corelib/tools: add qMakeArray() API
This function can be used to create std::array without the need to explicitly provide the size of array. It also has a specialization that allow to generate sorted array at compile time. Sorted array can be beneficial for example in binary search. Change-Id: Ifc7e06e451812fce2ab94293959db5e9cc038793 Reviewed-by: Gatis Paeglis <gatis.paeglis@qt.io>
This commit is contained in:
Mikhail Svetkin
Simon Hausmann
parent
80dea66424
commit
d1dcc4d8cd
179
src/corelib/tools/qmakearray_p.h
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179
src/corelib/tools/qmakearray_p.h
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/****************************************************************************
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**
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** Copyright (C) 2018 The Qt Company Ltd.
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** Contact: https://www.qt.io/licensing/
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**
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** This file is part of the QtCore module of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:LGPL$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and The Qt Company. For licensing terms
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** and conditions see https://www.qt.io/terms-conditions. For further
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** information use the contact form at https://www.qt.io/contact-us.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 3 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL3 included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU Lesser General Public License version 3 requirements
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** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
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**
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** GNU General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU
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** General Public License version 2.0 or (at your option) the GNU General
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** Public license version 3 or any later version approved by the KDE Free
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** Qt Foundation. The licenses are as published by the Free Software
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** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
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** included in the packaging of this file. Please review the following
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** information to ensure the GNU General Public License requirements will
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** be met: https://www.gnu.org/licenses/gpl-2.0.html and
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** https://www.gnu.org/licenses/gpl-3.0.html.
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#ifndef QMAKEARRAY_P_H
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#define QMAKEARRAY_P_H
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//
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// W A R N I N G
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// -------------
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//
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// This file is not part of the Qt API. It exists purely as an
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// implementation detail. This header file may change from version to
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// version without notice, or even be removed.
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//
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// We mean it.
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//
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#include "QtCore/qglobal.h"
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#include <array>
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#include <type_traits>
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#include <utility>
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QT_BEGIN_NAMESPACE
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namespace QtPrivate {
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template<typename T>
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constexpr T&& Forward(typename std::remove_reference<T>::type& t) noexcept
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{
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return static_cast<T&&>(t);
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}
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template<typename T>
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constexpr T&& Forward(typename std::remove_reference<T>::type&& t) noexcept
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{
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static_assert(!std::is_lvalue_reference<T>::value,
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"template argument substituting T is an lvalue reference type");
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return static_cast<T&&>(t);
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}
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template <typename ManualType, typename ...>
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struct ArrayTypeHelper
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{
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using type = ManualType;
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};
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template <typename ... Types>
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struct ArrayTypeHelper<void, Types...> : std::common_type<Types...> { };
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template <typename ManualType, typename... Types>
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using ArrayType = std::array<typename ArrayTypeHelper<ManualType, Types...>::type,
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sizeof...(Types)>;
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template<typename ... Values>
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struct QuickSortData { };
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template <template <typename> class Predicate,
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typename ... Values>
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struct QuickSortFilter;
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template <typename ... Right, typename ... Left>
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constexpr QuickSortData<Right..., Left...> quickSortConcat(
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QuickSortData<Right...>, QuickSortData<Left...>) noexcept;
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template<typename ... Right, typename Middle, typename ... Left>
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constexpr QuickSortData<Right..., Middle, Left...> quickSortConcat(
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QuickSortData<Right...>,
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QuickSortData<Middle>,
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QuickSortData<Left...>) noexcept;
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template <template <typename> class Predicate,
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typename Head, typename ... Tail>
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struct QuickSortFilter<Predicate, QuickSortData<Head, Tail...>>
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{
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using TailFilteredData = typename QuickSortFilter<
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Predicate, QuickSortData<Tail...>>::Type;
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using Type = typename QConditional<
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Predicate<Head>::value,
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decltype(quickSortConcat(QuickSortData<Head> {}, TailFilteredData{})),
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TailFilteredData>::Type;
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};
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template <template <typename> class Predicate>
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struct QuickSortFilter<Predicate, QuickSortData<>>
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{
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using Type = QuickSortData<>;
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};
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template <typename ... Values>
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struct QuickSort;
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template <typename Pivot, typename ... Values>
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struct QuickSort<QuickSortData<Pivot, Values...>>
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{
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template <typename Left>
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struct LessThan {
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static constexpr const bool value = Left::data() <= Pivot::data();
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};
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template <typename Left>
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struct MoreThan {
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static constexpr const bool value = !(Left::data() <= Pivot::data());
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};
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using LeftSide = typename QuickSortFilter<LessThan, QuickSortData<Values...>>::Type;
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using RightSide = typename QuickSortFilter<MoreThan, QuickSortData<Values...>>::Type;
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using LeftQS = typename QuickSort<LeftSide>::Type;
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using RightQS = typename QuickSort<RightSide>::Type;
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using Type = decltype(quickSortConcat(LeftQS{}, QuickSortData<Pivot> {}, RightQS{}));
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};
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template <>
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struct QuickSort<QuickSortData<>>
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{
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using Type = QuickSortData<>;
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};
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} // namespace QtPrivate
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template <typename ManualType = void, typename ... Types>
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constexpr QtPrivate::ArrayType<ManualType, Types...> qMakeArray(Types && ... t) noexcept
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{
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return {{QtPrivate::Forward<typename QtPrivate::ArrayType<ManualType, Types...>::value_type>(t)...}};
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}
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template<typename ... Values>
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struct QSortedData {
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using Data = typename QtPrivate::QuickSort<typename QtPrivate::QuickSortData<Values...>>::Type;
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};
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template<typename ... Values>
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constexpr auto qMakeArray(QtPrivate::QuickSortData<Values...>) noexcept -> decltype(qMakeArray(Values::data()...))
