Source for gnu.java.util.regex.REMatchEnumeration

   1: /* gnu/regexp/REMatchEnumeration.java
   2:    Copyright (C) 1998-2001, 2004 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: package gnu.java.util.regex;
  39: 
  40: import gnu.java.lang.CPStringBuilder;
  41: 
  42: import java.io.Serializable;
  43: import java.util.Enumeration;
  44: import java.util.NoSuchElementException;
  45: 
  46: /**
  47:  * An REMatchEnumeration enumerates regular expression matches over a
  48:  * given input text.  You obtain a reference to an enumeration using
  49:  * the <code>getMatchEnumeration()</code> methods on an instance of
  50:  * RE.
  51:  *
  52:  * <P>
  53:  *
  54:  * REMatchEnumeration does lazy computation; that is, it will not
  55:  * search for a match until it needs to.  If you'd rather just get all
  56:  * the matches at once in a big array, use the
  57:  * <code>getAllMatches()</code> methods on RE.  However, using an
  58:  * enumeration can help speed performance when the entire text does
  59:  * not need to be searched immediately.
  60:  *
  61:  * <P>
  62:  *
  63:  * The enumerated type is especially useful when searching on a Reader
  64:  * or InputStream, because the InputStream read position cannot be
  65:  * guaranteed after calling <code>getMatch()</code> (see the
  66:  * description of that method for an explanation of why).  Enumeration
  67:  * also saves a lot of overhead required when calling
  68:  * <code>getMatch()</code> multiple times.
  69:  *
  70:  * @author <A HREF="mailto:wes@cacas.org">Wes Biggs</A>
  71:  */
  72: public class REMatchEnumeration
  73:   implements Enumeration < REMatch >, Serializable
  74: {
  75:   private static final int YES = 1;
  76:   private static final int MAYBE = 0;
  77:   private static final int NO = -1;
  78: 
  79:   private int more;
  80:   private REMatch match;
  81:   private final RE expr;
  82:   private final CharIndexed input;
  83:   private final int eflags;
  84:   private int index;
  85: 
  86:   // Package scope constructor is used by RE.getMatchEnumeration()
  87:     REMatchEnumeration (RE expr, CharIndexed input, int index, int eflags)
  88:   {
  89:     more = MAYBE;
  90:     this.expr = expr;
  91:     this.input = input;
  92:     this.index = index;
  93:     this.eflags = eflags;
  94:   }
  95: 
  96:   /** Returns true if there are more matches in the input text. */
  97:   public boolean hasMoreElements ()
  98:   {
  99:     return hasMoreMatches (null);
 100:   }
 101: 
 102:   /** Returns true if there are more matches in the input text. */
 103:   public boolean hasMoreMatches ()
 104:   {
 105:     return hasMoreMatches (null);
 106:   }
 107: 
 108:   /** Returns true if there are more matches in the input text.
 109:    * Saves the text leading up to the match (or to the end of the input)
 110:    * in the specified buffer.
 111:    */
 112:   public boolean hasMoreMatches (CPStringBuilder buffer)
 113:   {
 114:     if (more == MAYBE)
 115:       {
 116:         match = expr.getMatchImpl (input, index, eflags, buffer);
 117:         if (match != null)
 118:           {
 119:             input.move ((match.end[0] > 0) ? match.end[0] : 1);
 120: 
 121:             index =
 122:               (match.end[0] > 0) ? match.end[0] + match.offset : index + 1;
 123:             more = YES;
 124:           }
 125:         else
 126:           more = NO;
 127:       }
 128:     return (more == YES);
 129:   }
 130: 
 131:   /** Returns the next match in the input text. */
 132:   public REMatch nextElement () throws NoSuchElementException
 133:   {
 134:     if (hasMoreElements ())
 135:       {
 136:         more = (input.isValid ())? MAYBE : NO;
 137:         return match;
 138:       }
 139:     throw new NoSuchElementException ();
 140:   }
 141: }