Source for gnu.java.util.regex.REFilterInputStream

   1: /* gnu/regexp/REFilterInputStream.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: 
  39: package gnu.java.util.regex;
  40: import java.io.FilterInputStream;
  41: import java.io.InputStream;
  42: 
  43: /**
  44:  * Replaces instances of a given RE found within an InputStream
  45:  * with replacement text.   The replacements are interpolated into the
  46:  * stream when a match is found.
  47:  *
  48:  * @author <A HREF="mailto:wes@cacas.org">Wes Biggs</A>
  49:  * @deprecated This class cannot properly handle all character
  50:  *             encodings.  For proper handling, use the REFilterReader
  51:  *             class instead.
  52:  */
  53: 
  54: public class REFilterInputStream extends FilterInputStream
  55: {
  56: 
  57:   private RE expr;
  58:   private String replace;
  59:   private String buffer;
  60:   private int bufpos;
  61:   private int offset;
  62:   private CharIndexedInputStream stream;
  63: 
  64:   /**
  65:    * Creates an REFilterInputStream.  When reading from this stream,
  66:    * occurrences of patterns matching the supplied regular expression
  67:    * will be replaced with the supplied replacement text (the
  68:    * metacharacters $0 through $9 may be used to refer to the full
  69:    * match or subexpression matches).
  70:    *
  71:    * @param stream The InputStream to be filtered.
  72:    * @param expr The regular expression to search for.
  73:    * @param replace The text pattern to replace matches with.
  74:    */
  75:   public REFilterInputStream (InputStream stream, RE expr, String replace)
  76:   {
  77:     super (stream);
  78:     this.stream = new CharIndexedInputStream (stream, 0);
  79:     this.expr = expr;
  80:     this.replace = replace;
  81:   }
  82: 
  83:   /**
  84:    * Reads the next byte from the stream per the general contract of
  85:    * InputStream.read().  Returns -1 on error or end of stream.
  86:    */
  87:   public int read ()
  88:   {
  89:     // If we have buffered replace data, use it.
  90:     if ((buffer != null) && (bufpos < buffer.length ()))
  91:       {
  92:         return (int) buffer.charAt (bufpos++);
  93:       }
  94: 
  95:     // check if input is at a valid position
  96:     if (!stream.isValid ())
  97:       return -1;
  98: 
  99:     REMatch mymatch = new REMatch (expr.getNumSubs (), offset, 0);
 100:     if (expr.match (stream, mymatch))
 101:       {
 102:         mymatch.end[0] = mymatch.index;
 103:         mymatch.finish (stream);
 104:         stream.move (mymatch.toString ().length ());
 105:         offset += mymatch.toString ().length ();
 106:         buffer = mymatch.substituteInto (replace);
 107:         bufpos = 1;
 108: 
 109:         // This is prone to infinite loops if replace string turns out empty.
 110:         if (buffer.length () > 0)
 111:           {
 112:             return buffer.charAt (0);
 113:           }
 114:       }
 115:     char ch = stream.charAt (0);
 116:     if (ch == CharIndexed.OUT_OF_BOUNDS)
 117:       return -1;
 118:     stream.move (1);
 119:     offset++;
 120:     return ch;
 121:   }
 122: 
 123:   /**
 124:    * Returns false.  REFilterInputStream does not support mark() and
 125:    * reset() methods.
 126:    */
 127:   public boolean markSupported ()
 128:   {
 129:     return false;
 130:   }
 131: 
 132:   /** Reads from the stream into the provided array. */
 133:   public int read (byte[]b, int off, int len)
 134:   {
 135:     int i;
 136:     int ok = 0;
 137:     while (len-- > 0)
 138:       {
 139:         i = read ();
 140:         if (i == -1)
 141:           return (ok == 0) ? -1 : ok;
 142:         b[off++] = (byte) i;
 143:         ok++;
 144:       }
 145:     return ok;
 146:   }
 147: 
 148:   /** Reads from the stream into the provided array. */
 149:   public int read (byte[]b)
 150:   {
 151:     return read (b, 0, b.length);
 152:   }
 153: }