| /**************************************************************************** |
| ** |
| ** Copyright (C) 2020 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Marc Mutz <marc.mutz@kdab.com> |
| ** Contact: http://www.qt.io/licensing/ |
| ** |
| ** This file is part of the QtCore module of the Qt Toolkit. |
| ** |
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| ** GNU General Public License Usage |
| ** Alternatively, this file may be used under the terms of the GNU |
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| ****************************************************************************/ |
| #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 QT_HAS_INCLUDE(<memory_resource>) && __cplusplus > 201402L |
| # include <unordered_set> |
| # include <memory_resource> |
| #else |
| # include <qset.h> |
| #endif |
| |
| QT_BEGIN_NAMESPACE |
| |
| template <typename T, size_t Prealloc = 32> |
| class QDuplicateTracker { |
| #ifdef __cpp_lib_memory_resource |
| char buffer[Prealloc * sizeof(T)]; |
| std::pmr::monotonic_buffer_resource res{buffer, sizeof buffer}; |
| std::pmr::unordered_set<T> set{&res}; |
| #else |
| QSet<T> set; |
| int setSize = 0; |
| #endif |
| Q_DISABLE_COPY_MOVE(QDuplicateTracker); |
| public: |
| QDuplicateTracker() = default; |
| void reserve(int n) { set.reserve(n); } |
| Q_REQUIRED_RESULT 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; |
| } |
| }; |
| |
| QT_END_NAMESPACE |
| |
| #endif /* QDUPLICATETRACKER_P_H */ |