Separate SpellCheckerSession from SpellCheckerService

Bug: 6789576
Change-Id: I7c55d36afad7ef6046353b3c9e849a54a6dc83ae

1 files changed, 420 insertions, 0 deletions

diff --git a/java/src/com/android/inputmethod/latin/spellcheck/AndroidSpellCheckerSession.java b/java/src/com/android/inputmethod/latin/spellcheck/AndroidSpellCheckerSession.java
new file mode 100644
index 000000000..e0f340879
--- /dev/null
+++ b/java/src/com/android/inputmethod/latin/spellcheck/AndroidSpellCheckerSession.java
@@ -0,0 +1,420 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.android.inputmethod.latin.spellcheck;
+
+
+import android.service.textservice.SpellCheckerService.Session;
+import android.text.TextUtils;
+import android.util.Log;
+import android.util.LruCache;
+import android.view.textservice.SentenceSuggestionsInfo;
+import android.view.textservice.SuggestionsInfo;
+import android.view.textservice.TextInfo;
+
+import com.android.inputmethod.compat.SuggestionsInfoCompatUtils;
+import com.android.inputmethod.latin.LocaleUtils;
+import com.android.inputmethod.latin.WordComposer;
+import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
+import com.android.inputmethod.latin.spellcheck.AndroidSpellCheckerService.SuggestionsGatherer;
+
+import java.util.ArrayList;
+import java.util.Locale;
+
+public class AndroidSpellCheckerSession extends Session {
+    private static final String TAG = AndroidSpellCheckerSession.class.getSimpleName();
+    private static final boolean DBG = false;
+    private final static String[] EMPTY_STRING_ARRAY = new String[0];
+
+    // Immutable, but need the locale which is not available in the constructor yet
+    private DictionaryPool mDictionaryPool;
+    // Likewise
+    private Locale mLocale;
+    // Cache this for performance
+    private int mScript; // One of SCRIPT_LATIN or SCRIPT_CYRILLIC for now.
+    private final AndroidSpellCheckerService mService;
+    private final SuggestionsCache mSuggestionsCache = new SuggestionsCache();
+
+    private static class SuggestionsParams {
+        public final String[] mSuggestions;
+        public final int mFlags;
+        public SuggestionsParams(String[] suggestions, int flags) {
+            mSuggestions = suggestions;
+            mFlags = flags;
+        }
+    }
+
+    private static class SuggestionsCache {
+        private static final char CHAR_DELIMITER = '\uFFFC';
+        private static final int MAX_CACHE_SIZE = 50;
+        private final LruCache<String, SuggestionsParams> mUnigramSuggestionsInfoCache =
+                new LruCache<String, SuggestionsParams>(MAX_CACHE_SIZE);
+
+        // TODO: Support n-gram input
+        private static String generateKey(String query, String prevWord) {
+            if (TextUtils.isEmpty(query) || TextUtils.isEmpty(prevWord)) {
+                return query;
+            }
+            return query + CHAR_DELIMITER + prevWord;
+        }
+
+        // TODO: Support n-gram input
+        public SuggestionsParams getSuggestionsFromCache(String query, String prevWord) {
+            return mUnigramSuggestionsInfoCache.get(generateKey(query, prevWord));
+        }
+
+        // TODO: Support n-gram input
+        public void putSuggestionsToCache(
+                String query, String prevWord, String[] suggestions, int flags) {
+            if (suggestions == null || TextUtils.isEmpty(query)) {
+                return;
+            }
+            mUnigramSuggestionsInfoCache.put(
+                    generateKey(query, prevWord), new SuggestionsParams(suggestions, flags));
+        }
+    }
+
+    AndroidSpellCheckerSession(final AndroidSpellCheckerService service) {
+        mService = service;
+    }
+
+    @Override
+    public void onCreate() {
+        final String localeString = getLocale();
+        mDictionaryPool = mService.getDictionaryPool(localeString);
+        mLocale = LocaleUtils.constructLocaleFromString(localeString);
+        mScript = AndroidSpellCheckerService.getScriptFromLocale(mLocale);
+    }
+
+    /*
+     * Returns whether the code point is a letter that makes sense for the specified
+     * locale for this spell checker.
