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Java example source code file (CESU_8.java)

This example Java source code file (CESU_8.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

arraydecoder, arrayencoder, bytebuffer, cesu8, cesu\-8, cesu_8, charbuffer, charsetdecoder, charsetencoder, coderresult, decoder, encoder, nio, string, unicode

The CESU_8.java Java example source code

/*
 * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
 * 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.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package sun.nio.cs;

import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CharsetEncoder;
import java.nio.charset.CoderResult;
import java.nio.charset.CodingErrorAction;

/* Legal CESU-8 Byte Sequences
 *
 * #    Code Points      Bits   Bit/Byte pattern
 * 1                     7      0xxxxxxx
 *      U+0000..U+007F          00..7F
 *
 * 2                     11     110xxxxx    10xxxxxx
 *      U+0080..U+07FF          C2..DF      80..BF
 *
 * 3                     16     1110xxxx    10xxxxxx    10xxxxxx
 *      U+0800..U+0FFF          E0          A0..BF      80..BF
 *      U+1000..U+FFFF          E1..EF      80..BF      80..BF
 *
 */

class CESU_8 extends Unicode
{
    public CESU_8() {
        super("CESU-8", StandardCharsets.aliases_CESU_8);
    }

    public String historicalName() {
        return "CESU8";
    }

    public CharsetDecoder newDecoder() {
        return new Decoder(this);
    }

    public CharsetEncoder newEncoder() {
        return new Encoder(this);
    }

    private static final void updatePositions(Buffer src, int sp,
                                              Buffer dst, int dp) {
        src.position(sp - src.arrayOffset());
        dst.position(dp - dst.arrayOffset());
    }

    private static class Decoder extends CharsetDecoder
                                 implements ArrayDecoder {
        private Decoder(Charset cs) {
            super(cs, 1.0f, 1.0f);
        }

        private static boolean isNotContinuation(int b) {
            return (b & 0xc0) != 0x80;
        }

        //  [E0]     [A0..BF] [80..BF]
        //  [E1..EF] [80..BF] [80..BF]
        private static boolean isMalformed3(int b1, int b2, int b3) {
            return (b1 == (byte)0xe0 && (b2 & 0xe0) == 0x80) ||
                   (b2 & 0xc0) != 0x80 || (b3 & 0xc0) != 0x80;
        }

        // only used when there is only one byte left in src buffer
        private static boolean isMalformed3_2(int b1, int b2) {
            return (b1 == (byte)0xe0 && (b2 & 0xe0) == 0x80) ||
                   (b2 & 0xc0) != 0x80;
        }


        //  [F0]     [90..BF] [80..BF] [80..BF]
        //  [F1..F3] [80..BF] [80..BF] [80..BF]
        //  [F4]     [80..8F] [80..BF] [80..BF]
        //  only check 80-be range here, the [0xf0,0x80...] and [0xf4,0x90-...]
        //  will be checked by Character.isSupplementaryCodePoint(uc)
        private static boolean isMalformed4(int b2, int b3, int b4) {
            return (b2 & 0xc0) != 0x80 || (b3 & 0xc0) != 0x80 ||
                   (b4 & 0xc0) != 0x80;
        }

        // only used when there is less than 4 bytes left in src buffer
        private static boolean isMalformed4_2(int b1, int b2) {
            return (b1 == 0xf0 && b2 == 0x90) ||
                   (b2 & 0xc0) != 0x80;
        }

        private static boolean isMalformed4_3(int b3) {
            return (b3 & 0xc0) != 0x80;
        }

        private static CoderResult malformedN(ByteBuffer src, int nb) {
            switch (nb) {
            case 1:
            case 2:                    // always 1
                return CoderResult.malformedForLength(1);
            case 3:
                int b1 = src.get();
                int b2 = src.get();    // no need to lookup b3
                return CoderResult.malformedForLength(
                    ((b1 == (byte)0xe0 && (b2 & 0xe0) == 0x80) ||
                     isNotContinuation(b2)) ? 1 : 2);
            case 4:  // we don't care the speed here
                b1 = src.get() & 0xff;
                b2 = src.get() & 0xff;
                if (b1 > 0xf4 ||
                    (b1 == 0xf0 && (b2 < 0x90 || b2 > 0xbf)) ||
                    (b1 == 0xf4 && (b2 & 0xf0) != 0x80) ||
                    isNotContinuation(b2))
                    return CoderResult.malformedForLength(1);
                if (isNotContinuation(src.get()))
                    return CoderResult.malformedForLength(2);
                return CoderResult.malformedForLength(3);
            default:
                assert false;
                return null;
            }
        }

