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/*
* 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 "defines.h"
#include "dictionary/property/historical_info.h"
#include "dictionary/utils/entry_counters.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 bool needsToKeep(const HistoricalInfo *const historicalInfo,
const HeaderPolicy *const headerPolicy);
static bool needsToDecay(const bool mindsBlockByDecay, const EntryCounts &entryCounters,
const HeaderPolicy *const headerPolicy);
// TODO: Improve probability computation method and remove this.
static int getProbabilityBiasForNgram(const int n) {
return (n - 1) * MULTIPLIER_TWO_IN_PROBABILITY_SCALE;
}
AK_FORCE_INLINE static int getEntryCountHardLimit(const int maxEntryCount) {
return static_cast<int>(static_cast<float>(maxEntryCount)
* ENTRY_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 int OCCURRENCES_TO_RAISE_THE_LEVEL;
static const int DURATION_TO_LOWER_THE_LEVEL_IN_SECONDS;
static const float ENTRY_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 */
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