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media / learning / impl / feature_provider.h [blame]
// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef MEDIA_LEARNING_IMPL_FEATURE_PROVIDER_H_
#define MEDIA_LEARNING_IMPL_FEATURE_PROVIDER_H_
#include "base/component_export.h"
#include "base/functional/callback.h"
#include "base/threading/sequence_bound.h"
#include "media/learning/common/labelled_example.h"
#include "media/learning/common/learning_task.h"
namespace media {
namespace learning {
// Add features to a training example. If the LearningTask's feature
// description includes feature names that a FeatureProvider knows about, then
// it will replace their value in the examples with whatever value that feature
// should have. For example, "NetworkType" might be replaced by a value that
// indicates the type of network connection.
class COMPONENT_EXPORT(LEARNING_IMPL) FeatureProvider {
public:
using FeatureVectorCB = base::OnceCallback<void(FeatureVector)>;
FeatureProvider();
FeatureProvider(const FeatureProvider&) = delete;
FeatureProvider& operator=(const FeatureProvider&) = delete;
virtual ~FeatureProvider();
// Update |features| to include whatever features are specified by |task_|,
// and call |cb| once they're filled in.
virtual void AddFeatures(FeatureVector features, FeatureVectorCB cb) = 0;
};
// Since FeatureProviders are often going to thread-hop, provide this typedef.
using SequenceBoundFeatureProvider = base::SequenceBound<FeatureProvider>;
// Factory callback, since things that create implementations will likely be
// elsewhere (e.g., content/) from the things which use them (e.g., here). May
// return an empty provider if the task doesn't require one.
using FeatureProviderFactoryCB =
base::RepeatingCallback<SequenceBoundFeatureProvider(const LearningTask&)>;
} // namespace learning
} // namespace media
#endif // MEDIA_LEARNING_IMPL_FEATURE_PROVIDER_H_