Diff: tvmet/TypePromotion.h

Revision:

15:9c5aaeda36dc

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tvmet/TypePromotion.h	Sat Apr 06 20:57:54 2013 +0000
@@ -0,0 +1,232 @@
+/*
+ * Tiny Vector Matrix Library
+ * Dense Vector Matrix Libary of Tiny size using Expression Templates
+ *
+ * Copyright (C) 2001 - 2007 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 1.10 2007-06-23 15:58:58 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(unsigned int, 200)
+TVMET_PRECISION(long, 300)
+TVMET_PRECISION(unsigned long, 400)
+
+#if defined(TVMET_HAVE_LONG_LONG)
+TVMET_PRECISION(long long, 500)
+TVMET_PRECISION(unsigned long long, 600)
+#endif // defined(TVMET_HAVE_LONG_LONG)
+
+TVMET_PRECISION(float, 700)
+TVMET_PRECISION(double, 800)
+
+#if defined(TVMET_HAVE_LONG_DOUBLE)
+TVMET_PRECISION(long double, 900)
+#endif // defined(TVMET_HAVE_LONG_DOUBLE)
+
+
+/*
+ * complex types
+ */
+#if defined(TVMET_HAVE_COMPLEX)
+TVMET_PRECISION(std::complex<int>, 1000)
+TVMET_PRECISION(std::complex<unsigned int>, 1100)
+TVMET_PRECISION(std::complex<long>, 1200)
+TVMET_PRECISION(std::complex<unsigned long>, 1300)
+
+#if defined(TVMET_HAVE_LONG_LONG)
+TVMET_PRECISION(std::complex<long long>, 1400)
+TVMET_PRECISION(std::complex<unsigned long long>, 1500)
+#endif // defined(TVMET_HAVE_LONG_LONG)
+
+TVMET_PRECISION(std::complex<float>, 1600)
+TVMET_PRECISION(std::complex<double>, 1700)
+
+#if defined(TVMET_HAVE_LONG_DOUBLE)
+TVMET_PRECISION(std::complex<long double>, 1800)
+#endif // defined(TVMET_HAVE_LONG_DOUBLE)
+
+#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;
+};
+
+
+/*
+ * Defines a macro for specializing/defining
+ * the promotion traits. bool, char, unsigned char, short int, etc. will
+ * be autopromote to int, as in C and C++.
+ */
+#define TVMET_AUTOPROMOTE(T1,T2)                       \
+template<>                                               \
+struct AutopromoteTraits<T1> {                         \
+  typedef T2 value_type;                              \
+};
+
+TVMET_AUTOPROMOTE(bool, int)
+TVMET_AUTOPROMOTE(char, int)
+TVMET_AUTOPROMOTE(unsigned char, int)
+TVMET_AUTOPROMOTE(short int, int)
+TVMET_AUTOPROMOTE(short unsigned int, unsigned int)
+
+/** \class AutopromoteTraits<bool>    TypePromotion.h "tvmet/TypePromotion.h" */
+/** \class AutopromoteTraits<char>    TypePromotion.h "tvmet/TypePromotion.h" */
+/** \class AutopromoteTraits<unsigned char> TypePromotion.h "tvmet/TypePromotion.h" */
+/** \class AutopromoteTraits<short int>    TypePromotion.h "tvmet/TypePromotion.h" */
+/** \class AutopromoteTraits<short unsigned int> TypePromotion.h "tvmet/TypePromotion.h" */
+
+#undef TVMET_AUTOPROMOTE
+
+
+/**
+ * \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++
+// tab-width:8
+// End: