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/*
* Tiny Vector Matrix Library
* Dense Vector Matrix Libary of Tiny size using Expression Templates
*
* Copyright (C) 2001 - 2003 Olaf Petzold <opetzold@users.sourceforge.net>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* $Id: TypePromotion.h,v 1.6 2003/11/30 08:26:25 opetzold Exp $
*/
#ifndef TVMET_TYPE_PROMOTION_H
#define TVMET_TYPE_PROMOTION_H
namespace tvmet {
/**
* \class PrecisionTraits TypePromotion.h "tvmet/TypePromotion.h"
* \brief Declaring ranks of types to avoid specializing
*
* All possible promoted types. For example, bool=1, int=2, float=3, double=4,
* etc. We can use a traits class to map from a type such as float onto its
* "precision rank". We will promote to whichever type has a higher
* "precision rank". f there is no "precision rank" for a type, we'll
* promote to whichever type requires more storage space
* (and hopefully more precision).
*/
template<class T>
struct PrecisionTraits {
enum {
rank = 0, /**< the rank of type. */
known = 0 /**< true, if the rank is specialized = known. */
};
};
#define TVMET_PRECISION(T,R) \
template<> \
struct PrecisionTraits< T > { \
enum { \
rank = R, \
known = 1 \
}; \
};
/*
* pod types
*/
TVMET_PRECISION(int, 100)
TVMET_PRECISION(float, 700)
TVMET_PRECISION(double, 800)
/*
* complex types
*/
#if defined(TVMET_HAVE_COMPLEX)
TVMET_PRECISION(std::complex<int>, 1000)
TVMET_PRECISION(std::complex<float>, 1600)
TVMET_PRECISION(std::complex<double>, 1700)
#endif // defined(TVMET_HAVE_COMPLEX)
/** \class PrecisionTraits<int> TypePromotion.h "tvmet/TypePromotion.h" */
/** \class PrecisionTraits<unsigned int> TypePromotion.h "tvmet/TypePromotion.h" */
/** \class PrecisionTraits<long> TypePromotion.h "tvmet/TypePromotion.h" */
/** \class PrecisionTraits<unsigned long> TypePromotion.h "tvmet/TypePromotion.h" */
/** \class PrecisionTraits<long long> TypePromotion.h "tvmet/TypePromotion.h" */
/** \class PrecisionTraits<unsigned long long> TypePromotion.h "tvmet/TypePromotion.h" */
/** \class PrecisionTraits<float> TypePromotion.h "tvmet/TypePromotion.h" */
/** \class PrecisionTraits<double> TypePromotion.h "tvmet/TypePromotion.h" */
/** \class PrecisionTraits<long double> TypePromotion.h "tvmet/TypePromotion.h" */
/** \class PrecisionTraits< std::complex<int> > TypePromotion.h "tvmet/TypePromotion.h" */
/** \class PrecisionTraits< std::complex<unsigned int> > TypePromotion.h "tvmet/TypePromotion.h" */
/** \class PrecisionTraits< std::complex<long> > TypePromotion.h "tvmet/TypePromotion.h" */
/** \class PrecisionTraits< std::complex<unsigned long> > TypePromotion.h "tvmet/TypePromotion.h" */
/** \class PrecisionTraits< std::complex<long long> > TypePromotion.h "tvmet/TypePromotion.h" */
/** \class PrecisionTraits< std::complex<unsigned long long> > TypePromotion.h "tvmet/TypePromotion.h" */
/** \class PrecisionTraits< std::complex<float> > TypePromotion.h "tvmet/TypePromotion.h" */
/** \class PrecisionTraits< std::complex<double> > TypePromotion.h "tvmet/TypePromotion.h" */
/** \class PrecisionTraits< std::complex<long double> > TypePromotion.h "tvmet/TypePromotion.h" */
#undef TVMET_PRECISION
/**
* \class AutopromoteTraits TypePromotion.h "tvmet/TypePromotion.h"
* \brief The promoted types traits.
*/
template<class T>
struct AutopromoteTraits {
typedef T value_type;
};
/**
* \class promoteTo TypePromotion.h "tvmet/TypePromotion.h"
* \brief Promote to T1.
*/
template<class T1, class T2, int promoteToT1>
struct promoteTo {
typedef T1 value_type;
};
/**
* \class promoteTo<T1,T2,0> TypePromotion.h "tvmet/TypePromotion.h"
* \brief Promote to T2
*/
template<class T1, class T2>
struct promoteTo<T1,T2,0> {
typedef T2 value_type;
};
/**
* \class PromoteTraits TypePromotion.h "tvmet/TypePromotion.h"
* \brief Promote type traits
*/
template<class T1org, class T2org>
class PromoteTraits {
// Handle promotion of small integers to int/unsigned int
typedef typename AutopromoteTraits<T1org>::value_type T1;
typedef typename AutopromoteTraits<T2org>::value_type T2;
enum {
// True if T1 is higher ranked
T1IsBetter = int(PrecisionTraits<T1>::rank) > int(PrecisionTraits<T2>::rank),
// True if we know ranks for both T1 and T2
knowBothRanks = PrecisionTraits<T1>::known && PrecisionTraits<T2>::known,
// True if we know T1 but not T2
knowT1butNotT2 = PrecisionTraits<T1>::known && !(PrecisionTraits<T2>::known),
// True if we know T2 but not T1
knowT2butNotT1 = PrecisionTraits<T2>::known && !(PrecisionTraits<T1>::known),
// True if T1 is bigger than T2
T1IsLarger = sizeof(T1) >= sizeof(T2),
// We know T1 but not T2: true
// We know T2 but not T1: false
// Otherwise, if T1 is bigger than T2: true
defaultPromotion = knowT1butNotT2 ? false : (knowT2butNotT1 ? true : T1IsLarger),
// If we have both ranks, then use them.
// If we have only one rank, then use the unknown type.
// If we have neither rank, then promote to the larger type.
promoteToT1 = (knowBothRanks ? T1IsBetter : defaultPromotion) ? 1 : 0
};
public:
typedef typename promoteTo<T1,T2,promoteToT1>::value_type value_type;
};
} // namespace tvmet
#endif // TVMET_TYPE_PROMOTION_H
// Local Variables:
// mode:C++
// End:
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