Suggest.java revision 6080f6878b10916013a8a5e1d5f58f8041452c56
1/* 2 * Copyright (C) 2008 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not 5 * use this file except in compliance with the License. You may obtain a copy of 6 * the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 13 * License for the specific language governing permissions and limitations under 14 * the License. 15 */ 16 17package com.android.inputmethod.latin; 18 19import android.content.Context; 20import android.text.TextUtils; 21import android.util.Log; 22 23import com.android.inputmethod.keyboard.Keyboard; 24import com.android.inputmethod.keyboard.ProximityInfo; 25import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo; 26 27import java.io.File; 28import java.util.ArrayList; 29import java.util.HashSet; 30import java.util.Locale; 31import java.util.concurrent.ConcurrentHashMap; 32 33/** 34 * This class loads a dictionary and provides a list of suggestions for a given sequence of 35 * characters. This includes corrections and completions. 36 */ 37public class Suggest implements Dictionary.WordCallback { 38 public static final String TAG = Suggest.class.getSimpleName(); 39 40 public static final int APPROX_MAX_WORD_LENGTH = 32; 41 42 public static final int CORRECTION_NONE = 0; 43 public static final int CORRECTION_FULL = 1; 44 public static final int CORRECTION_FULL_BIGRAM = 2; 45 46 // It seems the following values are only used for logging. 47 public static final int DIC_USER_TYPED = 0; 48 public static final int DIC_MAIN = 1; 49 public static final int DIC_USER = 2; 50 public static final int DIC_USER_HISTORY = 3; 51 public static final int DIC_CONTACTS = 4; 52 public static final int DIC_WHITELIST = 6; 53 // If you add a type of dictionary, increment DIC_TYPE_LAST_ID 54 // TODO: this value seems unused. Remove it? 55 public static final int DIC_TYPE_LAST_ID = 6; 56 public static final String DICT_KEY_MAIN = "main"; 57 public static final String DICT_KEY_CONTACTS = "contacts"; 58 // User dictionary, the system-managed one. 59 public static final String DICT_KEY_USER = "user"; 60 // User history dictionary for the unigram map, internal to LatinIME 61 public static final String DICT_KEY_USER_HISTORY_UNIGRAM = "history_unigram"; 62 // User history dictionary for the bigram map, internal to LatinIME 63 public static final String DICT_KEY_USER_HISTORY_BIGRAM = "history_bigram"; 64 public static final String DICT_KEY_WHITELIST ="whitelist"; 65 66 private static final boolean DBG = LatinImeLogger.sDBG; 67 68 private Dictionary mMainDictionary; 69 private ContactsBinaryDictionary mContactsDict; 70 private WhitelistDictionary mWhiteListDictionary; 71 private final ConcurrentHashMap<String, Dictionary> mUnigramDictionaries = 72 new ConcurrentHashMap<String, Dictionary>(); 73 private final ConcurrentHashMap<String, Dictionary> mBigramDictionaries = 74 new ConcurrentHashMap<String, Dictionary>(); 75 76 private int mPrefMaxSuggestions = 18; 77 78 private static final int PREF_MAX_BIGRAMS = 60; 79 80 private float mAutoCorrectionThreshold; 81 82 private ArrayList<SuggestedWordInfo> mSuggestions = new ArrayList<SuggestedWordInfo>(); 83 private ArrayList<SuggestedWordInfo> mBigramSuggestions = new ArrayList<SuggestedWordInfo>(); 84 private CharSequence mConsideredWord; 85 86 // TODO: Remove these member variables by passing more context to addWord() callback method 87 private boolean mIsFirstCharCapitalized; 88 private boolean mIsAllUpperCase; 89 private int mTrailingSingleQuotesCount; 90 91 private static final int MINIMUM_SAFETY_NET_CHAR_LENGTH = 4; 92 93 public Suggest(final Context context, final Locale locale) { 94 initAsynchronously(context, locale); 95 } 96 97 /* package for test */ Suggest(final Context context, final File dictionary, 98 final long startOffset, final long