Add spell checking core methods.

Bug: 4176026
Change-Id: Ic6ea3e084b3ebacfc5fd998d2c7b0130f7b0ec48

java/proguard.flags

@@ -22,3 +22,7 @@
 -keep class com.android.inputmethod.latin.Utils {
   boolean equalsIgnoreCase(...);
 }
+
+-keep class com.android.inputmethod.latin.spellcheck.SpellChecker {
+  *;
+}

java/src/com/android/inputmethod/latin/spellcheck/SpellChecker.java

@@ -0,0 +1,114 @@
+/*
+ * Copyright (C) 2011 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.content.Context;
+import android.content.res.Resources;
+
+import com.android.inputmethod.latin.Dictionary;
+import com.android.inputmethod.latin.Dictionary.DataType;
+import com.android.inputmethod.latin.Dictionary.WordCallback;
+import com.android.inputmethod.latin.DictionaryFactory;
+import com.android.inputmethod.latin.Utils;
+import com.android.inputmethod.latin.WordComposer;
+
+import java.util.Arrays;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Locale;
+
+/**
+ * Implements spell checking methods.
+ */
+public class SpellChecker {
+
+    public final Dictionary mDictionary;
+
+    public SpellChecker(final Context context, final Locale locale) {
+        final Resources resources = context.getResources();
+        final int fallbackResourceId = Utils.getMainDictionaryResourceId(resources);
+        mDictionary = DictionaryFactory.createDictionaryFromManager(context, locale,
+                fallbackResourceId);
+    }
+
+    // Note : this must be reentrant
+    /**
+     * Finds out whether a word is in the dictionary or not.
+     *
+     * @param text the sequence containing the word to check for.
+     * @param start the index of the first character of the word in text.
+     * @param end the index of the next-to-last character in text.
+     * @return true if the word is in the dictionary, false otherwise.
+     */
+    public boolean isCorrect(final CharSequence text, final int start, final int end) {
+        return mDictionary.isValidWord(text.subSequence(start, end));
+    }
+
+    private static class SuggestionsGatherer implements WordCallback {
+        private final int DEFAULT_SUGGESTION_LENGTH = 16;
+        private final List<String> mSuggestions = new LinkedList<String>();
+        private int[] mScores = new int[DEFAULT_SUGGESTION_LENGTH];
+        private int mLength = 0;
+
+        synchronized public boolean addWord(char[] word, int wordOffset, int wordLength, int score,
+                int dicTypeId, DataType dataType) {
+            if (mLength >= mScores.length) {
+                final int newLength = mScores.length * 2;
+                mScores = new int[newLength];
+            }
+            final int positionIndex = Arrays.binarySearch(mScores, 0, mLength, score);
+            // binarySearch returns the index if the element exists, and -<insertion index> - 1
+            // if it doesn't. See documentation for binarySearch.
+            final int insertionIndex = positionIndex >= 0 ? positionIndex : -positionIndex - 1;
+            System.arraycopy(mScores, insertionIndex, mScores, insertionIndex + 1,
+                    mLength - insertionIndex);
+            mLength += 1;
+            mScores[insertionIndex] = score;
+            mSuggestions.add(insertionIndex, new String(word, wordOffset, wordLength));
+            return true;
+        }
+
+        public List<String> getGatheredSuggestions() {
+            return mSuggestions;
+        }
+    }
+
+    // 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
+     * arguments. It may split or group words, and even perform grammatical
+     * analysis.
+     *
+     * @param text the sequence containing the word to check for.
+     * @param start the index of the first character of the word in text.
+     * @param end the index of the next-to-last character in text.
+     * @return a list of possible suggestions to replace the text.
+     */
+    public List<String> getSuggestions(final CharSequence text, final int start, final int end) {
+        final SuggestionsGatherer suggestionsGatherer = new SuggestionsGatherer();
+        final WordComposer composer = new WordComposer();
+        for (int i = start; i < end; ++i) {
+            int character = text.charAt(i);
+            composer.add(character, new int[] { character },
+                    WordComposer.NOT_A_COORDINATE, WordComposer.NOT_A_COORDINATE);
+        }
+        mDictionary.getWords(composer, suggestionsGatherer);
+        return suggestionsGatherer.getGatheredSuggestions();
+    }
+}