package client.net.sf.saxon.ce.tree.util;
/**
* This class defines properties of the UTF-8 character encoding
*/
public final class UTF8CharacterSet {
/**
* Private constructor to force the singular instance to be used
*/
private UTF8CharacterSet() {}
/**
* Static method to generate the UTF-8 representation of a Unicode character
* @param in the Unicode character, or the high half of a surrogate pair
* @param in2 the low half of a surrogate pair (ignored unless the first argument is in the
* range for a surrogate pair)
* @param out an array of at least 4 bytes to hold the UTF-8 representation.
* @return the number of bytes in the UTF-8 representation
*/
public static int getUTF8Encoding(char in, char in2, byte[] out) {
// See Tony Graham, "Unicode, a Primer", page 92
int i = (int)in;
if (i<=0x7f) {
out[0] = (byte)i;
return 1;
} else if (i<=0x7ff) {
out[0] = (byte)(0xc0 | ((in >> 6) & 0x1f));
out[1] = (byte)(0x80 | (in & 0x3f));
return 2;
} else if (i>=0xd800 && i<=0xdbff) {
// surrogate pair
int j = (int)in2;
if (!(j>=0xdc00 && j<=0xdfff)) {
throw new IllegalArgumentException("Malformed Unicode Surrogate Pair (" + i + ',' + j + ')');
}
byte xxxxxx = (byte)(j & 0x3f);
byte yyyyyy = (byte)(((i & 0x03) << 4) | ((j >> 6) & 0x0f));
byte zzzz = (byte)((i >> 2) & 0x0f);
byte uuuuu = (byte)(((i >> 6) & 0x0f) + 1);
out[0] = (byte)(0xf0 | ((uuuuu >> 2) & 0x07));
out[1] = (byte)(0x80 | ((uuuuu & 0x03) << 4) | zzzz);
out[2] = (byte)(0x80 | yyyyyy);
out[3] = (byte)(0x80 | xxxxxx);
return 4;
} else if (i>=0xdc00 && i<=0xdfff) {
// second half of surrogate pair - ignore it
return 0;
} else {
out[0] = (byte)(0xe0 | ((in >> 12) & 0x0f));
out[1] = (byte)(0x80 | ((in >> 6) & 0x3f));
out[2] = (byte)(0x80 | (in & 0x3f));
return 3;
}
}
/**
* Decode a UTF8 character
* @param in array of bytes representing a single UTF-8 encoded character
* @param used number of bytes in the array that are actually used
* @return the Unicode codepoint of this character
* @throws IllegalArgumentException if the byte sequence is not a valid UTF-8 representation
*/
public static int decodeUTF8(byte[] in, int used) throws IllegalArgumentException {
int bottom = 0;
for (int i=1; i<used; i++) {
if ((in[i] & 0xc0) != 0x80) {
throw new IllegalArgumentException("Byte " + (i+1) + " in UTF-8 sequence has wrong top bits");
}
bottom = (bottom<<6) + (in[i] & 0x3f);
}
if ((in[0] & 0x80) == 0) {
// single byte sequence 0xxxxxxx
if (used == 1) {
return in[0];
} else {
throw new IllegalArgumentException("UTF8 single byte expected");
}
} else if ((in[0] & 0xe0) == 0xc0) {
// two byte sequence
if (used != 2) {
throw new IllegalArgumentException("UTF8 sequence of two bytes expected");
}
return ((in[0] & 0x1f) << 6) + bottom;
} else if ((in[0] & 0xf0) == 0xe0) {
// three byte sequence
if (used != 3) {
throw new IllegalArgumentException("UTF8 sequence of three bytes expected");
}
return ((in[0] & 0x0f) << 12) + bottom;
} else if ((in[0] & 0xf8) == 0xf8) {
// four-byte sequence 11110uuu 10uuzzzz 10yyyyyy 10xxxxxx
if (used != 4) {
throw new IllegalArgumentException("UTF8 sequence of four bytes expected");
}
return ((in[0] & 0x07) << 24) + bottom;
} else {
throw new IllegalArgumentException("UTF8 invalid first byte");
}
}
}
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is “Incompatible With Secondary Licenses”, as defined by the Mozilla Public License, v. 2.0.