        private static CoderResult malformed(ByteBuffer src, int sp,
                                             CharBuffer dst, int dp,
                                             int nb)
        {
            src.position(sp - src.arrayOffset());
            CoderResult cr = malformedN(src, nb);
            updatePositions(src, sp, dst, dp);
            return cr;
        }


        private static CoderResult malformed(ByteBuffer src,
                                             int mark, int nb)
        {
            src.position(mark);
            CoderResult cr = malformedN(src, nb);
            src.position(mark);
            return cr;
        }

        private static CoderResult malformedForLength(ByteBuffer src,
                                                      int sp,
                                                      CharBuffer dst,
                                                      int dp,
                                                      int malformedNB)
        {
            updatePositions(src, sp, dst, dp);
            return CoderResult.malformedForLength(malformedNB);
        }

        private static CoderResult malformedForLength(ByteBuffer src,
                                                      int mark,
                                                      int malformedNB)
        {
            src.position(mark);
            return CoderResult.malformedForLength(malformedNB);
        }


        private static CoderResult xflow(Buffer src, int sp, int sl,
                                         Buffer dst, int dp, int nb) {
            updatePositions(src, sp, dst, dp);
            return (nb == 0 || sl - sp < nb)
                   ? CoderResult.UNDERFLOW : CoderResult.OVERFLOW;
        }

        private static CoderResult xflow(Buffer src, int mark, int nb) {
            src.position(mark);
            return (nb == 0 || src.remaining() < nb)
                   ? CoderResult.UNDERFLOW : CoderResult.OVERFLOW;
        }

        private CoderResult decodeArrayLoop(ByteBuffer src,
                                            CharBuffer dst)
        {
            // This method is optimized for ASCII input.
            byte[] sa = src.array();
            int sp = src.arrayOffset() + src.position();
            int sl = src.arrayOffset() + src.limit();

            char[] da = dst.array();
            int dp = dst.arrayOffset() + dst.position();
            int dl = dst.arrayOffset() + dst.limit();
            int dlASCII = dp + Math.min(sl - sp, dl - dp);

            // ASCII only loop
            while (dp < dlASCII && sa[sp] >= 0)
                da[dp++] = (char) sa[sp++];
            while (sp < sl) {
                int b1 = sa[sp];
                if (b1 >= 0) {
                    // 1 byte, 7 bits: 0xxxxxxx
                    if (dp >= dl)
                        return xflow(src, sp, sl, dst, dp, 1);
                    da[dp++] = (char) b1;
                    sp++;
                } else if ((b1 >> 5) == -2 && (b1 & 0x1e) != 0) {
                    // 2 bytes, 11 bits: 110xxxxx 10xxxxxx
                    if (sl - sp < 2 || dp >= dl)
                        return xflow(src, sp, sl, dst, dp, 2);
                    int b2 = sa[sp + 1];
                    if (isNotContinuation(b2))
                        return malformedForLength(src, sp, dst, dp, 1);
                    da[dp++] = (char) (((b1 << 6) ^ b2)
                                       ^
                                       (((byte) 0xC0 << 6) ^
                                        ((byte) 0x80 << 0)));
                    sp += 2;
                } else if ((b1 >> 4) == -2) {
                    // 3 bytes, 16 bits: 1110xxxx 10xxxxxx 10xxxxxx
                    int srcRemaining = sl - sp;
                    if (srcRemaining < 3 || dp >= dl) {
                        if (srcRemaining > 1 && isMalformed3_2(b1, sa[sp + 1]))
                            return malformedForLength(src, sp, dst, dp, 1);
                        return xflow(src, sp, sl, dst, dp, 3);
                    }
                    int b2 = sa[sp + 1];
                    int b3 = sa[sp + 2];
                    if (isMalformed3(b1, b2, b3))
                        return malformed(src, sp, dst, dp, 3);
                    da[dp++] = (char)
                        ((b1 << 12) ^
                         (b2 <<  6) ^
                         (b3 ^
                          (((byte) 0xE0 << 12) ^
                           ((byte) 0x80 <<  6) ^
                           ((byte) 0x80 <<  0))));
                    sp += 3;
                } else {
                    return malformed(src, sp, dst, dp, 1);
                }
            }
            return xflow(src, sp, sl, dst, dp, 0);
        }

