traits.hh

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#pragma once

#include <memory>

#include <vcsn/labelset/fwd.hh> // tupleset.
#include <vcsn/misc/type_traits.hh>

namespace vcsn
{

  template <typename T>
  using base_t = std::remove_cv_t<std::remove_reference_t<T>>;

  /*------------------.
  | Computing types.  |
  `------------------*/


#define DEFINE(Type)                                                    \
  namespace detail                                                      \
  {                                                                     \
    template <typename ValueSet, typename = void_t<>>                   \
    struct Type ## _of_impl;                                            \
                                                                        \
    template <typename ValueSet>                                        \
    struct Type ## _of_impl<ValueSet,                                   \
                            void_t<typename ValueSet::Type>>            \
    {                                                                   \
      using type = typename ValueSet::Type;                             \
    };                                                                  \
                                                                        \
    template <typename ValueSet>                                        \
    struct Type ## _of_impl<std::shared_ptr<ValueSet>,                  \
                            void_t<typename ValueSet::Type>>            \
    {                                                                   \
      using type = typename ValueSet::Type;                             \
    };                                                                  \
                                                                        \
    template <typename ValueSet>                                        \
    struct Type ## _of_impl<ValueSet*,                                  \
                            void_t<typename ValueSet::Type>>            \
    {                                                                   \
      using type = typename ValueSet::Type;                             \
    };                                                                  \
  }                                                                     \
                                                                        \
  template <typename ValueSet>                                          \
  using Type ## _of                                                     \
    = typename detail::Type ## _of_impl<base_t<ValueSet>>::type

  DEFINE(context_t);
  DEFINE(label_t);
  DEFINE(labelset_t);
  DEFINE(state_t);
  DEFINE(transition_t);
  DEFINE(weight_t);
  DEFINE(weightset_t);

#undef DEFINE

  template <typename Aut, typename Context = context_t_of<Aut>>
  using fresh_automaton_t_of
    = typename Aut::element_type::template fresh_automaton_t<Context>;

  template <typename ValueSet>
  using letter_t_of
    = typename labelset_t_of<base_t<ValueSet>>::letter_t;

  template <typename ValueSet>
  using word_t_of
    = typename labelset_t_of<base_t<ValueSet>>::word_t;

  template <typename LS1, typename LS2>
  struct are_labelsets_composable : std::false_type
  {};

  template <typename... LS1, typename... LS2>
  struct are_labelsets_composable<tupleset<LS1...>, tupleset<LS2...>>
    : std::is_same<typename tupleset<LS1...>::template valueset_t<sizeof...(LS1) - 1>,
                   typename tupleset<LS2...>::template valueset_t<0>>
  {};

  template <typename Ctx1, typename Ctx2 = Ctx1>
  struct are_composable
    : are_labelsets_composable<labelset_t_of<Ctx1>, labelset_t_of<Ctx2>>
  {};

  /*----------------.
  | is_multitape.   |
  `----------------*/

  template <typename ValueSet>
  struct is_multitape
    : std::false_type
  {};


  /*-------------------.
  | Number of tapes.   |
  `-------------------*/

  template <typename LabelSet>
  struct number_of_tapes
  {
    constexpr static auto value = 0;
  };
}