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234 lines
8.5 KiB
Java
234 lines
8.5 KiB
Java
/*
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* Copyright (c) 2003, 2023, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package sun.nio.cs.ext;
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import java.nio.ByteBuffer;
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import java.nio.CharBuffer;
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import java.nio.charset.Charset;
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import java.nio.charset.CharsetDecoder;
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import java.nio.charset.CharsetEncoder;
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import java.nio.charset.CoderResult;
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import java.nio.charset.CharacterCodingException;
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import java.nio.charset.MalformedInputException;
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import sun.nio.cs.DelegatableDecoder;
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import sun.nio.cs.HistoricallyNamedCharset;
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import sun.nio.cs.*;
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import static java.lang.Character.UnicodeBlock;
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import jdk.internal.util.OperatingSystem;
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public class JISAutoDetect
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extends Charset
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implements HistoricallyNamedCharset
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{
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private static final int EUCJP_MASK = 0x01;
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private static final int SJIS2B_MASK = 0x02;
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private static final int SJIS1B_MASK = 0x04;
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private static final int EUCJP_KANA1_MASK = 0x08;
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private static final int EUCJP_KANA2_MASK = 0x10;
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public JISAutoDetect() {
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super("x-JISAutoDetect", ExtendedCharsets.aliasesFor("x-JISAutoDetect"));
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}
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public boolean contains(Charset cs) {
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return ((cs.name().equals("US-ASCII"))
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|| (cs instanceof SJIS)
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|| (cs instanceof EUC_JP)
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|| (cs instanceof ISO2022_JP)
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|| (cs instanceof JISAutoDetect));
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}
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public boolean canEncode() {
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return false;
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}
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public CharsetDecoder newDecoder() {
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return new Decoder(this);
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}
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public String historicalName() {
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return "JISAutoDetect";
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}
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public CharsetEncoder newEncoder() {
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throw new UnsupportedOperationException();
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}
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// A heuristic algorithm for guessing if EUC-decoded text really
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// might be Japanese text. Better heuristics are possible...
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private static boolean looksLikeJapanese(CharBuffer cb) {
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int hiragana = 0; // Fullwidth Hiragana
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int katakana = 0; // Halfwidth Katakana
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while (cb.hasRemaining()) {
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char c = cb.get();
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if (0x3040 <= c && c <= 0x309f && ++hiragana > 1) return true;
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if (0xff65 <= c && c <= 0xff9f && ++katakana > 1) return true;
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}
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return false;
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}
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private static class Decoder extends CharsetDecoder {
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private static final String SJISName = getSJISName();
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private static final String EUCJPName = "EUC_JP";
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private DelegatableDecoder detectedDecoder = null;
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public Decoder(Charset cs) {
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super(cs, 0.5f, 1.0f);
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}
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private static boolean isPlainASCII(byte b) {
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return b >= 0 && b != 0x1b;
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}
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private static void copyLeadingASCII(ByteBuffer src, CharBuffer dst) {
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int start = src.position();
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int limit = start + Math.min(src.remaining(), dst.remaining());
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int p;
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byte b;
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for (p = start; p < limit && isPlainASCII(b = src.get(p)); p++)
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dst.put((char)(b & 0xff));
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src.position(p);
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}
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private CoderResult decodeLoop(DelegatableDecoder decoder,
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ByteBuffer src, CharBuffer dst) {
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((CharsetDecoder)decoder).reset();
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detectedDecoder = decoder;
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return detectedDecoder.decodeLoop(src, dst);
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}
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protected CoderResult decodeLoop(ByteBuffer src, CharBuffer dst) {
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if (detectedDecoder == null) {
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copyLeadingASCII(src, dst);
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// All ASCII?
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if (! src.hasRemaining())
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return CoderResult.UNDERFLOW;
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// Overflow only if there is still ascii but no out buffer.
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if (!dst.hasRemaining() &&
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isPlainASCII(src.get(src.position())))
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return CoderResult.OVERFLOW;
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// We need to perform double, not float, arithmetic; otherwise
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// we lose low order bits when src is larger than 2**24.
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int cbufsiz = (int)(src.limit() * (double)maxCharsPerByte());
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CharBuffer sandbox = CharBuffer.allocate(cbufsiz);
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// First try ISO-2022-JP, since there is no ambiguity
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Charset cs2022 = Charset.forName("ISO-2022-JP");
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DelegatableDecoder dd2022
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= (DelegatableDecoder) cs2022.newDecoder();
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ByteBuffer src2022 = src.asReadOnlyBuffer();
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CoderResult res2022 = dd2022.decodeLoop(src2022, sandbox);
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if (! res2022.isError())
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return decodeLoop(dd2022, src, dst);
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// We must choose between EUC and SJIS
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Charset csEUCJ = Charset.forName(EUCJPName);
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Charset csSJIS = Charset.forName(SJISName);
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DelegatableDecoder ddEUCJ
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= (DelegatableDecoder) csEUCJ.newDecoder();
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DelegatableDecoder ddSJIS
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= (DelegatableDecoder) csSJIS.newDecoder();
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ByteBuffer srcEUCJ = src.asReadOnlyBuffer();
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sandbox.clear();
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CoderResult resEUCJ = ddEUCJ.decodeLoop(srcEUCJ, sandbox);
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// If EUC decoding fails, must be SJIS
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if (resEUCJ.isError())
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return decodeLoop(ddSJIS, src, dst);
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ByteBuffer srcSJIS = src.asReadOnlyBuffer();
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CharBuffer sandboxSJIS = CharBuffer.allocate(cbufsiz);
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CoderResult resSJIS = ddSJIS.decodeLoop(srcSJIS, sandboxSJIS);
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// If SJIS decoding fails, must be EUC
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if (resSJIS.isError())
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return decodeLoop(ddEUCJ, src, dst);
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// From here on, we have some ambiguity, and must guess.
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// We prefer input that does not appear to end mid-character.
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if (srcEUCJ.position() > srcSJIS.position())
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return decodeLoop(ddEUCJ, src, dst);
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if (srcEUCJ.position() < srcSJIS.position())
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return decodeLoop(ddSJIS, src, dst);
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// end-of-input is after the first byte of the first char?
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if (src.position() == srcEUCJ.position())
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return CoderResult.UNDERFLOW;
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// Use heuristic knowledge of typical Japanese text
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sandbox.flip();
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return decodeLoop(looksLikeJapanese(sandbox) ? ddEUCJ : ddSJIS,
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src, dst);
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}
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return detectedDecoder.decodeLoop(src, dst);
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}
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protected void implReset() {
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detectedDecoder = null;
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}
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protected CoderResult implFlush(CharBuffer out) {
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if (detectedDecoder != null)
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return detectedDecoder.implFlush(out);
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else
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return super.implFlush(out);
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}
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public boolean isAutoDetecting() {
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return true;
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}
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public boolean isCharsetDetected() {
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return detectedDecoder != null;
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}
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public Charset detectedCharset() {
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if (detectedDecoder == null)
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throw new IllegalStateException("charset not yet detected");
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return ((CharsetDecoder) detectedDecoder).charset();
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}
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/**
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* Returned Shift_JIS Charset name is OS dependent
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*/
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private static String getSJISName() {
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if (OperatingSystem.isWindows())
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return("windows-31J");
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else
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return("Shift_JIS");
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}
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}
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}
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