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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 WTF_HashCountedSet_h
#define WTF_HashCountedSet_h
#include "wtf/Assertions.h"
#include "wtf/HashMap.h"
#include "wtf/Vector.h"
#include "wtf/allocator/PartitionAllocator.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 HashFunctions = typename DefaultHash<Value>::Hash,
typename Traits = HashTraits<Value>,
typename Allocator = PartitionAllocator>
class HashCountedSet {
USE_ALLOCATOR(HashCountedSet, Allocator);
WTF_MAKE_NONCOPYABLE(HashCountedSet);
private:
typedef HashMap<Value,
unsigned,
HashFunctions,
Traits,
HashTraits<unsigned>,
Allocator>
ImplType;
public:
typedef Value ValueType;
typedef typename ImplType::iterator iterator;
typedef typename ImplType::const_iterator const_iterator;
typedef typename ImplType::AddResult AddResult;
HashCountedSet() {
static_assert(Allocator::isGarbageCollected ||
!IsPointerToGarbageCollectedType<Value>::value,
"Cannot put raw pointers to garbage-collected classes into "
"an off-heap HashCountedSet. Use "
"HeapHashCountedSet<Member<T>> instead.");
}
void swap(HashCountedSet& other) { m_impl.swap(other.m_impl); }
unsigned size() const { return m_impl.size(); }
unsigned capacity() const { return m_impl.capacity(); }
bool isEmpty() const { return m_impl.isEmpty(); }
// Iterators iterate over pairs of values (called key) and counts (called
// value).
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 count(const ValueType& value) const { return m_impl.get(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 add(const ValueType&);
// Generalized add(), adding the value N times.
AddResult add(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 remove(const ValueType& value) { return remove(find(value)); }
bool remove(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() { m_impl.clear(); }
Vector<Value> asVector() const;
template <typename VisitorDispatcher>
void trace(VisitorDispatcher visitor) {
m_impl.trace(visitor);
}
private:
ImplType m_impl;
};
template <typename T, typename U, typename V, typename W>
inline typename HashCountedSet<T, U, V, W>::AddResult
HashCountedSet<T, U, V, W>::add(const ValueType& value, unsigned count) {
DCHECK_GT(count, 0u);
AddResult result = m_impl.add(value, 0);
result.storedValue->value += count;
return result;
}
template <typename T, typename U, typename V, typename W>
inline typename HashCountedSet<T, U, V, W>::AddResult
HashCountedSet<T, U, V, W>::add(const ValueType& value) {
return add(value, 1u);
}
template <typename T, typename U, typename V, typename W>
inline bool HashCountedSet<T, U, V, W>::remove(iterator it) {
if (it == end())
return false;
unsigned oldVal = it->value;
DCHECK(oldVal);
unsigned newVal = oldVal - 1;
if (newVal) {
it->value = newVal;
return false;
}
m_impl.remove(it);
return true;
}
template <typename T, typename U, typename V, typename W>
inline void HashCountedSet<T, U, V, W>::removeAll(iterator it) {
if (it == end())
return;
m_impl.remove(it);
}
template <typename Value,
typename HashFunctions,
typename Traits,
typename Allocator,
typename VectorType>
inline void copyToVector(
const HashCountedSet<Value, HashFunctions, Traits, Allocator>& collection,
VectorType& vector) {
{
// Disallow GC across resize allocation, see crbug.com/568173
typename VectorType::GCForbiddenScope scope;
vector.resize(collection.size());
}
auto it = collection.begin();
auto end = collection.end();
for (unsigned i = 0; it != end; ++it, ++i)
vector[i] = (*it).key;
}
template <typename T, typename U, typename V, typename W>
inline Vector<T> HashCountedSet<T, U, V, W>::asVector() const {
Vector<T> vector;
copyToVector(*this, vector);
return vector;
}
} // namespace WTF
using WTF::HashCountedSet;
#endif // WTF_HashCountedSet_h
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