absl/types/internal/conformance_profile.h

// Copyright 2019 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// -----------------------------------------------------------------------------
// conformance_profiles.h
// -----------------------------------------------------------------------------
//
// This file contains templates for representing "Regularity Profiles" and
// concisely-named versions of commonly used Regularity Profiles.
//
// A Regularity Profile is a compile-time description of the types of operations
// that a given type supports, along with properties of those operations when
// they do exist. For instance, a Regularity Profile may describe a type that
// has a move-constructor that is noexcept and a copy constructor that is not
// noexcept. This description can then be examined and passed around to other
// templates for the purposes of asserting expectations on user-defined types
// via a series trait checks, or for determining what kinds of run-time tests
// are able to be performed.
//
// Regularity Profiles are also used when creating "archetypes," which are
// minimum-conforming types that meet all of the requirements of a given
// Regularity Profile. For more information regarding archetypes, see
// "conformance_archetypes.h".

#ifndef ABSL_TYPES_INTERNAL_CONFORMANCE_PROFILE_H_
#define ABSL_TYPES_INTERNAL_CONFORMANCE_PROFILE_H_

#include <type_traits>
#include <utility>

#include "absl/meta/type_traits.h"

// TODO(calabrese) Add support for extending profiles.

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace types_internal {

template <class T, class /*Enabler*/ = void>
struct PropertiesOfImpl {};

template <class T>
struct PropertiesOfImpl<T, absl::void_t<typename T::properties>> {
  using type = typename T::properties;
};

template <class T>
struct PropertiesOfImpl<T, absl::void_t<typename T::profile_alias_of>> {
  using type = typename PropertiesOfImpl<typename T::profile_alias_of>::type;
};

template <class T>
struct PropertiesOf : PropertiesOfImpl<T> {};

template <class T>
using PropertiesOfT = typename PropertiesOf<T>::type;

// NOTE: These enums use this naming convention to be consistent with the
// standard trait names, which is useful since it allows us to match up each
// enum name with a corresponding trait name in macro definitions.

enum class function_kind { maybe, yes, nothrow, trivial };

#define ABSL_INTERNAL_SPECIAL_MEMBER_FUNCTION_ENUM(name) \
  enum class name { maybe, yes, nothrow, trivial }

ABSL_INTERNAL_SPECIAL_MEMBER_FUNCTION_ENUM(default_constructible);
ABSL_INTERNAL_SPECIAL_MEMBER_FUNCTION_ENUM(move_constructible);
ABSL_INTERNAL_SPECIAL_MEMBER_FUNCTION_ENUM(copy_constructible);
ABSL_INTERNAL_SPECIAL_MEMBER_FUNCTION_ENUM(move_assignable);
ABSL_INTERNAL_SPECIAL_MEMBER_FUNCTION_ENUM(copy_assignable);
ABSL_INTERNAL_SPECIAL_MEMBER_FUNCTION_ENUM(destructible);

#undef ABSL_INTERNAL_SPECIAL_MEMBER_FUNCTION_ENUM

#define ABSL_INTERNAL_INTRINSIC_FUNCTION_ENUM(name) \
  enum class name { maybe, yes, nothrow }

ABSL_INTERNAL_INTRINSIC_FUNCTION_ENUM(equality_comparable);
ABSL_INTERNAL_INTRINSIC_FUNCTION_ENUM(inequality_comparable);
ABSL_INTERNAL_INTRINSIC_FUNCTION_ENUM(less_than_comparable);
ABSL_INTERNAL_INTRINSIC_FUNCTION_ENUM(less_equal_comparable);
ABSL_INTERNAL_INTRINSIC_FUNCTION_ENUM(greater_equal_comparable);
ABSL_INTERNAL_INTRINSIC_FUNCTION_ENUM(greater_than_comparable);

ABSL_INTERNAL_INTRINSIC_FUNCTION_ENUM(swappable);

#undef ABSL_INTERNAL_INTRINSIC_FUNCTION_ENUM

enum class hashable { maybe, yes };

constexpr const char* PropertyName(hashable v) {
  return "support for std::hash";
}

template <
    default_constructible DefaultConstructibleValue =
        default_constructible::maybe,
    move_constructible MoveConstructibleValue = move_constructible::maybe,
    copy_constructible CopyConstructibleValue = copy_constructible::maybe,
    move_assignable MoveAssignableValue = move_assignable::maybe,
    copy_assignable CopyAssignableValue = copy_assignable::maybe,
    destructible DestructibleValue = destructible::maybe,
    equality_comparable EqualityComparableValue = equality_comparable::maybe,
    inequality_comparable InequalityComparableValue =
        inequality_comparable::maybe,
    less_than_comparable LessThanComparableValue = less_than_comparable::maybe,
    less_equal_comparable LessEqualComparableValue =
        less_equal_comparable::maybe,
    greater_equal_comparable GreaterEqualComparableValue =
        greater_equal_comparable::maybe,
    greater_than_comparable GreaterThanComparableValue =
        greater_than_comparable::maybe,
    swappable SwappableValue = swappable::maybe,
    hashable HashableValue = hashable::maybe>
struct ConformanceProfile {
  using properties = ConformanceProfile;

