UTF8.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
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package jdk.internal.reflect;

/** It is necessary to use a "bootstrap" UTF-8 encoder for encoding
    constant pool entries because the character set converters rely on
    Class.newInstance(). */

class UTF8 {
    // This encoder is not quite correct.  It does not handle surrogate pairs.
    static byte[] encode(String str) {
        int len = str.length();
        byte[] res = new byte[utf8Length(str)];
        int utf8Idx = 0;
        try {
            for (int i = 0; i < len; i++) {
                int c = str.charAt(i) & 0xFFFF;
                if (c >= 0x0001 && c <= 0x007F) {
                    res[utf8Idx++] = (byte) c;
                } else if (c == 0x0000 ||
                           (c >= 0x0080 && c <= 0x07FF)) {
                    res[utf8Idx++] = (byte) (0xC0 + (c >> 6));
                    res[utf8Idx++] = (byte) (0x80 + (c & 0x3F));
                } else {
                    res[utf8Idx++] = (byte) (0xE0 + (c >> 12));
                    res[utf8Idx++] = (byte) (0x80 + ((c >> 6) & 0x3F));
                    res[utf8Idx++] = (byte) (0x80 + (c & 0x3F));
                }
            }
        } catch (ArrayIndexOutOfBoundsException e) {
            throw new InternalError
                ("Bug in sun.reflect bootstrap UTF-8 encoder", e);
        }
        return res;
    }

    private static int utf8Length(String str) {
        int len = str.length();
        int utf8Len = 0;
        for (int i = 0; i < len; i++) {
            int c = str.charAt(i) & 0xFFFF;
            if (c >= 0x0001 && c <= 0x007F) {
                utf8Len += 1;
            } else if (c == 0x0000 ||
                       (c >= 0x0080 && c <= 0x07FF)) {
                utf8Len += 2;
            } else {
                utf8Len += 3;
            }
        }
        return utf8Len;
    }
}