Source for java.util.StringTokenizer

   1: /* StringTokenizer -- breaks a String into tokens
   2:    Copyright (C) 1998, 1999, 2001, 2002, 2005  Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: 
  39: package java.util;
  40: 
  41: /**
  42:  * This class splits a string into tokens.  The caller can set on which
  43:  * delimiters the string should be split and if the delimiters should be
  44:  * returned. This is much simpler than {@link java.io.StreamTokenizer}.
  45:  *
  46:  * <p>You may change the delimiter set on the fly by calling
  47:  * nextToken(String).  But the semantic is quite difficult; it even
  48:  * depends on calling <code>hasMoreTokens()</code>.  You should call
  49:  * <code>hasMoreTokens()</code> before, otherwise the old delimiters
  50:  * after the last token are candidates for being returned.
  51:  *
  52:  * <p>If you want to get the delimiters, you have to use the three argument
  53:  * constructor.  The delimiters are returned as token consisting of a
  54:  * single character.
  55:  *
  56:  * @author Jochen Hoenicke
  57:  * @author Warren Levy (warrenl@cygnus.com)
  58:  * @see java.io.StreamTokenizer
  59:  * @status updated to 1.4
  60:  */
  61: public class StringTokenizer implements Enumeration<Object>
  62: {
  63:   // WARNING: StringTokenizer is a CORE class in the bootstrap cycle. See the
  64:   // comments in vm/reference/java/lang/Runtime for implications of this fact.
  65: 
  66:   /**
  67:    * The position in the str, where we currently are.
  68:    */
  69:   private int pos;
  70: 
  71:   /**
  72:    * The string that should be split into tokens.
  73:    */
  74:   private final String str;
  75: 
  76:   /**
  77:    * The length of the string.
  78:    */
  79:   private final int len;
  80: 
  81:   /**
  82:    * The string containing the delimiter characters.
  83:    */
  84:   private String delim;
  85: 
  86:   /**
  87:    * Tells, if we should return the delimiters.
  88:    */
  89:   private final boolean retDelims;
  90: 
  91:   /**
  92:    * Creates a new StringTokenizer for the string <code>str</code>,
  93:    * that should split on the default delimiter set (space, tab,
  94:    * newline, return and formfeed), and which doesn't return the
  95:    * delimiters.
  96:    *
  97:    * @param str The string to split
  98:    * @throws NullPointerException if str is null
  99:    */
 100:   public StringTokenizer(String str)
 101:   {
 102:     this(str, " \t\n\r\f", false);
 103:   }
 104: 
 105:   /**
 106:    * Create a new StringTokenizer, that splits the given string on
 107:    * the given delimiter characters.  It doesn't return the delimiter
 108:    * characters.
 109:    *
 110:    * @param str the string to split
 111:    * @param delim a string containing all delimiter characters
 112:    * @throws NullPointerException if either argument is null
 113:    */
 114:   public StringTokenizer(String str, String delim)
 115:   {
 116:     this(str, delim, false);
 117:   }
 118: 
 119:   /**
 120:    * Create a new StringTokenizer, that splits the given string on
 121:    * the given delimiter characters.  If you set
 122:    * <code>returnDelims</code> to <code>true</code>, the delimiter
 123:    * characters are returned as tokens of their own.  The delimiter
 124:    * tokens always consist of a single character.
 125:    *
 126:    * @param str the string to split
 127:    * @param delim a string containing all delimiter characters
 128:    * @param returnDelims tells, if you want to get the delimiters
 129:    * @throws NullPointerException if str or delim is null
 130:    */
 131:   public StringTokenizer(String str, String delim, boolean returnDelims)
 132:   {
 133:     len = str.length();
 134:     this.str = str;
 135:     this.delim = delim;
 136:     this.retDelims = returnDelims;
 137:     this.pos = 0;
 138:   }
 139: 
 140:   /**
 141:    * Tells if there are more tokens.
