efsm.hh

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#pragma once

#include <algorithm>
#include <iostream>

#include <boost/range/algorithm/sort.hpp>

#include <vcsn/algos/grail.hh> // outputter
#include <vcsn/dyn/fwd.hh>
#include <vcsn/labelset/fwd.hh>
#include <vcsn/misc/escape.hh>
#include <vcsn/misc/getargs.hh>

namespace vcsn
{

  /*--------------------------.
  | efsm(automaton, stream).  |
  `--------------------------*/
  namespace detail
  {
    template <typename LabelSet>
    struct rank
    {
      static constexpr size_t value = 1;
    };

    template <typename... LabelSet>
    struct rank<tupleset<LabelSet...>>
    {
      static constexpr size_t value = sizeof...(LabelSet);
    };

    template <typename Aut>
    class efsmer: public outputter<Aut>
    {
    protected:
      using automaton_t = Aut;
      using super_t = outputter<Aut>;

      using label_t = typename super_t::label_t;
      using state_t = typename super_t::state_t;
      using transition_t = typename super_t::transition_t;

      using super_t::os_;
      using super_t::aut_;
      using super_t::ls_;
      using super_t::ws_;

    public:
      using super_t::super_t;

      void operator()()
      {
        os_ <<
          "#! /bin/sh\n"
          "\n"
          "me=$(basename \"$0\")\n"
          "medir=$(mktemp -d \"/tmp/$me.XXXXXX\") || exit 1\n"
          "\n";

        os_ <<
          "arc_type=" << arc_type_() << "\n"
          "\n";

          // Provide the symbols first, as when reading EFSM, knowing
          // how \e is represented will help reading the transitions.
        output_symbols_();

        os_ <<
          "cat >$medir/transitions.fsm <<\\EOFSM";
        output_transitions_();
        os_ <<
          "\n"
          "EOFSM\n"
          "\n"

          // Some OpenFST tools seem to require an output-symbol list,
          // even for acceptors.  While fstrmepsilon perfectly works
          // with just the isymbols, fstintersect (equivalent to our
          // conjunction) for instance, seems to require the osymbols;
          // this seems to be due to the fact that Open FST bases its
          // implementation of intersect on its (transducer)
          // composition.
          "fstcompile" << (is_transducer ? "" : " --acceptor") << " \\\n"
          "  --arc_type=$arc_type \\\n"
          "  --keep_isymbols --isymbols=" << isymbols_ << " \\\n"
          "  --keep_osymbols --osymbols=" << osymbols_ << " \\\n"
          "  $medir/transitions.fsm \"$@\"\n"
          "sta=$?\n"
          "\n"
          "rm -rf $medir\n"
          "exit $sta" // No final \n.
          ;
      }

    private:
      std::string arc_type_() const
      {
        auto map = std::map<std::string, std::string>
          {
            {"b",    "standard"},
            {"zmin", "standard"},
            {"rmin", "standard"},
            {"nmin", "standard"},
            {"log",  "log64"},
          };
        return getargs("weightset", map, ws_.sname());
      }

      template <typename LS>
      void output_label_(const LS& ls, const typename LS::value_t& l) const
      {
        if (ls.is_special(l))
          os_ << "\\e";
        else
          ls.print(l, os_, format::raw);
      }

      template <typename Label>
      void output_label_(const Label& l, std::false_type) const
      {
        output_label_(ls_, l);
      }

      template <typename Label>
      void output_label_(const Label& l, std::true_type) const
      {
        output_label_(ls_.template set<0>(), std::get<0>(l));
        os_ << '\t';
        output_label_(ls_.template set<1>(), std::get<1>(l));
      }

      void output_transition_(const transition_t t) const override
      {
        // Don't output "pre", but an integer.
        if (aut_->src_of(t) == aut_->pre())
          os_ << aut_->pre() - 2;
        else
          aut_->print_state(aut_->src_of(t), os_);
        if (aut_->dst_of(t) != aut_->post())
          {
            os_ << '\t';
            aut_->print_state(aut_->dst_of(t), os_);
            os_ << '\t';
            output_label_(aut_->label_of(t), is_transducer);
          }

        if (ws_.show_one() || !ws_.is_one(aut_->weight_of(t)))
          {
            os_ << '\t';
            ws_.print(aut_->weight_of(t), os_);
          }
      }

