corelib/tools: Add QOffsetStringArray API
This function allows to generate an array of offsets of substrings in a string at compile time. This produces less verbose and easier to maintain source code. Change-Id: I5774b8b91906f6191f2b1244a676c07e7eb15b47 Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Mikhail Svetkin
parent
2cdbe29ef0
commit
f0066cae8f
211
src/corelib/tools/qoffsetstringarray_p.h
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211
src/corelib/tools/qoffsetstringarray_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 QOFFSETSTRINGARRAY_P_H
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#define QOFFSETSTRINGARRAY_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 "private/qglobal_p.h"
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#include <tuple>
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#include <array>
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QT_BEGIN_NAMESPACE
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namespace QtPrivate {
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template<int N, int O, int I, int ... Idx>
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struct OffsetSequenceHelper : OffsetSequenceHelper<N - 1, O + I, Idx..., O> { };
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template<int O, int I, int ... Idx>
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struct OffsetSequenceHelper<0, O, I, Idx...> : IndexesList<O, Idx...>
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{
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static const constexpr auto Length = O;
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};
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template<int I, int ... Idx>
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struct OffsetSequence : OffsetSequenceHelper<sizeof ... (Idx) + 1, 0, I, Idx..., 0>
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{
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static const constexpr auto Count = sizeof ... (Idx) + 1;
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using Type = typename QConditional<
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Count <= std::numeric_limits<quint8>::max() + 1,
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quint8,
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typename QConditional<
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Count <= std::numeric_limits<quint16>::max() + 1,
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quint16,
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int>::Type
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>::Type;
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};
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template<int N>
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struct StaticString
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{
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const char data[N];
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constexpr StaticString(const char (&literal)[N]) noexcept
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: StaticString(literal, makeIndexSequence<N> {})
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{ }
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template<int ... Idx>
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constexpr StaticString(const char (&literal)[N],
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IndexesList<Idx...>) noexcept
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: data{literal[Idx]...}
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{ }
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template<typename ... T>
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constexpr StaticString(const T ... c) noexcept : data{c...} { }
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constexpr char operator[](int i) const noexcept
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{
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return data[i];
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}
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template<int N2>
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constexpr StaticString<N + N2> operator+(const StaticString<N2> &rs) const noexcept
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{
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return concatenate(rs, makeIndexSequence<N>{}, makeIndexSequence<N2>{});
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}
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template<int N2, int ... I1, int ... I2>
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constexpr StaticString<N + N2> concatenate(const StaticString<N2> &rs,
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IndexesList<I1...>,
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IndexesList<I2...>) const noexcept
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{
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return StaticString<N + N2>(data[I1]..., rs[I2]...);
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}
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constexpr int size() const noexcept
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{
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return N;
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}
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};
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template<>
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struct StaticString<0>
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{
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};
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template<int Sum>
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constexpr StaticString<0> staticString() noexcept
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{
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return StaticString<0>{};
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}
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template<int Sum, int I, int ... Ix>
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constexpr StaticString<Sum> staticString(const char (&s)[I], const char (&...sx)[Ix]) noexcept
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{
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return StaticString<I>(s) + staticString<Sum - I>(sx...);
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}
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} // namespace QtPrivate
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template<typename T, int SizeString, int SizeOffsets>
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class QOffsetStringArray
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{
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public:
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using Type = T;
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template<int ... Cx, int ... Ox>
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constexpr QOffsetStringArray(const QtPrivate::StaticString<SizeString> &str,
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QtPrivate::IndexesList<Cx...>,
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QtPrivate::IndexesList<SizeString, Ox...>) noexcept
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: m_string{str[Cx]...},
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m_offsets{Ox...}
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{ }
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constexpr inline const char *operator[](const int index) const noexcept
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{
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return m_string + m_offsets[qBound(int(0), index, SizeOffsets - 1)];
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}
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constexpr inline const char *at(const int index) const noexcept
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{
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return m_string + m_offsets[index];
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}
