HfstTropicalTransducerTransitionData.h

// Copyright (c) 2016 University of Helsinki                          
//                                                                    
// 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 3 of the License, or (at your option) any later version.
// See the file COPYING included with this distribution for more      
// information.

#include <string>
#include <map>
#include <set>
#include <cassert>
#include <cstdio>
#include <iostream>
#include <vector>
#include "../HfstExceptionDefs.h"

#include "../hfstdll.h"

namespace hfst {

  namespace implementations {

    struct string_comparison {
      bool operator() (const std::string &str1, const std::string &str2) const {
        return (str1.compare(str2) < 0);
      }
    };
    
    class HfstTropicalTransducerTransitionData {
    public:
      typedef std::string SymbolType;
      typedef float WeightType;
      typedef std::set<SymbolType> SymbolTypeSet;
      
      typedef std::vector<SymbolType> 
        Number2SymbolVector;
      typedef std::map<SymbolType, unsigned int, string_comparison> 
        Symbol2NumberMap;

      HFSTDLL static SymbolType get_epsilon()
      {
        return SymbolType("@_EPSILON_SYMBOL_@");
      }
      
      HFSTDLL static SymbolType get_unknown()
      {
        return SymbolType("@_UNKNOWN_SYMBOL_@");
      }
      
      HFSTDLL static SymbolType get_identity()
      {
        return SymbolType("@_IDENTITY_SYMBOL_@");
      }
      
    public: /* FIXME: Should be private. */
      /* Maps that contain information of the mappings between strings 
         and numbers */
      HFSTDLL static Number2SymbolVector number2symbol_map;
      HFSTDLL static Symbol2NumberMap symbol2number_map;
      /* The biggest number in use. */
      HFSTDLL static unsigned int max_number;

      /* Get the biggest number used to represent a symbol. */
      HFSTDLL static unsigned int get_max_number() {
        return max_number;
      }

      /* 
         Get a vector that defines how numbers of a transducer must
         be changed, i.e. harmonized, so that it follows the same 
         number-to-string encoding as all transducers that use the datatype
         HfstTropicalTransducerTransitionData.

         \a symbols defines how numbers are mapped to strings in the
         original transducer so that each index in \a symbols 
         is the number that corresponds to the string at that index.
         An empty string at an index means that the index is not
         used in the original transducer.

         The result is a vector whose each index is the number that
         must be replaced by the number at that index when a
         transducer is harmonized. If an index is not used in the
         transducer, the result will contain a zero at that index.
      */
      static std::vector<unsigned int> get_harmonization_vector
        (const std::vector<SymbolType> &symbols)
      {
        std::vector<unsigned int> harmv;
        harmv.reserve(symbols.size());
        harmv.resize(symbols.size(), 0);
        for (unsigned int i=0; i<symbols.size(); i++)
          {
            if (symbols.at(i) != "")
              harmv.at(i) = get_number(symbols.at(i));
          }
        return harmv;
      }

      static std::vector<unsigned int> get_reverse_harmonization_vector
        (const std::map<SymbolType, unsigned int> &symbols)
      {
        std::vector<unsigned int> harmv;
        harmv.reserve(max_number+1);
        harmv.resize(max_number+1, 0);
        for (unsigned int i=0; i<harmv.size(); i++)
          {
            std::map<SymbolType, unsigned int>::const_iterator it
              = symbols.find(get_symbol(i));
            if (it != symbols.end())
              harmv.at(i) = it->second;
          }
        return harmv;
      }

    protected:
      /* Get the symbol that is mapped as \a number */
      static const std::string &get_symbol(unsigned int number) 
      { 
        if (number >= number2symbol_map.size()) {
          std::string message("HfstTropicalTransducerTransitionData: "
                              "number ");
          std::ostringstream oss;
          oss << number;
          message.append(oss.str());
          message.append(" is not mapped to any symbol");
          HFST_THROW_MESSAGE
            (HfstFatalException, message);
        }
        return number2symbol_map[number];
      }

      /* Get the number that is used to represent \a symbol */
      static unsigned int get_number(const std::string &symbol) 
      {
        if(symbol == "") { // FAIL
          Symbol2NumberMap::iterator it = symbol2number_map.find(symbol);
          if (it == symbol2number_map.end()) {
            std::cerr << "ERROR: No number for the empty symbol\n" 
                      << std::endl;
          }
          else {
            std::cerr << "ERROR: The empty symbol corresdponds to number " 
                      << it->second << std::endl;
          }
          assert(false);
        }
        
        Symbol2NumberMap::iterator it = symbol2number_map.find(symbol);
        if (it == symbol2number_map.end()) 
          {
            max_number++;
            symbol2number_map[symbol] = max_number;
            number2symbol_map.push_back(symbol);            
            return max_number;
          }
        return it->second;
      }

