Source/JavaScriptCore/runtime/JSWeakObjectRef.cpp

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#include "config.h"
#include "JSWeakObjectRef.h"

#include "JSCInlines.h"

namespace JSC {

const ClassInfo JSWeakObjectRef::s_info = { "WeakRef"_s, &Base::s_info, nullptr, nullptr, CREATE_METHOD_TABLE(JSWeakObjectRef) };

void JSWeakObjectRef::finishCreation(VM& vm, JSCell* value)
{
    m_lastAccessVersion = vm.currentWeakRefVersion();
    m_value.set(vm, this, value);
    Base::finishCreation(vm);
}

template<typename Visitor>
void JSWeakObjectRef::visitChildrenImpl(JSCell* cell, Visitor& visitor)
{
    auto* thisObject = jsCast<JSWeakObjectRef*>(cell);
    ASSERT_GC_OBJECT_INHERITS(thisObject, info());
    Base::visitChildren(thisObject, visitor);
    // This doesn't need to be atomic because if we are out of date we will get write barriered and revisit ourselves.
    if (visitor.vm().currentWeakRefVersion() == thisObject->m_lastAccessVersion) {
        ASSERT(thisObject->m_value);
        visitor.append(thisObject->m_value);
    }
}

DEFINE_VISIT_CHILDREN(JSWeakObjectRef);

void JSWeakObjectRef::finalizeUnconditionally(VM& vm, CollectionScope)
{
    if (m_value && !vm.heap.isMarked(m_value.get()))
        m_value.clear();
}

}