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Diffstat (limited to 'src/corelib/tools/qduplicatetracker_p.h')
-rw-r--r-- | src/corelib/tools/qduplicatetracker_p.h | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/src/corelib/tools/qduplicatetracker_p.h b/src/corelib/tools/qduplicatetracker_p.h new file mode 100644 index 0000000000..99068c01a3 --- /dev/null +++ b/src/corelib/tools/qduplicatetracker_p.h @@ -0,0 +1,94 @@ +/**************************************************************************** +** +** 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. +** +** $QT_BEGIN_LICENSE:LGPL$ +** 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. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 3 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL3 included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 3 requirements +** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 2.0 or (at your option) the GNU General +** Public license version 3 or any later version approved by the KDE Free +** Qt Foundation. The licenses are as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 +** included in the packaging of this file. Please review the following +** information to ensure the GNU General Public License requirements will +** be met: https://www.gnu.org/licenses/gpl-2.0.html and +** https://www.gnu.org/licenses/gpl-3.0.html. +** +** $QT_END_LICENSE$ +** +****************************************************************************/ +#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 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 */ |