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qtypetraits.h: add is_signed/is_unsigned/not_/not_c predicates

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is_signed/is_unsigned check whether the type argument is signed
or unsigned, resp., and will be used in QFlags to select the
correct underlying integer type.

not_ is used in the implementation of is_signed

not_c is for completeness (version of not_ that takes a bool
instead of an integral_constant).

Change-Id: I77cc445e8c6cf3181336505c9c13478fba3e7890
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Marc Mutz 2012-09-20 15:01:09 +02:00 committed by The Qt Project
parent a19fd0f926
commit d85dd245f9
1 changed files with 90 additions and 1 deletions
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91
src/corelib/global/qtypetraits.h
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@ -1,3 +1,46 @@
/****************************************************************************
**
** Copyright (C) 2012 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Marc Mutz <marc.mutz@kdab.com>
** Contact: http://www.qt-project.org/legal
**
** 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 Digia. For licensing terms and
** conditions see http://qt.digia.com/licensing. For further information
** use the contact form at http://qt.digia.com/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 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Digia gives you certain additional
** rights. These rights are described in the Digia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
// BEGIN Google Code
// Copyright (c) 2006, Google Inc.
// All rights reserved.
//
@ -412,7 +455,53 @@ struct is_convertible
};
#endif
}
// END Google Code
// a metafunction to invert an integral_constant:
template <typename T>
struct not_
: integral_constant<bool, !T::value> {};
// same, with a bool argument:
template <bool B>
struct not_c
: integral_constant<bool, !B> {};
// Checks whether a type is unsigned (T must be convertible to unsigned int):
template <typename T>
struct is_unsigned
: integral_constant<bool, (T(0) < T(-1))> {};
// Checks whether a type is signed (T must be convertible to int):
template <typename T>
struct is_signed
: not_< is_unsigned<T> > {};
Q_STATIC_ASSERT(( is_unsigned<quint8>::value));
Q_STATIC_ASSERT((!is_unsigned<qint8>::value));
Q_STATIC_ASSERT((!is_signed<quint8>::value));
Q_STATIC_ASSERT(( is_signed<qint8>::value));
Q_STATIC_ASSERT(( is_unsigned<quint16>::value));
Q_STATIC_ASSERT((!is_unsigned<qint16>::value));
Q_STATIC_ASSERT((!is_signed<quint16>::value));
Q_STATIC_ASSERT(( is_signed<qint16>::value));
Q_STATIC_ASSERT(( is_unsigned<quint32>::value));
Q_STATIC_ASSERT((!is_unsigned<qint32>::value));
Q_STATIC_ASSERT((!is_signed<quint32>::value));
Q_STATIC_ASSERT(( is_signed<qint32>::value));
Q_STATIC_ASSERT(( is_unsigned<quint64>::value));
Q_STATIC_ASSERT((!is_unsigned<qint64>::value));
Q_STATIC_ASSERT((!is_signed<quint64>::value));
Q_STATIC_ASSERT(( is_signed<qint64>::value));
} // namespace QtPrivate
QT_END_NAMESPACE
QT_END_HEADER