Source for org.jfree.util.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: }