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/****************************************************************************
**
** Copyright (C) 2020 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Marc Mutz <marc.mutz@kdab.com>
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:COMM$
**
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** $QT_END_LICENSE$
**
**
**
**
**
**
**
**
**
**
**
**
**
**
**
**
**
**
**
******************************************************************************/
#ifndef QDUPLICATETRACKER_P_H
#define QDUPLICATETRACKER_P_H
//
// W A R N I N G
// -------------
//
// This file is not part of the Qt API. It exists purely as an
// implementation detail. This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
#include <qglobal.h>
#if __has_include(<memory_resource>) && __cplusplus > 201402L
# include <unordered_set>
# include <memory_resource>
# include <qhash.h> // for the hashing helpers
#else
# include <qset.h>
#endif
QT_BEGIN_NAMESPACE
template <typename T, size_t Prealloc = 32>
class QDuplicateTracker {
#ifdef __cpp_lib_memory_resource
template <typename HT>
struct QHasher {
size_t storedSeed = QHashSeed::globalSeed();
size_t operator()(const HT &t) const {
return QHashPrivate::calculateHash(t, storedSeed);
}
};
struct node_guesstimate { void *next; size_t hash; T value; };
static constexpr size_t bufferSize(size_t N) {
return N * sizeof(void*) // bucket list
+ N * sizeof(node_guesstimate); // nodes
}
char buffer[bufferSize(Prealloc)];
std::pmr::monotonic_buffer_resource res{buffer, sizeof buffer};
std::pmr::unordered_set<T, QHasher<T>> set{Prealloc, &res};
#else
static QSet<T> makeQSet() { QSet<T> r; r.reserve(Prealloc); return r; }
QSet<T> set = makeQSet();
int setSize = 0;
#endif
Q_DISABLE_COPY_MOVE(QDuplicateTracker);
public:
static constexpr inline bool uses_pmr =
#ifdef __cpp_lib_memory_resource
true
#else
false
#endif
;
QDuplicateTracker() = default;
void reserve(qsizetype n) { set.reserve(n); }
[[nodiscard]] bool hasSeen(const T &s)
{
bool inserted;
#ifdef __cpp_lib_memory_resource
inserted = set.insert(s).second;
#else
set.insert(s);
const int n = set.size();
inserted = qExchange(setSize, n) != n;
#endif
return !inserted;
}
[[nodiscard]] bool hasSeen(T &&s)
{
bool inserted;
#ifdef __cpp_lib_memory_resource
inserted = set.insert(std::move(s)).second;
#else
set.insert(std::move(s));
const int n = set.size();
inserted = qExchange(setSize, n) != n;
#endif
return !inserted;
}
template <typename C>
void appendTo(C &c) const &
{
for (const auto &e : set)
c.push_back(e);
}
template <typename C>
void appendTo(C &c) &&
{
if constexpr (uses_pmr) {
while (!set.empty())
c.push_back(std::move(set.extract(set.begin()).value()));
} else {
return appendTo(c); // lvalue version
}
}
void clear()
{
set.clear();
}
};
QT_END_NAMESPACE
#endif /* QDUPLICATETRACKER_P_H */
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