        private CoderResult decodeBufferLoop(ByteBuffer src,
                                             CharBuffer dst)
        {
            int mark = src.position();
            int limit = src.limit();
            while (mark < limit) {
                int b1 = src.get();
                if (b1 >= 0) {
                    // 1 byte, 7 bits: 0xxxxxxx
                    if (dst.remaining() < 1)
                        return xflow(src, mark, 1); // overflow
                    dst.put((char) b1);
                    mark++;
                } else if ((b1 >> 5) == -2 && (b1 & 0x1e) != 0) {
                    // 2 bytes, 11 bits: 110xxxxx 10xxxxxx
                    if (limit - mark < 2|| dst.remaining() < 1)
                        return xflow(src, mark, 2);
                    int b2 = src.get();
                    if (isNotContinuation(b2))
                        return malformedForLength(src, mark, 1);
                    dst.put((char) (((b1 << 6) ^ b2)
                                    ^
                                    (((byte) 0xC0 << 6) ^
                                     ((byte) 0x80 << 0))));
                    mark += 2;
                } else if ((b1 >> 4) == -2) {
                    // 3 bytes, 16 bits: 1110xxxx 10xxxxxx 10xxxxxx
                    int srcRemaining = limit - mark;
                    if (srcRemaining < 3 || dst.remaining() < 1) {
                        if (srcRemaining > 1 && isMalformed3_2(b1, src.get()))
                            return malformedForLength(src, mark, 1);
                        return xflow(src, mark, 3);
                    }
                    int b2 = src.get();
                    int b3 = src.get();
                    if (isMalformed3(b1, b2, b3))
                        return malformed(src, mark, 3);
                    dst.put((char)
                            ((b1 << 12) ^
                             (b2 <<  6) ^
                             (b3 ^
                              (((byte) 0xE0 << 12) ^
                               ((byte) 0x80 <<  6) ^
                               ((byte) 0x80 <<  0)))));
                    mark += 3;
                } else {
                    return malformed(src, mark, 1);
                }
            }
            return xflow(src, mark, 0);
        }

        protected CoderResult decodeLoop(ByteBuffer src,
                                         CharBuffer dst)
        {
            if (src.hasArray() && dst.hasArray())
                return decodeArrayLoop(src, dst);
            else
                return decodeBufferLoop(src, dst);
        }

        private static ByteBuffer getByteBuffer(ByteBuffer bb, byte[] ba, int sp)
        {
            if (bb == null)
                bb = ByteBuffer.wrap(ba);
            bb.position(sp);
            return bb;
        }

        // returns -1 if there is/are malformed byte(s) and the
        // "action" for malformed input is not REPLACE.
        public int decode(byte[] sa, int sp, int len, char[] da) {
            final int sl = sp + len;
            int dp = 0;
            int dlASCII = Math.min(len, da.length);
            ByteBuffer bb = null;  // only necessary if malformed

            // ASCII only optimized loop
            while (dp < dlASCII && sa[sp] >= 0)
                da[dp++] = (char) sa[sp++];