 142:    *
 143:    * @return true if the next call of nextToken() will succeed
 144:    */
 145:   public boolean hasMoreTokens()
 146:   {
 147:     if (! retDelims)
 148:       {
 149:         while (pos < len && delim.indexOf(str.charAt(pos)) >= 0)
 150:           pos++;
 151:       }
 152:     return pos < len;
 153:   }
 154: 
 155:   /**
 156:    * Returns the nextToken, changing the delimiter set to the given
 157:    * <code>delim</code>.  The change of the delimiter set is
 158:    * permanent, ie. the next call of nextToken(), uses the same
 159:    * delimiter set.
 160:    *
 161:    * @param delim a string containing the new delimiter characters
 162:    * @return the next token with respect to the new delimiter characters
 163:    * @throws NoSuchElementException if there are no more tokens
 164:    * @throws NullPointerException if delim is null
 165:    */
 166:   public String nextToken(String delim) throws NoSuchElementException
 167:   {
 168:     this.delim = delim;
 169:     return nextToken();
 170:   }
 171: 
 172:   /**
 173:    * Returns the nextToken of the string.
 174:    *
 175:    * @return the next token with respect to the current delimiter characters
 176:    * @throws NoSuchElementException if there are no more tokens
 177:    */
 178:   public String nextToken() throws NoSuchElementException
 179:   {
 180:     if (pos < len && delim.indexOf(str.charAt(pos)) >= 0)
 181:       {
 182:         if (retDelims)
 183:           return str.substring(pos, ++pos);
 184:         while (++pos < len && delim.indexOf(str.charAt(pos)) >= 0)
 185:           ;
 186:       }
 187:     if (pos < len)
 188:       {
 189:         int start = pos;
 190:         while (++pos < len && delim.indexOf(str.charAt(pos)) < 0)
 191:           ;
 192:         
 193:         return str.substring(start, pos);
 194:       }
 195:     throw new NoSuchElementException();
 196:   }
 197: 
 198:   /**
 199:    * This does the same as hasMoreTokens. This is the
 200:    * <code>Enumeration</code> interface method.
 201:    *
 202:    * @return true, if the next call of nextElement() will succeed
 203:    * @see #hasMoreTokens()
 204:    */
 205:   public boolean hasMoreElements()
 206:   {
 207:     return hasMoreTokens();
 208:   }
 209: 
 210:   /**
 211:    * This does the same as nextTokens. This is the
 212:    * <code>Enumeration</code> interface method.
 213:    *
 214:    * @return the next token with respect to the current delimiter characters
 215:    * @throws NoSuchElementException if there are no more tokens
 216:    * @see #nextToken()
 217:    */
 218:   public Object nextElement() throws NoSuchElementException
 219:   {
 220:     return nextToken();
 221:   }
 222: 
 223:   /**
 224:    * This counts the number of remaining tokens in the string, with
 225:    * respect to the current delimiter set.
 226:    *
 227:    * @return the number of times <code>nextTokens()</code> will succeed
 228:    * @see #nextToken()
 229:    */
 230:   public int countTokens()
 231:   {
 232:     int count = 0;
 233:     int delimiterCount = 0;
 234:     boolean tokenFound = false; // Set when a non-delimiter is found
 235:     int tmpPos = pos;
 236: 
 237:     // Note for efficiency, we count up the delimiters rather than check
 238:     // retDelims every time we encounter one.  That way, we can
 239:     // just do the conditional once at the end of the method
 240:     while (tmpPos < len)
 241:       {
 242:         if (delim.indexOf(str.charAt(tmpPos++)) >= 0)
 243:           {
 244:             if (tokenFound)
 245:               {
 246:                 // Got to the end of a token
 247:                 count++;
 248:                 tokenFound = false;
 249:               }
 250:             delimiterCount++; // Increment for this delimiter
 251:           }
 252:         else
 253:           {
 254:             tokenFound = true;
 255:             // Get to the end of the token
 256:             while (tmpPos < len
 257:                    && delim.indexOf(str.charAt(tmpPos)) < 0)
 258:               ++tmpPos;
 259:           }
 260:       }
 261: 
 262:     // Make sure to count the last token
 263:     if (tokenFound)
 264:       count++;
 265: 
 266:     // if counting delmiters add them into the token count
 267:     return retDelims ? count + delimiterCount : count;
 268:   }
 269: } // class StringTokenizer