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/*
* Copyright (C) 2005, 2006, 2008 Apple Inc. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
*/
#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_WTF_HASH_COUNTED_SET_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_WTF_HASH_COUNTED_SET_H_
#include "base/check_op.h"
#include "third_party/blink/renderer/platform/wtf/allocator/partition_allocator.h"
#include "third_party/blink/renderer/platform/wtf/hash_map.h"
#include "third_party/blink/renderer/platform/wtf/type_traits.h"
#include "third_party/blink/renderer/platform/wtf/vector.h"
namespace WTF {
// An unordered hash set that keeps track of how many times you added an item to
// the set. The iterators have fields ->key and ->value that return the set
// members and their counts, respectively.
template <typename Value,
typename Traits = HashTraits<Value>,
typename Allocator = PartitionAllocator>
class HashCountedSet {
USE_ALLOCATOR(HashCountedSet, Allocator);
private:
typedef HashMap<Value, unsigned, Traits, HashTraits<unsigned>, Allocator>
ImplType;
public:
typedef Value ValueType;
using value_type = ValueType;
typedef typename ImplType::iterator iterator;
typedef typename ImplType::const_iterator const_iterator;
typedef typename ImplType::AddResult AddResult;
HashCountedSet() = default;
HashCountedSet(const HashCountedSet&) = default;
HashCountedSet& operator=(const HashCountedSet&) = default;
void swap(HashCountedSet& other) { impl_.swap(other.impl_); }
unsigned size() const { return impl_.size(); }
unsigned Capacity() const { return impl_.capacity(); }
bool empty() const { return impl_.empty(); }
// Iterators iterate over pairs of values (called key) and counts (called
// value).
iterator begin() { return impl_.begin(); }
iterator end() { return impl_.end(); }
const_iterator begin() const { return impl_.begin(); }
const_iterator end() const { return impl_.end(); }
iterator find(const ValueType& value) { return impl_.find(value); }
const_iterator find(const ValueType& value) const {
return impl_.find(value);
}
bool Contains(const ValueType& value) const { return impl_.Contains(value); }
unsigned count(const ValueType& value) const { return impl_.at(value); }
// Increases the count if an equal value is already present the return value
// is a pair of an iterator to the new value's location, and a bool that is
// true if an new entry was added.
AddResult insert(const ValueType&);
// Generalized add(), adding the value N times.
AddResult insert(const ValueType&, unsigned);
// Reduces the count of the value, and removes it if count goes down to
// zero, returns true if the value is removed.
bool erase(const ValueType& value) { return erase(find(value)); }
bool erase(iterator);
// Removes the value, regardless of its count.
void RemoveAll(const ValueType& value) { RemoveAll(find(value)); }
void RemoveAll(iterator);
// Clears the whole set.
void clear() { impl_.clear(); }
const auto& Values() const {
// The values (vs counts) are the keys of ImplType.
return impl_.Keys();
}
void Trace(auto visitor) const
requires Allocator::kIsGarbageCollected
{
impl_.Trace(visitor);
}
protected:
typename ImplType::ValueType** GetBufferSlot() {
return impl_.GetBufferSlot();
}
private:
ImplType impl_;
struct TypeConstraints {
constexpr TypeConstraints() {
static_assert(!IsStackAllocatedTypeV<Value>);
static_assert(Allocator::kIsGarbageCollected ||
!IsPointerToGarbageCollectedType<Value>,
"Cannot put raw pointers to garbage-collected classes into "
"an off-heap HashCountedSet. Use "
"HeapHashCountedSet<Member<T>> instead.");
}
};
NO_UNIQUE_ADDRESS TypeConstraints type_constraints_;
};
template <typename T, typename U, typename V>
inline typename HashCountedSet<T, U, V>::AddResult
HashCountedSet<T, U, V>::insert(const ValueType& value, unsigned count) {
DCHECK_GT(count, 0u);
AddResult result = impl_.insert(value, 0);
result.stored_value->value += count;
return result;
}
template <typename T, typename U, typename V>
inline typename HashCountedSet<T, U, V>::AddResult
HashCountedSet<T, U, V>::insert(const ValueType& value) {
return insert(value, 1u);
}
template <typename T, typename U, typename V>
inline bool HashCountedSet<T, U, V>::erase(iterator it) {
if (it == end())
return false;
unsigned old_val = it->value;
DCHECK(old_val);
unsigned new_val = old_val - 1;
if (new_val) {
it->value = new_val;
return false;
}
impl_.erase(it);
return true;
}
template <typename T, typename U, typename V>
inline void HashCountedSet<T, U, V>::RemoveAll(iterator it) {
if (it == end())
return;
impl_.erase(it);
}
} // namespace WTF
using WTF::HashCountedSet;
#endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_WTF_HASH_COUNTED_SET_H_
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