XStringForChars


1   /*
2    * Copyright 1999-2004 The Apache Software Foundation.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *     http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  /*
17   * $Id: XStringForChars.java,v 1.8 2004/02/17 04:34:38 minchau Exp $
18   */
19  package org.apache.xpath.objects;
20  
21  import org.apache.xalan.res.XSLMessages;
22  import org.apache.xml.utils.FastStringBuffer;
23  import org.apache.xpath.res.XPATHErrorResources;
24  
25  
26  /**
27   * This class will wrap a FastStringBuffer and allow for
28   */
29  public class XStringForChars extends XString
30  {
31    /** The start position in the fsb. */
32    int m_start;
33    
34    /** The length of the string. */
35    int m_length;
36    
37    protected String   m_strCache = null;
38    
39    /**
40     * Construct a XNodeSet object.
41     *
42     * @param val FastStringBuffer object this will wrap, must be non-null.
43     * @param start The start position in the array.
44     * @param length The number of characters to read from the array.
45     */
46    public XStringForChars(char[] val, int start, int length)
47    {
48      super(val);
49      m_start = start;
50      m_length = length;
51      if(null == val)
52        throw new IllegalArgumentException  (
53                            XSLMessages.createXPATHMessage(XPATHErrorResources.ER_FASTSTRINGBUFFER_CANNOT_BE_NULL, null)); //"The FastStringBuffer argument can not be null!!");
54    }
55  
56  
57    /**
58     * Construct a XNodeSet object.
59     *
60     * @param val String object this will wrap.
61     */
62    private XStringForChars(String   val)
63    {
64      super(val);
65      throw new IllegalArgumentException  (
66                        XSLMessages.createXPATHMessage(XPATHErrorResources.ER_XSTRINGFORCHARS_CANNOT_TAKE_STRING, null)); //"XStringForChars can not take a string for an argument!");
67    }
68    
69    /**
70     * Cast result object to a string.
71     *
72     * @return The string this wraps or the empty string if null
73     */
74    public FastStringBuffer fsb()
75    {
76      throw new RuntimeException  (XSLMessages.createXPATHMessage(XPATHErrorResources.ER_FSB_NOT_SUPPORTED_XSTRINGFORCHARS, null)); //"fsb() not supported for XStringForChars!");
77    }
78    
79    /**
80     * Cast result object to a string.
81     *
82     * @return The string this wraps or the empty string if null
83     */
84    public void appendToFsb(org.apache.xml.utils.FastStringBuffer fsb)
85    {
86      fsb.append((char[])m_obj, m_start, m_length);
87    }
88  
89    
90    /**
91     * Tell if this object contains a java String object.
92     * 
93     * @return true if this XMLString can return a string without creating one.
94     */
95    public boolean hasString()
96    {
97      return (null != m_strCache);
98    }
99  
100   
101   /**
102    * Cast result object to a string.
103    *
104    * @return The string this wraps or the empty string if null
105    */
106   public String   str()
107   {
108     if(null == m_strCache)
109       m_strCache = new String  ((char[])m_obj, m_start, m_length);
110     
111     return m_strCache;
112   }
113   
114 
115   /**
116    * Since this object is incomplete without the length and the offset, we 
117    * have to convert to a string when this function is called.
118    *
119    * @return The java String representation of this object.
120    */
121   public Object   object()
122   {
123     return str();
124   }
125 
126   /**
127    * Directly call the
128    * characters method on the passed ContentHandler for the
129    * string-value. Multiple calls to the
130    * ContentHandler's characters methods may well occur for a single call to
131    * this method.
132    *
133    * @param ch A non-null reference to a ContentHandler.
134    *
135    * @throws org.xml.sax.SAXException
136    */
137   public void dispatchCharactersEvents(org.xml.sax.ContentHandler   ch)
138       throws org.xml.sax.SAXException  
139   {
140     ch.characters((char[])m_obj, m_start, m_length);
141   }
142       
143   /**
144    * Directly call the
145    * comment method on the passed LexicalHandler for the
146    * string-value.
147    *
148    * @param lh A non-null reference to a LexicalHandler.
149    *
150    * @throws org.xml.sax.SAXException
151    */
152   public void dispatchAsComment(org.xml.sax.ext.LexicalHandler   lh)
153       throws org.xml.sax.SAXException  
154   {
155     lh.comment((char[])m_obj, m_start, m_length);
156   }
157   
158   /**
159    * Returns the length of this string.
160    *
161    * @return  the length of the sequence of characters represented by this
162    *          object.
163    */
164   public int length()
165   {
166     return m_length;
167   }
168 
169   /**
170    * Returns the character at the specified index. An index ranges
171    * from <code>0</code> to <code>length() - 1</code>. The first character
172    * of the sequence is at index <code>0</code>, the next at index
173    * <code>1</code>, and so on, as for array indexing.
174    *
175    * @param      index   the index of the character.
176    * @return     the character at the specified index of this string.
177    *             The first character is at index <code>0</code>.
178    * @exception  IndexOutOfBoundsException  if the <code>index</code>
179    *             argument is negative or not less than the length of this
180    *             string.
181    */
182   public char charAt(int index)
183   {
184     return ((char[])m_obj)[index+m_start];
185   }
186 
187   /**
188    * Copies characters from this string into the destination character
189    * array.
190    *
191    * @param      srcBegin   index of the first character in the string
192    *                        to copy.
193    * @param      srcEnd     index after the last character in the string
194    *                        to copy.
195    * @param      dst        the destination array.
196    * @param      dstBegin   the start offset in the destination array.
197    * @exception IndexOutOfBoundsException If any of the following
198    *            is true:
199    *            <ul><li><code>srcBegin</code> is negative.
200    *            <li><code>srcBegin</code> is greater than <code>srcEnd</code>
201    *            <li><code>srcEnd</code> is greater than the length of this
202    *                string
203    *            <li><code>dstBegin</code> is negative
204    *            <li><code>dstBegin+(srcEnd-srcBegin)</code> is larger than
205    *                <code>dst.length</code></ul>
206    * @exception NullPointerException if <code>dst</code> is <code>null</code>
207    */
208   public void getChars(int srcBegin, int srcEnd, char dst[], int dstBegin)
209   {
210     System.arraycopy((char[])m_obj, m_start+srcBegin, dst, dstBegin, srcEnd);
211   }
212   
213 }
214
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