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   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2003 IBM Corporation and others.
   3  * All rights reserved. This program and the accompanying materials
   4  * are made available under the terms of the Common Public License v1.0
   5  * which accompanies this distribution, and is available at
   6  * http://www.eclipse.org/legal/cpl-v10.html
   7  *
   8  * Contributors:
   9  *     IBM Corporation - initial API and implementation
  10  *******************************************************************************/
  11
  12 package net.sourceforge.phpdt.internal.ui.text.spelling.engine;
  13
  14 import java.io.BufferedReader;
  15 import java.io.IOException;
  16 import java.io.InputStream;
  17 import java.io.InputStreamReader;
  18 import java.net.MalformedURLException;
  19 import java.net.URL;
  20 import java.util.ArrayList;
  21 import java.util.HashMap;
  22 import java.util.HashSet;
  23 import java.util.List;
  24 import java.util.Map;
  25 import java.util.Set;
  26
  27 /**
  28  * Partial implementation of a spell dictionary.
  29  *
  30  * @since 3.0
  31  */
  32 public abstract class AbstractSpellDictionary implements ISpellDictionary {
  33
  34         /** The bucket capacity */
  35         protected static final int BUCKET_CAPACITY = 4;
  36
  37         /** The word buffer capacity */
  38         protected static final int BUFFER_CAPACITY = 32;
  39
  40         /** The distance threshold */
  41         protected static final int DISTANCE_THRESHOLD = 160;
  42
  43         /** The hash capacity */
  44         protected static final int HASH_CAPACITY = 22 * 1024;
  45
  46         /** The phonetic distance algorithm */
  47         private IPhoneticDistanceAlgorithm fDistanceAlgorithm = new DefaultPhoneticDistanceAlgorithm();
  48
  49         /** The mapping from phonetic hashes to word lists */
  50         private final Map fHashBuckets = new HashMap(HASH_CAPACITY);
  51
  52         /** The phonetic hash provider */
  53         private IPhoneticHashProvider fHashProvider = new DefaultPhoneticHashProvider();
  54
  55         /** Is the dictionary already loaded? */
  56         private boolean fLoaded = false;
  57
  58         /**
  59          * Returns all candidates with the same phonetic hash.
  60          *
  61          * @param hash
  62          *            The hash to retrieve the candidates of
  63          * @return Array of candidates for the phonetic hash
  64          */
  65         protected final ArrayList getCandidates(final String hash) {
  66
  67                 ArrayList list = (ArrayList) fHashBuckets.get(hash);
  68                 if (list == null)
  69                         list = new ArrayList(0);
  70
  71                 return list;
  72         }
  73
  74         /**
  75          * Returns all candidates that have a phonetic hash within a bounded
  76          * distance to the specified word.
  77          *
  78          * @param word
  79          *            The word to find the nearest matches for
  80          * @param sentence
  81          *            <code>true</code> iff the proposals start a new sentence,
  82          *            <code>false</code> otherwise
  83          * @param hashs
  84          *            Array of close hashes to find the matches
  85          * @return Set of ranked words with bounded distance to the specified word
  86          */
  87         protected final HashSet getCandidates(final String word,
  88                         final boolean sentence, final ArrayList hashs) {
  89
  90                 int distance = 0;
  91                 String hash = null;
  92
  93                 String candidate = null;
  94                 List candidates = null;
  95
  96                 final StringBuffer buffer = new StringBuffer(BUFFER_CAPACITY);
  97                 final HashSet result = new HashSet(BUCKET_CAPACITY * hashs.size());
  98
  99                 for (int index = 0; index < hashs.size(); index++) {
 100
 101                         hash = (String) hashs.get(index);
 102                         candidates = getCandidates(hash);
 103
 104                         for (int offset = 0; offset < candidates.size(); offset++) {
 105
 106                                 candidate = (String) candidates.get(offset);
 107                                 distance = fDistanceAlgorithm.getDistance(word, candidate);
 108
 109                                 if (distance < DISTANCE_THRESHOLD) {
 110
 111                                         buffer.setLength(0);
 112                                         buffer.append(candidate);
 113
 114                                         if (sentence)
 115                                                 buffer.setCharAt(0, Character.toUpperCase(buffer
 116                                                                 .charAt(0)));
 117
 118                                         result.add(new RankedWordProposal(buffer.toString(),
 119                                                         -distance));
 120                                 }
 121                         }
 122                 }
 123                 return result;
 124         }
 125
 126         /**
 127          * Returns all approximations that have a phonetic hash with smallest
 128          * possible distance to the specified word.