+     * The dictionaries supported by Latin IME are described in res/xml/spellchecker.xml
+     * and is limited to EFIGS languages and Russian.
+     * Hence at the moment this explicitly tests for Cyrillic characters or Latin characters
+     * as appropriate, and explicitly excludes CJK, Arabic and Hebrew characters.
+     */
+    private static boolean isLetterCheckableByLanguage(final int codePoint,
+            final int script) {
+        switch (script) {
+        case AndroidSpellCheckerService.SCRIPT_LATIN:
+            // Our supported latin script dictionaries (EFIGS) at the moment only include
+            // characters in the C0, C1, Latin Extended A and B, IPA extensions unicode
+            // blocks. As it happens, those are back-to-back in the code range 0x40 to 0x2AF,
+            // so the below is a very efficient way to test for it. As for the 0-0x3F, it's
+            // excluded from isLetter anyway.
+            return codePoint <= 0x2AF && Character.isLetter(codePoint);
+        case AndroidSpellCheckerService.SCRIPT_CYRILLIC:
+            // All Cyrillic characters are in the 400~52F block. There are some in the upper
+            // Unicode range, but they are archaic characters that are not used in modern
+            // russian and are not used by our dictionary.
+            return codePoint >= 0x400 && codePoint <= 0x52F && Character.isLetter(codePoint);
+        default:
+            // Should never come here
+            throw new RuntimeException("Impossible value of script: " + script);
+        }
+    }
+
+    /**
+     * Finds out whether a particular string should be filtered out of spell checking.
+     *
+     * This will loosely match URLs, numbers, symbols. To avoid always underlining words that
+     * we know we will never recognize, this accepts a script identifier that should be one
+     * of the SCRIPT_* constants defined above, to rule out quickly characters from very
+     * different languages.
+     *
+     * @param text the string to evaluate.
+     * @param script the identifier for the script this spell checker recognizes
+     * @return true if we should filter this text out, false otherwise
+     */
+    private static boolean shouldFilterOut(final String text, final int script) {
+        if (TextUtils.isEmpty(text) || text.length() <= 1) return true;
+
+        // TODO: check if an equivalent processing can't be done more quickly with a
+        // compiled regexp.
+        // Filter by first letter
+        final int firstCodePoint = text.codePointAt(0);
+        // Filter out words that don't start with a letter or an apostrophe
+        if (!isLetterCheckableByLanguage(firstCodePoint, script)
+                && '\'' != firstCodePoint) return true;
+
+        // Filter contents
+        final int length = text.length();
+        int letterCount = 0;
+        for (int i = 0; i < length; i = text.offsetByCodePoints(i, 1)) {
+            final int codePoint = text.codePointAt(i);
+            // Any word containing a '@' is probably an e-mail address
+            // Any word containing a '/' is probably either an ad-hoc combination of two
+            // words or a URI - in either case we don't want to spell check that
+            if ('@' == codePoint || '/' == codePoint) return true;
+            if (isLetterCheckableByLanguage(codePoint, script)) ++letterCount;
+        }
+        // Guestimate heuristic: perform spell checking if at least 3/4 of the characters
+        // in this word are letters
+        return (letterCount * 4 < length * 3);
+    }
+
+    private SentenceSuggestionsInfo fixWronglyInvalidatedWordWithSingleQuote(
+            TextInfo ti, SentenceSuggestionsInfo ssi) {
+        final String typedText = ti.getText();
+        if (!typedText.contains(AndroidSpellCheckerService.SINGLE_QUOTE)) {
+            return null;
+        }
+        final int N = ssi.getSuggestionsCount();
+        final ArrayList<Integer> additionalOffsets = new ArrayList<Integer>();
+        final ArrayList<Integer> additionalLengths = new ArrayList<Integer>();
+        final ArrayList<SuggestionsInfo> additionalSuggestionsInfos =
+                new ArrayList<SuggestionsInfo>();
+        String currentWord = null;
+        for (int i = 0; i < N; ++i) {