length, final Locale locale) { 99 final Dictionary mainDict = DictionaryFactory.createDictionaryForTest(context, dictionary, 100 startOffset, length /* useFullEditDistance */, false, locale); 101 mMainDictionary = mainDict; 102 addOrReplaceDictionary(mUnigramDictionaries, DICT_KEY_MAIN, mainDict); 103 addOrReplaceDictionary(mBigramDictionaries, DICT_KEY_MAIN, mainDict); 104 initWhitelistAndAutocorrectAndPool(context, locale); 105 } 106 107 private void initWhitelistAndAutocorrectAndPool(final Context context, final Locale locale) { 108 mWhiteListDictionary = new WhitelistDictionary(context, locale); 109 addOrReplaceDictionary(mUnigramDictionaries, DICT_KEY_WHITELIST, mWhiteListDictionary); 110 } 111 112 private void initAsynchronously(final Context context, final Locale locale) { 113 resetMainDict(context, locale); 114 115 // TODO: read the whitelist and init the pool asynchronously too. 116 // initPool should be done asynchronously now that the pool is thread-safe. 117 initWhitelistAndAutocorrectAndPool(context, locale); 118 } 119 120 private static void addOrReplaceDictionary( 121 final ConcurrentHashMap<String, Dictionary> dictionaries, 122 final String key, final Dictionary dict) { 123 final Dictionary oldDict = (dict == null) 124 ? dictionaries.remove(key) 125 : dictionaries.put(key, dict); 126 if (oldDict != null && dict != oldDict) { 127 oldDict.close(); 128 } 129 } 130 131 public void resetMainDict(final Context context, final Locale locale) { 132 mMainDictionary = null; 133 new Thread("InitializeBinaryDictionary") { 134 @Override 135 public void run() { 136 final DictionaryCollection newMainDict = 137 DictionaryFactory.createMainDictionaryFromManager(context, locale); 138 addOrReplaceDictionary(mUnigramDictionaries, DICT_KEY_MAIN, newMainDict); 139 addOrReplaceDictionary(mBigramDictionaries, DICT_KEY_MAIN, newMainDict); 140 mMainDictionary = newMainDict; 141 } 142 }.start(); 143 } 144 145 // The main dictionary could have been loaded asynchronously. Don't cache the return value 146 // of this method. 147 public boolean hasMainDictionary() { 148 return null != mMainDictionary && mMainDictionary.isInitialized(); 149 } 150 151 public Dictionary getMainDictionary() { 152 return mMainDictionary; 153 } 154 155 public ContactsBinaryDictionary getContactsDictionary() { 156 return mContactsDict; 157 } 158 159 public ConcurrentHashMap<String, Dictionary> getUnigramDictionaries() { 160 return mUnigramDictionaries; 161 } 162 163 public static int getApproxMaxWordLength() { 164 return APPROX_MAX_WORD_LENGTH; 165 } 166 167 /** 168 * Sets an optional user dictionary resource to be loaded. The user dictionary is consulted 169 * before the main dictionary, if set. This refers to the system-managed user dictionary. 170 */ 171 public void setUserDictionary(UserBinaryDictionary userDictionary) { 172 addOrReplaceDictionary(mUnigramDictionaries, DICT_KEY_USER, userDictionary); 173 } 174 175 /** 176 * Sets an optional contacts dictionary resource to be loaded. It is also possible to remove 177 * the contacts dictionary by passing null to this method. In this case no contacts dictionary 178 * won't be used. 179 */ 180 public void setContactsDictionary(ContactsBinaryDictionary contactsDictionary) { 181 mContactsDict = contactsDictionary; 182 addOrReplaceDictionary(mUnigramDictionaries, DICT_KEY_CONTACTS, contactsDictionary); 183 addOrReplaceDictionary(mBigramDictionaries, DICT_KEY_CONTACTS, contactsDictionary); 184 } 185 186 public void setUserHistoryDictionary(UserHistoryDictionary userHistoryDictionary) { 187 addOrReplaceDictionary(mUnigramDictionaries, DICT_KEY_USER_HISTORY_UNIGRAM, 188 userHistoryDictionary); 189 addOrReplaceDictionary(mBigramDictionaries, DICT_KEY_USER_HISTORY_BIGRAM, 190 userHistoryDictionary); 191 } 192 193 public void setAutoCorrectionThreshold(float threshold) { 194 mAutoCorrectionThreshold = threshold; 195 } 196 197 private static CharSequence capitalizeWord(final boolean all, final boolean first, 198 final CharSequence word) { 199 if (TextUtils.isEmpty(word) || !(all || first)) return word; 200 final int wordLength = word.length(); 201 final StringBuilder sb = new StringBuilder(getApproxMaxWordLength()); 202 // TODO: Must pay attention to locale when changing case. 203 if (all) { 204 sb.append(word.toString().toUpperCase()); 205 } else if (first) { 206 sb.append(Character.toUpperCase(word.charAt(0))); 207 if (wordLength > 1) { 208 sb.append(word.subSequence(1, wordLength)); 209 } 210 } 211 return sb; 212 } 213 214 protected void addBigramToSuggestions(SuggestedWordInfo bigram) { 215 mSuggestions.add(bigram); 216 } 217 218 private static final WordComposer sEmptyWordComposer = new WordComposer(); 219 public SuggestedWords getBigramPredictions(CharSequence prevWordForBigram) { 220 LatinImeLogger.onStartSuggestion(prevWordForBigram); 221 mIsFirstCharCapitalized = false; 222 mIsAllUpperCase = false; 223 mTrailingSingleQuotesCount = 0; 224 mSuggestions = new ArrayList<SuggestedWordInfo>(mPrefMaxSuggestions); 225 226 // Treating USER_TYPED as UNIGRAM suggestion for logging now. 227 LatinImeLogger.onAddSuggestedWord("", Suggest.DIC_USER_TYPED, Dictionary.UNIGRAM); 228 mConsideredWord = ""; 229 230 mBigramSuggestions = new ArrayList<SuggestedWordInfo>(PREF_MAX_BIGRAMS); 231 232 getAllBigrams(prevWordForBigram, sEmptyWordComposer); 233 234 // Nothing entered: return all bigrams for the previous word 235 int insertCount = Math.min(mBigramSuggestions.size(), mPrefMaxSuggestions); 236 for (int i = 0; i < insertCount; ++i) { 237 addBigramToSuggestions(mBigramSuggestions.get(i)); 238 } 239 240 SuggestedWordInfo.removeDups(mSuggestions); 241 242 return new SuggestedWords(mSuggestions, 243 false /* typedWordValid */, 244 false /* hasAutoCorrectionCandidate */, 245 false /* allowsToBeAutoCorrected */, 246 false /* isPunctuationSuggestions */, 247 false /* isObsoleteSuggestions */, 248 true /* isPrediction */); 249 } 250 251 // TODO: cleanup dictionaries looking up and suggestions building with SuggestedWords.Builder 252 public SuggestedWords getSuggestedWords( 253 final WordComposer wordComposer, CharSequence prevWordForBigram, 254 final ProximityInfo proximityInfo, final int correctionMode) { 255 LatinImeLogger.onStartSuggestion(prevWordForBigram); 256 mIsFirstCharCapitalized = wordComposer.isFirstCharCapitalized(); 257 mIsAllUpperCase = wordComposer.isAllUpperCase(); 258 mTrailingSingleQuotesCount = wordComposer.trailingSingleQuotesCount(); 259 mSuggestions = new ArrayList<SuggestedWordInfo>(mPrefMaxSuggestions); 260 261 final String typedWord = wordComposer.getTypedWord(); 262 final String consideredWord = mTrailingSingleQuotesCount > 0 263 ? typedWord.substring(0, typedWord.length() - mTrailingSingleQuotesCount) 264 : typedWord; 265 // Treating USER_TYPED as UNIGRAM suggestion for logging now. 266 LatinImeLogger.onAddSuggestedWord(typedWord, Suggest.DIC_USER_TYPED, Dictionary.UNIGRAM); 267 mConsideredWord = consideredWord; 268 269 if (wordComposer.size() <= 1 && (correctionMode == CORRECTION_FULL_BIGRAM)) { 270 // At first character typed, search only the bigrams 271 mBigramSuggestions = new ArrayList<SuggestedWordInfo>(PREF_MAX_BIGRAMS); 272 273 if (!TextUtils.isEmpty(prevWordForBigram)) { 274 getAllBigrams(prevWordForBigram, wordComposer); 275 if (TextUtils.isEmpty(consideredWord)) { 276 // Nothing entered: return all bigrams for the previous word 277 int insertCount = Math.min(mBigramSuggestions.size(), mPrefMaxSuggestions); 278 for (int i = 0; i < insertCount; ++i) { 279 addBigramToSuggestions(mBigramSuggestions.get(i)); 280 } 281 } else { 282 // Word entered: return only bigrams that