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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_INTERNAL_POINTER_POLICIES_H_
#define INCLUDE_CPPGC_INTERNAL_POINTER_POLICIES_H_
#include <cstdint>
#include <type_traits>
#include "cppgc/internal/write-barrier.h"
#include "cppgc/source-location.h"
#include "v8config.h" // NOLINT(build/include_directory)
namespace cppgc {
namespace internal {
class PersistentRegion;
// Tags to distinguish between strong and weak member types.
class StrongMemberTag;
class WeakMemberTag;
class UntracedMemberTag;
struct DijkstraWriteBarrierPolicy {
static void InitializingBarrier(const void*, const void*) {
// Since in initializing writes the source object is always white, having no
// barrier doesn't break the tri-color invariant.
}
static void AssigningBarrier(const void* slot, const void* value) {
WriteBarrier::MarkingBarrier(slot, value);
}
};
struct NoWriteBarrierPolicy {
static void InitializingBarrier(const void*, const void*) {}
static void AssigningBarrier(const void*, const void*) {}
};
class V8_EXPORT EnabledCheckingPolicy {
protected:
EnabledCheckingPolicy();
void CheckPointer(const void* ptr);
private:
void* impl_;
};
class DisabledCheckingPolicy {
protected:
void CheckPointer(const void* raw) {}
};
#if V8_ENABLE_CHECKS
using DefaultCheckingPolicy = EnabledCheckingPolicy;
#else
using DefaultCheckingPolicy = DisabledCheckingPolicy;
#endif
class KeepLocationPolicy {
public:
constexpr const SourceLocation& Location() const { return location_; }
protected:
constexpr KeepLocationPolicy() = default;
constexpr explicit KeepLocationPolicy(const SourceLocation& location)
: location_(location) {}
// KeepLocationPolicy must not copy underlying source locations.
KeepLocationPolicy(const KeepLocationPolicy&) = delete;
KeepLocationPolicy& operator=(const KeepLocationPolicy&) = delete;
// Location of the original moved from object should be preserved.
KeepLocationPolicy(KeepLocationPolicy&&) = default;
KeepLocationPolicy& operator=(KeepLocationPolicy&&) = default;
private:
SourceLocation location_;
};
class IgnoreLocationPolicy {
public:
constexpr SourceLocation Location() const { return {}; }
protected:
constexpr IgnoreLocationPolicy() = default;
constexpr explicit IgnoreLocationPolicy(const SourceLocation&) {}
};
#if CPPGC_SUPPORTS_OBJECT_NAMES
using DefaultLocationPolicy = KeepLocationPolicy;
#else
using DefaultLocationPolicy = IgnoreLocationPolicy;
#endif
struct StrongPersistentPolicy {
using IsStrongPersistent = std::true_type;
static V8_EXPORT PersistentRegion& GetPersistentRegion(void* object);
};
struct WeakPersistentPolicy {
using IsStrongPersistent = std::false_type;
static V8_EXPORT PersistentRegion& GetPersistentRegion(void* object);
};
struct StrongCrossThreadPersistentPolicy {
using IsStrongPersistent = std::true_type;
static V8_EXPORT PersistentRegion& GetPersistentRegion(void* object);
};
struct WeakCrossThreadPersistentPolicy {
using IsStrongPersistent = std::false_type;
static V8_EXPORT PersistentRegion& GetPersistentRegion(void* object);
};
// Forward declarations setting up the default policies.
template <typename T, typename WeaknessPolicy,
typename LocationPolicy = DefaultLocationPolicy,
typename CheckingPolicy = DisabledCheckingPolicy>
class BasicCrossThreadPersistent;
template <typename T, typename WeaknessPolicy,
typename LocationPolicy = DefaultLocationPolicy,
typename CheckingPolicy = DefaultCheckingPolicy>
class BasicPersistent;
template <typename T, typename WeaknessTag, typename WriteBarrierPolicy,
typename CheckingPolicy = DefaultCheckingPolicy>
class BasicMember;
// Special tag type used to denote some sentinel member. The semantics of the
// sentinel is defined by the embedder.
struct SentinelPointer {
template <typename T>
operator T*() const { // NOLINT
static constexpr intptr_t kSentinelValue = 1;
return reinterpret_cast<T*>(kSentinelValue);
}
// Hidden friends.
friend bool operator==(SentinelPointer, SentinelPointer) { return true; }
friend bool operator!=(SentinelPointer, SentinelPointer) { return false; }
};
} // namespace internal
constexpr internal::SentinelPointer kSentinelPointer;
} // namespace cppgc
#endif // INCLUDE_CPPGC_INTERNAL_POINTER_POLICIES_H_
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