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{
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return qMakeArray(Values::data() ...);
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}
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QT_END_NAMESPACE
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#endif // QMAKEARRAY_P_H
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@ -34,6 +34,7 @@ HEADERS += \
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tools/qlocale_p.h \
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tools/qlocale_tools_p.h \
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tools/qlocale_data_p.h \
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tools/qmakearray_p.h \
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tools/qmap.h \
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tools/qmargins.h \
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tools/qmessageauthenticationcode.h \
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4
tests/auto/corelib/tools/qmakearray/qmakearray.pro
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4
tests/auto/corelib/tools/qmakearray/qmakearray.pro
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CONFIG += testcase
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TARGET = tst_qmakearray
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QT = core testlib core-private
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SOURCES = $$PWD/tst_qmakearray.cpp
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103
tests/auto/corelib/tools/qmakearray/tst_qmakearray.cpp
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103
tests/auto/corelib/tools/qmakearray/tst_qmakearray.cpp
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@ -0,0 +1,103 @@
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/****************************************************************************
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**
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** Copyright (C) 2018 The Qt Company Ltd.
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** Contact: https://www.qt.io/licensing/
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**
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** This file is part of the test suite of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:GPL-EXCEPT$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and The Qt Company. For licensing terms
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** and conditions see https://www.qt.io/terms-conditions. For further
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** information use the contact form at https://www.qt.io/contact-us.
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**
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** GNU General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU
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** General Public License version 3 as published by the Free Software
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** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
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** included in the packaging of this file. Please review the following
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** information to ensure the GNU General Public License requirements will
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** be met: https://www.gnu.org/licenses/gpl-3.0.html.
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#include <QtTest/QtTest>
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#include <private/qmakearray_p.h>
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class tst_QMakeArray : public QObject
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{
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Q_OBJECT
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private slots:
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void quicksort();
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};
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struct Pair {
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unsigned int key;
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unsigned int val;
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constexpr bool operator <=(const Pair &that) const noexcept
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{
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return key <= that.key;
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}
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constexpr bool operator<(const Pair &that) const noexcept
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{
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return key < that.key;
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}
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constexpr bool operator==(const Pair &that) const noexcept
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{
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return key == that.key;
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}
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};
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template<std::size_t Key, std::size_t Val>
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struct PairQuickSortElem
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{
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using Type = Pair;
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static constexpr Type data() noexcept { return Type{Key, Val}; }
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};
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void tst_QMakeArray::quicksort()
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{
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constexpr const auto sorted_array = qMakeArray(
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QSortedData<
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PairQuickSortElem<10, 0>,
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PairQuickSortElem<5, 0>,
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PairQuickSortElem<7, 0>,
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PairQuickSortElem<1, 0>,
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PairQuickSortElem<8, 0>,
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PairQuickSortElem<6, 0>,
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PairQuickSortElem<4, 0>,
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PairQuickSortElem<3, 0>,
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PairQuickSortElem<1, 0>,
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PairQuickSortElem<2, 0>,
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PairQuickSortElem<10, 0>,
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PairQuickSortElem<5, 0>
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>::Data{});
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static_assert(sorted_array.size() == 12, "sorted_array.size() != 12");
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QCOMPARE(sorted_array[0].key, 1u);
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QCOMPARE(sorted_array[1].key, 1u);
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QCOMPARE(sorted_array[2].key, 2u);
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QCOMPARE(sorted_array[3].key, 3u);
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QCOMPARE(sorted_array[4].key, 4u);
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QCOMPARE(sorted_array[5].key, 5u);
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QCOMPARE(sorted_array[6].key, 5u);
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QCOMPARE(sorted_array[7].key, 6u);
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QCOMPARE(sorted_array[8].key, 7u);
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QCOMPARE(sorted_array[9].key, 8u);
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QCOMPARE(sorted_array[10].key, 10u);
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QCOMPARE(sorted_array[11].key, 10u);
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}
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QTEST_APPLESS_MAIN(tst_QMakeArray)
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#include "tst_qmakearray.moc"
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@ -30,6 +30,7 @@ SUBDIRS=\
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qlist \
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qlist_strictiterators \
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qlocale \
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qmakearray \
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qmap \
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qmap_strictiterators \
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qmargins \
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