tuple-automaton.hh

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#pragma once

#include <deque>
#include <iostream>
#include <map>
#include <utility>

#include <vcsn/core/automaton-decorator.hh>
#include <vcsn/ctx/context.hh>
#include <vcsn/ctx/traits.hh>
#include <vcsn/misc/map.hh> // has
#include <vcsn/misc/tuple.hh>

namespace vcsn
{
  namespace detail
  {
    /*-------------------------------------.
    | tuple_automaton_impl<Aut, Auts...>.  |
    `-------------------------------------*/

    template <typename Aut, typename... Auts>
    class tuple_automaton_impl
      : public automaton_decorator<Aut>
    {
      using automaton_t = Aut;
      using super_t = automaton_decorator<automaton_t>;

    public:
      static symbol sname()
      {
        static symbol res("tuple_automaton" + sname_());
        return res;
      }

      std::ostream& print_set(std::ostream& o, format fmt = {}) const
      {
        o << "tuple_automaton";
        print_set_(o, fmt);
        return o;
      }

      using context_t = context_t_of<Aut>;
      using labelset_t = labelset_t_of<context_t>;
      using weightset_t = weightset_t_of<context_t>;

      using label_t = typename labelset_t::value_t;
      using weight_t = typename weightset_t::value_t;

    public:
      using automata_t = std::tuple<Auts...>;

      template <size_t I>
      using input_automaton_t = base_t<tuple_element_t<I, automata_t>>;

      using super_t::aut_;

      tuple_automaton_impl(const automaton_t& aut, const Auts&... auts)
        : super_t(aut)
        , auts_(auts...)
      {
        pmap_[pre_()] = aut_->pre();
        pmap_[post_()] = aut_->post();
      }

      bool state_has_name(typename super_t::state_t s) const
      {
        return has(origins(), s);
      }

      std::ostream&
      print_state_name(typename super_t::state_t s, std::ostream& o,
                       format fmt = {}, bool delimit = false)
                      const
      {
        if (delimit)
          o << '(';
        print_state_name_(s, o, fmt, indices);
        if (delimit)
          o << ')';
        return o;
      }

      using state_t = state_t_of<automaton_t>;
      using state_name_t = std::tuple<state_t_of<Auts>...>;

      using origins_t = std::map<state_t, state_name_t>;

      const origins_t& origins() const
      {
        origins_.clear();
        for (const auto& p: pmap_)
          origins_.emplace(p.second, p.first);
        return origins_;
      }

      // FIXME: protected:
      template <std::size_t... I>
      using seq = vcsn::detail::index_sequence<I...>;

      using indices_t = vcsn::detail::make_index_sequence<sizeof...(Auts)>;
      static constexpr indices_t indices{};

      static std::string sname_()
      {
        std::string res = "<" + Aut::element_type::sname() + ", ";
        const char* sep = "";
        using swallow = int[];
        (void) swallow
          {
            (res += sep + Auts::element_type::sname(), sep = ", ", 0)...
          };
        res += ">";
        return res;
      }

      std::ostream& print_set_(std::ostream& o, format fmt) const
      {
        return print_set_(o, fmt, indices);
      }

      template <size_t... I>
      std::ostream& print_set_(std::ostream& o, format fmt,
                               seq<I...>) const
      {
        o << '<';
        aut_->print_set(o, fmt);
        o << ", ";
        const char* sep = "";
        using swallow = int[];
        (void) swallow
          {
            (o << sep,
             std::get<I>(auts_)->print_set(o, fmt),
             sep = ", ",
             0)...
          };
        return o << '>';
      }

      state_name_t pre_() const
      {
        return pre_(indices);
      }

      template <size_t... I>
      state_name_t pre_(seq<I...>) const
      {
        // clang 3.4 on top of libstdc++ wants this ctor to be
        // explicitly called.
        return state_name_t{(std::get<I>(auts_)->pre())...};
      }

      state_name_t post_() const
      {
        return post_(indices);
      }

      template <size_t... I>
      state_name_t post_(seq<I...>) const
      {
        // clang 3.4 on top of libstdc++ wants this ctor to be
        // explicitly called.
        return state_name_t{(std::get<I>(auts_)->post())...};
      }

      state_t state(const state_name_t& state)
      {
        auto lb = pmap_.lower_bound(state);
        if (lb == pmap_.end() || pmap_.key_comp()(state, lb->first))
          {
            state_t s = aut_->new_state();
            lb = pmap_.emplace_hint(lb, state, s);
            todo_.emplace_back(state, s);
          }
        return lb->second;
      }

      state_t state(state_t_of<Auts>... ss)
      {
        return state(std::make_tuple(ss...));
      }

      template <size_t... I>
      std::ostream&
      print_state_name_(typename super_t::state_t s, std::ostream& o,
                        format fmt,
                        seq<I...>) const
      {
        const auto& origs = origins();
        auto i = origs.find(s);
        if (i == std::end(origs))
          this->print_state(s, o);
        else
          {
            const char* sep = "";
            using swallow = int[];
            (void) swallow
              {
                (o << sep,
                 std::get<I>(auts_)->print_state_name(std::get<I>(i->second),
                                                      o, fmt, true),
                 sep = ", ",
                 0)...
               };
          }
        return o;
      }

      automata_t auts_;

      using map = std::map<state_name_t, state_t>;
      map pmap_;

      std::deque<std::pair<state_name_t, state_t>> todo_;

      mutable origins_t origins_;
    };
  }

  template <typename... Auts>
  using tuple_automaton
    = std::shared_ptr<detail::tuple_automaton_impl<Auts...>>;

  template <typename... Auts>
  inline
  auto
  make_tuple_automaton(const Auts&... auts)
    -> tuple_automaton<Auts...>
  {
    using res_t = tuple_automaton<Auts...>;
    return make_shared_ptr<res_t>(auts...);
  }
}