unlikely case

   * that reading information from the environment throws us an

   * exception. (Is this really the best thing to do?)</p>

   *

   * @param myContext an <code>ExpressionContext</code> passed in by the

   *                  extension mechanism.  This must be an XPathContext.

   * @return a Node as described above.

   */

  public static Node checkEnvironment(ExpressionContext myContext)

  {

    Document factoryDocument;

    try

    {

      DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

      DocumentBuilder db = dbf.newDocumentBuilder();

      factoryDocument = db.newDocument();

    }

    catch(ParserConfigurationException pce)

    {

      throw new com.sun.org.apache.xml.internal.utils.WrappedRuntimeException(pce);

    }

    Node resultNode = null;

    try

    {

      // First use reflection to try to load Which, which is a

      //  better version of EnvironmentCheck

      resultNode = checkEnvironmentUsingWhich(myContext, factoryDocument);

      if (null != resultNode)

        return resultNode;

      // If reflection failed, fallback to our internal EnvironmentCheck

      EnvironmentCheck envChecker = new EnvironmentCheck();

      Hashtable h = envChecker.getEnvironmentHash();

      resultNode = factoryDocument.createElement("checkEnvironmentExtension");

      envChecker.appendEnvironmentReport(resultNode, factoryDocument, h);

      envChecker = null;

    }

    catch(Exception e)

    {

      throw new com.sun.org.apache.xml.internal.utils.WrappedRuntimeException(e);

    }

    return resultNode;

  }

  /**

   * Private worker method to attempt to use org.apache.env.Which.

   *

   * @param myContext an <code>ExpressionContext</code> passed in by the

   *                  extension mechanism.  This must be an XPathContext.

   * @param factoryDocument providing createElement services, etc.

   * @return a Node with environment info; null if any error

   */

  private static Node checkEnvironmentUsingWhich(ExpressionContext myContext,

        Document factoryDocument)

  {

    final String WHICH_CLASSNAME = "org.apache.env.Which";

    final String WHICH_METHODNAME = "which";

    final Class WHICH_METHOD_ARGS[] = { java.util.Hashtable.class,

                                        java.lang.String.class,

                                        java.lang.String.class };

    try

    {

      // Use reflection to try to find xml-commons utility 'Which'

      Class clazz = ObjectFactory.findProviderClass(WHICH_CLASSNAME, true);

      if (null == clazz)

        return null;

      // Fully qualify names since this is the only method they're used in

      java.lang.reflect.Method method = clazz.getMethod(WHICH_METHODNAME, WHICH_METHOD_ARGS);

      Hashtable report = new Hashtable();

      // Call the method with our Hashtable, common options, and ignore return value

      Object[] methodArgs = { report, "XmlCommons;Xalan;Xerces;Crimson;Ant", "" };

      Object returnValue = method.invoke(null, methodArgs);

      // Create a parent to hold the report and append hash to it

      Node resultNode = factoryDocument.createElement("checkEnvironmentExtension");

      com.sun.org.apache.xml.internal.utils.Hashtree2Node.appendHashToNode(report, "whichReport",

            resultNode, factoryDocument);

      return resultNode;

    }

    catch (Throwable t)

    {

      // Simply return null; no need to report error

      return null;

    }

  }

    /**

     * This class is not loaded until first referenced (see Java Language

     * Specification by Gosling/Joy/Steele, section 12.4.1)

     *

     * The static members are created when this class is first referenced, as a

     * lazy initialization not needing checking against null or any

     * synchronization.

     *

     */

    private static class DocumentHolder

    {

        // Reuse the Document object to reduce memory usage.

        private static final Document m_doc;

        static

        {

            try

            {

                m_doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();

            }

            catch(ParserConfigurationException pce)

            {

                  throw new com.sun.org.apache.xml.internal.utils.WrappedRuntimeException(pce);

            }

        }

    }

}