match the first char of the typed word 283 final char currentChar = consideredWord.charAt(0); 284 // TODO: Must pay attention to locale when changing case. 285 // TODO: Use codepoint instead of char 286 final char currentCharUpper = Character.toUpperCase(currentChar); 287 int count = 0; 288 final int bigramSuggestionSize = mBigramSuggestions.size(); 289 for (int i = 0; i < bigramSuggestionSize; i++) { 290 final SuggestedWordInfo bigramSuggestion = mBigramSuggestions.get(i); 291 final char bigramSuggestionFirstChar = 292 (char)bigramSuggestion.codePointAt(0); 293 if (bigramSuggestionFirstChar == currentChar 294 || bigramSuggestionFirstChar == currentCharUpper) { 295 addBigramToSuggestions(bigramSuggestion); 296 if (++count > mPrefMaxSuggestions) break; 297 } 298 } 299 } 300 } 301 302 } else if (wordComposer.size() > 1) { 303 final WordComposer wordComposerForLookup; 304 if (mTrailingSingleQuotesCount > 0) { 305 wordComposerForLookup = new WordComposer(wordComposer); 306 for (int i = mTrailingSingleQuotesCount - 1; i >= 0; --i) { 307 wordComposerForLookup.deleteLast(); 308 } 309 } else { 310 wordComposerForLookup = wordComposer; 311 } 312 // At second character typed, search the unigrams (scores being affected by bigrams) 313 for (final String key : mUnigramDictionaries.keySet()) { 314 // Skip UserUnigramDictionary and WhitelistDictionary to lookup 315 if (key.equals(DICT_KEY_USER_HISTORY_UNIGRAM) || key.equals(DICT_KEY_WHITELIST)) 316 continue; 317 final Dictionary dictionary = mUnigramDictionaries.get(key); 318 dictionary.getWords(wordComposerForLookup, prevWordForBigram, this, proximityInfo); 319 } 320 } 321 322 final CharSequence whitelistedWord = capitalizeWord(mIsAllUpperCase, 323 mIsFirstCharCapitalized, mWhiteListDictionary.getWhitelistedWord(consideredWord)); 324 325 final boolean hasAutoCorrection; 326 if (CORRECTION_FULL == correctionMode || CORRECTION_FULL_BIGRAM == correctionMode) { 327 final CharSequence autoCorrection = 328 AutoCorrection.computeAutoCorrectionWord(mUnigramDictionaries, wordComposer, 329 mSuggestions, consideredWord, mAutoCorrectionThreshold, 330 whitelistedWord); 331 hasAutoCorrection = (null != autoCorrection); 332 } else { 333 hasAutoCorrection = false; 334 } 335 336 if (whitelistedWord != null) { 337 if (mTrailingSingleQuotesCount > 0) { 338 final StringBuilder sb = new StringBuilder(whitelistedWord); 339 for (int i = mTrailingSingleQuotesCount - 1; i >= 0; --i) { 340 sb.appendCodePoint(Keyboard.CODE_SINGLE_QUOTE); 341 } 342 mSuggestions.add(0, new SuggestedWordInfo( 343 sb.toString(), SuggestedWordInfo.MAX_SCORE)); 344 } else { 345 mSuggestions.add(0, new SuggestedWordInfo( 346 whitelistedWord, SuggestedWordInfo.MAX_SCORE)); 347 } 348 } 349 350 mSuggestions.add(0, new SuggestedWordInfo(typedWord, SuggestedWordInfo.MAX_SCORE)); 351 SuggestedWordInfo.removeDups(mSuggestions); 352 353 final ArrayList<SuggestedWordInfo> suggestionsList; 354 if (DBG) { 355 suggestionsList = getSuggestionsInfoListWithDebugInfo(typedWord, mSuggestions); 356 } else { 357 suggestionsList = mSuggestions; 358 } 359 360 // TODO: Change this scheme - a boolean is not enough. A whitelisted word may be "valid" 361 // but still autocorrected from - in the case the whitelist only capitalizes the word. 362 // The whitelist should be case-insensitive, so it's not possible to be consistent with 363 // a boolean flag. Right now this is handled with a slight hack in 364 // WhitelistDictionary#shouldForciblyAutoCorrectFrom. 365 final boolean allowsToBeAutoCorrected = AutoCorrection.allowsToBeAutoCorrected( 366 getUnigramDictionaries(), consideredWord, wordComposer.isFirstCharCapitalized()) 367 // If we don't have a main dictionary, we never want to auto-correct. The reason for this 368 // is, the user may have a contact whose name happens to match a valid word in their 369 // language, and it will unexpectedly auto-correct. For example, if the user types in 370 // English with no dictionary and has a "Will" in their contact list, "will" would 371 // always auto-correct to "Will" which is unwanted. Hence, no main dict => no auto-correct. 