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Java JDBC driver for MogDB
/*
* Copyright (c) 2003, PostgreSQL Global Development Group
* See the LICENSE file in the project root for more information.
*/
package io.mogdb.core;
import io.mogdb.util.GT;
import java.io.IOException;
class UTF8Encoding extends Encoding {
private static final int MIN_2_BYTES = 0x80;
private static final int MIN_3_BYTES = 0x800;
private static final int MIN_4_BYTES = 0x10000;
private static final int MAX_CODE_POINT = 0x10ffff;
private char[] decoderArray = new char[1024];
UTF8Encoding(String jvmEncoding) {
super(jvmEncoding);
}
// helper for decode
private static void checkByte(int ch, int pos, int len) throws IOException {
if ((ch & 0xc0) != 0x80) {
throw new IOException(
GT.tr("Illegal UTF-8 sequence: byte {0} of {1} byte sequence is not 10xxxxxx: {2}",
pos, len, ch));
}
}
private static void checkMinimal(int ch, int minValue) throws IOException {
if (ch >= minValue) {
return;
}
int actualLen;
switch (minValue) {
case MIN_2_BYTES:
actualLen = 2;
break;
case MIN_3_BYTES:
actualLen = 3;
break;
case MIN_4_BYTES:
actualLen = 4;
break;
default:
throw new IllegalArgumentException(
"unexpected minValue passed to checkMinimal: " + minValue);
}
int expectedLen;
if (ch < MIN_2_BYTES) {
expectedLen = 1;
} else if (ch < MIN_3_BYTES) {
expectedLen = 2;
} else if (ch < MIN_4_BYTES) {
expectedLen = 3;
} else {
throw new IllegalArgumentException("unexpected ch passed to checkMinimal: " + ch);
}
throw new IOException(
GT.tr("Illegal UTF-8 sequence: {0} bytes used to encode a {1} byte value: {2}",
actualLen, expectedLen, ch));
}
/**
* Custom byte[] -> String conversion routine for UTF-8 only. This is about twice as fast as using
* the String(byte[],int,int,String) ctor, at least under JDK 1.4.2. The extra checks for illegal
* representations add about 10-15% overhead, but they seem worth it given the number of SQL_ASCII
* databases out there.
*
* @param data the array containing UTF8-encoded data
* @param offset the offset of the first byte in {@code data} to decode from
* @param length the number of bytes to decode
* @return a decoded string
* @throws IOException if something goes wrong
*/
@Override
public synchronized String decode(byte[] data, int offset, int length) throws IOException {
char[] cdata = decoderArray;
if (cdata.length < length) {
cdata = decoderArray = new char[length];
}
int in = offset;
int out = 0;
int end = length + offset;
try {
while (in < end) {
int ch = data[in++] & 0xff;
// Convert UTF-8 to 21-bit codepoint.
if (ch < 0x80) {
// 0xxxxxxx -- length 1.
} else if (ch < 0xc0) {
// 10xxxxxx -- illegal!
throw new IOException(GT.tr("Illegal UTF-8 sequence: initial byte is {0}: {1}",
"10xxxxxx", ch));
} else if (ch < 0xe0) {
// 110xxxxx 10xxxxxx
ch = ((ch & 0x1f) << 6);
checkByte(data[in], 2, 2);
ch = ch | (data[in++] & 0x3f);
checkMinimal(ch, MIN_2_BYTES);
} else if (ch < 0xf0) {
// 1110xxxx 10xxxxxx 10xxxxxx
ch = ((ch & 0x0f) << 12);
checkByte(data[in], 2, 3);
ch = ch | ((data[in++] & 0x3f) << 6);
checkByte(data[in], 3, 3);
ch = ch | (data[in++] & 0x3f);
checkMinimal(ch, MIN_3_BYTES);
} else if (ch < 0xf8) {
// 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
ch = ((ch & 0x07) << 18);
checkByte(data[in], 2, 4);
ch = ch | ((data[in++] & 0x3f) << 12);
checkByte(data[in], 3, 4);
ch = ch | ((data[in++] & 0x3f) << 6);
checkByte(data[in], 4, 4);
ch = ch | (data[in++] & 0x3f);
checkMinimal(ch, MIN_4_BYTES);
} else {
throw new IOException(GT.tr("Illegal UTF-8 sequence: initial byte is {0}: {1}",
"11111xxx", ch));
}
if (ch > MAX_CODE_POINT) {
throw new IOException(
GT.tr("Illegal UTF-8 sequence: final value is out of range: {0}", ch));
}
// Convert 21-bit codepoint to Java chars:
// 0..ffff are represented directly as a single char
// 10000..10ffff are represented as a "surrogate pair" of two chars
// See: http://java.sun.com/developer/technicalArticles/Intl/Supplementary/
if (ch > 0xffff) {
// Use a surrogate pair to represent it.
ch -= 0x10000; // ch is now 0..fffff (20 bits)
cdata[out++] = (char) (0xd800 + (ch >> 10)); // top 10 bits
cdata[out++] = (char) (0xdc00 + (ch & 0x3ff)); // bottom 10 bits
} else if (ch >= 0xd800 && ch < 0xe000) {
// Not allowed to encode the surrogate range directly.
throw new IOException(
GT.tr("Illegal UTF-8 sequence: final value is a surrogate value: {0}", ch));
} else {
// Normal case.
cdata[out++] = (char) ch;
}
}
} catch (ArrayIndexOutOfBoundsException a) {
throw new IOException("Illegal UTF-8 sequence: multibyte sequence was truncated");
}
// Check if we ran past the end without seeing an exception.
if (in > end) {
throw new IOException("Illegal UTF-8 sequence: multibyte sequence was truncated");
}
return new String(cdata, 0, out);
}
}