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/*
* Copyright (C) 2013-2018 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include "Node.h"
#include <wtf/HashCountedSet.h>
#include <wtf/RawPtrTraits.h>
#include <wtf/RefPtr.h>
namespace WebCore {
class Node;
class GCReachableRefMap {
public:
static inline bool contains(EventTarget& target) { return target.isInGCReacheableRefMap(); }
static inline void add(EventTarget& target)
{
if (map().add(&target).isNewEntry)
target.setIsInGCReacheableRefMap(true);
}
static inline void remove(EventTarget& target)
{
if (map().remove(&target))
target.setIsInGCReacheableRefMap(false);
}
private:
WEBCORE_EXPORT static HashCountedSet<EventTarget*>& map();
};
template <typename T, typename = std::enable_if_t<std::is_same<T, typename std::remove_const<T>::type>::value>>
class GCReachableRef {
WTF_MAKE_NONCOPYABLE(GCReachableRef);
public:
GCReachableRef(T& object)
: m_ptr(&object)
{
GCReachableRefMap::add(*m_ptr);
}
~GCReachableRef()
{
if (m_ptr)
GCReachableRefMap::remove(*m_ptr);
}
GCReachableRef(GCReachableRef&& other)
: m_ptr(WTFMove(other.m_ptr))
{
}
T* operator->() const { return &get(); }
T* ptr() const RETURNS_NONNULL { return &get(); }
T& get() const { ASSERT(m_ptr); return *m_ptr; }
operator T&() const { return get(); }
bool operator!() const { return !get(); }
// Hash table deleted values, which are only constructed and never copied or destroyed.
GCReachableRef(WTF::HashTableDeletedValueType)
: m_ptr(RefPtr<T>::PtrTraits::hashTableDeletedValue())
{ }
bool isHashTableDeletedValue() const { return m_ptr.isHashTableDeletedValue(); }
GCReachableRef(WTF::HashTableEmptyValueType)
: m_ptr(nullptr)
{ }
bool isHashTableEmptyValue() const { return !m_ptr; }
const T* ptrAllowingHashTableEmptyValue() const { ASSERT(m_ptr || isHashTableEmptyValue()); return m_ptr.get(); }
T* ptrAllowingHashTableEmptyValue() { ASSERT(m_ptr || isHashTableEmptyValue()); return m_ptr.get(); }
void assignToHashTableEmptyValue(GCReachableRef&& reference)
{
ASSERT(!m_ptr);
m_ptr = WTFMove(reference.m_ptr);
ASSERT(m_ptr);
}
private:
RefPtr<T> m_ptr;
};
} // namespace WebCore
namespace WTF {
template<typename P> struct HashTraits<WebCore::GCReachableRef<P>> : SimpleClassHashTraits<WebCore::GCReachableRef<P>> {
static const bool emptyValueIsZero = true;
static WebCore::GCReachableRef<P> emptyValue() { return HashTableEmptyValue; }
template <typename>
static void constructEmptyValue(WebCore::GCReachableRef<P>& slot)
{
new (NotNull, std::addressof(slot)) WebCore::GCReachableRef<P>(HashTableEmptyValue);
}
static const bool hasIsEmptyValueFunction = true;
static bool isEmptyValue(const WebCore::GCReachableRef<P>& value) { return value.isHashTableEmptyValue(); }
static void assignToEmpty(WebCore::GCReachableRef<P>& emptyValue, WebCore::GCReachableRef<P>&& newValue)
{
ASSERT(isEmptyValue(emptyValue));
emptyValue.assignToHashTableEmptyValue(WTFMove(newValue));
}
typedef P* PeekType;
static PeekType peek(const Ref<P>& value) { return const_cast<PeekType>(value.ptrAllowingHashTableEmptyValue()); }
static PeekType peek(P* value) { return value; }
typedef std::optional<Ref<P>> TakeType;
static TakeType take(Ref<P>&& value) { return isEmptyValue(value) ? std::nullopt : std::optional<Ref<P>>(WTFMove(value)); }
};
template <typename T, typename U>
struct GetPtrHelper<WebCore::GCReachableRef<T, U>> {
using PtrType = T*;
using UnderlyingType = T;
static T* getPtr(const WebCore::GCReachableRef<T, U>& reference) { return const_cast<T*>(reference.ptr()); }
};
template <typename T, typename U>
struct IsSmartPtr<WebCore::GCReachableRef<T, U>> {
static const bool value = true;
static constexpr bool isNullable = true;
};
template<typename P> struct PtrHash<WebCore::GCReachableRef<P>> : PtrHashBase<WebCore::GCReachableRef<P>, IsSmartPtr<WebCore::GCReachableRef<P>>::value> {
static const bool safeToCompareToEmptyOrDeleted = false;
};
template<typename P> struct DefaultHash<WebCore::GCReachableRef<P>> : PtrHash<WebCore::GCReachableRef<P>> { };
} // namespace WTF
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