z.hh

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#ifndef VCSN_WEIGHTSET_Z_HH
# define VCSN_WEIGHTSET_Z_HH

# include <ostream>
# include <string>

# include <vcsn/core/join.hh>
# include <vcsn/misc/raise.hh>
# include <vcsn/misc/star_status.hh>
# include <vcsn/misc/stream.hh>
# include <vcsn/weightset/b.hh>
# include <vcsn/weightset/fwd.hh>

namespace vcsn
{
  namespace detail
  {
  class z_impl
  {
  public:
    using self_type = z;

    static std::string sname()
    {
      return "z";
    }

    std::string vname(bool = true) const
    {
      return sname();
    }

    static z make(std::istream& is)
    {
      eat(is, sname());
      return {};
    }

    using value_t = int;

    static value_t
    zero()
    {
      return 0;
    }

    static value_t
    one()
    {
      return 1;
    }

    static value_t
    add(const value_t l, const value_t r)
    {
      return l + r;
    }

    static value_t
    sub(const value_t l, const value_t r)
    {
      return l - r;
    }

    static value_t
    mul(const value_t l, const value_t r)
    {
      return l * r;
    }

    static value_t
    rdiv(const value_t l, const value_t r)
    {
      require(!is_zero(r), "div: division by zero");
      require(!(l % r),
              "z: div: invalid division: ", l, '/', r);
      return l / r;
    }

    static value_t
    ldiv(const value_t l, const value_t r)
    {
      return rdiv(r, l);
    }

    value_t
    star(const value_t v) const
    {
      if (is_zero(v))
        return one();
      else
        raise("z: star: invalid value: ", to_string(*this, v));
    }

    constexpr static bool is_special(value_t)
    {
      return false;
    }

    static bool
    is_zero(const value_t v)
    {
      return v == 0;
    }

    static bool
    is_one(const value_t v)
    {
      return v == 1;
    }

    static bool
    equals(const value_t l, const value_t r)
    {
      return l == r;
    }

    static bool less_than(value_t lhs, value_t rhs)
    {
      return lhs < rhs;
    }

    static constexpr bool is_commutative() { return true; }
    static constexpr bool is_idempotent() { return false; }

    static constexpr bool show_one() { return false; }
    static constexpr star_status_t star_status() { return star_status_t::NON_STARRABLE; }

    static value_t
    transpose(const value_t v)
    {
      return v;
    }

    static size_t hash(value_t v)
    {
      return hash_value(v);
    }

    static value_t
    conv(self_type, value_t v)
    {
      return v;
    }

    static value_t
    conv(b, b::value_t v)
    {
      // Conversion from bool to int.
      return v;
    }

    static value_t
    conv(std::istream& stream)
    {
      int res;
      if (stream >> res)
        return res;
      else
        vcsn::fail_reading(stream, sname() + ": invalid value");
     }

    static std::ostream&
    print(const value_t v, std::ostream& o,
          const std::string& = "text")
    {
      return o << v;
    }

    std::ostream&
    print_set(std::ostream& o, symbol format = symbol{"text"}) const
    {
      if (format == "latex")
        o << "\\mathbb{Z}";
      else if (format == "text")
        o << vname();
      else
        raise("invalid format: ", format);
      return o;
    }
  };

    /*-------.
    | join.  |
    `-------*/

    VCSN_JOIN_SIMPLE(b, z);
    VCSN_JOIN_SIMPLE(z, z);
  }

}

#endif // !VCSN_WEIGHTSET_Z_HH