001/* 002 * gnu/regexp/REFilterReader.java 003 * Copyright (C) 2001 Lee Sau Dan 004 * Based on gnu.regexp.REFilterInputStream by Wes Biggs 005 * 006 * This library is free software; you can redistribute it and/or modify 007 * it under the terms of the GNU Lesser General Public License as published 008 * by the Free Software Foundation; either version 2.1 of the License, or 009 * (at your option) any later version. 010 * 011 * This library is distributed in the hope that it will be useful, 012 * but WITHOUT ANY WARRANTY; without even the implied warranty of 013 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 014 * GNU Lesser General Public License for more details. 015 * 016 * You should have received a copy of the GNU Lesser General Public License 017 * along with this program; if not, write to the Free Software 018 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 019 */ 020 021package gnu.regexp; 022import java.io.FilterReader; 023import java.io.Reader; 024 025/** 026 * Replaces instances of a given RE with replacement text. 027 * 028 * @author <A HREF="http://www.csis.hku.hk/~sdlee/">Lee Sau Dan</A> 029 * @since gnu.regexp 1.1.0 030 */ 031 032public class REFilterReader extends FilterReader { 033 034 private RE expr; 035 private String replace; 036 private String buffer; 037 private int bufpos; 038 private int offset; 039 private CharIndexedReader stream; 040 041 /** 042 * Creates an REFilterReader. When reading from this stream, 043 * occurrences of patterns matching the supplied regular expression 044 * will be replaced with the supplied replacement text (the 045 * metacharacters $0 through $9 may be used to refer to the full 046 * match or subexpression matches. 047 * 048 * @param stream The Reader to be filtered. 049 * @param expr The regular expression to search for. 050 * @param replace The text pattern to replace matches with. 051 */ 052 public REFilterReader(Reader stream, RE expr, String replace) { 053 super(stream); 054 this.stream = new CharIndexedReader(stream,0); 055 this.expr = expr; 056 this.replace = replace; 057 } 058 059 /** 060 * Reads the next character from the stream per the general contract of 061 * Reader.read(). Returns -1 on error or end of stream. 062 */ 063 public int read() { 064 // If we have buffered replace data, use it. 065 if ((buffer != null) && (bufpos < buffer.length())) { 066 return (int) buffer.charAt(bufpos++); 067 } 068 069 // check if input is at a valid position 070 if (!stream.isValid()) return -1; 071 072 REMatch mymatch = new REMatch(expr.getNumSubs(),offset,0); 073 if (expr.match(stream,mymatch)) { 074 mymatch.end[0] = mymatch.index; 075 mymatch.finish(stream); 076 stream.move(mymatch.toString().length()); 077 offset += mymatch.toString().length(); 078 buffer = mymatch.substituteInto(replace); 079 bufpos = 1; 080 081 if (buffer.length() > 0) { 082 return buffer.charAt(0); 083 } 084 } 085 char ch = stream.charAt(0); 086 if (ch == CharIndexed.OUT_OF_BOUNDS) return -1; 087 stream.move(1); 088 offset++; 089 return ch; 090 } 091 092 /** 093 * Returns false. REFilterReader does not support mark() and 094 * reset() methods. 095 */ 096 public boolean markSupported() { 097 return false; 098 } 099 100 /** Reads from the stream into the provided array. */ 101 public int read(char[] b, int off, int len) { 102 int i; 103 int ok = 0; 104 while (len-- > 0) { 105 i = read(); 106 if (i == -1) return (ok == 0) ? -1 : ok; 107 b[off++] = (char) i; 108 ok++; 109 } 110 return ok; 111 } 112 113 /** Reads from the stream into the provided array. */ 114 public int read(char[] b) { 115 return read(b,0,b.length); 116 } 117}