 129          *
 130          * @param word
 131          *            The word to find the nearest matches for
 132          * @param sentence
 133          *            <code>true</code> iff the proposals start a new sentence,
 134          *            <code>false</code> otherwise
 135          * @param result
 136          *            Set of ranked words with smallest possible distance to the
 137          *            specified word
 138          */
 139         protected final void getCandidates(final String word,
 140                         final boolean sentence, final HashSet result) {
 141
 142                 int distance = 0;
 143                 int minimum = Integer.MAX_VALUE;
 144
 145                 String candidate = null;
 146                 StringBuffer buffer = new StringBuffer(BUFFER_CAPACITY);
 147
 148                 final ArrayList candidates = getCandidates(fHashProvider.getHash(word));
 149                 final ArrayList matches = new ArrayList(candidates.size());
 150
 151                 for (int index = 0; index < candidates.size(); index++) {
 152
 153                         candidate = (String) candidates.get(index);
 154                         distance = fDistanceAlgorithm.getDistance(word, candidate);
 155
 156                         if (distance <= minimum) {
 157
 158                                 buffer.setLength(0);
 159                                 buffer.append(candidate);
 160
 161                                 if (sentence)
 162                                         buffer
 163                                                         .setCharAt(0, Character.toUpperCase(buffer
 164                                                                         .charAt(0)));
 165
 166                                 matches
 167                                                 .add(new RankedWordProposal(buffer.toString(),
 168                                                                 -distance));
 169                                 minimum = distance;
 170                         }
 171                 }
 172
 173                 RankedWordProposal match = null;
 174
 175                 for (int index = 0; index < matches.size(); index++) {
 176
 177                         match = (RankedWordProposal) matches.get(index);
 178                         if (match.getRank() == minimum)
 179                                 result.add(match);
 180                 }
 181         }
 182
 183         /**
 184          * Returns the used phonetic distance algorithm.
 185          *
 186          * @return The phonetic distance algorithm
 187          */
 188         protected final IPhoneticDistanceAlgorithm getDistanceAlgorithm() {
 189                 return fDistanceAlgorithm;
 190         }
 191
 192         /**
 193          * Returns the used phonetic hash provider.
 194          *
 195          * @return The phonetic hash provider
 196          */
 197         protected final IPhoneticHashProvider getHashProvider() {
 198                 return fHashProvider;
 199         }
 200
 201         /*
 202          * @see net.sourceforge.phpdt.internal.ui.text.spelling.engine.ISpellDictionary#getProposals(java.lang.String,boolean)
 203          */
 204         public Set getProposals(final String word, final boolean sentence) {
 205
 206                 try {
 207
 208                         if (!fLoaded)
 209                                 load(getURL());
 210
 211                 } catch (MalformedURLException exception) {
 212                         // Do nothing
 213                 }
 214
 215                 final String hash = fHashProvider.getHash(word);
 216                 final char[] mutators = fHashProvider.getMutators();
 217
 218                 final ArrayList neighborhood = new ArrayList((word.length() + 1)
 219                                 * (mutators.length + 2));
 220                 neighborhood.add(hash);
 221
 222                 final HashSet candidates = getCandidates(word, sentence, neighborhood);
 223                 neighborhood.clear();
 224
 225                 char previous = 0;
 226                 char next = 0;
 227
 228                 char[] characters = word.toCharArray();
 229                 for (int index = 0; index < word.length() - 1; index++) {
 230
 231                         next = characters[index];
 232                         previous = characters[index + 1];
 233
 234                         characters[index] = previous;
 235                         characters[index + 1] = next;
 236
 237                         neighborhood.add(fHashProvider.getHash(new String(characters)));
 238
 239                         characters[index] = next;
 240                         characters[index + 1] = previous;
 241                 }
 242
 243                 final String sentinel = word + " "; //$NON-NLS-1$
 244
 245                 characters = sentinel.toCharArray();
 246                 int offset = characters.length - 1;
 247
 248                 while (true) {
 249
 250                         for (int index = 0; index < mutators.length; index++) {
 251
 252                                 characters[offset] = mutators[index];
 253                                 neighborhood.add(fHashProvider.getHash(new String(characters)));
 254                         }
 255
 256                         if (offset == 0)
 257                                 break;
 258
 259                         characters[offset] = characters[offset - 1];
 260                         --offset;
 261                 }
 262
 263                 char mutated = 0;
 264                 characters = word.toCharArray();
 265
 266                 for (int index = 0; index < word.length(); index++) {
 267
 268                         mutated = characters[index];
 269                         for (int mutator = 0; mutator < mutators.length; mutator++) {
 270
 271                                 characters[index] = mutators[mutator];
 272                                 neighborhood.add(fHashProvider.getHash(new String(characters)));
 273                         }
 274                         characters[index] = mutated;
 275                 }
 276
 277                 characters = word.toCharArray();
 278                 final char[] deleted = new char[characters.length - 1];
 279
 280                 for (int index = 0; index < deleted.length; index++)
 281                         deleted[index] = characters[index];
 282
 283                 next = characters[characters.length - 1];
 284                 offset = deleted.length;
 285
 286                 while (true) {
 287
 288                         neighborhood.add(fHashProvider.getHash(new String(characters)));
 289                         if (offset == 0)
 290                                 break;
 291
 292                         previous = next;
 293                         next = deleted[offset - 1];
 294
 295                         deleted[offset - 1] = previous;
 296                         --offset;
 297                 }
 298
 299                 neighborhood.remove(hash);
 300                 final HashSet matches = getCandidates(word, sentence, neighborhood);
 301
 302                 if (matches.size() == 0 && candidates.size() == 0)
 303                         getCandidates(word, sentence, candidates);
 304
 305                 candidates.addAll(matches);
 306
 307                 return candidates;
 308         }
 309
 310         /**
 311          * Returns the URL of the dictionary word list.