+            final SuggestionsInfo si = ssi.getSuggestionsInfoAt(i);
+            final int flags = si.getSuggestionsAttributes();
+            if ((flags & SuggestionsInfo.RESULT_ATTR_IN_THE_DICTIONARY) == 0) {
+                continue;
+            }
+            final int offset = ssi.getOffsetAt(i);
+            final int length = ssi.getLengthAt(i);
+            final String subText = typedText.substring(offset, offset + length);
+            final String prevWord = currentWord;
+            currentWord = subText;
+            if (!subText.contains(AndroidSpellCheckerService.SINGLE_QUOTE)) {
+                continue;
+            }
+            final String[] splitTexts = subText.split(AndroidSpellCheckerService.SINGLE_QUOTE, -1);
+            if (splitTexts == null || splitTexts.length <= 1) {
+                continue;
+            }
+            final int splitNum = splitTexts.length;
+            for (int j = 0; j < splitNum; ++j) {
+                final String splitText = splitTexts[j];
+                if (TextUtils.isEmpty(splitText)) {
+                    continue;
+                }
+                if (mSuggestionsCache.getSuggestionsFromCache(
+                        splitText, prevWord) == null) {
+                    continue;
+                }
+                final int newLength = splitText.length();
+                // Neither RESULT_ATTR_IN_THE_DICTIONARY nor RESULT_ATTR_LOOKS_LIKE_TYPO
+                final int newFlags = 0;
+                final SuggestionsInfo newSi = new SuggestionsInfo(newFlags, EMPTY_STRING_ARRAY);
+                newSi.setCookieAndSequence(si.getCookie(), si.getSequence());
+                if (DBG) {
+                    Log.d(TAG, "Override and remove old span over: "
+                            + splitText + ", " + offset + "," + newLength);
+                }
+                additionalOffsets.add(offset);
+                additionalLengths.add(newLength);
+                additionalSuggestionsInfos.add(newSi);
+            }
+        }
+        final int additionalSize = additionalOffsets.size();
+        if (additionalSize <= 0) {
+            return null;
+        }
+        final int suggestionsSize = N + additionalSize;
+        final int[] newOffsets = new int[suggestionsSize];
+        final int[] newLengths = new int[suggestionsSize];
+        final SuggestionsInfo[] newSuggestionsInfos = new SuggestionsInfo[suggestionsSize];
+        int i;
+        for (i = 0; i < N; ++i) {
+            newOffsets[i] = ssi.getOffsetAt(i);
+            newLengths[i] = ssi.getLengthAt(i);
+            newSuggestionsInfos[i] = ssi.getSuggestionsInfoAt(i);
+        }
+        for (; i < suggestionsSize; ++i) {
+            newOffsets[i] = additionalOffsets.get(i - N);
+            newLengths[i] = additionalLengths.get(i - N);
+            newSuggestionsInfos[i] = additionalSuggestionsInfos.get(i - N);
+        }
+        return new SentenceSuggestionsInfo(newSuggestionsInfos, newOffsets, newLengths);
+    }
+
+    @Override
+    public SentenceSuggestionsInfo[] onGetSentenceSuggestionsMultiple(
+            TextInfo[] textInfos, int suggestionsLimit) {
+        final SentenceSuggestionsInfo[] retval = super.onGetSentenceSuggestionsMultiple(
+                textInfos, suggestionsLimit);
+        if (retval == null || retval.length != textInfos.length) {
+            return retval;
+        }
+        for (int i = 0; i < retval.length; ++i) {
+            final SentenceSuggestionsInfo tempSsi =
+                    fixWronglyInvalidatedWordWithSingleQuote(textInfos[i], retval[i]);
+            if (tempSsi != null) {
+                retval[i] = tempSsi;
+            }
+        }
+        return retval;
+    }
+
+    @Override
+    public SuggestionsInfo[] onGetSuggestionsMultiple(TextInfo[] textInfos,
+            int suggestionsLimit, boolean sequentialWords) {
+        final int length = textInfos.length;
+        final SuggestionsInfo[] retval = new SuggestionsInfo[length];
+        for (int i = 0; i < length; ++i) {
+            final String prevWord;
+            if (sequentialWords && i > 0) {
+                final String prevWordCandidate = textInfos[i - 1].getText();
+                // Note that an empty string would be used to indicate the initial word
+                // in the future.
