Add spellcheck and word suggestion to the prediction service

third_party/android_prediction/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.h

Index: third_party/android_prediction/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.h
diff --git a/third_party/android_prediction/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.h b/third_party/android_prediction/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.h
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index 0000000000000000000000000000000000000000..703cca2d777e5b5abe9545fdfaac186b6a56e91a
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+++ b/third_party/android_prediction/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.h
@@ -0,0 +1,113 @@
+/*
+ * Copyright (C) 2013, 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.
+ */
+
+#ifndef LATINIME_FORGETTING_CURVE_UTILS_H
+#define LATINIME_FORGETTING_CURVE_UTILS_H
+
+#include <vector>
+
+#include "third_party/android_prediction/defines.h"
+#include "third_party/android_prediction/suggest/policyimpl/dictionary/utils/historical_info.h"
+
+namespace latinime {
+
+class HeaderPolicy;
+
+class ForgettingCurveUtils {
+ public:
+    static const HistoricalInfo createUpdatedHistoricalInfo(
+            const HistoricalInfo *const originalHistoricalInfo, const int newProbability,
+            const HistoricalInfo *const newHistoricalInfo, const HeaderPolicy *const headerPolicy);
+
+    static const HistoricalInfo createHistoricalInfoToSave(
+            const HistoricalInfo *const originalHistoricalInfo,
+            const HeaderPolicy *const headerPolicy);
+
+    static int decodeProbability(const HistoricalInfo *const historicalInfo,
+            const HeaderPolicy *const headerPolicy);
+
+    static int getProbability(const int encodedUnigramProbability,
+            const int encodedBigramProbability);
+
+    static bool needsToKeep(const HistoricalInfo *const historicalInfo,
+            const HeaderPolicy *const headerPolicy);
+
+    static bool needsToDecay(const bool mindsBlockByDecay, const int unigramCount,
+            const int bigramCount, const HeaderPolicy *const headerPolicy);
+
+    AK_FORCE_INLINE static int getUnigramCountHardLimit(const int maxUnigramCount) {
+        return static_cast<int>(static_cast<float>(maxUnigramCount)
+                * UNIGRAM_COUNT_HARD_LIMIT_WEIGHT);
+    }
+
+    AK_FORCE_INLINE static int getBigramCountHardLimit(const int maxBigramCount) {
+        return static_cast<int>(static_cast<float>(maxBigramCount)
+                * BIGRAM_COUNT_HARD_LIMIT_WEIGHT);
+    }
+
+ private:
+    DISALLOW_IMPLICIT_CONSTRUCTORS(ForgettingCurveUtils);
+
+    class ProbabilityTable {
+     public:
+        ProbabilityTable();
+
+        int getProbability(const int tableId, const int level,
+                const int elapsedTimeStepCount) const {
+            return mTables[tableId][level][elapsedTimeStepCount];
+        }
+
+     private:
+        DISALLOW_COPY_AND_ASSIGN(ProbabilityTable);
+
+        static const int PROBABILITY_TABLE_COUNT;
+        static const int WEAK_PROBABILITY_TABLE_ID;
+        static const int MODEST_PROBABILITY_TABLE_ID;
+        static const int STRONG_PROBABILITY_TABLE_ID;
+        static const int AGGRESSIVE_PROBABILITY_TABLE_ID;
+
+        static const int WEAK_MAX_PROBABILITY;
+        static const int MODEST_BASE_PROBABILITY;
+        static const int STRONG_BASE_PROBABILITY;
+        static const int AGGRESSIVE_BASE_PROBABILITY;
+
+        std::vector<std::vector<std::vector<int>>> mTables;
+
+        static int getBaseProbabilityForLevel(const int tableId, const int level);
+    };
+
+    static const int MULTIPLIER_TWO_IN_PROBABILITY_SCALE;
+    static const int DECAY_INTERVAL_SECONDS;
+
+    static const int MAX_LEVEL;
+    static const int MIN_VISIBLE_LEVEL;
+    static const int MAX_ELAPSED_TIME_STEP_COUNT;
+    static const int DISCARD_LEVEL_ZERO_ENTRY_TIME_STEP_COUNT_THRESHOLD;
+
+    static const float UNIGRAM_COUNT_HARD_LIMIT_WEIGHT;
+    static const float BIGRAM_COUNT_HARD_LIMIT_WEIGHT;
+
+    static const ProbabilityTable sProbabilityTable;
+
+    static int backoff(const int unigramProbability);
+    static int getElapsedTimeStepCount(const int timestamp, const int durationToLevelDown);
+    static int clampToVisibleEntryLevelRange(const int level);
+    static int clampToValidLevelRange(const int level);
+    static int clampToValidCountRange(const int count, const HeaderPolicy *const headerPolicy);
+    static int clampToValidTimeStepCountRange(const int timeStepCount);
+};
+} // namespace latinime
+#endif /* LATINIME_FORGETTING_CURVE_UTILS_H */