1 /* 2 * Copyright (c) 2001, 2013, 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 java.nio.charset; 27 28 import java.lang.ref.WeakReference; 29 import java.nio.*; 30 import java.util.Map; 31 import java.util.HashMap; 32 33 34 /** 35 * A description of the result state of a coder. 36 * 37 * <p> A charset coder, that is, either a decoder or an encoder, consumes bytes 38 * (or characters) from an input buffer, translates them, and writes the 39 * resulting characters (or bytes) to an output buffer. A coding process 40 * terminates for one of four categories of reasons, which are described by 41 * instances of this class: 42 * 43 * <ul> 44 * 45 * <li><p> <i>Underflow</i> is reported when there is no more input to be 46 * processed, or there is insufficient input and additional input is 47 * required. This condition is represented by the unique result object 48 * {@link #UNDERFLOW}, whose {@link #isUnderflow() isUnderflow} method 49 * returns <tt>true</tt>. </p></li> 50 * 51 * <li><p> <i>Overflow</i> is reported when there is insufficient room 52 * remaining in the output buffer. This condition is represented by the 53 * unique result object {@link #OVERFLOW}, whose {@link #isOverflow() 54 * isOverflow} method returns <tt>true</tt>. </p></li> 55 * 56 * <li><p> A <i>malformed-input error</i> is reported when a sequence of 57 * input units is not well-formed. Such errors are described by instances of 58 * this class whose {@link #isMalformed() isMalformed} method returns 59 * <tt>true</tt> and whose {@link #length() length} method returns the length 60 * of the malformed sequence. There is one unique instance of this class for 61 * all malformed-input errors of a given length. </p></li> 62 * 63 * <li><p> An <i>unmappable-character error</i> is reported when a sequence 64 * of input units denotes a character that cannot be represented in the 65 * output charset. Such errors are described by instances of this class 66 * whose {@link #isUnmappable() isUnmappable} method returns <tt>true</tt> and 67 * whose {@link #length() length} method returns the length of the input 68 * sequence denoting the unmappable character. There is one unique instance 69 * of this class for all unmappable-character errors of a given length. 70 * </p></li> 71 * 72 * </ul> 73 * 74 * <p> For convenience, the {@link #isError() isError} method returns <tt>true</tt> 75 * for result objects that describe malformed-input and unmappable-character 76 * errors but <tt>false</tt> for those that describe underflow or overflow 77 * conditions. </p> 78 * 79 * 80 * @author Mark Reinhold 81 * @author JSR-51 Expert Group 82 * @since 1.4 83 */ 84 85 public class CoderResult { 86 87 private static final int CR_UNDERFLOW = 0; 88 private static final int CR_OVERFLOW = 1; 89 private static final int CR_ERROR_MIN = 2; 90 private static final int CR_MALFORMED = 2; 91 private static final int CR_UNMAPPABLE = 3; 92 93 private static final String[] names 94 = { "UNDERFLOW", "OVERFLOW", "MALFORMED", "UNMAPPABLE" }; 95 96 private final int type; 97 private final int length; 98 CoderResult(int type, int length)99 private CoderResult(int type, int length) { 100 this.type = type; 101 this.length = length; 102 } 103 104 /** 105 * Returns a string describing this coder result. 106 * 107 * @return A descriptive string 108 */ toString()109 public String toString() { 110 String nm = names[type]; 111 return isError() ? nm + "[" + length + "]" : nm; 112 } 113 114 /** 115 * Tells whether or not this object describes an underflow condition. 116 * 117 * @return <tt>true</tt> if, and only if, this object denotes underflow 118 */ isUnderflow()119 public boolean isUnderflow() { 120 return (type == CR_UNDERFLOW); 121 } 122 123 /** 124 * Tells whether or not this object describes an overflow condition. 125 * 126 * @return <tt>true</tt> if, and only if, this object denotes overflow 127 */ isOverflow()128 public boolean isOverflow() { 129 return (type == CR_OVERFLOW); 130 } 131 132 /** 133 * Tells whether or not this object describes an error condition. 134 * 135 * @return <tt>true</tt> if, and only if, this object denotes either a 136 * malformed-input error or an unmappable-character error 137 */ isError()138 public boolean isError() { 139 return (type >= CR_ERROR_MIN); 140 } 141 142 /** 143 * Tells whether or not this object describes a malformed-input error. 