/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/*

 * 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: ExsltSets.java,v 1.1.2.1 2005/08/01 02:08:50 jeffsuttor Exp $

 */

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

import java.util.Hashtable;

import com.sun.org.apache.xml.internal.utils.DOMHelper;

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

import org.w3c.dom.Node;

import org.w3c.dom.NodeList;

/**

 * This class contains EXSLT set extension functions.

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

 * <pre>

 *    xmlns:set="http://exslt.org/sets"

 * </pre>

 *

 * The documentation for each function has been copied from the relevant

 * EXSLT Implementer page.

 *

 * @see <a href="http://www.exslt.org/">EXSLT</a>

 * @xsl.usage general

 */

public class ExsltSets extends ExsltBase

{

  /**

   * The set:leading function returns the nodes in the node set passed as the first argument that

   * precede, in document order, the first node in the node set passed as the second argument. If

   * the first node in the second node set is not contained in the first node set, then an empty

   * node set is returned. If the second node set is empty, then the first node set is returned.

   *

   * @param nl1 NodeList for first node-set.

   * @param nl2 NodeList for second node-set.

   * @return a NodeList containing the nodes in nl1 that precede in document order the first

   * node in nl2; an empty node-set if the first node in nl2 is not in nl1; all of nl1 if nl2

   * is empty.

   *

   * @see <a href="http://www.exslt.org/">EXSLT</a>

   */

  public static NodeList leading (NodeList nl1, NodeList nl2)

  {

    if (nl2.getLength() == 0)

      return nl1;

    NodeSet ns1 = new NodeSet(nl1);

    NodeSet leadNodes = new NodeSet();

    Node endNode = nl2.item(0);

    if (!ns1.contains(endNode))

      return leadNodes; // empty NodeSet

    for (int i = 0; i < nl1.getLength(); i++)

    {

      Node testNode = nl1.item(i);

      if (DOMHelper.isNodeAfter(testNode, endNode)

          && !DOMHelper.isNodeTheSame(testNode, endNode))

        leadNodes.addElement(testNode);

    }

    return leadNodes;

  }

  /**

   * The set:trailing function returns the nodes in the node set passed as the first argument that

   * follow, in document order, the first node in the node set passed as the second argument. If

   * the first node in the second node set is not contained in the first node set, then an empty

   * node set is returned. If the second node set is empty, then the first node set is returned.

   *

   * @param nl1 NodeList for first node-set.

   * @param nl2 NodeList for second node-set.

   * @return a NodeList containing the nodes in nl1 that follow in document order the first

   * node in nl2; an empty node-set if the first node in nl2 is not in nl1; all of nl1 if nl2

   * is empty.

   *

   * @see <a href="http://www.exslt.org/">EXSLT</a>

   */

  public static NodeList trailing (NodeList nl1, NodeList nl2)

  {

    if (nl2.getLength() == 0)

      return nl1;

    NodeSet ns1 = new NodeSet(nl1);

    NodeSet trailNodes = new NodeSet();

    Node startNode = nl2.item(0);

    if (!ns1.contains(startNode))

      return trailNodes; // empty NodeSet

    for (int i = 0; i < nl1.getLength(); i++)

    {

      Node testNode = nl1.item(i);

      if (DOMHelper.isNodeAfter(startNode, testNode)

          && !DOMHelper.isNodeTheSame(startNode, testNode))

        trailNodes.addElement(testNode);

    }

    return trailNodes;

  }

  /**

   * The set:intersection function returns a node set comprising the nodes that are within

   * both the node sets passed as arguments to it.

   *

   * @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.

   *

   * @see <a href="http://www.exslt.org/">EXSLT</a>

   */

  public static NodeList intersection(NodeList nl1, NodeList nl2)

  {

    NodeSet ns1 = new NodeSet(nl1);

    NodeSet ns2 = new NodeSet(nl2);

    NodeSet inter = new NodeSet();

    inter.setShouldCacheNodes(true);

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

    {

      Node n = ns1.elementAt(i);

      if (ns2.contains(n))

        inter.addElement(n);

    }

    return inter;

  }

  /**

   * The set:difference function returns the difference between two node sets - those nodes that

   * are in the node set passed as the first argument that are not in the node set passed as the

   * second argument.

   *

   * @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.

   *

   * @see <a href="http://www.exslt.org/">EXSLT</a>

   */

  public static NodeList difference(NodeList nl1, NodeList nl2)

  {

    NodeSet ns1 = new NodeSet(nl1);

    NodeSet ns2 = new NodeSet(nl2);

    NodeSet diff = new NodeSet();

    diff.setShouldCacheNodes(true);

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

    {

      Node n = ns1.elementAt(i);

      if (!ns2.contains(n))

        diff.addElement(n);

    }

    return diff;

  }

  /**

   * The set:distinct function returns a subset of the nodes contained in the node-set NS passed

   * as the first argument. Specifically, it selects a node N if there is no node in NS that has

   * the same string value as N, and that precedes N in document order.

   *

   * @param nl NodeList for the 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.

   *

   * @see <a href="http://www.exslt.org/">EXSLT</a>

   */

  public static NodeList distinct(NodeList nl)

  {

    NodeSet dist = new NodeSet();

    dist.setShouldCacheNodes(true);

    Hashtable stringTable = new Hashtable();

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

    {

      Node currNode = nl.item(i);

      String key = toString(currNode);

      if (key == null)

        dist.addElement(currNode);

      else if (!stringTable.containsKey(key))

      {

        stringTable.put(key, currNode);

        dist.addElement(currNode);

      }

    }

    return dist;

  }

  /**

   * The set:has-same-node function returns true if the node set passed as the first argument shares

   * any nodes with the node set passed as the second argument. If there are no nodes that are in both

   * node sets, then it returns false.

   *

   * The Xalan extensions MethodResolver converts 'has-same-node' to 'hasSameNode'.

   *

   * Note: Not to be confused with hasSameNodes in the Xalan namespace, which returns true if

   * the two node sets contain the exactly the same nodes (perhaps in a different order),

   * otherwise false.

   *

   * @see <a href="http://www.exslt.org/">EXSLT</a>

   */

  public static boolean hasSameNode(NodeList nl1, NodeList nl2)

  {

    NodeSet ns1 = new NodeSet(nl1);

    NodeSet ns2 = new NodeSet(nl2);

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

    {

      if (ns2.contains(ns1.elementAt(i)))

        return true;

    }

    return false;

  }

}