1 /*
   2  * Copyright (c) 2000, 2004, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package sun.nio.cs;
  27 
  28 import java.nio.ByteBuffer;
  29 import java.nio.CharBuffer;
  30 import java.nio.charset.Charset;
  31 import java.nio.charset.CharsetDecoder;
  32 import java.nio.charset.CharsetEncoder;
  33 import java.nio.charset.CoderResult;
  34 import java.util.Arrays;
  35 
  36 public class US_ASCII
  37     extends Charset
  38     implements HistoricallyNamedCharset
  39 {
  40 
  41     public US_ASCII() {
  42         super("US-ASCII", StandardCharsets.aliases_US_ASCII);
  43     }
  44 
  45     public String historicalName() {
  46         return "ASCII";
  47     }
  48 
  49     public boolean contains(Charset cs) {
  50         return (cs instanceof US_ASCII);
  51     }
  52 
  53     public CharsetDecoder newDecoder() {
  54         return new Decoder(this);
  55     }
  56 
  57     public CharsetEncoder newEncoder() {
  58         return new Encoder(this);
  59     }
  60 
  61     private static class Decoder extends CharsetDecoder
  62                                  implements ArrayDecoder {
  63 
  64         private Decoder(Charset cs) {
  65             super(cs, 1.0f, 1.0f);
  66         }
  67 
  68         private CoderResult decodeArrayLoop(ByteBuffer src,
  69                                             CharBuffer dst)
  70         {
  71             byte[] sa = src.array();
  72             int sp = src.arrayOffset() + src.position();
  73             int sl = src.arrayOffset() + src.limit();
  74             assert (sp <= sl);
  75             sp = (sp <= sl ? sp : sl);
  76             char[] da = dst.array();
  77             int dp = dst.arrayOffset() + dst.position();
  78             int dl = dst.arrayOffset() + dst.limit();
  79             assert (dp <= dl);
  80             dp = (dp <= dl ? dp : dl);
  81 
  82             try {
  83                 while (sp < sl) {
  84                     byte b = sa[sp];
  85                     if (b >= 0) {
  86                         if (dp >= dl)
  87                             return CoderResult.OVERFLOW;
  88                         da[dp++] = (char)b;
  89                         sp++;
  90                         continue;
  91                     }
  92                     return CoderResult.malformedForLength(1);
  93                 }
  94                 return CoderResult.UNDERFLOW;
  95             } finally {
  96                 src.position(sp - src.arrayOffset());
  97                 dst.position(dp - dst.arrayOffset());
  98             }
  99         }
 100 
 101         private CoderResult decodeBufferLoop(ByteBuffer src,
 102                                              CharBuffer dst)
 103         {
 104             int mark = src.position();
 105             try {
 106                 while (src.hasRemaining()) {
 107                     byte b = src.get();
 108                     if (b >= 0) {
 109                         if (!dst.hasRemaining())
 110                             return CoderResult.OVERFLOW;
 111                         dst.put((char)b);
 112                         mark++;
 113                         continue;
 114                     }
 115                     return CoderResult.malformedForLength(1);
 116                 }
 117                 return CoderResult.UNDERFLOW;
 118             } finally {
 119                 src.position(mark);
 120             }
 121         }
 122 
 123         protected CoderResult decodeLoop(ByteBuffer src,
 124                                          CharBuffer dst)
 125         {
 126             if (src.hasArray() && dst.hasArray())
 127                 return decodeArrayLoop(src, dst);
 128             else
 129                 return decodeBufferLoop(src, dst);
 130         }
 131 
 132         private char repl = '\uFFFD';
 133         protected void implReplaceWith(String newReplacement) {
 134             repl = newReplacement.charAt(0);
 135         }
 136 
 137         public int decode(byte[] src, int sp, int len, char[] dst) {
 138             int dp = 0;
 139             len = Math.min(len, dst.length);
 140             while (dp < len) {
 141                 byte b = src[sp++];
 142                 if (b >= 0)
 143                     dst[dp++] = (char)b;
 144                 else
 145                     dst[dp++] = repl;
 146             }
 147             return dp;
