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diff --git a/src/gnu/regexp/REFilterReader.java b/src/gnu/regexp/REFilterReader.java
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+++ b/src/gnu/regexp/REFilterReader.java
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+/*
+ *  gnu/regexp/REFilterReader.java
+ *  Copyright (C) 2001 Lee Sau Dan
+ *  Based on gnu.regexp.REFilterInputStream by Wes Biggs
+ *
+ *  This library is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU Lesser General Public License as published
+ *  by the Free Software Foundation; either version 2.1 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+package gnu.regexp;
+import java.io.FilterReader;
+import java.io.Reader;
+
+/**
+ * Replaces instances of a given RE with replacement text. 
+ *
+ * @author <A HREF="http://www.csis.hku.hk/~sdlee/">Lee Sau Dan</A>
+ * @since gnu.regexp 1.1.0
+ */
+
+public class REFilterReader extends FilterReader {
+
+  private RE expr;
+  private String replace;
+  private String buffer;
+  private int bufpos;
+  private int offset;
+  private CharIndexedReader stream;
+
+  /**
+   * Creates an REFilterReader.  When reading from this stream,
+   * occurrences of patterns matching the supplied regular expression
+   * will be replaced with the supplied replacement text (the
+   * metacharacters $0 through $9 may be used to refer to the full
+   * match or subexpression matches.
+   *
+   * @param stream The Reader to be filtered.
+   * @param expr The regular expression to search for.
+   * @param replace The text pattern to replace matches with.  
+   */
+  public REFilterReader(Reader stream, RE expr, String replace) {
+    super(stream);
+    this.stream = new CharIndexedReader(stream,0);
+    this.expr = expr;
+    this.replace = replace;
+  }
+
+  /**
+   * Reads the next character from the stream per the general contract of
+   * Reader.read().  Returns -1 on error or end of stream.
+   */
+  public int read() {
+    // If we have buffered replace data, use it.
+    if ((buffer != null) && (bufpos < buffer.length())) {
+      return (int) buffer.charAt(bufpos++);
+    }
+
+    // check if input is at a valid position
+    if (!stream.isValid()) return -1;
+
+    REMatch mymatch = new REMatch(expr.getNumSubs(),offset,0);
+    if (expr.match(stream,mymatch)) {
+      mymatch.end[0] = mymatch.index;
+      mymatch.finish(stream);
+      stream.move(mymatch.toString().length());
+      offset += mymatch.toString().length();
+      buffer = mymatch.substituteInto(replace);
+      bufpos = 1;
+
+      if (buffer.length() > 0) {
+	  return buffer.charAt(0);
+      }
+    }
+    char ch = stream.charAt(0);
+    if (ch == CharIndexed.OUT_OF_BOUNDS) return -1;
+    stream.move(1);
+    offset++;
+    return ch;
+  }
+
+  /** 
+   * Returns false.  REFilterReader does not support mark() and
+   * reset() methods. 
+   */
+  public boolean markSupported() {
+    return false;
+  }
+
+  /** Reads from the stream into the provided array. */
+  public int read(char[] b, int off, int len) {
+    int i;
+    int ok = 0;
+    while (len-- > 0) {
+      i = read();
+      if (i == -1) return (ok == 0) ? -1 : ok;
+      b[off++] = (char) i;
+      ok++;
+    }
+    return ok;
+  }
+
+  /** Reads from the stream into the provided array. */
+  public int read(char[] b) {
+    return read(b,0,b.length);
+  }
+}