xstring.java

来自「java jdk 1.4的源码」· Java 代码 · 共 1,212 行 · 第 1/3 页

/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 1999 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 [e-mail].
 *
 * 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.xpath.objects;

//import org.w3c.dom.*;
import java.util.Locale;

import org.apache.xml.dtm.DTM;
import org.apache.xml.utils.XMLCharacterRecognizer;
import org.apache.xml.utils.XMLString;
import org.apache.xml.utils.XMLStringFactory;
import org.apache.xpath.ExpressionOwner;
import org.apache.xpath.XPathContext;
import org.apache.xpath.XPathVisitor;
import org.xml.sax.ContentHandler;
import org.xml.sax.SAXException;
import org.xml.sax.ext.LexicalHandler;

/**
 * <meta name="usage" content="general"/>
 * This class represents an XPath string object, and is capable of
 * converting the string to other types, such as a number.
 */
public class XString extends XObject implements XMLString
{

  /** Empty string XString object */
  public static XString EMPTYSTRING = new XString("");

  /**
   * Construct a XString object.  This constructor exists for derived classes.
   *
   * @param val String object this will wrap.
   */
  protected XString(Object val)
  {
    super(val);
  }

  /**
   * Construct a XNodeSet object.
   *
   * @param val String object this will wrap.
   */
  public XString(String val)
  {
    super(val);
  }

  /**
   * Tell that this is a CLASS_STRING.
   *
   * @return type CLASS_STRING
   */
  public int getType()
  {
    return CLASS_STRING;
  }

  /**
   * Given a request type, return the equivalent string.
   * For diagnostic purposes.
   *
   * @return type string "#STRING"
   */
  public String getTypeString()
  {
    return "#STRING";
  }

  /**
   * Tell if this object contains a java String object.
   *
   * @return true if this XMLString can return a string without creating one.
   */
  public boolean hasString()
  {
    return true;
  }

  /**
   * Cast result object to a number.
   *
   * @return 0.0 if this string is null, numeric value of this string
   * or NaN
   */
  public double num()
  {
    return toDouble();
  }

  /**
   * Convert a string to a double -- Allowed input is in fixed
   * notation ddd.fff.
   *
   * @return A double value representation of the string, or return Double.NaN
   * if the string can not be converted.
   */
  public double toDouble()
  {
    int end = length();
    
    if(0 == end)
      return Double.NaN;

    double result = 0.0;
    int start = 0;
    int punctPos = end-1;

    // Scan to first whitespace character.
    for (int i = start; i < end; i++)
    {
      char c = charAt(i);

      if (!XMLCharacterRecognizer.isWhiteSpace(c))
      {
        break;
      }
      else
        start++;
    }

    double sign = 1.0;

    if (start < end && charAt(start) == '-')
    {
      sign = -1.0;

      start++;
    }

    int digitsFound = 0;

    for (int i = start; i < end; i++)  // parse the string from left to right converting the integer part
    {
      char c = charAt(i);

      if (c != '.')
      {
        if (XMLCharacterRecognizer.isWhiteSpace(c))
          break;
        else if (Character.isDigit(c))
        {
          result = result * 10.0 + (c - 0x30);

          digitsFound++;
        }
        else
        {
          return Double.NaN;
        }
      }
      else
      {
        punctPos = i;

        break;
      }
    }

    if (charAt(punctPos) == '.')  // parse the string from the end to the '.' converting the fractional part
    {
      double fractPart = 0.0;

      for (int i = end - 1; i > punctPos; i--)
      {
        char c = charAt(i);

        if (XMLCharacterRecognizer.isWhiteSpace(c))
          break;
        else if (Character.isDigit(c))
        {
          fractPart = fractPart / 10.0 + (c - 0x30);

          digitsFound++;
        }
        else
        {
          return Double.NaN;
        }
      }

      result += fractPart / 10.0;
    }

    if (0 == digitsFound)
      return Double.NaN;

    return result * sign;
  }

  /**
   * Cast result object to a boolean.
   *
   * @return True if the length of this string object is greater
   * than 0.
   */
  public boolean bool()
  {
    return str().length() > 0;
  }