+                prevWord = TextUtils.isEmpty(prevWordCandidate) ? null : prevWordCandidate;
+            } else {
+                prevWord = null;
+            }
+            retval[i] = onGetSuggestions(textInfos[i], prevWord, suggestionsLimit);
+            retval[i].setCookieAndSequence(
+                    textInfos[i].getCookie(), textInfos[i].getSequence());
+        }
+        return retval;
+    }
+
+    // Note : this must be reentrant
+    /**
+     * Gets a list of suggestions for a specific string. This returns a list of possible
+     * corrections for the text passed as an argument. It may split or group words, and
+     * even perform grammatical analysis.
+     */
+    @Override
+    public SuggestionsInfo onGetSuggestions(final TextInfo textInfo,
+            final int suggestionsLimit) {
+        return onGetSuggestions(textInfo, null, suggestionsLimit);
+    }
+
+    private SuggestionsInfo onGetSuggestions(
+            final TextInfo textInfo, final String prevWord, final int suggestionsLimit) {
+        try {
+            final String inText = textInfo.getText();
+            final SuggestionsParams cachedSuggestionsParams =
+                    mSuggestionsCache.getSuggestionsFromCache(inText, prevWord);
+            if (cachedSuggestionsParams != null) {
+                if (DBG) {
+                    Log.d(TAG, "Cache hit: " + inText + ", " + cachedSuggestionsParams.mFlags);
+                }
+                return new SuggestionsInfo(
+                        cachedSuggestionsParams.mFlags, cachedSuggestionsParams.mSuggestions);
+            }
+
+            if (shouldFilterOut(inText, mScript)) {
+                DictAndProximity dictInfo = null;
+                try {
+                    dictInfo = mDictionaryPool.takeOrGetNull();
+                    if (null == dictInfo) {
+                        return AndroidSpellCheckerService.getNotInDictEmptySuggestions();
+                    }
+                    return dictInfo.mDictionary.isValidWord(inText)
+                            ? AndroidSpellCheckerService.getInDictEmptySuggestions()
+                            : AndroidSpellCheckerService.getNotInDictEmptySuggestions();
+                } finally {
+                    if (null != dictInfo) {
+                        if (!mDictionaryPool.offer(dictInfo)) {
+                            Log.e(TAG, "Can't re-insert a dictionary into its pool");
+                        }
+                    }
+                }
+            }
+            final String text = inText.replaceAll(
+                    AndroidSpellCheckerService.APOSTROPHE, AndroidSpellCheckerService.SINGLE_QUOTE);
+
+            // TODO: Don't gather suggestions if the limit is <= 0 unless necessary
+            //final SuggestionsGatherer suggestionsGatherer = new SuggestionsGatherer(text,
+            //mService.mSuggestionThreshold, mService.mRecommendedThreshold,
+            //suggestionsLimit);
+            final SuggestionsGatherer suggestionsGatherer = mService.newSuggestionsGatherer(
+                    text, suggestionsLimit);
+            final WordComposer composer = new WordComposer();
+            final int length = text.length();
+            for (int i = 0; i < length; i = text.offsetByCodePoints(i, 1)) {
+                final int codePoint = text.codePointAt(i);
+                // The getXYForCodePointAndScript method returns (Y << 16) + X
+                final int xy = SpellCheckerProximityInfo.getXYForCodePointAndScript(
+                        codePoint, mScript);
+                if (SpellCheckerProximityInfo.NOT_A_COORDINATE_PAIR == xy) {
+                    composer.add(codePoint, WordComposer.NOT_A_COORDINATE,
