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/*
* 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_ANNOTATOR_CACHED_FEATURES_H_
#define LIBTEXTCLASSIFIER_ANNOTATOR_CACHED_FEATURES_H_
#include <memory>
#include <vector>
#include "annotator/model-executor.h"
#include "annotator/model_generated.h"
#include "annotator/types.h"
namespace libtextclassifier3 {
// Holds state for extracting features across multiple calls and reusing them.
// Assumes that features for each Token are independent.
class CachedFeatures {
public:
static std::unique_ptr<CachedFeatures> Create(
const TokenSpan& extraction_span,
std::unique_ptr<std::vector<float>> features,
std::unique_ptr<std::vector<float>> padding_features,
const FeatureProcessorOptions* options, int feature_vector_size);
// Appends the click context features for the given click position to
// 'output_features'.
void AppendClickContextFeaturesForClick(
int click_pos, std::vector<float>* output_features) const;
// Appends the bounds-sensitive features for the given token span to
// 'output_features'.
void AppendBoundsSensitiveFeaturesForSpan(
TokenSpan selected_span, std::vector<float>* output_features) const;
// Returns number of features that 'AppendFeaturesForSpan' appends.
int OutputFeaturesSize() const { return output_features_size_; }
private:
CachedFeatures() {}
// Appends token features to the output. The intended_span specifies which
// tokens' features should be used in principle. The read_mask_span restricts
// which tokens are actually read. For tokens outside of the read_mask_span,
// padding tokens are used instead.
void AppendFeaturesInternal(const TokenSpan& intended_span,
const TokenSpan& read_mask_span,
std::vector<float>* output_features) const;
// Appends features of one padding token to the output.
void AppendPaddingFeatures(std::vector<float>* output_features) const;
// Appends the features of tokens from the given span to the output. The
// features are averaged so that the appended features have the size
// corresponding to one token.
void AppendBagFeatures(const TokenSpan& bag_span,
std::vector<float>* output_features) const;
int NumFeaturesPerToken() const;
TokenSpan extraction_span_;
const FeatureProcessorOptions* options_;
int output_features_size_;
std::unique_ptr<std::vector<float>> features_;
std::unique_ptr<std::vector<float>> padding_features_;
};
} // namespace libtextclassifier3
#endif // LIBTEXTCLASSIFIER_ANNOTATOR_CACHED_FEATURES_H_