      void output_transitions_()
      {
        // FSM format supports a single initial state with one as
        // weight.  This requires, when we have several initial
        // states or an non, to "exhibit" pre() and spontaneous transitions.
        // Avoid this when possible.
        auto inis =  aut_->initial_transitions();
        if (inis.size() != 1
            || !ws_.is_one(aut_->weight_of(inis.front())))
          for (auto t : inis)
            {
              os_ << '\n';
              // Yes, this means that we display pre as -1U, which is
              // a large unsigned integer.  But that is well supported
              // by OpenFST which renumbers the states continuously
              // from 0.
              output_transition_(t);
            }

        // We _must_ start by the initial state.
        {
          std::vector<state_t> states(std::begin(aut_->states()),
                                      std::end(aut_->states()));
          boost::sort(states,
                      [this](state_t l, state_t r)
                      {
                        return (std::forward_as_tuple(!aut_->is_initial(l), l)
                                < std::forward_as_tuple(!aut_->is_initial(r), r));
                      });
          for (auto s: states)
            this->output_state_(s);
        }
        for (auto t : aut_->final_transitions())
          {
            os_ << '\n';
            output_transition_(t);
          }
      }

      template <typename LabelSet, typename Labels, typename GetLabel>
      auto add_alphabet_(const LabelSet& ls, Labels& labels, GetLabel get_label)
        -> enable_if_t<has_genset_mem_fn<LabelSet>{}>
      {
        for (auto l : ls.genset())
          labels.insert(get_label(ls.value(l)));
      }

      template <typename LabelSet, typename Labels, typename GetLabel>
      auto add_alphabet_(const LabelSet&, Labels&, GetLabel)
        -> enable_if_t<!has_genset_mem_fn<LabelSet>{}>
      {}

      template <typename LabelSet, typename GetLabel>
      void output_symbols_(const std::string& name,
                           const LabelSet& ls,
                           GetLabel get_label)
      {
        // The labels we declare.
        using labelset_t = LabelSet;
        using label_t = typename labelset_t::value_t;

        auto labels = std::set<label_t, vcsn::less<labelset_t>>{};
        // If there is an alphabet, include it, to preserve the
        // context in round trips.
        add_alphabet_(*aut_->labelset(), labels, get_label);
        // In any case, insert all our labels.
        for (auto t : aut_->transitions())
          labels.insert(get_label(aut_->label_of(t)));

        // Sorted per label name, which is fine, and deterministic.
        // Start with special/epsilon.  Show it as \e.
        os_ <<
          "cat >" << name << " <<\\EOFSM\n"
          "\\e\t0\n";
        size_t num = 0;
        for (const auto& l: labels)
          if (!ls.is_one(l))
            {
              ls.print(l, os_, format::raw);
              os_ << '\t' << ++num << '\n';
            }
        os_ <<
          "EOFSM\n"
          "\n";
      }

      template <typename>
      void
      output_symbols_impl_(std::false_type)
      {
        output_symbols_(isymbols_,
                        ls_,
                        [](label_t l) { return l; });
      }

      template <typename>
      void
      output_symbols_impl_(std::true_type)
      {
        output_symbols_(isymbols_,
                        ls_.template set<0>(),
                        [](const label_t& l) { return std::get<0>(l); });
        output_symbols_(osymbols_,
                        ls_.template set<1>(),
                        [](const label_t& l) { return std::get<1>(l); });
      }

      void
      output_symbols_()
      {
        output_symbols_impl_<automaton_t>(is_transducer);
      }

      using is_transducer_t =
        std::integral_constant<bool,
                               2 <= rank<labelset_t_of<automaton_t>>::value>;
      const is_transducer_t is_transducer = {};

      const char* isymbols_ =
        is_transducer ? "$medir/isymbols.txt" : "$medir/symbols.txt";
      const char* osymbols_ =
        is_transducer ? "$medir/osymbols.txt" : "$medir/symbols.txt";
    };
  }


  template <typename Aut>
  std::ostream&
  efsm(const Aut& aut, std::ostream& out)
  {
    detail::efsmer<Aut> efsm{aut, out};
    efsm();
    return out;
  }
}