      //private: TEST
    public:
      /* The actual transition data */
      unsigned int input_number;
      unsigned int output_number;
      WeightType weight;

    public:
      HFSTDLL void print_transition_data() 
      {
    fprintf(stderr, "%i:%i %f\n", 
        input_number, output_number, weight);
      }

    public:

    HFSTDLL HfstTropicalTransducerTransitionData(): 
      input_number(0), output_number(0), weight(0) {}
      
      HFSTDLL HfstTropicalTransducerTransitionData
        (const HfstTropicalTransducerTransitionData &data) {
        input_number = data.input_number;
        output_number = data.output_number;
        weight = data.weight;
      }

      HFSTDLL HfstTropicalTransducerTransitionData(SymbolType isymbol,
                       SymbolType osymbol,
                       WeightType weight) {
    if (isymbol == "" || osymbol == "")
      HFST_THROW_MESSAGE
        (EmptyStringException,
         "HfstTropicalTransducerTransitionData"
         "(SymbolType, SymbolType, WeightType)");
    
        input_number = get_number(isymbol);
        output_number = get_number(osymbol);
        this->weight = weight;
      }

      HFSTDLL HfstTropicalTransducerTransitionData
        (unsigned int inumber,
         unsigned int onumber,
         WeightType weight) {
        input_number = inumber;
        output_number = onumber;
        this->weight = weight;
      }

      HFSTDLL const SymbolType &get_input_symbol() const {
        return get_symbol(input_number);
      }

      HFSTDLL const SymbolType &get_output_symbol() const {
        return get_symbol(output_number);
      }

      HFSTDLL unsigned int get_input_number() const {
        return input_number;
      }

      HFSTDLL unsigned int get_output_number() const {
        return output_number;
      }
      
      HFSTDLL WeightType get_weight() const {
        return weight;
      }

      HFSTDLL void set_weight(WeightType w) {
        weight = w;
      }


      /* Are these needed? */
      HFSTDLL static bool is_epsilon(const SymbolType &symbol) {
        return (symbol.compare("@_EPSILON_SYMBOL_@") == 0);
      }
      HFSTDLL static bool is_unknown(const SymbolType &symbol) {
        return (symbol.compare("@_UNKNOWN_SYMBOL_@") == 0);
      }
      HFSTDLL static bool is_identity(const SymbolType &symbol) {
        return (symbol.compare("@_IDENTITY_SYMBOL_@") == 0);
      }
      HFSTDLL static bool is_valid_symbol(const SymbolType &symbol) {
        if (symbol == "")
          return false;
        return true;
      }

      HFSTDLL static SymbolType get_marker(const SymbolTypeSet &sts) {
        (void)sts;
        return SymbolType("@_MARKER_SYMBOL_@");
      }

      HFSTDLL bool operator<(const HfstTropicalTransducerTransitionData &another) 
        const {
        if (input_number < another.input_number )
          return true;
        if (input_number > another.input_number)
          return false;
        if (output_number < another.output_number)
          return true;
        if (output_number > another.output_number)
          return false;
        return (weight < another.weight);
      }

      // same as operator< but weight is ignored
      HFSTDLL bool less_than_ignore_weight(const HfstTropicalTransducerTransitionData &another) 
        const {
        if (input_number < another.input_number )
          return true;
        if (input_number > another.input_number)
          return false;
        if (output_number < another.output_number)
          return true;
        if (output_number > another.output_number)
          return false;
        return false;
      }
      
      HFSTDLL void operator=(const HfstTropicalTransducerTransitionData &another)
        {
          input_number = another.input_number;
          output_number = another.output_number;
          weight = another.weight;
        }
      
      friend class Number2SymbolVectorInitializer;
      friend class Symbol2NumberMapInitializer;

      friend class ComposeIntersectFst;
      friend class ComposeIntersectLexicon;
      friend class ComposeIntersectRule;
      friend class ComposeIntersectRulePair;
      template <class C> friend class HfstTransitionGraph;

    };

    // Initialization of static members in class 
    // HfstTropicalTransducerTransitionData..
    class Number2SymbolVectorInitializer {
    public:
      HFSTDLL Number2SymbolVectorInitializer
        (HfstTropicalTransducerTransitionData::Number2SymbolVector &vect) {
        vect.push_back(std::string("@_EPSILON_SYMBOL_@"));
        vect.push_back(std::string("@_UNKNOWN_SYMBOL_@"));
        vect.push_back(std::string("@_IDENTITY_SYMBOL_@"));
      }
    };

    class Symbol2NumberMapInitializer {
    public:
      HFSTDLL Symbol2NumberMapInitializer
        (HfstTropicalTransducerTransitionData::Symbol2NumberMap &map) {
        map["@_EPSILON_SYMBOL_@"] = 0;
        map["@_UNKNOWN_SYMBOL_@"] = 1;
        map["@_IDENTITY_SYMBOL_@"] = 2;
      }
    };

  } // namespace implementations

} // namespace hfst