+                            WordComposer.NOT_A_COORDINATE);
+                } else {
+                    composer.add(codePoint, xy & 0xFFFF, xy >> 16);
+                }
+            }
+
+            final int capitalizeType = AndroidSpellCheckerService.getCapitalizationType(text);
+            boolean isInDict = true;
+            DictAndProximity dictInfo = null;
+            try {
+                dictInfo = mDictionaryPool.takeOrGetNull();
+                if (null == dictInfo) {
+                    return AndroidSpellCheckerService.getNotInDictEmptySuggestions();
+                }
+                final ArrayList<SuggestedWordInfo> suggestions = dictInfo.mDictionary.getWords(
+                        composer, prevWord, dictInfo.mProximityInfo);
+                for (final SuggestedWordInfo suggestion : suggestions) {
+                    final String suggestionStr = suggestion.mWord.toString();
+                    suggestionsGatherer.addWord(suggestionStr.toCharArray(), null, 0,
+                            suggestionStr.length(), suggestion.mScore);
+                }
+                isInDict = dictInfo.mDictionary.isValidWord(text);
+                if (!isInDict && AndroidSpellCheckerService.CAPITALIZE_NONE != capitalizeType) {
+                    // We want to test the word again if it's all caps or first caps only.
+                    // If it's fully down, we already tested it, if it's mixed case, we don't
+                    // want to test a lowercase version of it.
+                    isInDict = dictInfo.mDictionary.isValidWord(text.toLowerCase(mLocale));
+                }
+            } finally {
+                if (null != dictInfo) {
+                    if (!mDictionaryPool.offer(dictInfo)) {
+                        Log.e(TAG, "Can't re-insert a dictionary into its pool");
+                    }
+                }
+            }
+
+            final SuggestionsGatherer.Result result = suggestionsGatherer.getResults(
+                    capitalizeType, mLocale);
+
+            if (DBG) {
+                Log.i(TAG, "Spell checking results for " + text + " with suggestion limit "
+                        + suggestionsLimit);
+                Log.i(TAG, "IsInDict = " + isInDict);
+                Log.i(TAG, "LooksLikeTypo = " + (!isInDict));
+                Log.i(TAG, "HasRecommendedSuggestions = " + result.mHasRecommendedSuggestions);
+                if (null != result.mSuggestions) {
+                    for (String suggestion : result.mSuggestions) {
+                        Log.i(TAG, suggestion);
+                    }
+                }
+            }
+
+            final int flags =
+                    (isInDict ? SuggestionsInfo.RESULT_ATTR_IN_THE_DICTIONARY
+                            : SuggestionsInfo.RESULT_ATTR_LOOKS_LIKE_TYPO)
+                    | (result.mHasRecommendedSuggestions
+                            ? SuggestionsInfoCompatUtils
+                                    .getValueOf_RESULT_ATTR_HAS_RECOMMENDED_SUGGESTIONS()
+                            : 0);
+            final SuggestionsInfo retval = new SuggestionsInfo(flags, result.mSuggestions);
+            mSuggestionsCache.putSuggestionsToCache(text, prevWord, result.mSuggestions, flags);
+            return retval;
+        } catch (RuntimeException e) {
+            // Don't kill the keyboard if there is a bug in the spell checker
+            if (DBG) {
+                throw e;
+            } else {
+                Log.e(TAG, "Exception while spellcheking: " + e);
+                return AndroidSpellCheckerService.getNotInDictEmptySuggestions();
+            }
+        }
+    }
+}