  static constexpr default_constructible
      default_constructible_support =  // NOLINT
      DefaultConstructibleValue;

  static constexpr move_constructible move_constructible_support =  // NOLINT
      MoveConstructibleValue;

  static constexpr copy_constructible copy_constructible_support =  // NOLINT
      CopyConstructibleValue;

  static constexpr move_assignable move_assignable_support =  // NOLINT
      MoveAssignableValue;

  static constexpr copy_assignable copy_assignable_support =  // NOLINT
      CopyAssignableValue;

  static constexpr destructible destructible_support =  // NOLINT
      DestructibleValue;

  static constexpr equality_comparable equality_comparable_support =  // NOLINT
      EqualityComparableValue;

  static constexpr inequality_comparable
      inequality_comparable_support =  // NOLINT
      InequalityComparableValue;

  static constexpr less_than_comparable
      less_than_comparable_support =  // NOLINT
      LessThanComparableValue;

  static constexpr less_equal_comparable
      less_equal_comparable_support =  // NOLINT
      LessEqualComparableValue;

  static constexpr greater_equal_comparable
      greater_equal_comparable_support =  // NOLINT
      GreaterEqualComparableValue;

  static constexpr greater_than_comparable
      greater_than_comparable_support =  // NOLINT
      GreaterThanComparableValue;

  static constexpr swappable swappable_support = SwappableValue;  // NOLINT

  static constexpr hashable hashable_support = HashableValue;  // NOLINT

  static constexpr bool is_default_constructible =  // NOLINT
      DefaultConstructibleValue != default_constructible::maybe;

  static constexpr bool is_move_constructible =  // NOLINT
      MoveConstructibleValue != move_constructible::maybe;

  static constexpr bool is_copy_constructible =  // NOLINT
      CopyConstructibleValue != copy_constructible::maybe;

  static constexpr bool is_move_assignable =  // NOLINT
      MoveAssignableValue != move_assignable::maybe;

  static constexpr bool is_copy_assignable =  // NOLINT
      CopyAssignableValue != copy_assignable::maybe;

  static constexpr bool is_destructible =  // NOLINT
      DestructibleValue != destructible::maybe;

  static constexpr bool is_equality_comparable =  // NOLINT
      EqualityComparableValue != equality_comparable::maybe;

  static constexpr bool is_inequality_comparable =  // NOLINT
      InequalityComparableValue != inequality_comparable::maybe;

  static constexpr bool is_less_than_comparable =  // NOLINT
      LessThanComparableValue != less_than_comparable::maybe;

  static constexpr bool is_less_equal_comparable =  // NOLINT
      LessEqualComparableValue != less_equal_comparable::maybe;

  static constexpr bool is_greater_equal_comparable =  // NOLINT
      GreaterEqualComparableValue != greater_equal_comparable::maybe;

  static constexpr bool is_greater_than_comparable =  // NOLINT
      GreaterThanComparableValue != greater_than_comparable::maybe;

  static constexpr bool is_swappable =  // NOLINT
      SwappableValue != swappable::maybe;

  static constexpr bool is_hashable =  // NOLINT
      HashableValue != hashable::maybe;
};

#define ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF_IMPL(type, name)     \
  template <default_constructible DefaultConstructibleValue,                   \
            move_constructible MoveConstructibleValue,                         \
            copy_constructible CopyConstructibleValue,                         \
            move_assignable MoveAssignableValue,                               \
            copy_assignable CopyAssignableValue,                               \
            destructible DestructibleValue,                                    \
            equality_comparable EqualityComparableValue,                       \
            inequality_comparable InequalityComparableValue,                   \
            less_than_comparable LessThanComparableValue,                      \
            less_equal_comparable LessEqualComparableValue,                    \
            greater_equal_comparable GreaterEqualComparableValue,              \
            greater_than_comparable GreaterThanComparableValue,                \
            swappable SwappableValue, hashable HashableValue>                  \
  constexpr type ConformanceProfile<                                           \
      DefaultConstructibleValue, MoveConstructibleValue,                       \
      CopyConstructibleValue, MoveAssignableValue, CopyAssignableValue,        \
      DestructibleValue, EqualityComparableValue, InequalityComparableValue,   \
      LessThanComparableValue, LessEqualComparableValue,                       \
      GreaterEqualComparableValue, GreaterThanComparableValue, SwappableValue, \
      HashableValue>::name

#define ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF(type)           \
  ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF_IMPL(type,            \
                                                         type##_support); \
  ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF_IMPL(bool, is_##type)

ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF(default_constructible);
ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF(move_constructible);
ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF(copy_constructible);
ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF(move_assignable);
ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF(copy_assignable);
ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF(destructible);
ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF(equality_comparable);
ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF(inequality_comparable);
ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF(less_than_comparable);
ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF(less_equal_comparable);
ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF(greater_equal_comparable);
ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF(greater_than_comparable);
ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF(swappable);
ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF(hashable);

#undef ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF
#undef ABSL_INTERNAL_CONFORMANCE_TESTING_DATA_MEMBER_DEF_IMPL

// Converts an enum to its underlying integral value.
template <class Enum>
constexpr absl::underlying_type_t<Enum> UnderlyingValue(Enum value) {
  return static_cast<absl::underlying_type_t<Enum>>(value);
}

// Retrieve the enum with the greatest underlying value.
// Note: std::max is not constexpr in C++11, which is why this is necessary.
template <class H>
constexpr H MaxEnum(H head) {
  return head;
}

template <class H, class N, class... T>
constexpr H MaxEnum(H head, N next, T... tail) {
  return (UnderlyingValue)(next) < (UnderlyingValue)(head)
             ? (MaxEnum)(head, tail...)
             : (MaxEnum)(next, tail...);
}

template <class... Profs>
struct CombineProfilesImpl {
  static constexpr default_constructible
      default_constructible_support =  // NOLINT
      (MaxEnum)(PropertiesOfT<Profs>::default_constructible_support...);

  static constexpr move_constructible move_constructible_support =  // NOLINT
      (MaxEnum)(PropertiesOfT<Profs>::move_constructible_support...);

  static constexpr copy_constructible copy_constructible_support =  // NOLINT
      (MaxEnum)(PropertiesOfT<Profs>::copy_constructible_support...);

  static constexpr move_assignable move_assignable_support =  // NOLINT
      (MaxEnum)(PropertiesOfT<Profs>::move_assignable_support...);

  static constexpr copy_assignable copy_assignable_support =  // NOLINT
      (MaxEnum)(PropertiesOfT<Profs>::copy_assignable_support...);

  static constexpr destructible destructible_support =  // NOLINT
      (MaxEnum)(PropertiesOfT<Profs>::destructible_support...);

  static constexpr equality_comparable equality_comparable_support =  // NOLINT
      (MaxEnum)(PropertiesOfT<Profs>::equality_comparable_support...);

  static constexpr inequality_comparable
      inequality_comparable_support =  // NOLINT
      (MaxEnum)(PropertiesOfT<Profs>::inequality_comparable_support...);

  static constexpr less_than_comparable
      less_than_comparable_support =  // NOLINT
      (MaxEnum)(PropertiesOfT<Profs>::less_than_comparable_support...);

  static constexpr less_equal_comparable
      less_equal_comparable_support =  // NOLINT
      (MaxEnum)(PropertiesOfT<Profs>::less_equal_comparable_support...);

  static constexpr greater_equal_comparable
      greater_equal_comparable_support =  // NOLINT
      (MaxEnum)(PropertiesOfT<Profs>::greater_equal_comparable_support...);

  static constexpr greater_than_comparable
      greater_than_comparable_support =  // NOLINT
      (MaxEnum)(PropertiesOfT<Profs>::greater_than_comparable_support...);

  static constexpr swappable swappable_support =  // NOLINT
      (MaxEnum)(PropertiesOfT<Profs>::swappable_support...);

  static constexpr hashable hashable_support =  // NOLINT
      (MaxEnum)(PropertiesOfT<Profs>::hashable_support...);

  using properties = ConformanceProfile<
      default_constructible_support, move_constructible_support,
      copy_constructible_support, move_assignable_support,
      copy_assignable_support, destructible_support,
      equality_comparable_support, inequality_comparable_support,
      less_than_comparable_support, less_equal_comparable_support,
      greater_equal_comparable_support, greater_than_comparable_support,
      swappable_support, hashable_support>;
};

// NOTE: We use this as opposed to a direct alias of CombineProfilesImpl so that
// when named aliases of CombineProfiles are created (such as in
// conformance_aliases.h), we only pay for the combination algorithm on the
// profiles that are actually used.
template <class... Profs>
struct CombineProfiles {
  using profile_alias_of = CombineProfilesImpl<Profs...>;
};

template <>
struct CombineProfiles<> {
  using properties = ConformanceProfile<>;
};

template <class Profile, class Tag>
struct StrongProfileTypedef {
  using properties = PropertiesOfT<Profile>;
};

template <class T, class /*Enabler*/ = void>
struct IsProfileImpl : std::false_type {};

template <class T>
struct IsProfileImpl<T, absl::void_t<PropertiesOfT<T>>> : std::true_type {};

template <class T>
struct IsProfile : IsProfileImpl<T>::type {};

}  // namespace types_internal
ABSL_NAMESPACE_END
}  // namespace absl

#endif  // ABSL_TYPES_INTERNAL_CONFORMANCE_PROFILE_H_