libjava/classpath/gnu/java/util/regex/REFilterInputStream.java

   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 }