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/*
* Copyright (C) 2022 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 <wtf/WeakHashMap.h>
namespace WTF {
template<typename Value, typename Counter = EmptyCounter>
class WeakHashCountedSet {
WTF_MAKE_FAST_ALLOCATED;
private:
using ImplType = WeakHashMap<Value, unsigned, Counter>;
public:
using ValueType = Value;
using iterator = typename ImplType::iterator;
using const_iterator = typename ImplType::const_iterator;
using AddResult = typename ImplType::AddResult;
// Iterators iterate over pairs of values and counts.
iterator begin() { return m_impl.begin(); }
iterator end() { return m_impl.end(); }
const_iterator begin() const { return m_impl.begin(); }
const_iterator end() const { return m_impl.end(); }
iterator find(const ValueType& value) { return m_impl.find(value); }
const_iterator find(const ValueType& value) const { return m_impl.find(value); }
bool contains(const ValueType& value) const { return m_impl.contains(value); }
unsigned computeSize() const { return m_impl.computeSize(); }
// Increments the count if an equal value is already present.
// The return value includes both an iterator to the value's location,
// and an isNewEntry bool that indicates whether it is a new or existing entry.
AddResult add(const ValueType&);
AddResult add(ValueType&&);
// Decrements the count of the value, and removes it if count goes down to zero.
// Returns true if the value is removed.
bool remove(const ValueType&);
bool remove(iterator);
// Clears the whole set.
void clear() { m_impl.clear(); }
private:
WeakHashMap<Value, unsigned, Counter> m_impl;
};
template<typename Value, typename Counter>
inline auto WeakHashCountedSet<Value, Counter>::add(const ValueType &value) -> AddResult
{
auto result = m_impl.add(value, 0);
++result.iterator->value;
return result;
}
template<typename Value, typename Counter>
inline auto WeakHashCountedSet<Value, Counter>::add(ValueType&& value) -> AddResult
{
auto result = m_impl.add(std::forward<Value>(value), 0);
++result.iterator->value;
return result;
}
template<typename Value, typename Counter>
inline bool WeakHashCountedSet<Value, Counter>::remove(const ValueType& value)
{
return remove(find(value));
}
template<typename Value, typename Counter>
inline bool WeakHashCountedSet<Value, Counter>::remove(iterator it)
{
if (it == end())
return false;
unsigned oldVal = it->value;
ASSERT(oldVal);
unsigned newVal = oldVal - 1;
if (newVal) {
it->value = newVal;
return false;
}
m_impl.remove(it);
return true;
}
} // namespace WTF
using WTF::WeakHashCountedSet;
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