Add spellcheck and word suggestion to the prediction service

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

+/*
+ * 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/prediction/defines.h"
+#include "third_party/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 */