 312          *
 313          * @throws MalformedURLException
 314          *             if the URL could not be retrieved
 315          * @return The URL of the dictionary word list
 316          */
 317         protected abstract URL getURL() throws MalformedURLException;
 318
 319         /**
 320          * Hashes the word into the dictionary.
 321          *
 322          * @param word
 323          *            The word to hash in the dictionary
 324          */
 325         protected final void hashWord(final String word) {
 326
 327                 final String hash = fHashProvider.getHash(word);
 328                 ArrayList bucket = (ArrayList) fHashBuckets.get(hash);
 329
 330                 if (bucket == null) {
 331
 332                         bucket = new ArrayList(BUCKET_CAPACITY);
 333                         fHashBuckets.put(hash, bucket);
 334                 }
 335
 336                 bucket.add(word);
 337         }
 338
 339         /*
 340          * @see net.sourceforge.phpdt.internal.ui.text.spelling.engine.ISpellDictionary#isCorrect(java.lang.String)
 341          */
 342         public boolean isCorrect(final String word) {
 343
 344                 try {
 345
 346                         if (!fLoaded)
 347                                 load(getURL());
 348
 349                 } catch (MalformedURLException exception) {
 350                         // Do nothing
 351                 }
 352
 353                 final ArrayList candidates = getCandidates(fHashProvider.getHash(word));
 354
 355                 if (candidates.contains(word)
 356                                 || candidates.contains(word.toLowerCase()))
 357                         return true;
 358
 359                 return false;
 360         }
 361
 362         /*
 363          * @see net.sourceforge.phpdt.ui.text.spelling.engine.ISpellDictionary#isLoaded()
 364          */
 365         public final synchronized boolean isLoaded() {
 366                 return fLoaded || fHashBuckets.size() > 0;
 367         }
 368
 369         /**
 370          * Loads a dictionary word list from disk.
 371          *
 372          * @param url
 373          *            The URL of the word list to load
 374          * @return <code>true</code> iff the word list could be loaded,
 375          *         <code>false</code> otherwise
 376          */
 377         protected synchronized boolean load(final URL url) {
 378
 379                 if (url != null) {
 380
 381                         try {
 382
 383                                 final InputStream stream = url.openStream();
 384                                 if (stream != null) {
 385
 386                                         String word = null;
 387
 388                                         final BufferedReader reader = new BufferedReader(
 389                                                         new InputStreamReader(stream));
 390                                         while ((word = reader.readLine()) != null)
 391                                                 hashWord(word);
 392
 393                                         return fLoaded = true;
 394                                 }
 395                         } catch (IOException exception) {
 396                                 // Do nothing
 397                         }
 398                 }
 399                 return false;
 400         }
 401
 402         /**
 403          * Sets the phonetic distance algorithm to use.
 404          *
 405          * @param algorithm
 406          *            The phonetic distance algorithm
 407          */
 408         protected final void setDistanceAlgorithm(
 409                         final IPhoneticDistanceAlgorithm algorithm) {
 410                 fDistanceAlgorithm = algorithm;
 411         }
 412
 413         /**
 414          * Sets the phonetic hash provider to use.
 415          *
 416          * @param provider
 417          *            The phonetic hash provider
 418          */
 419         protected final void setHashProvider(final IPhoneticHashProvider provider) {
 420                 fHashProvider = provider;
 421         }
 422
 423         /*
 424          * @see net.sourceforge.phpdt.ui.text.spelling.engine.ISpellDictionary#unload()
 425          */
 426         public synchronized void unload() {
 427
 428                 fLoaded = false;
 429                 fHashBuckets.clear();
 430         }
 431
 432         /*
 433          * @see net.sourceforge.phpdt.ui.text.spelling.engine.ISpellDictionary#acceptsWords()
 434          */
 435         public boolean acceptsWords() {
 436                 return false;
 437         }
 438
 439         /*
 440          * @see net.sourceforge.phpdt.internal.ui.text.spelling.engine.ISpellDictionary#addWord(java.lang.String)
 441          */
 442         public void addWord(final String word) {
 443                 // Do nothing
 444         }
 445 }