Package org.apache.xalan.lib

Source Code of org.apache.xalan.lib.ExsltStrings

/*
* The Apache Software License, Version 1.1
*
*
* Copyright (c) 1999-2003 The Apache Software Foundation.  All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in
*    the documentation and/or other materials provided with the
*    distribution.
*
* 3. The end-user documentation included with the redistribution,
*    if any, must include the following acknowledgment:
*       "This product includes software developed by the
*        Apache Software Foundation (http://www.apache.org/)."
*    Alternately, this acknowledgment may appear in the software itself,
*    if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Xalan" and "Apache Software Foundation" must
*    not be used to endorse or promote products derived from this
*    software without prior written permission. For written
*    permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache",
*    nor may "Apache" appear in their name, without prior written
*    permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation and was
* originally based on software copyright (c) 1999, Lotus
* Development Corporation., http://www.lotus.com.  For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*/
package org.apache.xalan.lib;

import java.util.StringTokenizer;

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.apache.xpath.NodeSet;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.Text;

/**
* <meta name="usage" content="general"/>
* This class contains EXSLT strings extension functions.
*
* It is accessed by specifying a namespace URI as follows:
* <pre>
*    xmlns:str="http://exslt.org/strings"
* </pre>
* The documentation for each function has been copied from the relevant
* EXSLT Implementer page.
*
* @see <a href="http://www.exslt.org/">EXSLT</a>

*/
public class ExsltStrings extends ExsltBase
{
  // Reuse the Document object to reduce memory usage.
  private static Document m_doc = null;
  private static ExsltStrings m_instance = new ExsltStrings();

  /**
   * The str:align function aligns a string within another string.
   * <p>
   * The first argument gives the target string to be aligned. The second argument gives
   * the padding string within which it is to be aligned.
   * <p>
   * If the target string is shorter than the padding string then a range of characters
   * in the padding string are repaced with those in the target string. Which characters
   * are replaced depends on the value of the third argument, which gives the type of
   * alignment. It can be one of 'left', 'right' or 'center'. If no third argument is
   * given or if it is not one of these values, then it defaults to left alignment.
   * <p>
   * With left alignment, the range of characters replaced by the target string begins
   * with the first character in the padding string. With right alignment, the range of
   * characters replaced by the target string ends with the last character in the padding
   * string. With center alignment, the range of characters replaced by the target string
   * is in the middle of the padding string, such that either the number of unreplaced
   * characters on either side of the range is the same or there is one less on the left
   * than there is on the right.
   * <p>
   * If the target string is longer than the padding string, then it is truncated to be
   * the same length as the padding string and returned.
   *
   * @param targetStr The target string
   * @param paddingStr The padding string
   * @param type The type of alignment
   *
   * @return The string after alignment
   */
  public static String align(String targetStr, String paddingStr, String type)
  {
    if (targetStr.length() >= paddingStr.length())
      return targetStr.substring(0, paddingStr.length());
   
    if (type.equals("right"))
    {
      return paddingStr.substring(0, paddingStr.length() - targetStr.length()) + targetStr;
    }
    else if (type.equals("center"))
    {
      int startIndex = (paddingStr.length() - targetStr.length()) / 2;
      return paddingStr.substring(0, startIndex) + targetStr + paddingStr.substring(startIndex + targetStr.length());
    }
    // Default is left
    else
    {
      return targetStr + paddingStr.substring(paddingStr.length() - targetStr.length());
    }   
  }

  /**
   * See above
   */
  public static String align(String targetStr, String paddingStr)
  {
    return align(targetStr, paddingStr, "left");
  }
 
  /**
   * The str:concat function takes a node set and returns the concatenation of the
   * string values of the nodes in that node set. If the node set is empty, it returns
   * an empty string.
   *
   * @param nl A node set
   * @return The concatenation of the string values of the nodes in that node set
   */
  public static String concat(NodeList nl)
  {
    StringBuffer sb = new StringBuffer();
    for (int i = 0; i < nl.getLength(); i++)
    {
      Node node = nl.item(i);
      String value = toString(node);
     
      if (value != null && value.length() > 0)
        sb.append(value);
    }
   
    return sb.toString();
  }
   
  /**
   * The str:padding function creates a padding string of a certain length.
   * The first argument gives the length of the padding string to be created.
   * The second argument gives a string to be used to create the padding. This
   * string is repeated as many times as is necessary to create a string of the
   * length specified by the first argument; if the string is more than a character
   * long, it may have to be truncated to produce the required length. If no second
   * argument is specified, it defaults to a space (' '). If the second argument is
   * an empty string, str:padding returns an empty string.
   *
   * @param length The length of the padding string to be created
   * @param pattern The string to be used as pattern
   *
   * @return A padding string of the given length
   */
  public static String padding(double length, String pattern)
  {
    if (pattern == null || pattern.length() == 0)
      return "";
   
