hmm_tagger.h

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//
//    FreeLing - Open Source Language Analyzers
//
//    Copyright (C) 2004   TALP Research Center
//                         Universitat Politecnica de Catalunya
//
//    This library is free software; you can redistribute it and/or
//    modify it under the terms of the GNU General Public
//    License as published by the Free Software Foundation; either
//    version 3 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
//    General Public License for more details.
//
//    You should have received a copy of the GNU General Public
//    License along with this library; if not, write to the Free Software
//    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//
//    contact: Lluis Padro (padro@lsi.upc.es)
//             TALP Research Center
//             despatx C6.212 - Campus Nord UPC
//             08034 Barcelona.  SPAIN
//

#ifndef _TAGGER
#define _TAGGER

#include <map>
#include <list>
#include <set>

#include "freeling/windll.h"
#include "freeling/morfo/language.h"
#include "freeling/morfo/tagger.h"


class trellis {  
 private:

  class element {
   public:
     std::wstring state;
     int kbest;
     double prob;

     element(const std::wstring &, int, double);
     ~element();
     bool operator<(const element &) const;
     bool operator==(const element &) const;
  };

  std::map <std::wstring, std::multiset<element> > *trl;
  unsigned int kbest;

 public:
  trellis(int, unsigned int kb=1);
  ~trellis();

  void insert(int, const std::wstring &, const std::wstring &, int kb, double);
  double delta(int, const std::wstring &, unsigned int k=0);
  std::pair<std::wstring,int> phi(int, const std::wstring &, unsigned int k=0);
  int nbest(int, const std::wstring &);

  static float ZERO_logprob;
};



class emission_states: public std::set<std::wstring> {};



class WINDLL hmm_tagger: public POS_tagger {
 private:
  // Configuration options
  std::wstring Language;

  std::map <std::wstring, double> PTag;
  std::map <std::wstring, double> PBg;
  std::map <std::wstring, double> PTrg;
  std::map <std::wstring, double> PInitial;
  std::map <std::wstring, double> PWord;

  std::multimap <std::wstring, std::wstring> Forbidden;

  std::map<std::wstring,double> pA_cache;
  std::map<std::wstring,double> pB_cache;

  unsigned int kbest;

  double c[3];

  bool is_forbidden(const std::wstring &, sentence::const_iterator) const;
  double ProbA_log(const std::wstring &, const std::wstring &, sentence::const_iterator);
  double ProbB_log(const std::wstring &, const word &);
  double ProbPi_log(const std::wstring &) const;

  std::list<emission_states> FindStates(const sentence &) const;

 public:
  hmm_tagger(const std::wstring &, const std::wstring &, bool, unsigned int, unsigned int kb=1);

  void annotate(sentence &);
  double SequenceProb_log(const sentence &, int k=0);

};

#endif