LineBreakIterator


1   /* ========================================================================
2    * JCommon : a free general purpose class library for the Java(tm) platform
3    * ========================================================================
4    *
5    * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
6    * 
7    * Project Info:  http://www.jfree.org/jcommon/index.html
8    *
9    * This library is free software; you can redistribute it and/or modify it 
10   * under the terms of the GNU Lesser General Public License as published by 
11   * the Free Software Foundation; either version 2.1 of the License, or 
12   * (at your option) any later version.
13   *
14   * This library is distributed in the hope that it will be useful, but 
15   * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
16   * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
17   * License for more details.
18   *
19   * You should have received a copy of the GNU Lesser General Public
20   * License along with this library; if not, write to the Free Software
21   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
22   * USA.  
23   *
24   * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
25   * in the United States and other countries.]
26   *
27   * ----------------------
28   * LineBreakIterator.java
29   * ----------------------
30   * (C)opyright 2003, by Thomas Morgner and Contributors.
31   *
32   * Original Author:  Thomas Morgner;
33   * Contributor(s):   David Gilbert (for Object Refinery Limited);
34   *
35   * $Id: LineBreakIterator.java,v 1.4 2005/11/03 09:55:26 mungady Exp $
36   *
37   * Changes
38   * -------
39   * 13-03-2003 : Initial version
40   */
41  package org.jfree.util;
42  
43  import java.util.Iterator  ;
44  
45  /**
46   * An iterator that breaks text into lines.
47   * The result is equal to BufferedReader.readLine().
48   *
49   * @author Thomas Morgner
50   */
51  public class LineBreakIterator implements Iterator  
52  {
53    /** A useful constant. */
54    public static final int DONE = -1;
55  
56    /** Storage for the text. */
57    private char[] text;
58  
59    /** The current position. */
60    private int position;
61  
62    /**
63     * Default constructor.
64     */
65    public LineBreakIterator()
66    {
67      setText("");
68    }
69  
70    /**
71     * Creates a new line break iterator.
72     *
73     * @param text the text to be broken up.
74     */
75    public LineBreakIterator(final String   text)
76    {
77      setText(text);
78    }
79  
80    /**
81     * Returns the position of the next break.
82     *
83     * @return A position.
84     */
85    public synchronized int nextPosition()
86    {
87      if (this.text == null)
88      {
89        return DONE;
90      }
91      if (this.position == DONE)
92      {
93        return DONE;
94      }
95  
96      // recognize \n, \r, \r\n
97  
98      final int nChars = this.text.length;
99      int nextChar = this.position;
100 
101     for (;;)
102     {
103       if (nextChar >= nChars)
104       {
105         /* End of text reached */
106         this.position = DONE;
107         return DONE;
108       }
109 
110       boolean eol = false;
111       char c = 0;
112       int i;
113 
114       // search the next line break, either \n or \r
115       for (i = nextChar; i < nChars; i++)
116       {
117         c = this.text[i];
118         if ((c == '\n') || (c == '\r'))
119         {
120           eol = true;
121           break;
122         }
123       }
124 
125       nextChar = i;
126       if (eol)
127       {
128         nextChar++;
129         if (c == '\r')
130         {
131           if ((nextChar < nChars) && (this.text[nextChar] == '\n'))
132           {
133             nextChar++;
134           }
135         }
136         this.position = nextChar;
137         return (this.position);
138       }
139     }
140   }
141 
142   /**
143    * Same like next(), but returns the End-Of-Text as
144    * if there was a linebreak added (Reader.readLine() compatible)
145    *
146    * @return The next position.
147    */
148   public int nextWithEnd()
149   {
150     final int pos = this.position;
151     if (pos == DONE)
152     {
153       return DONE;
154     }
155     if (pos == this.text.length)
156     {
157       this.position = DONE;
158       return DONE;
159     }
160     final int retval = nextPosition();
161     if (retval == DONE)
162     {
163       return this.text.length;
164     }
165     return retval;
166   }
167 
168   /**
169    * Returns the text to be broken up.
170    *
171    * @return The text.
172    */
173   public String   getText()
174   {
175     return new String  (this.text);
176   }
177 
178   /**
179    * Sets the text to be broken up.
180    *
181    * @param text  the text.
182    */
183   public void setText(final String   text)
184   {
185     this.position = 0;
186     this.text = text.toCharArray();
187   }
188 
189   /**
190    * Returns <tt>true</tt> if the iteration has more elements. (In other
191    * words, returns <tt>true</tt> if <tt>next</tt> would return an element
192    * rather than throwing an exception.)
193    *
194    * @return <tt>true</tt> if the iterator has more elements.
195    */
196   public boolean hasNext()
197   {
198     return (this.position != DONE);
199   }
200 
201   /**
202    * Returns the next element in the iteration.
203    *
204    * @return the next element in the iteration.
205    */
206   public Object   next()
207   {
208     if (this.position == DONE)
209     {
210       // allready at the end ...
211       return null;
212     }
213 
214     final int lastFound = this.position;
215     int pos = nextWithEnd();
216     if (pos == DONE)
217     {
218       // the end of the text has been reached ...
219       return new String  (this.text, lastFound, this.text.length - lastFound);
220     }
221 
222     // step one char back
223     if (pos > 0)
224     {
225       final int end = lastFound;
226       for (; ((pos) > end) && ((this.text[pos - 1] == '\n') || this.text[pos - 1] == '\r'); pos--)
227       {
228         // search the end of the current linebreak sequence ..
229       }
230     }
231     //System.out.println ("text: " + new String (text));
232     //System.out.println ("pos: " + pos + " lastFound: " + lastFound);
233     return new String  (this.text, lastFound, pos - lastFound);
234   }
235 
236   /**
237    *
238    * Removes from the underlying collection the last element returned by the
239    * iterator (optional operation).  This method can be called only once per
240    * call to <tt>next</tt>.  The behavior of an iterator is unspecified if
241    * the underlying collection is modified while the iteration is in
242    * progress in any way other than by calling this method.
243    *
244    * @exception UnsupportedOperationException if the <tt>remove</tt>
245    *    operation is not supported by this Iterator.
246    * @exception IllegalStateException if the <tt>next</tt> method has not
247    *    yet been called, or the <tt>remove</tt> method has already
248    *    been called after the last call to the <tt>next</tt>
249    *    method.
250    */
251   public void remove()
252   {
253       throw new UnsupportedOperationException  ("This iterator is read-only.");
254   }
255 }
256
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags