/*
* $Id: UTF8XMLDecoder.java,v 1.3 2004/06/25 17:22:37 cliffsch Exp $
*
* (C) Copyright 2002 by Yuval Oren. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.bluecast.xml;
import com.bluecast.io.CharsetDecoder;
import java.io.CharConversionException;
/**
* A decoder for UTF-8 text. Also converts
* carriage returns into linefeeds and CRLF into LF.
*
* @author Yuval Oren, yuval@bluecast.com
* @version $Revision: 1.3 $
*/
final public class UTF8XMLDecoder
implements XMLDecoder {
private boolean sawCR = false;
public CharsetDecoder newCharsetDecoder() { return newXMLDecoder(); }
public XMLDecoder newXMLDecoder() { return new UTF8XMLDecoder(); }
public int minBytesPerChar () {
return 1;
}
public int maxBytesPerChar () {
return 3;
}
public void reset() { sawCR = false; }
public void decode (byte[] in_buf, int in_off, int in_len, char[] out_buf,
int out_off, int out_len, int[] result) throws CharConversionException {
int i, o;
for (i = o = 0; i < in_len && o < out_len; i++) {
// A UTF-8 character can be 1 or more bytes. Length
// is determined by the bitmask of the first byte
int c, c2, c3, c4;
c = in_buf[in_off + i];
// Check for 1 byte first, since it's the most common.
// One byte: 0xxxxxxx
if ((c & 0x80) == 0) {
/* We got the character */
}
else {
// It's at least two bytes long
if (++i < in_len)
c2 = in_buf[in_off + i];
else {
result[0] = i - 1;
result[1] = o;
return;
}
// Two bytes: 110xxxxx 10xxxxxx
if ((c & 0xE0) == 0xC0) {
// Subsequent bytes must begin with 0x10
if ((c2 & 0x80) != 0x80)
throw new CharConversionException(
"Malformed UTF-8 character: 0x"
+ Integer.toHexString(c&0xFF) + " 0x"
+ Integer.toHexString(c2&0xFF));
c = ((c & 0x1F) << 6) | (c2 & 0x3F);
// Make sure this is not an overlong character:
// this character must not fit within 7 bits
if ((c & 0x780) == 0)
throw new CharConversionException("2-byte UTF-8 character is overlong: 0x"
+ Integer.toHexString(in_buf[in_off + i - 1] & 0xFF)
+ " 0x" + Integer.toHexString(c2 & 0xFF));
}
// Three bytes: 1110xxxx 10xxxxxx 10xxxxxx
else if ((c & 0xF0) == 0xE0) {
if (++i < in_len)
c3 = in_buf[in_off + i];
else {
result[0] = i - 2;
result[1] = o;
return;
}
// Subsequent bytes must begin with 0x10
if ( ((c2 & 0x80) != 0x80) ||
((c3 & 0x80) != 0x80) )
throw new CharConversionException(
"Malformed UTF-8 character: 0x"
+ Integer.toHexString(c&0xFF) + " 0x"
+ Integer.toHexString(c2&0xFF) + " 0x"
+ Integer.toHexString(c3&0xFF));
c = ((c & 0xF) << 12) | ((c2 & 0x3F) << 6) | (c3 & 0x3F);
// Make sure this is not an overlong character:
// this character must not fit within 11 bits
if ((c & 0xF800) == 0)
throw new CharConversionException("3-byte UTF-8 character is overlong: 0x"
+ Integer.toHexString(in_buf[in_off+i-2] & 0xFF)
+ " 0x" + Integer.toHexString(c2 & 0xFF) + " 0x" + Integer.toHexString(c3 & 0xFF));
}
// Four bytes: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
// This is returned as a surrogate pair of characters
else if ((c & 0xF0) == 0xF0) {
if (i + 2 < in_len) {
c3 = in_buf[in_off + (++i)];
c4 = in_buf[in_off + (++i)];
}
else {
result[0] = i - 2;
result[1] = o;
return;
}
// Subsequent bytes must begin with 0x10
if ( ((c2 & 0x80) != 0x80) ||
((c3 & 0x80) != 0x80) ||
((c4 & 0x80) != 0x80) )
throw new CharConversionException(
"Malformed UTF-8 character: 0x"
+ Integer.toHexString(c&0xFF) + " 0x"
+ Integer.toHexString(c2&0xFF) + " 0x"
+ Integer.toHexString(c3&0xFF) + " 0x"
+ Integer.toHexString(c4&0xFF));
c = ((c & 0x7) << 18) | ((c2 & 0x3F) << 12) | ((c3 & 0x3F) << 6) | (c4 & 0x3F);
if (c < 0x10000 || c > 0x10FFFF)
throw new CharConversionException("Illegal XML character: 0x"
+ Integer.toHexString(c));
// Construct the surrogate pair
c -= 0x10000;
out_buf[out_off + (o++)] = (char)((c >> 10) | 0xD800);
out_buf[out_off + (o++)] = (char)((c & ((1 << 10) - 1)) | 0xDC00);
sawCR = false;
continue;
}
else {
throw new CharConversionException("Characters larger than 4 bytes are "
+ "not supported: byte 0x" + Integer.toHexString(c & 0xFF) + " implies a length of more than 4 bytes");
}
if ( (c >= 0xD800 && c < 0xE000)
|| (c == 0xFFFE || c == 0xFFFF) )
throw new CharConversionException("Illegal XML character: 0x"
+ Integer.toHexString(c));
}
// Now condense CRLF into LF and transform a lone CR into LF
if (c >= 0x20) {
sawCR = false;
out_buf[out_off + o++] = (char)c;
}
else {
switch (c) {
case '\n':
if (sawCR) {
sawCR = false;
}
else
out_buf[out_off + o++] = '\n';
break;
case '\r':
sawCR = true;
out_buf[out_off + o++] = '\n';
break;
case '\t':
out_buf[out_off + o++] = '\t';
break;
default:
throw new CharConversionException(
"Illegal XML character: 0x"
+ Integer.toHexString(c));
}
}
}
result[0] = i;
result[1] = o;
}
public void decodeXMLDecl (byte[] in_buf, int in_off, int in_len, char[] out_buf,
int out_off, int out_len, int[] result) throws CharConversionException {
int i, o;
inputLoop:
for (i = o = 0; i < in_len && o < out_len; i++) {
// A UTF-8 character can be 1 or more bytes. Length
// is determined by the bitmask of the first byte
int c = in_buf[in_off + i];
// Check for 1 byte first, since it's the most common.
// One byte: 0xxxxxxx
if ((c & 0x80) != 0) {
// XML declarations don't use more than 1 byte per char.
break inputLoop;
}
// Now condense CRLF into LF and transform a lone CR into LF
if (c >= 0x20) {
sawCR = false;
out_buf[out_off + o++] = (char)c;
// Stop decoding after the first '>' because anything more
// can't be part of the declaration
if (c == '>') {
i++;
break inputLoop;
}
}
else {
switch (c) {
case '\n':
if (sawCR) {
sawCR = false;
}
else
out_buf[out_off + o++] = '\n';
break;
case '\r':
sawCR = true;
out_buf[out_off + o++] = '\n';
break;
case '\t':
out_buf[out_off + o++] = '\t';
break;
default:
// Illegal character. Stop decoding
break inputLoop;
}
}
}
result[0] = i;
result[1] = o;
}
}