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// Copyright 2020 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef INCLUDE_CPPGC_TYPE_TRAITS_H_
#define INCLUDE_CPPGC_TYPE_TRAITS_H_
// This file should stay with minimal dependencies to allow embedder to check
// against Oilpan types without including any other parts.
#include <cstddef>
#include <type_traits>
namespace cppgc {
class Visitor;
namespace internal {
template <typename T, typename WeaknessTag, typename WriteBarrierPolicy,
typename CheckingPolicy>
class BasicMember;
struct DijkstraWriteBarrierPolicy;
struct NoWriteBarrierPolicy;
class StrongMemberTag;
class UntracedMemberTag;
class WeakMemberTag;
// Not supposed to be specialized by the user.
template <typename T>
struct IsWeak : std::false_type {};
// IsTraceMethodConst is used to verify that all Trace methods are marked as
// const. It is equivalent to IsTraceable but for a non-const object.
template <typename T, typename = void>
struct IsTraceMethodConst : std::false_type {};
template <typename T>
struct IsTraceMethodConst<T, std::void_t<decltype(std::declval<const T>().Trace(
std::declval<Visitor*>()))>> : std::true_type {
};
template <typename T, typename = void>
struct IsTraceable : std::false_type {
// static_assert(sizeof(T), "T must be fully defined");
};
template <typename T>
struct IsTraceable<
T, std::void_t<decltype(std::declval<T>().Trace(std::declval<Visitor*>()))>>
: std::true_type {
// All Trace methods should be marked as const. If an object of type
// 'T' is traceable then any object of type 'const T' should also
// be traceable.
static_assert(IsTraceMethodConst<T>(),
"Trace methods should be marked as const.");
};
template <typename T>
constexpr bool IsTraceableV = IsTraceable<T>::value;
template <typename T, typename = void>
struct HasGarbageCollectedMixinTypeMarker : std::false_type {
static_assert(sizeof(T), "T must be fully defined");
};
template <typename T>
struct HasGarbageCollectedMixinTypeMarker<
T, std::void_t<
typename std::remove_const_t<T>::IsGarbageCollectedMixinTypeMarker>>
: std::true_type {
static_assert(sizeof(T), "T must be fully defined");
};
template <typename T, typename = void>
struct HasGarbageCollectedTypeMarker : std::false_type {
static_assert(sizeof(T), "T must be fully defined");
};
template <typename T>
struct HasGarbageCollectedTypeMarker<
T,
std::void_t<typename std::remove_const_t<T>::IsGarbageCollectedTypeMarker>>
: std::true_type {
static_assert(sizeof(T), "T must be fully defined");
};
template <typename T, bool = HasGarbageCollectedTypeMarker<T>::value,
bool = HasGarbageCollectedMixinTypeMarker<T>::value>
struct IsGarbageCollectedMixinType : std::false_type {
static_assert(sizeof(T), "T must be fully defined");
};
template <typename T>
struct IsGarbageCollectedMixinType<T, false, true> : std::true_type {
static_assert(sizeof(T), "T must be fully defined");
};
template <typename T, bool = HasGarbageCollectedTypeMarker<T>::value>
struct IsGarbageCollectedType : std::false_type {
static_assert(sizeof(T), "T must be fully defined");
};
template <typename T>
struct IsGarbageCollectedType<T, true> : std::true_type {
static_assert(sizeof(T), "T must be fully defined");
};
template <typename T>
struct IsGarbageCollectedOrMixinType
: std::integral_constant<bool, IsGarbageCollectedType<T>::value ||
IsGarbageCollectedMixinType<T>::value> {
static_assert(sizeof(T), "T must be fully defined");
};
template <typename T, bool = (HasGarbageCollectedTypeMarker<T>::value &&
HasGarbageCollectedMixinTypeMarker<T>::value)>
struct IsGarbageCollectedWithMixinType : std::false_type {
static_assert(sizeof(T), "T must be fully defined");
};
template <typename T>
struct IsGarbageCollectedWithMixinType<T, true> : std::true_type {