372 && hasMainDictionary(); 373 374 boolean autoCorrectionAvailable = hasAutoCorrection; 375 if (correctionMode == CORRECTION_FULL || correctionMode == CORRECTION_FULL_BIGRAM) { 376 autoCorrectionAvailable |= !allowsToBeAutoCorrected; 377 } 378 // Don't auto-correct words with multiple capital letter 379 autoCorrectionAvailable &= !wordComposer.isMostlyCaps(); 380 autoCorrectionAvailable &= !wordComposer.isResumed(); 381 if (allowsToBeAutoCorrected && suggestionsList.size() > 1 && mAutoCorrectionThreshold > 0 382 && Suggest.shouldBlockAutoCorrectionBySafetyNet(typedWord, 383 suggestionsList.get(1).mWord)) { 384 autoCorrectionAvailable = false; 385 } 386 return new SuggestedWords(suggestionsList, 387 !allowsToBeAutoCorrected /* typedWordValid */, 388 autoCorrectionAvailable /* hasAutoCorrectionCandidate */, 389 allowsToBeAutoCorrected /* allowsToBeAutoCorrected */, 390 false /* isPunctuationSuggestions */, 391 false /* isObsoleteSuggestions */, 392 false /* isPrediction */); 393 } 394 395 /** 396 * Adds all bigram predictions for prevWord. Also checks the lower case version of prevWord if 397 * it contains any upper case characters. 398 */ 399 private void getAllBigrams(final CharSequence prevWord, final WordComposer wordComposer) { 400 if (StringUtils.hasUpperCase(prevWord)) { 401 // TODO: Must pay attention to locale when changing case. 402 final CharSequence lowerPrevWord = prevWord.toString().toLowerCase(); 403 for (final Dictionary dictionary : mBigramDictionaries.values()) { 404 dictionary.getBigrams(wordComposer, lowerPrevWord, this); 405 } 406 } 407 for (final Dictionary dictionary : mBigramDictionaries.values()) { 408 dictionary.getBigrams(wordComposer, prevWord, this); 409 } 410 } 411 412 private static ArrayList<SuggestedWordInfo> getSuggestionsInfoListWithDebugInfo( 413 final String typedWord, final ArrayList<SuggestedWordInfo> suggestions) { 414 final SuggestedWordInfo typedWordInfo = suggestions.get(0); 415 typedWordInfo.setDebugString("+"); 416 final int suggestionsSize = suggestions.size(); 417 final ArrayList<SuggestedWordInfo> suggestionsList = 418 new ArrayList<SuggestedWordInfo>(suggestionsSize); 419 suggestionsList.add(typedWordInfo); 420 // Note: i here is the index in mScores[], but the index in mSuggestions is one more 421 // than i because we added the typed word to mSuggestions without touching mScores. 422 for (int i = 0; i < suggestionsSize - 1; ++i) { 423 final SuggestedWordInfo cur = suggestions.get(i + 1); 424 final float normalizedScore = BinaryDictionary.calcNormalizedScore( 425 typedWord, cur.toString(), cur.mScore); 426 final String scoreInfoString; 427 if (normalizedScore > 0) { 428 scoreInfoString = String.format("%d (%4.2f)", cur.mScore, normalizedScore); 429 } else { 430 scoreInfoString = Integer.toString(cur.mScore); 431 } 432 cur.setDebugString(scoreInfoString); 433 suggestionsList.add(cur); 434 } 435 return suggestionsList; 436 } 437 438 // TODO: Use codepoint instead of char 439 @Override 440 public boolean addWord(final char[] word, final int offset, final int length, int score, 441 final int dicTypeId, final int dataType) { 442 int dataTypeForLog = dataType; 443 final ArrayList<SuggestedWordInfo> suggestions; 444 final int prefMaxSuggestions; 445 if (dataType == Dictionary.BIGRAM) { 446 suggestions = mBigramSuggestions; 447 prefMaxSuggestions = PREF_MAX_BIGRAMS; 448 } else { 449 suggestions = mSuggestions; 450 prefMaxSuggestions = mPrefMaxSuggestions; 451 } 452 453 int pos = 0; 454 455 // Check if it's the same word, only caps are different 456 if (StringUtils.equalsIgnoreCase(mConsideredWord, word, offset, length)) { 457 // TODO: remove this surrounding if clause and move this logic to 458 // getSuggestedWordBuilder. 