ChartHypothesisCollection.h

// $Id$
// vim:tabstop=2
/***********************************************************************
 Moses - factored phrase-based language decoder
 Copyright (C) 2010 Hieu Hoang

 This library is free software; you can redistribute it and/or
 modify it under the terms of the GNU Lesser General Public
 License as published by the Free Software Foundation; either
 version 2.1 of the License, or (at your option) any later version.

 This library is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 Lesser General Public License for more details.

 You should have received a copy of the GNU Lesser General Public
 License along with this library; if not, write to the Free Software
 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 ***********************************************************************/
#pragma once

#include <set>
#include "ChartHypothesis.h"
#include "RuleCube.h"


namespace Moses
{

class ChartSearchGraphWriter;

//! functor to compare (chart) hypotheses by (descending) score
class ChartHypothesisScoreOrderer
{
public:
  bool operator()(const ChartHypothesis* hypoA, const ChartHypothesis* hypoB) const {
    return hypoA->GetTotalScore() > hypoB->GetTotalScore();
  }
};

/** functor to compare (chart) hypotheses by feature function states.
 *  If 2 hypos are equal, according to this functor, then they can be recombined.
 */
class ChartHypothesisRecombinationOrderer
{
public:
  bool operator()(const ChartHypothesis* hypoA, const ChartHypothesis* hypoB) const {
    // assert in same cell
    assert(hypoA->GetCurrSourceRange() == hypoB->GetCurrSourceRange());

    // shouldn't be mixing hypos with different lhs
    assert(hypoA->GetTargetLHS() == hypoB->GetTargetLHS());

    int ret = hypoA->RecombineCompare(*hypoB);
    if (ret != 0)
      return (ret < 0);

    return false;
  }
};

/** Contains a set of unique hypos that have the same HS non-term.
  * ie. 1 of these for each target LHS in each cell
  */
class ChartHypothesisCollection
{
  friend std::ostream& operator<<(std::ostream&, const ChartHypothesisCollection&);

protected:
  typedef std::set<ChartHypothesis*, ChartHypothesisRecombinationOrderer> HCType;
  HCType m_hypos;
  HypoList m_hyposOrdered;

  float m_bestScore; /**< score of the best hypothesis in collection */
  float m_beamWidth; /**< minimum score due to threashold pruning */
  size_t m_maxHypoStackSize; /**< maximum number of hypothesis allowed in this stack */
  bool m_nBestIsEnabled; /**< flag to determine whether to keep track of old arcs */

  std::pair<HCType::iterator, bool> Add(ChartHypothesis *hypo, ChartManager &manager);

public:
  typedef HCType::iterator iterator;
  typedef HCType::const_iterator const_iterator;
  //! iterators
  const_iterator begin() const {
    return m_hypos.begin();
  }
  const_iterator end() const {
    return m_hypos.end();
  }

  ChartHypothesisCollection();
  ~ChartHypothesisCollection();
  bool AddHypothesis(ChartHypothesis *hypo, ChartManager &manager);

  void Detach(const HCType::iterator &iter);
  void Remove(const HCType::iterator &iter);

  void PruneToSize(ChartManager &manager);

  size_t GetSize() const {
    return m_hypos.size();
  }
  size_t GetHypo() const {
    return m_hypos.size();
  }

  void SortHypotheses();
  void CleanupArcList();

  //! return vector of hypothesis that has been sorted by score
  const HypoList &GetSortedHypotheses() const {
    return m_hyposOrdered;
  }

  //! return the best total score of all hypos in this collection
  float GetBestScore() const {
    return m_bestScore;
  }

  void WriteSearchGraph(const ChartSearchGraphWriter& writer, const std::map<unsigned,bool> &reachable) const;

};

} // namespace