static_assert(sizeof(T), "T must be fully defined");
};
template <typename BasicMemberCandidate, typename WeaknessTag,
typename WriteBarrierPolicy>
struct IsSubclassOfBasicMemberTemplate {
private:
template <typename T, typename CheckingPolicy>
static std::true_type SubclassCheck(
BasicMember<T, WeaknessTag, WriteBarrierPolicy, CheckingPolicy>*);
static std::false_type SubclassCheck(...);
public:
static constexpr bool value =
decltype(SubclassCheck(std::declval<BasicMemberCandidate*>()))::value;
};
template <typename T,
bool = IsSubclassOfBasicMemberTemplate<
T, StrongMemberTag, DijkstraWriteBarrierPolicy>::value>
struct IsMemberType : std::false_type {};
template <typename T>
struct IsMemberType<T, true> : std::true_type {};
template <typename T, bool = IsSubclassOfBasicMemberTemplate<
T, WeakMemberTag, DijkstraWriteBarrierPolicy>::value>
struct IsWeakMemberType : std::false_type {};
template <typename T>
struct IsWeakMemberType<T, true> : std::true_type {};
template <typename T, bool = IsSubclassOfBasicMemberTemplate<
T, UntracedMemberTag, NoWriteBarrierPolicy>::value>
struct IsUntracedMemberType : std::false_type {};
template <typename T>
struct IsUntracedMemberType<T, true> : std::true_type {};
template <typename T>
struct IsComplete {
private:
template <typename U, size_t = sizeof(U)>
static std::true_type IsSizeOfKnown(U*);
static std::false_type IsSizeOfKnown(...);
public:
static constexpr bool value =
decltype(IsSizeOfKnown(std::declval<T*>()))::value;
};
template <typename T, typename U>
constexpr bool IsDecayedSameV =
std::is_same_v<std::decay_t<T>, std::decay_t<U>>;
template <typename B, typename D>
constexpr bool IsStrictlyBaseOfV =
std::is_base_of_v<std::decay_t<B>, std::decay_t<D>> &&
!IsDecayedSameV<B, D>;
} // namespace internal
/**
* Value is true for types that inherit from `GarbageCollectedMixin` but not
* `GarbageCollected<T>` (i.e., they are free mixins), and false otherwise.
*/
template <typename T>
constexpr bool IsGarbageCollectedMixinTypeV =
internal::IsGarbageCollectedMixinType<T>::value;
/**
* Value is true for types that inherit from `GarbageCollected<T>`, and false
* otherwise.
*/
template <typename T>
constexpr bool IsGarbageCollectedTypeV =
internal::IsGarbageCollectedType<T>::value;
/**
* Value is true for types that inherit from either `GarbageCollected<T>` or
* `GarbageCollectedMixin`, and false otherwise.
*/
template <typename T>
constexpr bool IsGarbageCollectedOrMixinTypeV =
internal::IsGarbageCollectedOrMixinType<T>::value;
/**
* Value is true for types that inherit from `GarbageCollected<T>` and
* `GarbageCollectedMixin`, and false otherwise.
*/
template <typename T>
constexpr bool IsGarbageCollectedWithMixinTypeV =
internal::IsGarbageCollectedWithMixinType<T>::value;
/**
* Value is true for types of type `Member<T>`, and false otherwise.
*/
template <typename T>
constexpr bool IsMemberTypeV = internal::IsMemberType<T>::value;
/**
* Value is true for types of type `UntracedMember<T>`, and false otherwise.
*/
template <typename T>
constexpr bool IsUntracedMemberTypeV = internal::IsUntracedMemberType<T>::value;
/**
* Value is true for types of type `WeakMember<T>`, and false otherwise.
*/
template <typename T>
constexpr bool IsWeakMemberTypeV = internal::IsWeakMemberType<T>::value;
/**
* Value is true for types that are considered weak references, and false
* otherwise.
*/
template <typename T>
constexpr bool IsWeakV = internal::IsWeak<T>::value;
/**
* Value is true for types that are complete, and false otherwise.
*/
template <typename T>
constexpr bool IsCompleteV = internal::IsComplete<T>::value;
} // namespace cppgc
#endif // INCLUDE_CPPGC_TYPE_TRAITS_H_
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