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// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_TRANSLATE_CORE_LANGUAGE_DETECTION_LANGUAGE_DETECTION_MODEL_H_
#define COMPONENTS_TRANSLATE_CORE_LANGUAGE_DETECTION_LANGUAGE_DETECTION_MODEL_H_
#include <memory>
#include <string>
#include "base/feature_list.h"
#include "base/files/file.h"
#include "build/build_config.h"
#include "components/language_detection/core/language_detection_model.h"
#include "partition_alloc/pointers/raw_ref.h"
namespace translate {
// Exposed for testing.
// The number of characters to sample and provide as a buffer to the model
// for determining its language.
inline constexpr size_t kTextSampleLength = 256;
// The number of samples of |kTextSampleLength| to evaluate the model when
// determining the language of the page content.
inline constexpr int kNumTextSamples = 3;
// A language detection model that will use a TFLite model to determine the
// language of the content of the web page.
class LanguageDetectionModel {
public:
explicit LanguageDetectionModel(
language_detection::LanguageDetectionModel& shared_tflite_model);
explicit LanguageDetectionModel(
std::unique_ptr<language_detection::LanguageDetectionModel>
owned_tflite_model);
~LanguageDetectionModel();
// Updates the language detection model for use by memory-mapping
// |model_file| used to detect the language of the page.
//
// This method is blocking and should only be called in context where
// it is valid to block the current thread. If this is not the case,
// use UpdateWithFileAsync(...) instead.
void UpdateWithFile(base::File model_file);
// Asynchronously updates the language detection model for use by
// memory-mapping |model_file| used to detect the language of the
// page and invokes |callback| when the update is done.
void UpdateWithFileAsync(base::File model_file, base::OnceClosure callback);
// Returns whether |this| is initialized and is available to handle requests
// to determine the language of the page.
bool IsAvailable() const;
// Determines content page language from Content-Language code and contents.
// Returns the contents language results in |predicted_language|,
// |is_prediction_reliable|, and |prediction_reliability_score|.
std::string DeterminePageLanguage(const std::string& code,
const std::string& html_lang,
const std::u16string& contents,
std::string* predicted_language,
bool* is_prediction_reliable,
float& prediction_reliability_score) const;
language_detection::Prediction DetectLanguage(
const std::u16string& contents) const;
std::string GetModelVersion() const;
language_detection::LanguageDetectionModel& tflite_model() {
return *tflite_model_;
}
private:
// The tflite classifier that can determine the language of text.
std::unique_ptr<language_detection::LanguageDetectionModel>
owned_tflite_model_;
const raw_ref<language_detection::LanguageDetectionModel> tflite_model_;
};
} // namespace translate
#endif // COMPONENTS_TRANSLATE_CORE_LANGUAGE_DETECTION_LANGUAGE_DETECTION_MODEL_H_
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