enum_type.hpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <https://www.gnu.org/licenses/old-licenses/gpl-2.0>.
 */

 
#ifndef ENUM_TYPE_HPP
#define ENUM_TYPE_HPP
 
#include "base_bitset_type.hpp"

template <typename enum_type>
constexpr std::underlying_type_t<enum_type> to_underlying(enum_type e) { return static_cast<std::underlying_type_t<enum_type>>(e); }

template <class T> constexpr bool is_scoped_enum_v = std::conjunction_v<std::is_enum<T>, std::negation<std::is_convertible<T, int>>>;

template <typename enum_type>
struct is_enum_incrementable {
  static constexpr bool value = false;
};
 
template <typename enum_type>
constexpr bool is_enum_incrementable_v = is_enum_incrementable<enum_type>::value;

template <typename enum_type, std::enable_if_t<is_enum_incrementable_v<enum_type>, bool> = true>
inline constexpr enum_type &operator ++(enum_type &e)
{
  e = static_cast<enum_type>(to_underlying(e) + 1);
  return e;
}

template <typename enum_type, std::enable_if_t<is_enum_incrementable_v<enum_type>, bool> = true>
inline constexpr enum_type operator ++(enum_type &e, int)
{
  enum_type e_org = e;
  ++e;
  return e_org;
}

template <typename enum_type, std::enable_if_t<is_enum_incrementable_v<enum_type>, bool> = true>
inline constexpr enum_type &operator --(enum_type &e)
{
  e = static_cast<enum_type>(to_underlying(e) - 1);
  return e;
}

template <typename enum_type, std::enable_if_t<is_enum_incrementable_v<enum_type>, bool> = true>
inline constexpr enum_type operator --(enum_type &e, int)
{
  enum_type e_org = e;
  --e;
  return e_org;
}

#define DECLARE_INCREMENT_DECREMENT_OPERATORS(enum_type) \
  template <> struct is_enum_incrementable<enum_type> { \
    static const bool value = true; \
  };

template <typename enum_type>
struct is_enum_sequential {
  static constexpr bool value = false;
};
 
template <typename enum_type>
constexpr bool is_enum_sequential_v = is_enum_sequential<enum_type>::value;

template <typename enum_type, std::enable_if_t<is_enum_sequential_v<enum_type>, bool> = true>
inline constexpr enum_type operator+(enum_type e, int offset)
{
  return static_cast<enum_type>(to_underlying(e) + offset);
}
 
template <typename enum_type, std::enable_if_t<is_enum_sequential_v<enum_type>, bool> = true>
inline constexpr enum_type &operator+=(enum_type &e, int offset)
{
  e = e + offset;
  return e;
}

template <typename enum_type, std::enable_if_t<is_enum_sequential_v<enum_type>, bool> = true>
inline constexpr enum_type operator-(enum_type e, int offset)
{
  return static_cast<enum_type>(to_underlying(e) - offset);
}
 
template <typename enum_type, std::enable_if_t<is_enum_sequential_v<enum_type>, bool> = true>
inline constexpr enum_type &operator-=(enum_type &e, int offset)
{
  e = e - offset;
  return e;
}

template <typename enum_type, std::enable_if_t<is_enum_sequential_v<enum_type>, bool> = true>
inline constexpr auto operator-(enum_type a, enum_type b)
{
  return to_underlying(a) - to_underlying(b);
}

#define DECLARE_ENUM_AS_SEQUENTIAL(enum_type) \
  template <> struct is_enum_sequential<enum_type> { \
    static const bool value = true; \
  };

#define DECLARE_ENUM_AS_BIT_SET(enum_type) \
  inline constexpr enum_type operator | (enum_type m1, enum_type m2) { return static_cast<enum_type>(to_underlying(m1) | to_underlying(m2)); } \
  inline constexpr enum_type operator & (enum_type m1, enum_type m2) { return static_cast<enum_type>(to_underlying(m1) & to_underlying(m2)); } \
  inline constexpr enum_type operator ^ (enum_type m1, enum_type m2) { return static_cast<enum_type>(to_underlying(m1) ^ to_underlying(m2)); } \
  inline constexpr enum_type& operator |= (enum_type& m1, enum_type m2) { m1 = m1 | m2; return m1; } \
  inline constexpr enum_type& operator &= (enum_type& m1, enum_type m2) { m1 = m1 & m2; return m1; } \
  inline constexpr enum_type& operator ^= (enum_type& m1, enum_type m2) { m1 = m1 ^ m2; return m1; } \
  inline constexpr enum_type operator ~(enum_type m) { return static_cast<enum_type>(~to_underlying(m)); }