144 * 145 * @return <tt>true</tt> if, and only if, this object denotes a 146 * malformed-input error 147 */ isMalformed()148 public boolean isMalformed() { 149 return (type == CR_MALFORMED); 150 } 151 152 /** 153 * Tells whether or not this object describes an unmappable-character 154 * error. 155 * 156 * @return <tt>true</tt> if, and only if, this object denotes an 157 * unmappable-character error 158 */ isUnmappable()159 public boolean isUnmappable() { 160 return (type == CR_UNMAPPABLE); 161 } 162 163 /** 164 * Returns the length of the erroneous input described by this 165 * object <i>(optional operation)</i>. 166 * 167 * @return The length of the erroneous input, a positive integer 168 * 169 * @throws UnsupportedOperationException 170 * If this object does not describe an error condition, that is, 171 * if the {@link #isError() isError} does not return <tt>true</tt> 172 */ length()173 public int length() { 174 if (!isError()) 175 throw new UnsupportedOperationException(); 176 return length; 177 } 178 179 /** 180 * Result object indicating underflow, meaning that either the input buffer 181 * has been completely consumed or, if the input buffer is not yet empty, 182 * that additional input is required. 183 */ 184 public static final CoderResult UNDERFLOW 185 = new CoderResult(CR_UNDERFLOW, 0); 186 187 /** 188 * Result object indicating overflow, meaning that there is insufficient 189 * room in the output buffer. 190 */ 191 public static final CoderResult OVERFLOW 192 = new CoderResult(CR_OVERFLOW, 0); 193 194 private static abstract class Cache { 195 196 private Map<Integer,WeakReference<CoderResult>> cache = null; 197 create(int len)198 protected abstract CoderResult create(int len); 199 get(int len)200 private synchronized CoderResult get(int len) { 201 if (len <= 0) 202 throw new IllegalArgumentException("Non-positive length"); 203 Integer k = new Integer(len); 204 WeakReference<CoderResult> w; 205 CoderResult e = null; 206 if (cache == null) { 207 cache = new HashMap<Integer,WeakReference<CoderResult>>(); 208 } else if ((w = cache.get(k)) != null) { 209 e = w.get(); 210 } 211 if (e == null) { 212 e = create(len); 213 cache.put(k, new WeakReference<CoderResult>(e)); 214 } 215 return e; 216 } 217 218 } 219 220 private static Cache malformedCache 221 = new Cache() { 222 public CoderResult create(int len) { 223 return new CoderResult(CR_MALFORMED, len); 224 }}; 225 226 /** 227 * Static factory method that returns the unique object describing a 228 * malformed-input error of the given length. 229 * 230 * @param length 231 * The given length 232 * 233 * @return The requested coder-result object 234 */ malformedForLength(int length)235 public static CoderResult malformedForLength(int length) { 236 return malformedCache.get(length); 237 } 238 239 private static Cache unmappableCache 240 = new Cache() { 241 public CoderResult create(int len) { 242 return new CoderResult(CR_UNMAPPABLE, len); 243 }}; 244 245 /** 246 * Static factory method that returns the unique result object describing 247 * an unmappable-character error of the given length. 248 * 249 * @param length 250 * The given length 251 * 252 * @return The requested coder-result object 253 */ unmappableForLength(int length)254 public static CoderResult unmappableForLength(int length) { 255 return unmappableCache.get(length); 256 } 257 258 /** 259 * Throws an exception appropriate to the result described by this object. 260 * 261 * @throws BufferUnderflowException 262 * If this object is {@link #UNDERFLOW} 263 * 264 * @throws BufferOverflowException 265 * If this object is {@link #OVERFLOW} 266 * 267 * @throws MalformedInputException 268 * If this object represents a malformed-input error; the 269 * exception's length value will be that of this object 270 * 271 * @throws UnmappableCharacterException 272 * If this object represents an unmappable-character error; the 273 * exceptions length value will be that of this object 274 */ throwException()275 public void throwException() 276 throws CharacterCodingException 277 { 278 switch (type) { 279 case CR_UNDERFLOW: throw new BufferUnderflowException(); 280 case CR_OVERFLOW: throw new BufferOverflowException(); 281 case CR_MALFORMED: throw new MalformedInputException(length); 282 case CR_UNMAPPABLE: throw new UnmappableCharacterException(length); 283 default: 284 assert false; 285 } 286 } 287 288 } 289