candidate-set-iterator.H

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#ifndef RERANKER_CANDIDATE_SET_ITERATOR_H_
#define RERANKER_CANDIDATE_SET_ITERATOR_H_

#include <memory>
#include <vector>

#include "candidate-set.H"
#include "candidate-set-reader.H"
#include "executive-feature-extractor.H"

namespace reranker {

using std::vector;
using std::shared_ptr;

class CandidateSetIterator {
 public:
  virtual ~CandidateSetIterator() { }
  virtual bool HasNext() const = 0;
  virtual CandidateSet &Next() = 0;
  virtual void Reset() = 0;
};

template <typename Collection>
class CollectionCandidateSetIterator : public CandidateSetIterator {
 public:
  CollectionCandidateSetIterator(Collection &collection) :
      collection_(collection) {
    it_ = collection_.begin();
  }

  virtual bool HasNext() const { return it_ != collection_.end(); }
  virtual CandidateSet &Next() { return **it_++; }
  virtual void Reset() { it_ = collection_.begin(); }
 private:
  typename Collection::iterator it_;
  Collection &collection_;
};


class MultiFileCandidateSetIterator : public CandidateSetIterator {
 public:
  MultiFileCandidateSetIterator(vector<string> files,
                                shared_ptr<const ExecutiveFeatureExtractor> efe,
                                int max_examples,
                                int max_candidates,
                                int reporting_interval,
                                int verbosity,
                                bool compressed,
                                bool use_base64) :
      files_(files), efe_(efe),
      compressed_(compressed), use_base64_(use_base64),
      reader_valid_(false), file_open_(false),
      csr_(max_examples, max_candidates, reporting_interval),
      verbosity_(verbosity),
      next_candidate_set_(),
      prev_candidate_set_() {
    file_it_ = files_.begin();
    csr_.set_verbosity(0);
    Reset();
    csr_.set_verbosity(verbosity);
  }

  virtual bool HasNext() const {
    return next_candidate_set_.get() != NULL;
  }

  virtual CandidateSet &Next() {
    prev_candidate_set_ = next_candidate_set_;
    next_candidate_set_ = shared_ptr<CandidateSet>();
    ReadNext();
    return *prev_candidate_set_;
  }

  const string curr_file() const {
    return file_open_ ? *file_it_ : string("");
  }

  virtual void Reset() {
    if (file_open_) {
      csr_.Close();
      file_open_ = false;
    }
    file_it_ = files_.begin();
    if (file_it_ != files_.end()) {
      csr_.Open(*file_it_, compressed_, use_base64_);
      file_open_ = true;
    }
    next_candidate_set_ = shared_ptr<CandidateSet>();
    if (efe_.get() != NULL) {
      efe_->Reset();
    }
    ReadNext();
  }
 private:
  void ReadNext() {
    reader_valid_ = false;
    while (file_it_ != files_.end() && next_candidate_set_.get() == NULL) {
      next_candidate_set_ = csr_.ReadNext(reader_valid_);
      if (!reader_valid_ || next_candidate_set_.get() == NULL) {
        if (verbosity_ >= 1) {
          if (csr_.num_read() == 0) {
            cerr << "Warning: could not read any training examples from file \""
                 << *file_it_ << "\"." << endl;
          }
        }
        // Reached eof.  Try to open next file.
        csr_.Close();
        file_open_ = false;
        ++file_it_;
        if (file_it_ != files_.end()) {
          csr_.Open(*file_it_, compressed_, use_base64_);
          file_open_ = true;
        }
      }
    }
    if (efe_.get() != NULL && next_candidate_set_.get() != NULL) {
      efe_->Extract(*next_candidate_set_);
    }
  }

  // data members
  vector<string> files_;
  shared_ptr<const ExecutiveFeatureExtractor> efe_;
  bool compressed_;
  bool use_base64_;
  bool reader_valid_;
  bool file_open_;
  CandidateSetReader csr_;
  int verbosity_;
  vector<string>::const_iterator file_it_;
  shared_ptr<CandidateSet> next_candidate_set_;
  shared_ptr<CandidateSet> prev_candidate_set_;
};

}  // namespace reranker

#endif