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Java > Open Source Codes > org > columba > ristretto > coder > CanonizeFilterInputStream


1 /* ***** BEGIN LICENSE BLOCK *****
2  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
3  *
4  * The contents of this file are subject to the Mozilla Public License Version
5  * 1.1 (the "License"); you may not use this file except in compliance with
6  * the License. You may obtain a copy of the License at
7  * http://www.mozilla.org/MPL/
8  *
9  * Software distributed under the License is distributed on an "AS IS" basis,
10  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
11  * for the specific language governing rights and limitations under the
12  * License.
13  *
14  * The Original Code is Ristretto Mail API.
15  *
16  * The Initial Developers of the Original Code are
17  * Timo Stich and Frederik Dietz.
18  * Portions created by the Initial Developers are Copyright (C) 2004
19  * All Rights Reserved.
20  *
21  * Contributor(s):
22  *
23  * Alternatively, the contents of this file may be used under the terms of
24  * either the GNU General Public License Version 2 or later (the "GPL"), or
25  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
26  * in which case the provisions of the GPL or the LGPL are applicable instead
27  * of those above. If you wish to allow use of your version of this file only
28  * under the terms of either the GPL or the LGPL, and not to allow others to
29  * use your version of this file under the terms of the MPL, indicate your
30  * decision by deleting the provisions above and replace them with the notice
31  * and other provisions required by the GPL or the LGPL. If you do not delete
32  * the provisions above, a recipient may use your version of this file under
33  * the terms of any one of the MPL, the GPL or the LGPL.
34  *
35  * ***** END LICENSE BLOCK ***** */

36 package org.columba.ristretto.coder;
37
38 import java.io.FilterInputStream JavaDoc;
39 import java.io.IOException JavaDoc;
40 import java.io.InputStream JavaDoc;
41
42 /**
43  * FilterInputStream that converts CR or LF lineendings to CRLF.
44  *
45  * @author Timo Stich <tstich@users.sourceforge.net>
46  */

47 public class CanonizeFilterInputStream extends FilterInputStream JavaDoc {
48     
49     private static final int NOOP = 0;
50     private static final int CRFOUND = 1;
51     private static final int PRINTLF = 2;
52     private static final int PRINTBUFFER = 3;
53     
54     
55     private int mode = 0;
56     private int buffer;
57
58     /**
59      * Constructs a CanonizeFilterInputStream.
60      *
61      * @param in inputstream to canonize
62      */

63     public CanonizeFilterInputStream(InputStream JavaDoc in) {
64         super(in);
65     }
66
67     /**
68      * @see java.io.InputStream#read()
69      */

70     public int read() throws IOException JavaDoc {
71         // First handle things that must be inserted in order
72
// to canonize
73

74         // A LF must be returned in order to complete the begin CR
75
if( mode == PRINTLF ) {
76             mode = NOOP;
77             return '\n';
78         }
79         
80         // Print what was in the buffer
81
if( mode == PRINTBUFFER ) {
82             mode = NOOP;
83             return buffer;
84         }
85         
86         // Nothing must be inserted, so we can read another byte
87
// from the inputstream;
88
int read = in.read();
89         
90         // if we read a CR next char must be a LF so go in CRFOUND mode
91
if( read == '\r' ) {
92             mode = CRFOUND;
93             return read;
94         }
95
96         // if we are in CRFOUND mode but the next char wasn't a LF
97
// save the read byte in the buffer and insert a LF
98
// Go to PRINTBUFFER mode so the read byte is read next.
99
if( read != '\n' && mode == CRFOUND ) {
100             mode = PRINTBUFFER;
101             buffer = read;
102             return '\n';
103         }
104                 
105         // if we read a LF without being in CRFOUND mode we have to
106
// insert a CR and ensure that the next read byte is a LF.
107
if( read == '\n' && mode != CRFOUND ) {
108             mode = PRINTLF;
109             return '\r';
110         }
111
112         // Everything is okay, return the read byte and go to NOOP
113
mode = NOOP;
114         return read;
115     }
116
117
118     /**
119      * @see java.io.InputStream#read(byte[], int, int)
120      */

121     public int read(byte[] b, int off, int len) throws IOException JavaDoc {
122         int read;
123         for( int i=0; i<len ; i++) {
124             read = in.read();
125             if( read == -1) {
126                 if( i == 0 ) return -1;
127                 else return i;
128             }
129             b[off+i] = (byte) read;
130         }
131         
132         return len;
133     }
134
135 }
136
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