file-backed-ngram-feature-extractor.H

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#ifndef RERANKER_FILE_BACKED_NGRAM_FEATURE_EXTRACTOR_H_
#define RERANKER_FILE_BACKED_NGRAM_FEATURE_EXTRACTOR_H_

#include "basic-file-backed-feature-extractor.H"
#include "ngram-feature-extractor.H"

namespace reranker {


class FileBackedNgramFeatureExtractor :
      public BasicFileBackedFeatureExtractor {
 public:
  FileBackedNgramFeatureExtractor() : BasicFileBackedFeatureExtractor() {
  }
  ~FileBackedNgramFeatureExtractor() { }


  virtual void RegisterInitializers(Initializers &initializers) {
    bool required = true;
    initializers.Add("filename", &filename_, required);
    initializers.Add("n", &n_, required);
    initializers.Add("prefix", &prefix_);
  }

  virtual void Extract(Candidate &candidate,
                       FeatureVector<int,double> &features) { }

  virtual void ExtractSymbolic(Candidate &candidate,
                               FeatureVector<string,double> &symbolic_features);
 protected:
  // data members
  int n_;
  string prefix_;
  NgramExtractor ngram_extractor_;
};

}  // namespace reranker

#endif