example-feature-extractor.H

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#ifndef RERANKER_EXAMPLE_FEATURE_EXTRACTOR_H_
#define RERANKER_EXAMPLE_FEATURE_EXTRACTOR_H_

#include <iostream>
#include <string>
#include <vector>

#include "feature-extractor.H"

namespace reranker {

using std::cout;
using std::string;
using std::vector;

class ExampleFeatureExtractor : public FeatureExtractor {
 public:
  ExampleFeatureExtractor() : FeatureExtractor() {
    cout << "ExampleFeatureExtractor: creating instance!" << endl;
  }
  virtual ~ExampleFeatureExtractor() { }

  virtual void RegisterInitializers(Initializers &initializers) {
    initializers.Add("arg", &arg_);
    initializers.Add("strvec", &strvec_);
    initializers.Add("b", &b_);
  }

  virtual void Init(const Environment *env, const string &arg) {
    cout << "ExampleFeatureExtractor: set arg to \"" << arg_ << "\"" << endl;
    cout << "ExampleFeatureExtractor: set strvec to {";
    for (vector<string>::const_iterator it = strvec_.begin();
         it != strvec_.end();
         ++it) {
      cout << "\"" << *it << "\", ";
    }
    cout << "}" << endl;
    cout << "ExampleFeatureExtractor: set b to " << (b_ ? "true" : "false")
         << endl;

    cout << "Environment during construction: " << endl;
    env->Print(cout);
  }

  virtual void Extract(Candidate &candidate,
                       FeatureVector<int,double> &features) {
    features.IncrementWeight(0, 5.0);
    features.IncrementWeight(27, 4.2);
  }

  virtual void ExtractSymbolic(Candidate &candidate,
                               FeatureVector<string,double> &symbolic_features)
  {
    symbolic_features.IncrementWeight(arg_ + "foo", 3.2);
    symbolic_features.IncrementWeight(arg_ + "bar", 6734.3);
    const string &candidate_sentence = candidate.raw_data();
    size_t first_space_idx = candidate_sentence.find_first_of(" ");
    const string feature = candidate_sentence.substr(0, first_space_idx);
    symbolic_features.IncrementWeight(arg_ + feature, 34.2);
  }

 private:
  // data members
  string arg_;
  vector<string> strvec_;
  bool b_;
};

REGISTER_FEATURE_EXTRACTOR(ExampleFeatureExtractor)

}  // namespace reranker

#endif