  /**
   * Cast result object to a string.
   *
   * @return The string this wraps or the empty string if null
   */
  public XMLString xstr()
  {
    return this;
  }

  /**
   * Cast result object to a string.
   *
   * @return The string this wraps or the empty string if null
   */
  public String str()
  {
    return (null != m_obj) ? ((String) m_obj) : "";
  }

  /**
   * Cast result object to a result tree fragment.
   *
   * @param support Xpath context to use for the conversion
   *
   * @return A document fragment with this string as a child node
   */
  public int rtf(XPathContext support)
  {

    DTM frag = support.createDocumentFragment();

    frag.appendTextChild(str());

    return frag.getDocument();
  }

  /**
   * Directly call the
   * characters method on the passed ContentHandler for the
   * string-value. Multiple calls to the
   * ContentHandler's characters methods may well occur for a single call to
   * this method.
   *
   * @param ch A non-null reference to a ContentHandler.
   *
   * @throws org.xml.sax.SAXException
   */
  public void dispatchCharactersEvents(org.xml.sax.ContentHandler ch)
          throws org.xml.sax.SAXException
  {

    String str = str();

    ch.characters(str.toCharArray(), 0, str.length());
  }

  /**
   * Directly call the
   * comment method on the passed LexicalHandler for the
   * string-value.
   *
   * @param lh A non-null reference to a LexicalHandler.
   *
   * @throws org.xml.sax.SAXException
   */
  public void dispatchAsComment(org.xml.sax.ext.LexicalHandler lh)
          throws org.xml.sax.SAXException
  {

    String str = str();

    lh.comment(str.toCharArray(), 0, str.length());
  }

  /**
   * Returns the length of this string.
   *
   * @return  the length of the sequence of characters represented by this
   *          object.
   */
  public int length()
  {
    return str().length();
  }

  /**
   * Returns the character at the specified index. An index ranges
   * from <code>0</code> to <code>length() - 1</code>. The first character
   * of the sequence is at index <code>0</code>, the next at index
   * <code>1</code>, and so on, as for array indexing.
   *
   * @param      index   the index of the character.
   * @return     the character at the specified index of this string.
   *             The first character is at index <code>0</code>.
   * @exception  IndexOutOfBoundsException  if the <code>index</code>
   *             argument is negative or not less than the length of this
   *             string.
   */
  public char charAt(int index)
  {
    return str().charAt(index);
  }

  /**
   * Copies characters from this string into the destination character
   * array.
   *
   * @param      srcBegin   index of the first character in the string
   *                        to copy.
   * @param      srcEnd     index after the last character in the string
   *                        to copy.
   * @param      dst        the destination array.
   * @param      dstBegin   the start offset in the destination array.
   * @exception IndexOutOfBoundsException If any of the following
   *            is true:
   *            <ul><li><code>srcBegin</code> is negative.
   *            <li><code>srcBegin</code> is greater than <code>srcEnd</code>
   *            <li><code>srcEnd</code> is greater than the length of this
   *                string
   *            <li><code>dstBegin</code> is negative
   *            <li><code>dstBegin+(srcEnd-srcBegin)</code> is larger than
   *                <code>dst.length</code></ul>
   * @exception NullPointerException if <code>dst</code> is <code>null</code>
   */
  public void getChars(int srcBegin, int srcEnd, char dst[], int dstBegin)
  {
    str().getChars(srcBegin, srcEnd, dst, dstBegin);
  }

  /**
   * Tell if two objects are functionally equal.
   *
   * @param obj2 Object to compare this to
   *
   * @return true if the two objects are equal
   *
   * @throws javax.xml.transform.TransformerException
   */
  public boolean equals(XObject obj2)
  {

    // In order to handle the 'all' semantics of 
    // nodeset comparisons, we always call the 
    // nodeset function.
    int t = obj2.getType();
    try
    {