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/****************************************************************************
**
** Copyright (C) 2020 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtQml 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 QJSNUMBERCOERCION_H
#define QJSNUMBERCOERCION_H
#include <QtCore/qglobal.h>
#include <cstring>
QT_BEGIN_NAMESPACE
class QJSNumberCoercion
{
public:
static constexpr int toInteger(double d) {
int i = static_cast<int>(d);
if (equals(i, d))
return i;
return QJSNumberCoercion(d).toInteger();
}
static constexpr bool equals(double lhs, double rhs)
{
QT_WARNING_PUSH
QT_WARNING_DISABLE_FLOAT_COMPARE
return lhs == rhs;
QT_WARNING_POP
}
private:
constexpr QJSNumberCoercion(double dbl)
{
// the dbl == 0 path is guaranteed constexpr. The other one may or may not be, depending
// on whether and how the compiler inlines the memcpy.
// In order to declare the ctor constexpr we need one guaranteed constexpr path.
if (!equals(dbl, 0))
memcpy(&d, &dbl, sizeof(double));
}
constexpr int sign() const
{
return (d >> 63) ? -1 : 1;
}
constexpr bool isDenormal() const
{
return static_cast<int>((d << 1) >> 53) == 0;
}
constexpr int exponent() const
{
return static_cast<int>((d << 1) >> 53) - 1023;
}
constexpr quint64 significant() const
{
quint64 m = (d << 12) >> 12;
if (!isDenormal())
m |= (static_cast<quint64>(1) << 52);
return m;
}
constexpr int toInteger()
{
int e = exponent() - 52;
if (e < 0) {
if (e <= -53)
return 0;
return sign() * static_cast<int>(significant() >> -e);
} else {
if (e > 31)
return 0;
return sign() * (static_cast<int>(significant()) << e);
}
}
quint64 d = 0;
};
QT_END_NAMESPACE
#endif // QJSNUMBERCOERCION_H
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