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constexpr inline const char *str() const { return m_string; }
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constexpr inline const int *offsets() const { return m_offsets; }
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constexpr inline int count() const { return SizeOffsets; };
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static constexpr const auto sizeString = SizeString;
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static constexpr const auto sizeOffsets = SizeOffsets;
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private:
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const char m_string[SizeString];
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const T m_offsets[SizeOffsets];
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};
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template<typename T, int N, int ... Ox>
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constexpr QOffsetStringArray<T, N, sizeof ... (Ox)> qOffsetStringArray(
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const QtPrivate::StaticString<N> &string,
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QtPrivate::IndexesList<N, Ox...> offsets) noexcept
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{
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return QOffsetStringArray<T, N, sizeof ... (Ox)>(
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string,
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QtPrivate::makeIndexSequence<N> {},
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offsets);
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}
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template<int ... Nx>
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struct QOffsetStringArrayRet
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{
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using Offsets = QtPrivate::OffsetSequence<Nx...>;
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using Type = QOffsetStringArray<typename Offsets::Type, Offsets::Length, sizeof ... (Nx)>;
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};
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template<int ... Nx>
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constexpr auto qOffsetStringArray(const char (&...strings)[Nx]) noexcept -> typename QOffsetStringArrayRet<Nx...>::Type
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{
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using Offsets = QtPrivate::OffsetSequence<Nx...>;
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return qOffsetStringArray<typename Offsets::Type>(
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QtPrivate::staticString<Offsets::Length>(strings...), Offsets{});
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}
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QT_END_NAMESPACE
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#endif // QOFFSETSTRINGARRAY_P_H
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@ -39,6 +39,7 @@ HEADERS += \
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tools/qmargins.h \
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tools/qmessageauthenticationcode.h \
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tools/qcontiguouscache.h \
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tools/qoffsetstringarray_p.h \
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tools/qpair.h \
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tools/qpoint.h \
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tools/qqueue.h \
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@ -0,0 +1,6 @@
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CONFIG += testcase
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TARGET = tst_qoffsetstringarray
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QT = core testlib core-private
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CONFIG += c++11
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CONFIG += strict_c++
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SOURCES = $$PWD/tst_qoffsetstringarray.cpp
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@ -0,0 +1,109 @@
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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/qoffsetstringarray_p.h>
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class tst_QOffsetStringArray : public QObject
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{
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Q_OBJECT
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private slots:
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void init();
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void access();
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};
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constexpr const auto messages = qOffsetStringArray(
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"level - 0",
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"level - 1",
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"level - 2",
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"level - 3",
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"level - 4",
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""
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);
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constexpr const auto messages257 = qOffsetStringArray(
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "", "", "", "",
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"", "", "", "", "", "", "end"
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);
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void tst_QOffsetStringArray::init()
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{
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static_assert(messages.sizeString == 51, "message.sizeString");
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static_assert(messages.sizeOffsets == 6, "message.sizeOffsets");
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static_assert(std::is_same<decltype(messages)::Type, quint8>::value, "messages::Type != quint8");
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static_assert(messages257.sizeOffsets == 257, "messages257.sizeOffsets");
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static_assert(messages257.sizeString == 260, "messages257.sizeString");
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static_assert(std::is_same<decltype(messages257)::Type, quint16>::value,
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"messages257::Type != quint16");
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}
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void tst_QOffsetStringArray::access()
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{
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QCOMPARE(messages[0], "level - 0");
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QCOMPARE(messages[1], "level - 1");
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QCOMPARE(messages[2], "level - 2");
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QCOMPARE(messages[3], "level - 3");
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QCOMPARE(messages[4], "level - 4");
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QCOMPARE(messages[5], "");
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QCOMPARE(messages[6], "");
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}
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QTEST_APPLESS_MAIN(tst_QOffsetStringArray)
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#include "tst_qoffsetstringarray.moc"
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@ -35,6 +35,7 @@ SUBDIRS=\
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qmap_strictiterators \
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qmargins \
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qmessageauthenticationcode \
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qoffsetstringarray \
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qpair \
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qpoint \
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qpointf \
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