            while (sp < sl) {
                int b1 = sa[sp++];
                if (b1 >= 0) {
                    // 1 byte, 7 bits: 0xxxxxxx
                    da[dp++] = (char) b1;
                } else if ((b1 >> 5) == -2 && (b1 & 0x1e) != 0) {
                    // 2 bytes, 11 bits: 110xxxxx 10xxxxxx
                    if (sp < sl) {
                        int b2 = sa[sp++];
                        if (isNotContinuation(b2)) {
                            if (malformedInputAction() != CodingErrorAction.REPLACE)
                                return -1;
                            da[dp++] = replacement().charAt(0);
                            sp--;            // malformedN(bb, 2) always returns 1
                        } else {
                            da[dp++] = (char) (((b1 << 6) ^ b2)^
                                           (((byte) 0xC0 << 6) ^
                                            ((byte) 0x80 << 0)));
                        }
                        continue;
                    }
                    if (malformedInputAction() != CodingErrorAction.REPLACE)
                        return -1;
                    da[dp++] = replacement().charAt(0);
                    return dp;
                } else if ((b1 >> 4) == -2) {
                    // 3 bytes, 16 bits: 1110xxxx 10xxxxxx 10xxxxxx
                    if (sp + 1 < sl) {
                        int b2 = sa[sp++];
                        int b3 = sa[sp++];
                        if (isMalformed3(b1, b2, b3)) {
                            if (malformedInputAction() != CodingErrorAction.REPLACE)
                                return -1;
                            da[dp++] = replacement().charAt(0);
                            sp -=3;
                            bb = getByteBuffer(bb, sa, sp);
                            sp += malformedN(bb, 3).length();
                        } else {
                            da[dp++] = (char)((b1 << 12) ^
                                              (b2 <<  6) ^
                                              (b3 ^
                                              (((byte) 0xE0 << 12) ^
                                              ((byte) 0x80 <<  6) ^
                                              ((byte) 0x80 <<  0))));
                        }
                        continue;
                    }
                    if (malformedInputAction() != CodingErrorAction.REPLACE)
                        return -1;
                    if (sp  < sl && isMalformed3_2(b1, sa[sp])) {
                        da[dp++] = replacement().charAt(0);
                        continue;

                    }
                    da[dp++] = replacement().charAt(0);
                    return dp;
                } else {
                    if (malformedInputAction() != CodingErrorAction.REPLACE)
                        return -1;
                    da[dp++] = replacement().charAt(0);
                }
            }
            return dp;
        }
    }

    private static class Encoder extends CharsetEncoder
                                 implements ArrayEncoder {

        private Encoder(Charset cs) {
            super(cs, 1.1f, 3.0f);
        }

        public boolean canEncode(char c) {
            return !Character.isSurrogate(c);
        }

        public boolean isLegalReplacement(byte[] repl) {
            return ((repl.length == 1 && repl[0] >= 0) ||
                    super.isLegalReplacement(repl));
        }

        private static CoderResult overflow(CharBuffer src, int sp,
                                            ByteBuffer dst, int dp) {
            updatePositions(src, sp, dst, dp);
            return CoderResult.OVERFLOW;
        }

        private static CoderResult overflow(CharBuffer src, int mark) {
            src.position(mark);
            return CoderResult.OVERFLOW;
        }

        private static void to3Bytes(byte[] da, int dp, char c) {
            da[dp] = (byte)(0xe0 | ((c >> 12)));
            da[dp + 1] = (byte)(0x80 | ((c >>  6) & 0x3f));
            da[dp + 2] = (byte)(0x80 | (c & 0x3f));
        }

        private static void to3Bytes(ByteBuffer dst, char c) {
            dst.put((byte)(0xe0 | ((c >> 12))));
            dst.put((byte)(0x80 | ((c >>  6) & 0x3f)));
            dst.put((byte)(0x80 | (c & 0x3f)));
        }

        private Surrogate.Parser sgp;
        private char[] c2;
        private CoderResult encodeArrayLoop(CharBuffer src,
                                            ByteBuffer dst)
        {
            char[] sa = src.array();
            int sp = src.arrayOffset() + src.position();
            int sl = src.arrayOffset() + src.limit();

            byte[] da = dst.array();
            int dp = dst.arrayOffset() + dst.position();
            int dl = dst.arrayOffset() + dst.limit();
            int dlASCII = dp + Math.min(sl - sp, dl - dp);

