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/*
* Copyright (C) 2025 Samuel Weinig <sam@webkit.org>
* Copyright (C) 2003-2024 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. ``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
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* 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 "CalculationValue.h"
#include <wtf/HashMap.h>
namespace WebCore {
class CalculationValueMap {
public:
static CalculationValueMap& calculationValues();
unsigned insert(Ref<CalculationValue>&&);
void ref(unsigned handle);
void deref(unsigned handle);
CalculationValue& get(unsigned handle) const;
private:
friend NeverDestroyed<CalculationValueMap>;
CalculationValueMap();
struct Entry {
uint64_t referenceCountMinusOne { 0 };
RefPtr<CalculationValue> value;
Entry() = default;
Entry(Ref<CalculationValue>&&);
};
unsigned m_nextAvailableHandle { 1 };
HashMap<unsigned, Entry> m_map;
};
inline CalculationValueMap::Entry::Entry(Ref<CalculationValue>&& value)
: value(WTFMove(value))
{
}
inline unsigned CalculationValueMap::insert(Ref<CalculationValue>&& value)
{
ASSERT(m_nextAvailableHandle);
Entry entry(WTFMove(value));
// FIXME: This monotonically increasing handle generation scheme is potentially wasteful
// of the handle space. Consider reusing empty handles. https://bugs.webkit.org/show_bug.cgi?id=80489
while (!m_map.isValidKey(m_nextAvailableHandle) || !m_map.add(m_nextAvailableHandle, entry).isNewEntry)
++m_nextAvailableHandle;
return m_nextAvailableHandle++;
}
inline CalculationValue& CalculationValueMap::get(unsigned handle) const
{
ASSERT(m_map.contains(handle));
return *m_map.find(handle)->value.value;
}
inline void CalculationValueMap::ref(unsigned handle)
{
ASSERT(m_map.contains(handle));
++m_map.find(handle)->value.referenceCountMinusOne;
}
inline void CalculationValueMap::deref(unsigned handle)
{
ASSERT(m_map.contains(handle));
auto it = m_map.find(handle);
if (it->value.referenceCountMinusOne) {
--it->value.referenceCountMinusOne;
return;
}
m_map.remove(it);
}
} // namespace WebCore
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