mosesdecoder/moses/src/Factor.h

// $Id$

/***********************************************************************
Moses - factored phrase-based language decoder
Copyright (C) 2006 University of Edinburgh

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
***********************************************************************/

#ifndef moses_Factor_h
#define moses_Factor_h

#include <sstream>
#include <iostream>
#include <list>
#include <vector>
#include <map>
#include <string>
#include "TypeDef.h"
#include "Util.h"
#include "hash.h"

namespace Moses
{

class FactorCollection;

/** Represents a factor (word, POS, etc) on the E or F side
 *
 * A Factor object is a tuple of direction (Input or Output,
 * corresponding to French or English), a type (surface form,
 * POS, stem, etc), and the value of the factor.
 *
 */
class Factor
{
  friend std::ostream& operator<<(std::ostream&, const Factor&);

  // only these classes are allowed to instantiate this class
  friend class FactorCollection;

protected:

  //FactorDirection		m_direction;
  //FactorType				m_factorType;
  const std::string	*m_ptrString;
  const size_t			m_id;

  //! protected constructor. only friend class, FactorCollection, is allowed to create Factor objects
  Factor(FactorDirection direction, FactorType factorType, const std::string *factorString, size_t id);
  //! no id set. do not used to create new factors, only used for seeing if factor exists
  Factor(FactorDirection direction, FactorType factorType, const std::string *factorString);

public:
  //! returns whether this factor is part of the source ('Input') or target ('Output') language
  //inline FactorDirection GetFactorDirection() const
  //{
  //	return m_direction;
  //}
  //! index, FactorType. For example, 0=surface, 1=POS. The actual mapping is user defined
  //inline FactorType GetFactorType() const
  //{
  //	return m_factorType;
  //}
  //! original string representation of the factor
  inline const std::string &GetString() const {
    return *m_ptrString;
  }
  //! contiguous ID
  inline size_t GetId() const {
    return m_id;
  }

  /*
  //! Alternative comparison between factors. Not yet used
  inline unsigned int GetHash() const
  {
  	unsigned int h=quick_hash((const char*)&m_direction, sizeof(FactorDirection), 0xc7e7f2fd);
  	h=quick_hash((const char*)&m_factorType, sizeof(FactorType), h);
  	h=quick_hash((const char*)&m_ptrString, sizeof(const std::string *), h);
  	return h;
  }
  */

  /** transitive comparison between 2 factors.
  *	-1 = less than
  *	+1 = more than
  *	0	= same
  *	Used by operator< & operator==, as well as other classes
  */
  inline int Compare(const Factor &compare) const {
    if (m_ptrString < compare.m_ptrString)
      return -1;
    if (m_ptrString > compare.m_ptrString)
      return 1;
    /*
    		if (m_direction < compare.m_direction)
    			return -1;
    		if (m_direction > compare.m_direction)
    			return 1;

    		if (m_factorType < compare.m_factorType)
    			return -1;
    		if (m_factorType > compare.m_factorType)
    			return 1;
    */
    return 0;
  }
  //! transitive comparison used for adding objects into FactorCollection
  inline bool operator<(const Factor &compare) const {
    return Compare(compare) < 0;
  }

  // quick equality comparison. Not used
  inline bool operator==(const Factor &compare) const {
    return this == &compare;
  }

  TO_STRING();

};

#ifdef HAVE_BOOST
size_t hash_value(const Factor &f);
#endif

}
#endif