d5c53554e5
Using std::begin() and std::end() forces the user to have const begin()
and end() member functions being defined for the passed container. This
is because std::declval<T>() returns rvalue which forces the compiler
to select std::{begin, end}()(const Container &c) overloads and an test
for a presence of const {begin, end}() methods.
Change-Id: I9d96d9f73891ece53224f1741a1334500f7b35ad
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
78 lines
2.8 KiB
C++
78 lines
2.8 KiB
C++
/****************************************************************************
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**
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** Copyright (C) 2016 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 QtConcurrent 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 QTCONCURRENT_COMPILERTEST_H
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#define QTCONCURRENT_COMPILERTEST_H
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#include <QtConcurrent/qtconcurrent_global.h>
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#ifndef QT_NO_CONCURRENT
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QT_BEGIN_NAMESPACE
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namespace QtPrivate {
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template <class T, typename = void>
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struct IsIterable : std::false_type {};
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template <class T>
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struct IsIterable<T, std::void_t<decltype(std::declval<T>().begin()),
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decltype(std::declval<T>().end())>>
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: std::true_type
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{ };
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template <class T>
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inline constexpr bool IsIterableValue = IsIterable<T>::value;
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template <class T, typename = void>
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struct IsDereferenceable : std::false_type {};
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template <class T>
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struct IsDereferenceable<T, std::void_t<decltype(*std::declval<T>())>>
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: std::true_type
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{ };
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template <class T>
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inline constexpr bool IsDereferenceableValue = IsDereferenceable<T>::value;
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}
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QT_END_NAMESPACE
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#endif // QT_NO_CONCURRENT
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#endif
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