    StringBuffer sb = new StringBuffer();
    int len = (int)length;
    int numAdded = 0;
    int index = 0;
    while (numAdded < len)
    {
      if (index == pattern.length())
        index = 0;
       
      sb.append(pattern.charAt(index));
      index++;
      numAdded++;
    }
 
    return sb.toString();
  }

  /**
   * See above
   */
  public static String padding(double length)
  {
    return padding(length, " ");
  }
   
  /**
   * The str:split function splits up a string and returns a node set of token
   * elements, each containing one token from the string.
   * <p>
   * The first argument is the string to be split. The second argument is a pattern
   * string. The string given by the first argument is split at any occurrence of
   * this pattern. For example:
   * <pre>
   * str:split('a, simple, list', ', ') gives the node set consisting of:
   *
   * <token>a</token>
   * <token>simple</token>
   * <token>list</token>
   * </pre>
   * If the second argument is omitted, the default is the string '&#x20;' (i.e. a space).
   *
   * @param str The string to be split
   * @param pattern The pattern
   *
   * @return A node set of split tokens
   */
  public static NodeList split(String str, String pattern)
  {
    try
    {
      // Lock the instance to ensure thread safety
      if (m_doc == null)
      {
        synchronized (m_instance)
        {
          if (m_doc == null)
            m_doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();
        }
      }
    }
    catch(ParserConfigurationException pce)
    {
      throw new org.apache.xml.utils.WrappedRuntimeException(pce);
    }
   
    NodeSet resultSet = new NodeSet();
    resultSet.setShouldCacheNodes(true);
   
    boolean done = false;
    int fromIndex = 0;
    int matchIndex = 0;
    String token = null;
   
    while (!done && fromIndex < str.length())
    {
      matchIndex = str.indexOf(pattern, fromIndex);
      if (matchIndex >= 0)
      {
  token = str.substring(fromIndex, matchIndex);
  fromIndex = matchIndex + pattern.length();
      }
      else
      {
        done = true;
        token = str.substring(fromIndex);
      }
       
      synchronized (m_doc)
      {
        Element element = m_doc.createElement("token");
        Text text = m_doc.createTextNode(token);
        element.appendChild(text);
        resultSet.addNode(element);     
      }
    }
   
    return resultSet;
  }
 
  /**
   * See above
   */
  public static NodeList split(String str)
  {
    return split(str, " ");
  }

  /**
   * The str:tokenize function splits up a string and returns a node set of token
   * elements, each containing one token from the string.
   * <p>
   * The first argument is the string to be tokenized. The second argument is a
   * string consisting of a number of characters. Each character in this string is
   * taken as a delimiting character. The string given by the first argument is split
   * at any occurrence of any of these characters. For example:
   * <pre>
   * str:tokenize('2001-06-03T11:40:23', '-T:') gives the node set consisting of:
   *
   * <token>2001</token>
   * <token>06</token>
   * <token>03</token>
   * <token>11</token>
   * <token>40</token>
   * <token>23</token>
   * </pre>
   * If the second argument is omitted, the default is the string '&#x9;&#xA;&#xD;&#x20;'
   * (i.e. whitespace characters).
   * <p>
   * If the second argument is an empty string, the function returns a set of token
   * elements, each of which holds a single character.
   * <p>
   * Note: This one is different from the tokenize extension function in the Xalan
   * namespace. The one in Xalan returns a set of Text nodes, while this one wraps
   * the Text nodes inside the token Element nodes.
   *
   * @param toTokenize The string to be tokenized
   * @param delims The delimiter string
   *
   * @return A node set of split token elements
   */
  public static NodeList tokenize(String toTokenize, String delims)
  {
    try
    {
      // Lock the instance to ensure thread safety
      if (m_doc == null)
      {
        synchronized (m_instance)
        {
          if (m_doc == null)
            m_doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();
        }
      }
    }
    catch(ParserConfigurationException pce)
    {
      throw new org.apache.xml.utils.WrappedRuntimeException(pce);
    }

    NodeSet resultSet = new NodeSet();
   
    if (delims != null && delims.length() > 0)
    {
      StringTokenizer lTokenizer = new StringTokenizer(toTokenize, delims);

      synchronized (m_doc)
      {
        while (lTokenizer.hasMoreTokens())
        {
          Element element = m_doc.createElement("token");
          element.appendChild(m_doc.createTextNode(lTokenizer.nextToken()));
          resultSet.addNode(element);     
        }
      }
    }
    // If the delimiter is an empty string, create one token Element for
    // every single character.
    else
    {
      synchronized (m_doc)
      {
        for (int i = 0; i < toTokenize.length(); i++)
        {
          Element element = m_doc.createElement("token");
          element.appendChild(m_doc.createTextNode(toTokenize.substring(i, i+1)));
          resultSet.addNode(element);             
        }
      }
    }

    return resultSet;
  }

  /**
   * See above
   */
  public static NodeList tokenize(String toTokenize)
  {
    return tokenize(toTokenize, " \t\n\r");
  }
 
}
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