1/****************************************************************************
2**
3** Copyright (C) 2020 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Marc Mutz <marc.mutz@kdab.com>
4** Contact: http://www.qt.io/licensing/
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38****************************************************************************/
39#ifndef QDUPLICATETRACKER_P_H
40#define QDUPLICATETRACKER_P_H
41
42//
43// W A R N I N G
44// -------------
45//
46// This file is not part of the Qt API. It exists purely as an
47// implementation detail. This header file may change from version to
48// version without notice, or even be removed.
49//
50// We mean it.
51//
52
53#include <qglobal.h>
54
55#if QT_HAS_INCLUDE(<memory_resource>) && __cplusplus > 201402L
56# include <unordered_set>
57# include <memory_resource>
58#else
59# include <qset.h>
60#endif
61
62QT_BEGIN_NAMESPACE
63
64template <typename T, size_t Prealloc = 32>
65class QDuplicateTracker {
66#ifdef __cpp_lib_memory_resource
67 char buffer[Prealloc * sizeof(T)];
68 std::pmr::monotonic_buffer_resource res{buffer, sizeof buffer};
69 std::pmr::unordered_set<T> set{&res};
70#else
71 QSet<T> set;
72 int setSize = 0;
73#endif
74 Q_DISABLE_COPY_MOVE(QDuplicateTracker);
75public:
76 QDuplicateTracker() = default;
77 void reserve(int n) { set.reserve(n); }
78 [[nodiscard]] bool hasSeen(const T &s)
79 {
80 bool inserted;
81#ifdef __cpp_lib_memory_resource
82 inserted = set.insert(s).second;
83#else
84 set.insert(s);
85 const int n = set.size();
86 inserted = qExchange(setSize, n) != n;
87#endif
88 return !inserted;
89 }
90 [[nodiscard]] bool hasSeen(T &&s)
91 {
92 bool inserted;
93#ifdef __cpp_lib_memory_resource
94 inserted = set.insert(std::move(s)).second;
95#else
96 set.insert(std::move(s));
97 const int n = set.size();
98 inserted = qExchange(setSize, n) != n;
99#endif
100 return !inserted;
101 }
102
103 template <typename C>
104 void appendTo(C &c) const &
105 {
106 for (const auto &e : set)
107 c.push_back(e);
108 }
109
110 template <typename C>
111 void appendTo(C &c) &&
112 {
113 for (auto &e : set)
114 c.push_back(std::move(e));
115 }
116};
117
118QT_END_NAMESPACE
119
120#endif /* QDUPLICATETRACKER_P_H */
121