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/****************************************************************************
**
** Copyright (C) 2017 Intel Corporation.
** Contact: https://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 QRANDOM_H
#define QRANDOM_H
#include <QtCore/qglobal.h>
#include <algorithm> // for std::generate
QT_BEGIN_NAMESPACE
class QRandomGenerator
{
// restrict the template parameters to unsigned integers 32 bits wide or larger
template <typename UInt> using IfValidUInt =
typename std::enable_if<std::is_unsigned<UInt>::value && sizeof(UInt) >= sizeof(uint), bool>::type;
public:
static QRandomGenerator system() { return {}; }
static QRandomGenerator global() { return {}; }
QRandomGenerator() = default;
// ### REMOVE BEFORE 5.10
QRandomGenerator *operator->() { return this; }
static quint32 get32() { return generate(); }
static quint64 get64() { return generate64(); }
static qreal getReal() { return generateDouble(); }
static Q_CORE_EXPORT quint32 generate();
static Q_CORE_EXPORT quint64 generate64();
static double generateDouble()
{
// IEEE 754 double precision has:
// 1 bit sign
// 10 bits exponent
// 53 bits mantissa
// In order for our result to be normalized in the range [0, 1), we
// need exactly 53 bits of random data. Use generate64() to get enough.
quint64 x = generate64();
quint64 limit = Q_UINT64_C(1) << std::numeric_limits<double>::digits;
x >>= std::numeric_limits<quint64>::digits - std::numeric_limits<double>::digits;
return double(x) / double(limit);
}
static qreal bounded(qreal sup)
{
return generateDouble() * sup;
}
static quint32 bounded(quint32 sup)
{
quint64 value = generate();
value *= sup;
value /= (max)() + quint64(1);
return quint32(value);
}
static int bounded(int sup)
{
return int(bounded(quint32(sup)));
}
static quint32 bounded(quint32 min, quint32 sup)
{
return bounded(sup - min) + min;
}
static int bounded(int min, int sup)
{
return bounded(sup - min) + min;
}
template <typename UInt, IfValidUInt<UInt> = true>
static void fillRange(UInt *buffer, qssize_t count)
{
fillRange_helper(buffer, buffer + count);
}
template <typename UInt, size_t N, IfValidUInt<UInt> = true>
static void fillRange(UInt (&buffer)[N])
{
fillRange_helper(buffer, buffer + N);
}
// API like std::seed_seq
template <typename ForwardIterator>
void generate(ForwardIterator begin, ForwardIterator end)
{
auto generator = static_cast<quint32 (*)()>(&QRandomGenerator::generate);
std::generate(begin, end, generator);
}
void generate(quint32 *begin, quint32 *end)
{
fillRange_helper(begin, end);
}
// API like std::random_device
typedef quint32 result_type;
result_type operator()() { return generate(); }
double entropy() const Q_DECL_NOTHROW { return 0.0; }
static Q_DECL_CONSTEXPR result_type min() { return (std::numeric_limits<result_type>::min)(); }
static Q_DECL_CONSTEXPR result_type max() { return (std::numeric_limits<result_type>::max)(); }
private:
static Q_CORE_EXPORT void fillRange_helper(void *buffer, void *bufferEnd);
};
class QRandomGenerator64
{
public:
static QRandomGenerator64 system() { return {}; }
static QRandomGenerator64 global() { return {}; }
QRandomGenerator64() = default;
static quint64 generate() { return QRandomGenerator::generate64(); }
// API like std::random_device
typedef quint64 result_type;
result_type operator()() { return QRandomGenerator::generate64(); }
double entropy() const Q_DECL_NOTHROW { return 0.0; }
static Q_DECL_CONSTEXPR result_type min() { return (std::numeric_limits<result_type>::min)(); }
static Q_DECL_CONSTEXPR result_type max() { return (std::numeric_limits<result_type>::max)(); }
};
QT_END_NAMESPACE
#endif // QRANDOM_H
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