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:     private RE expr;
  57:     private String replace;
  58:     private String buffer;
  59:     private int bufpos;
  60:     private int offset;
  61:     private CharIndexedInputStream stream;
  62: 
  63:   /**
  64:    * Creates an REFilterInputStream.  When reading from this stream,
  65:    * occurrences of patterns matching the supplied regular expression
  66:    * will be replaced with the supplied replacement text (the
  67:    * metacharacters $0 through $9 may be used to refer to the full
  68:    * match or subexpression matches).
  69:    *
  70:    * @param stream The InputStream to be filtered.
  71:    * @param expr The regular expression to search for.
  72:    * @param replace The text pattern to replace matches with.  
  73:    */
  74:   public REFilterInputStream(InputStream stream, RE expr, String replace) {
  75:     super(stream);
  76:     this.stream = new CharIndexedInputStream(stream,0);
  77:     this.expr = expr;
  78:     this.replace = replace;
  79:   }
  80: 
  81:   /**
  82:    * Reads the next byte from the stream per the general contract of
  83:    * InputStream.read().  Returns -1 on error or end of stream.
  84:    */
  85:   public int read() {
  86:     // If we have buffered replace data, use it.
  87:     if ((buffer != null) && (bufpos < buffer.length())) {
  88:       return (int) buffer.charAt(bufpos++);
  89:     }
  90: 
  91:     // check if input is at a valid position
  92:     if (!stream.isValid()) return -1;
  93: 
  94:     REMatch mymatch = new REMatch(expr.getNumSubs(),offset,0);
  95:     if (expr.match(stream, mymatch)) {
  96:       mymatch.end[0] = mymatch.index;
  97:       mymatch.finish(stream);
  98:       stream.move(mymatch.toString().length());
  99:       offset += mymatch.toString().length();
 100:       buffer = mymatch.substituteInto(replace);
 101:       bufpos = 1;
 102: 
 103:       // This is prone to infinite loops if replace string turns out empty.
 104:       if (buffer.length() > 0) {
 105:       return buffer.charAt(0);
 106:       }
 107:     }
 108:     char ch = stream.charAt(0);
 109:     if (ch == CharIndexed.OUT_OF_BOUNDS) return -1;
 110:     stream.move(1);
 111:     offset++;
 112:     return ch;
 113:   }
 114: 
 115:   /** 
 116:    * Returns false.  REFilterInputStream does not support mark() and
 117:    * reset() methods. 
 118:    */
 119:   public boolean markSupported() {
 120:     return false;
 121:   }
 122: 
 123:   /** Reads from the stream into the provided array. */
 124:   public int read(byte[] b, int off, int len) {
 125:     int i;
 126:     int ok = 0;
 127:     while (len-- > 0) {
 128:       i = read();
 129:       if (i == -1) return (ok == 0) ? -1 : ok;
 130:       b[off++] = (byte) i;
 131:       ok++;
 132:     }
 133:     return ok;
 134:   }
 135: 
 136:   /** Reads from the stream into the provided array. */
 137:   public int read(byte[] b) {
 138:     return read(b,0,b.length);
 139:   }
 140: }