 148         }
 149     }
 150 
 151     private static class Encoder extends CharsetEncoder
 152                                  implements ArrayEncoder {
 153 
 154         private Encoder(Charset cs) {
 155             super(cs, 1.0f, 1.0f);
 156         }
 157 
 158         public boolean canEncode(char c) {
 159             return c < 0x80;
 160         }
 161 
 162         public boolean isLegalReplacement(byte[] repl) {
 163             return (repl.length == 1 && repl[0] >= 0) ||
 164                    super.isLegalReplacement(repl);
 165         }
 166 
 167         private final Surrogate.Parser sgp = new Surrogate.Parser();
 168         private CoderResult encodeArrayLoop(CharBuffer src,
 169                                             ByteBuffer dst)
 170         {
 171             char[] sa = src.array();
 172             int sp = src.arrayOffset() + src.position();
 173             int sl = src.arrayOffset() + src.limit();
 174             assert (sp <= sl);
 175             sp = (sp <= sl ? sp : sl);
 176             byte[] da = dst.array();
 177             int dp = dst.arrayOffset() + dst.position();
 178             int dl = dst.arrayOffset() + dst.limit();
 179             assert (dp <= dl);
 180             dp = (dp <= dl ? dp : dl);
 181 
 182             try {
 183                 while (sp < sl) {
 184                     char c = sa[sp];
 185                     if (c < 0x80) {
 186                         if (dp >= dl)
 187                             return CoderResult.OVERFLOW;
 188                         da[dp] = (byte)c;
 189                         sp++; dp++;
 190                         continue;
 191                     }
 192                     if (sgp.parse(c, sa, sp, sl) < 0)
 193                         return sgp.error();
 194                     return sgp.unmappableResult();
 195                 }
 196                 return CoderResult.UNDERFLOW;
 197             } finally {
 198                 src.position(sp - src.arrayOffset());
 199                 dst.position(dp - dst.arrayOffset());
 200             }
 201         }
 202 
 203         private CoderResult encodeBufferLoop(CharBuffer src,
 204                                              ByteBuffer dst)
 205         {
 206             int mark = src.position();
 207             try {
 208                 while (src.hasRemaining()) {
 209                     char c = src.get();
 210                     if (c < 0x80) {
 211                         if (!dst.hasRemaining())
 212                             return CoderResult.OVERFLOW;
 213                         dst.put((byte)c);
 214                         mark++;
 215                         continue;
 216                     }
 217                     if (sgp.parse(c, src) < 0)
 218                         return sgp.error();
 219                     return sgp.unmappableResult();
 220                 }
 221                 return CoderResult.UNDERFLOW;
 222             } finally {
 223                 src.position(mark);
 224             }
 225         }
 226 
 227         protected CoderResult encodeLoop(CharBuffer src,
 228                                          ByteBuffer dst)
 229         {
 230             if (src.hasArray() && dst.hasArray())
 231                 return encodeArrayLoop(src, dst);
 232             else
 233                 return encodeBufferLoop(src, dst);
 234         }
 235 
 236         private byte repl = (byte)'?';
 237         protected void implReplaceWith(byte[] newReplacement) {
 238             repl = newReplacement[0];
 239         }
 240 
 241         public int encode(char[] src, int sp, int len, byte[] dst) {
 242             int dp = 0;
 243             int sl = sp + Math.min(len, dst.length);
 244             while (sp < sl) {
 245                 char c = src[sp++];
 246                 if (c < 0x80) {
 247                     dst[dp++] = (byte)c;
 248                     continue;
 249                 }
 250                 if (Character.isHighSurrogate(c) && sp < sl &&
 251                     Character.isLowSurrogate(src[sp])) {
 252                     if (len > dst.length) {
 253                         sl++;
 254                         len--;
 255                     }
 256                     sp++;
 257                 }
 258                 dst[dp++] = repl;
 259             }
 260             return dp;
 261         }
 262     }
 263 
 264 }