            // ASCII only loop
            while (dp < dlASCII && sa[sp] < '\u0080')
                da[dp++] = (byte) sa[sp++];
            while (sp < sl) {
                char c = sa[sp];
                if (c < 0x80) {
                    // Have at most seven bits
                    if (dp >= dl)
                        return overflow(src, sp, dst, dp);
                    da[dp++] = (byte)c;
                } else if (c < 0x800) {
                    // 2 bytes, 11 bits
                    if (dl - dp < 2)
                        return overflow(src, sp, dst, dp);
                    da[dp++] = (byte)(0xc0 | (c >> 6));
                    da[dp++] = (byte)(0x80 | (c & 0x3f));
                } else if (Character.isSurrogate(c)) {
                    // Have a surrogate pair
                    if (sgp == null)
                        sgp = new Surrogate.Parser();
                    int uc = sgp.parse(c, sa, sp, sl);
                    if (uc < 0) {
                        updatePositions(src, sp, dst, dp);
                        return sgp.error();
                    }
                    if (dl - dp < 6)
                        return overflow(src, sp, dst, dp);
                    to3Bytes(da, dp, Character.highSurrogate(uc));
                    dp += 3;
                    to3Bytes(da, dp, Character.lowSurrogate(uc));
                    dp += 3;
                    sp++;  // 2 chars
                } else {
                    // 3 bytes, 16 bits
                    if (dl - dp < 3)
                        return overflow(src, sp, dst, dp);
                    to3Bytes(da, dp, c);
                    dp += 3;
                }
                sp++;
            }
            updatePositions(src, sp, dst, dp);
            return CoderResult.UNDERFLOW;
        }

        private CoderResult encodeBufferLoop(CharBuffer src,
                                             ByteBuffer dst)
        {
            int mark = src.position();
            while (src.hasRemaining()) {
                char c = src.get();
                if (c < 0x80) {
                    // Have at most seven bits
                    if (!dst.hasRemaining())
                        return overflow(src, mark);
                    dst.put((byte)c);
                } else if (c < 0x800) {
                    // 2 bytes, 11 bits
                    if (dst.remaining() < 2)
                        return overflow(src, mark);
                    dst.put((byte)(0xc0 | (c >> 6)));
                    dst.put((byte)(0x80 | (c & 0x3f)));
                } else if (Character.isSurrogate(c)) {
                    // Have a surrogate pair
                    if (sgp == null)
                        sgp = new Surrogate.Parser();
                    int uc = sgp.parse(c, src);
                    if (uc < 0) {
                        src.position(mark);
                        return sgp.error();
                    }
                    if (dst.remaining() < 6)
                        return overflow(src, mark);
                    to3Bytes(dst, Character.highSurrogate(uc));
                    to3Bytes(dst, Character.lowSurrogate(uc));
                    mark++;  // 2 chars
                } else {
                    // 3 bytes, 16 bits
                    if (dst.remaining() < 3)
                        return overflow(src, mark);
                    to3Bytes(dst, c);
                }
                mark++;
            }
            src.position(mark);
            return CoderResult.UNDERFLOW;
        }

        protected final CoderResult encodeLoop(CharBuffer src,
                                               ByteBuffer dst)
        {
            if (src.hasArray() && dst.hasArray())
                return encodeArrayLoop(src, dst);
            else
                return encodeBufferLoop(src, dst);
        }

        // returns -1 if there is malformed char(s) and the
        // "action" for malformed input is not REPLACE.
        public int encode(char[] sa, int sp, int len, byte[] da) {
            int sl = sp + len;
            int dp = 0;
            int dlASCII = dp + Math.min(len, da.length);

            // ASCII only optimized loop
            while (dp < dlASCII && sa[sp] < '\u0080')
                da[dp++] = (byte) sa[sp++];

            while (sp < sl) {
                char c = sa[sp++];
                if (c < 0x80) {
                    // Have at most seven bits
                    da[dp++] = (byte)c;
                } else if (c < 0x800) {
                    // 2 bytes, 11 bits
                    da[dp++] = (byte)(0xc0 | (c >> 6));
                    da[dp++] = (byte)(0x80 | (c & 0x3f));
                } else if (Character.isSurrogate(c)) {
                    if (sgp == null)
                        sgp = new Surrogate.Parser();
                    int uc = sgp.parse(c, sa, sp - 1, sl);
                    if (uc < 0) {
                        if (malformedInputAction() != CodingErrorAction.REPLACE)
                            return -1;
                        da[dp++] = replacement()[0];
                    } else {
                        to3Bytes(da, dp, Character.highSurrogate(uc));
                        dp += 3;
                        to3Bytes(da, dp, Character.lowSurrogate(uc));
                        dp += 3;
                        sp++;  // 2 chars
                    }
                } else {
                    // 3 bytes, 16 bits
                    to3Bytes(da, dp, c);
                    dp += 3;
                }
            }
            return dp;
        }
    }
}

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