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// Copyright (C) 2022 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#ifndef QTCORE_QMINIMALFLATSET_P_H
#define QTCORE_QMINIMALFLATSET_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 <QtCore/qcontainerfwd.h>
#include <QtCore/qfunctionaltools_impl.h> // CompactStorage
#include <QtCore/private/qglobal_p.h>
//#define QMINIMAL_FLAT_SET_DEBUG
#ifdef QMINIMAL_FLAT_SET_DEBUG
# include <QtCore/qscopeguard.h>
# include <QtCore/qdebug.h>
# define QMINIMAL_FLAT_SET_PRINT_AT_END \
const auto sg = qScopeGuard([&] { qDebug() << this << *this; });
#else
# define QMINIMAL_FLAT_SET_PRINT_AT_END
#endif
#include <algorithm> // for std::lower_bound
#include <functional> // for std::less, std::ref
QT_BEGIN_NAMESPACE
/*
This is a minimal version of a QFlatSet, the std::set version of QFlatMap.
Like QFlatMap, it has linear insertion and removal, not logarithmic, like
real QMap and std::set, so it's only a good container if you either have
very few entries or lots, but with separate setup and lookup stages.
Because a full QFlatSet would be 10x the work on writing this minimal one,
we keep it here for now. When more users pop up and the class has matured a
bit, we can consider moving it as QFlatSet alongside QFlatMap.
*/
template <typename T, typename Container = QList<T>, typename Compare = std::less<T>>
class QMinimalFlatSet : QtPrivate::CompactStorage<Compare>
{
Container c;
using CompareStorage = QtPrivate::CompactStorage<Compare>;
public:
QMinimalFlatSet() = default;
explicit QMinimalFlatSet(const Compare &cmp) : CompareStorage{cmp} {}
// Rule Of Zero applies
using const_iterator = typename Container::const_iterator;
using iterator = const_iterator;
using const_reverse_iterator = typename Container::const_reverse_iterator;
using reverse_iterator = const_reverse_iterator;
using value_type = T;
using key_compare = Compare;
using value_compare = Compare;
key_compare key_comp() const { return this->object(); }
value_compare value_comp() const { return key_comp(); }
iterator begin() const { return c.cbegin(); }
iterator end() const { return c.cend(); }
iterator cbegin() const { return begin(); }
iterator cend() const { return cend(); }
reverse_iterator rbegin() const { return c.crbegin(); }
reverse_iterator rend() const { return c.crend(); }
reverse_iterator crbegin() const { return rbegin(); }
reverse_iterator crend() const { return rend(); }
void clear() {
QMINIMAL_FLAT_SET_PRINT_AT_END
c.clear();
}
auto size() const { return c.size(); }
auto count() const { return size(); }
bool isEmpty() const { return size() == 0; }
std::pair<iterator, bool> insert(value_type &&v)
{
QMINIMAL_FLAT_SET_PRINT_AT_END
const auto r = lookup(v);
if (r.exists)
return {r.it, false};
else
return {c.insert(r.it, std::move(v)), true};
}
std::pair<iterator, bool> insert(const value_type &v)
{
QMINIMAL_FLAT_SET_PRINT_AT_END
const auto r = lookup(v);
if (r.exists)
return {r.it, false};
else
return {c.insert(r.it, v), true};
}
void erase(const value_type &v)
{
QMINIMAL_FLAT_SET_PRINT_AT_END
const auto r = lookup(v);
if (r.exists)
c.erase(r.it);
}
void remove(const value_type &v) { erase(v); }
bool contains(const value_type &v) const
{
return lookup(v).exists;
}
const Container &values() const & { return c; }
Container values() && { return std::move(c); }
private:
auto lookup(const value_type &v) const
{
struct R {
iterator it;
bool exists;
};
auto cmp = std::ref(this->object()); // don't let std::lower_bound copy it
const auto it = std::lower_bound(c.cbegin(), c.cend(), v, cmp);
return R{it, it != c.cend() && !cmp(v, *it)};
}
#ifdef QMINIMAL_FLAT_SET_DEBUG
friend QDebug operator<<(QDebug dbg, const QMinimalFlatSet &set)
{
const QDebugStateSaver saver(dbg);
dbg.nospace() << "QMinimalFlatSet{";
for (auto &e : set)
dbg << e << ", ";
return dbg << "}";
}
#endif
};
#undef QMINIMAL_FLAT_SET_PRINT_AT_END
template <typename T, qsizetype N = QVarLengthArrayDefaultPrealloc>
using QMinimalVarLengthFlatSet = QMinimalFlatSet<T, QVarLengthArray<T, N>>;
QT_END_NAMESPACE
#endif // QTCORE_QMINIMALFLATSET_P_H
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