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Java > Open Source Codes > gnu > regexp > REFilterInputStream


1 /*
2  * gnu/regexp/REFilterInputStream.java
3  * Copyright (C) 1998-2001 Wes Biggs
4  *
5  * This library is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU Lesser General Public License as published
7  * by the Free Software Foundation; either version 2.1 of the License, or
8  * (at your option) any later version.
9  *
10  * This library is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13  * GNU Lesser General Public License for more details.
14  *
15  * You should have received a copy of the GNU Lesser General Public License
16  * along with this program; if not, write to the Free Software
17  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
18  */
19
20 package gnu.regexp;
21 import java.io.FilterInputStream JavaDoc;
22 import java.io.InputStream JavaDoc;
23
24 /**
25  * Replaces instances of a given RE found within an InputStream
26  * with replacement text. The replacements are interpolated into the
27  * stream when a match is found.
28  *
29  * @author <A HREF="mailto:wes@cacas.org">Wes Biggs</A>
30  * @deprecated This class cannot properly handle all character
31  * encodings. For proper handling, use the REFilterReader
32  * class instead.
33  */
34
35 public class REFilterInputStream extends FilterInputStream JavaDoc {
36
37     private RE expr;
38     private String JavaDoc replace;
39     private String JavaDoc buffer;
40     private int bufpos;
41     private int offset;
42     private CharIndexedInputStream stream;
43
44   /**
45    * Creates an REFilterInputStream. When reading from this stream,
46    * occurrences of patterns matching the supplied regular expression
47    * will be replaced with the supplied replacement text (the
48    * metacharacters $0 through $9 may be used to refer to the full
49    * match or subexpression matches).
50    *
51    * @param stream The InputStream to be filtered.
52    * @param expr The regular expression to search for.
53    * @param replace The text pattern to replace matches with.
54    */
55   public REFilterInputStream(InputStream JavaDoc stream, RE expr, String JavaDoc replace) {
56     super(stream);
57     this.stream = new CharIndexedInputStream(stream,0);
58     this.expr = expr;
59     this.replace = replace;
60   }
61
62   /**
63    * Reads the next byte from the stream per the general contract of
64    * InputStream.read(). Returns -1 on error or end of stream.
65    */
66   public int read() {
67     // If we have buffered replace data, use it.
68 if ((buffer != null) && (bufpos < buffer.length())) {
69       return (int) buffer.charAt(bufpos++);
70     }
71
72     // check if input is at a valid position
73 if (!stream.isValid()) return -1;
74
75     REMatch mymatch = new REMatch(expr.getNumSubs(),offset,0);
76     if (expr.match(stream, mymatch)) {
77       mymatch.end[0] = mymatch.index;
78       mymatch.finish(stream);
79       stream.move(mymatch.toString().length());
80       offset += mymatch.toString().length();
81       buffer = mymatch.substituteInto(replace);
82       bufpos = 1;
83
84       // This is prone to infinite loops if replace string turns out empty.
85 if (buffer.length() > 0) {
86       return buffer.charAt(0);
87       }
88     }
89     char ch = stream.charAt(0);
90     if (ch == CharIndexed.OUT_OF_BOUNDS) return -1;
91     stream.move(1);
92     offset++;
93     return ch;
94   }
95
96   /**
97    * Returns false. REFilterInputStream does not support mark() and
98    * reset() methods.
99    */
100   public boolean markSupported() {
101     return false;
102   }
103
104   /** Reads from the stream into the provided array. */
105   public int read(byte[] b, int off, int len) {
106     int i;
107     int ok = 0;
108     while (len-- > 0) {
109       i = read();
110       if (i == -1) return (ok == 0) ? -1 : ok;
111       b[off++] = (byte) i;
112       ok++;
113     }
114     return ok;
115   }
116
117   /** Reads from the stream into the provided array. */
118   public int read(byte[] b) {
119     return read(b,0,b.length);
120   }
121 }
122
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