#define DECLARE_ENUM_AS_ADDABLE(EnumType) \
  template <typename OtherEnumType, typename = typename std::enable_if<std::is_enum_v<OtherEnumType>, OtherEnumType>::type> \
  constexpr OtherEnumType operator +(OtherEnumType m1, EnumType m2) { \
    return static_cast<OtherEnumType>(to_underlying(m1) + to_underlying(m2)); \
  } \
  template <typename OtherEnumType, typename = typename std::enable_if<std::is_enum_v<OtherEnumType>, OtherEnumType>::type> \
  constexpr OtherEnumType operator -(OtherEnumType m1, EnumType m2) { \
    return static_cast<OtherEnumType>(to_underlying(m1) - to_underlying(m2)); \
  }

template <typename T, class = typename std::enable_if_t<std::is_enum_v<T>>>
[[debug_inline]] inline constexpr bool HasFlag(const T x, const T y)
{
  return (x & y) == y;
}

template <typename T, class = typename std::enable_if_t<std::is_enum_v<T>>>
[[debug_inline]] inline constexpr void ToggleFlag(T &x, const T y)
{
  if (HasFlag(x, y)) {
    x &= ~y;
  } else {
    x |= y;
  }
}

template <typename Tenum>
class EnumRange {
private:
  Tenum first; 
  Tenum last; 
public:
  constexpr EnumRange(Tenum first, Tenum last) : first(first), last(last) {}

  constexpr EnumRange(Tenum last) : EnumRange({}, last) {}

  class Iterator {
  public:
    using value_type = Tenum; 
    using difference_type = value_type &; 
    using iterator_category = std::forward_iterator_tag; 
    using pointer = void; 
    using reference = void; 

    explicit Iterator(Tenum v) : value(v) {}

    constexpr Tenum operator*() const
    {
      return static_cast<Tenum>(value);
    }

    constexpr Iterator &operator++()
    {
      value = static_cast<Tenum>(to_underlying(value) + 1);
      return *this;
    }

    constexpr auto operator<=>(const Iterator &) const = default;
 
  private:
    Tenum value; 
  };

  constexpr Iterator begin() const { return Iterator(first); }

  constexpr Iterator end() const { return Iterator(last); }
};

template <typename Tstorage, typename Tenum, Tenum Tend_value>
struct EnumBitSetMask {
  static constexpr Tstorage value = std::numeric_limits<Tstorage>::max() >> (std::numeric_limits<Tstorage>::digits - to_underlying(Tend_value));
};

template <typename Tenum, typename Tstorage, Tenum Tend_value = Tenum{std::numeric_limits<Tstorage>::digits}>
class EnumBitSet : public BaseBitSet<EnumBitSet<Tenum, Tstorage, Tend_value>, Tenum, Tstorage, EnumBitSetMask<Tstorage, Tenum, Tend_value>::value> {
  using BaseClass = BaseBitSet<EnumBitSet<Tenum, Tstorage, Tend_value>, Tenum, Tstorage, EnumBitSetMask<Tstorage, Tenum, Tend_value>::value>;
public:
  using EnumType = BaseClass::ValueType;
 
  constexpr EnumBitSet() : BaseClass() {}

  constexpr EnumBitSet(Tenum value) : BaseClass()
  {
    /* MSVC 19.44 and older does not consider cast of dynamic type (e.g. BaseBitSet) to EnumBitSet as constant,
     * when the EnumBitSet is constructed inside an initializer list like we do for many lookup tables.
     * By setting the return type to BaseClass the cast becomes redundant and compilation does not fail. */
    this->template Set<BaseClass>(value);
  }
 
  explicit constexpr EnumBitSet(Tstorage data) : BaseClass(data) {}

  constexpr EnumBitSet(std::initializer_list<const Tenum> values) : BaseClass()
  {
    for (const Tenum &value : values) {
      /* MSVC 19.44 and older does not consider cast of dynamic type (e.g. BaseBitSet) to EnumBitSet as constant,
       * when the EnumBitSet is constructed inside an initializer list like we do for many lookup tables.
       * By setting the return type to BaseClass the cast becomes redundant and compilation does not fail. */
      this->template Set<BaseClass>(value);
    }
  }
 
  constexpr auto operator <=>(const EnumBitSet &) const noexcept = default;
 
  static constexpr size_t DecayValueType(const BaseClass::ValueType &value) { return to_underlying(value); }
};

template <typename Container, typename Index>
class EnumClassIndexContainer : public Container {
public:
  Container::reference at(size_t pos) = delete;
  Container::reference at(const Index &pos) { return this->Container::at(to_underlying(pos)); }
 
  Container::const_reference at(size_t pos) const = delete;
  Container::const_reference at(const Index &pos) const { return this->Container::at(to_underlying(pos)); }
 
  Container::reference operator[](size_t pos) = delete;
  Container::reference operator[](const Index &pos) { return this->Container::operator[](to_underlying(pos)); }
 
  Container::const_reference operator[](size_t pos) const = delete;
  Container::const_reference operator[](const Index &pos) const { return this->Container::operator[](to_underlying(pos)); }
};

template <typename T, typename Index, Index N>
using EnumIndexArray = EnumClassIndexContainer<std::array<T, to_underlying(N)>, Index>;
 
#endif /* ENUM_TYPE_HPP */