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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);
}
}
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