/interpreter/tags/at2dist130208/src/edu/vub/util/regexp/REFilterInputStream.java

  1/* gnu/regexp/REFilterInputStream.java
  2   Copyright (C) 1998-2001, 2004 Free Software Foundation, Inc.
  3
  4This file is part of GNU Classpath.
  5
  6GNU Classpath is free software; you can redistribute it and/or modify
  7it under the terms of the GNU General Public License as published by
  8the Free Software Foundation; either version 2, or (at your option)
  9any later version.
 10
 11GNU Classpath is distributed in the hope that it will be useful, but
 12WITHOUT ANY WARRANTY; without even the implied warranty of
 13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 14General Public License for more details.
 15
 16You should have received a copy of the GNU General Public License
 17along with GNU Classpath; see the file COPYING.  If not, write to the
 18Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 1902110-1301 USA.
 20
 21Linking this library statically or dynamically with other modules is
 22making a combined work based on this library.  Thus, the terms and
 23conditions of the GNU General Public License cover the whole
 24combination.
 25
 26As a special exception, the copyright holders of this library give you
 27permission to link this library with independent modules to produce an
 28executable, regardless of the license terms of these independent
 29modules, and to copy and distribute the resulting executable under
 30terms of your choice, provided that you also meet, for each linked
 31independent module, the terms and conditions of the license of that
 32module.  An independent module is a module which is not derived from
 33or based on this library.  If you modify this library, you may extend
 34this exception to your version of the library, but you are not
 35obligated to do so.  If you do not wish to do so, delete this
 36exception statement from your version. */
 37
 38
 39package edu.vub.util.regexp;
 40import java.io.FilterInputStream;
 41import 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
 54public 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}