vide_public/external/healpix/cxxsupport/safe_cast.h
2012-10-30 13:56:48 -04:00

92 lines
2.7 KiB
C++

/*
* This file is part of libcxxsupport.
*
* libcxxsupport is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* libcxxsupport is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with libcxxsupport; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
/*
* libcxxsupport is being developed at the Max-Planck-Institut fuer Astrophysik
* and financially supported by the Deutsches Zentrum fuer Luft- und Raumfahrt
* (DLR).
*/
/*! \file safe_cast.h
* Numerical cast operator with additional checks that the value is preserved.
*
* Copyright (C) 2009 Max-Planck-Society
* Author: Martin Reinecke
*/
#ifndef PLANCK_SAFE_CAST_H
#define PLANCK_SAFE_CAST_H
#include <limits>
#include "error_handling.h"
template<typename T1, typename T2, bool s1, bool s2> struct safe_cast_helper__
{};
template<typename T1, typename T2> struct safe_cast_helper__ <T1,T2,true,true>
{
static T1 cast (const T2 &arg)
{
T1 res = T1(arg);
planck_assert(T2(res)==arg, "safe_cast: value changed during cast");
return res;
}
};
template<typename T1, typename T2> struct safe_cast_helper__ <T1,T2,false,false>
{
static T1 cast (const T2 &arg)
{
T1 res = T1(arg);
planck_assert(T2(res)==arg, "safe_cast: value changed during cast");
return res;
}
};
template<typename T1, typename T2> struct safe_cast_helper__ <T1,T2,true,false>
{
static T1 cast (const T2 &arg)
{
T1 res = T1(arg);
planck_assert((res>=0) && (T2(res)==arg),
"safe_cast: value changed during cast");
return res;
}
};
template<typename T1, typename T2> struct safe_cast_helper__ <T1,T2,false,true>
{
static T1 cast (const T2 &arg)
{
T1 res = T1(arg);
planck_assert((arg>=0) && (T2(res)==arg),
"safe_cast: value changed during cast");
return res;
}
};
/*! Tries to cast \a arg from its type to a variable of type \c T1.
If this conversion leads to a change of the actual value (e.g. due to
overflow or truncation), an exception is thrown. */
template<typename T1, typename T2> inline T1 safe_cast(const T2 &arg)
{
return safe_cast_helper__<T1,T2,std::numeric_limits<T1>::is_signed,
std::numeric_limits<T2>::is_signed>::cast(arg);
}
#endif