/*
|
* Copyright (C) 2018 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 LIBTEXTCLASSIFIER_ACTIONS_NGRAM_MODEL_H_
|
#define LIBTEXTCLASSIFIER_ACTIONS_NGRAM_MODEL_H_
|
|
#include <memory>
|
|
#include "actions/actions_model_generated.h"
|
#include "utils/tokenizer.h"
|
#include "utils/utf8/unicodetext.h"
|
#include "utils/utf8/unilib.h"
|
|
namespace libtextclassifier3 {
|
|
class NGramModel {
|
public:
|
static std::unique_ptr<NGramModel> Create(
|
const NGramLinearRegressionModel* model, const Tokenizer* tokenizer,
|
const UniLib* unilib);
|
|
// Evaluates an n-gram linear regression model, and tests against the
|
// threshold. Returns true in case of a positive classification. The caller
|
// may also optionally query the score.
|
bool Eval(const UnicodeText& text, float* score = nullptr) const;
|
|
// Exposed for testing only.
|
static uint64 GetNumSkipGrams(int num_tokens, int max_ngram_length,
|
int max_skips);
|
|
private:
|
NGramModel(const NGramLinearRegressionModel* model,
|
const Tokenizer* tokenizer, const UniLib* unilib);
|
|
// Returns the (begin,end] range of n-grams where the first hashed token
|
// matches the given value.
|
std::pair<int, int> GetFirstTokenMatches(uint32 token_hash) const;
|
|
// Returns whether a given n-gram matches the token stream.
|
bool IsNGramMatch(const uint32* tokens, size_t num_tokens,
|
const uint32* ngram_tokens, size_t num_ngram_tokens,
|
int max_skips) const;
|
|
const NGramLinearRegressionModel* model_;
|
const Tokenizer* tokenizer_;
|
std::unique_ptr<Tokenizer> owned_tokenizer_;
|
};
|
|
} // namespace libtextclassifier3
|
|
#endif // LIBTEXTCLASSIFIER_ACTIONS_NGRAM_MODEL_H_
|
