YogaEnums.h

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/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */
 
#pragma once
 
#include <bit>
#include <iterator>
#include <type_traits>
 
namespace facebook::yoga {
 
template <typename EnumT>
concept Enumeration = std::is_enum_v<EnumT>;
 
template <Enumeration EnumT>
constexpr int32_t ordinalCount();
 
template <typename EnumT>
concept HasOrdinality = (ordinalCount<EnumT>() > 0);
 
template <HasOrdinality EnumT>
constexpr int32_t bitCount() {
  return std::bit_width(
      static_cast<std::underlying_type_t<EnumT>>(ordinalCount<EnumT>() - 1));
}
 
constexpr auto to_underlying(Enumeration auto e) noexcept {
  return static_cast<std::underlying_type_t<decltype(e)>>(e);
}
 
template <HasOrdinality EnumT>
auto ordinals() {
  struct Iterator {
    EnumT e{};
 
    EnumT operator*() const {
      return e;
    }
 
    Iterator& operator++() {
      e = static_cast<EnumT>(to_underlying(e) + 1);
      return *this;
    }
 
    bool operator==(const Iterator& other) const = default;
  };
 
  struct Range {
    Iterator begin() const {
      return Iterator{};
    }
    Iterator end() const {
      return Iterator{static_cast<EnumT>(ordinalCount<EnumT>())};
    }
  };
 
  return Range{};
}
 
} // namespace facebook::yoga