459 if (suggestions.size() > 0) { 460 final SuggestedWordInfo currentHighestWord = suggestions.get(0); 461 // If the current highest word is also equal to typed word, we need to compare 462 // frequency to determine the insertion position. This does not ensure strictly 463 // correct ordering, but ensures the top score is on top which is enough for 464 // removing duplicates correctly. 465 if (StringUtils.equalsIgnoreCase(currentHighestWord.mWord, word, offset, length) 466 && score <= currentHighestWord.mScore) { 467 pos = 1; 468 } 469 } 470 } else { 471 // Check the last one's score and bail 472 if (suggestions.size() >= prefMaxSuggestions 473 && suggestions.get(prefMaxSuggestions - 1).mScore >= score) return true; 474 while (pos < suggestions.size()) { 475 final int curScore = suggestions.get(pos).mScore; 476 if (curScore < score 477 || (curScore == score && length < suggestions.get(pos).codePointCount())) { 478 break; 479 } 480 pos++; 481 } 482 } 483 if (pos >= prefMaxSuggestions) { 484 return true; 485 } 486 487 final StringBuilder sb = new StringBuilder(getApproxMaxWordLength()); 488 // TODO: Must pay attention to locale when changing case. 489 if (mIsAllUpperCase) { 490 sb.append(new String(word, offset, length).toUpperCase()); 491 } else if (mIsFirstCharCapitalized) { 492 sb.append(Character.toUpperCase(word[offset])); 493 if (length > 1) { 494 sb.append(word, offset + 1, length - 1); 495 } 496 } else { 497 sb.append(word, offset, length); 498 } 499 for (int i = mTrailingSingleQuotesCount - 1; i >= 0; --i) { 500 sb.appendCodePoint(Keyboard.CODE_SINGLE_QUOTE); 501 } 502 suggestions.add(pos, new SuggestedWordInfo(sb, score)); 503 if (suggestions.size() > prefMaxSuggestions) { 504 suggestions.remove(prefMaxSuggestions); 505 } else { 506 LatinImeLogger.onAddSuggestedWord(sb.toString(), dicTypeId, dataTypeForLog); 507 } 508 return true; 509 } 510 511 public void close() { 512 final HashSet<Dictionary> dictionaries = new HashSet<Dictionary>(); 513 dictionaries.addAll(mUnigramDictionaries.values()); 514 dictionaries.addAll(mBigramDictionaries.values()); 515 for (final Dictionary dictionary : dictionaries) { 516 dictionary.close(); 517 } 518 mMainDictionary = null; 519 } 520 521 // TODO: Resolve the inconsistencies between the native auto correction algorithms and 522 // this safety net 523 public static boolean shouldBlockAutoCorrectionBySafetyNet(final String typedWord, 524 final CharSequence suggestion) { 525 // Safety net for auto correction. 526 // Actually if we hit this safety net, it's a bug. 527 // If user selected aggressive auto correction mode, there is no need to use the safety 528 // net. 529 // If the length of typed word is less than MINIMUM_SAFETY_NET_CHAR_LENGTH, 530 // we should not use net because relatively edit distance can be big. 531 final int typedWordLength = typedWord.length(); 532 if (typedWordLength < Suggest.MINIMUM_SAFETY_NET_CHAR_LENGTH) { 533 return false; 534 } 535 final int maxEditDistanceOfNativeDictionary = 536 (typedWordLength < 5 ? 2 : typedWordLength / 2) + 1; 537 final int distance = BinaryDictionary.editDistance(typedWord, suggestion.toString()); 538 if (DBG) { 539 Log.d(TAG, "Autocorrected edit distance = " + distance 540 + ", " + maxEditDistanceOfNativeDictionary); 541 } 542 if (distance > maxEditDistanceOfNativeDictionary) { 543 if (DBG) { 544 Log.e(TAG, "Safety net: before = " + typedWord + ", after = " + suggestion); 545 Log.e(TAG, "(Error) The edit distance of this correction exceeds limit. " 546 + "Turning off auto-correction."); 547 } 548 return true; 549 } else { 550 return false; 551 } 552 } 553} 554