Dogcows Code - chaz/yoink/blob - src/cml/et/scalar_promotions.h

   1 /* -*- C++ -*- ------------------------------------------------------------
   2
   3 Copyright (c) 2007 Jesse Anders and Demian Nave http://cmldev.net/
   4
   5 The Configurable Math Library (CML) is distributed under the terms of the
   6 Boost Software License, v1.0 (see cml/LICENSE for details).
   7
   8  *-----------------------------------------------------------------------*/
   9 /** @file
  10  *  @brief
  11  */
  12
  13 #ifndef scalar_promotions_h
  14 #define scalar_promotions_h
  15
  16 #include <cml/core/cml_meta.h>
  17
  18 namespace cml {
  19 namespace et {
  20
  21 namespace detail {
  22
  23 /** @class IntPromote
  24  *  @brief Helper template to int-promote a type.
  25  */
  26 template<class T> struct IntPromote
  27 {
  28     /* Signed -> signed int, unsigned -> unsigned int: */
  29     typedef typename select_switch<T,
  30             unsigned char,                       unsigned int,
  31             unsigned short,                      unsigned int,
  32             signed char,                         int,
  33             char,                                int,
  34             short,                               int,
  35             T,                                   T
  36     >::result   result;
  37 };
  38
  39 } // namespace detail
  40
  41 /** @class ScalarPromote
  42  *  @brief Template for compile-time type promotion via C promotion rules.
  43  */
  44 template<class E1_in, class E2_in> struct ScalarPromote
  45 {
  46
  47     /* Integral-promote the types (if possible). */
  48     typedef typename detail::IntPromote<E1_in>::result  E1;
  49     typedef typename detail::IntPromote<E2_in>::result  E2;
  50
  51     /* If sizeof(long) == sizeof(unsigned int), promote to unsigned long.
  52      * Otherwise, sizeof(long) > sizeof(int), so promote to long.
  53      */
  54     typedef typename select_if<sizeof(long) == sizeof(unsigned int),
  55             unsigned long,
  56             long
  57     >::result   uint_promotion;
  58
  59     /* Do the selection on the promoted types: */
  60     typedef typename select_switch<
  61         type_pair<E1,E2>,
  62
  63 #if defined(CML_USE_LONG_DOUBLE)
  64         type_pair<long double,long double>,       long double,
  65         type_pair<long double,E2>,                long double,
  66         type_pair<E1,long double>,                long double,
  67 #endif
  68
  69         type_pair<double,double>,                 double,
  70         type_pair<double,E2>,                     double,
  71         type_pair<E1,double>,                     double,
  72
  73         type_pair<float,float>,                   float,
  74         type_pair<float,E2>,                      float,
  75         type_pair<E1,float>,                      float,
  76
  77         type_pair<E1,E2>,                         void
  78
  79     >::result   float_filter;
  80
  81     /* The promoted integral types really matter here: */
  82     typedef typename select_switch<
  83         type_pair<E1,E2>,
  84
  85         type_pair<unsigned long,unsigned long>,   unsigned long,
  86         type_pair<unsigned long,E2>,              unsigned long,
  87         type_pair<E1,unsigned long>,              unsigned long,
  88
  89         type_pair<long,long>,                     long,
  90         type_pair<long,unsigned int>,             uint_promotion,
  91         type_pair<unsigned int,long>,             uint_promotion,
  92
  93         type_pair<long,E2>,                       long,
  94         type_pair<E1,long>,                       long,
  95
  96         type_pair<unsigned int,unsigned int>,     unsigned int,
  97         type_pair<unsigned int,E2>,               unsigned int,
  98         type_pair<E1,unsigned int>,               unsigned int,
  99
 100         type_pair<int,int>,                       int,
 101         type_pair<int,E2>,                        int,
 102         type_pair<E1,int>,                        int,
 103
 104         type_pair<E1,E2>,                         void
 105
 106     >::result   int_filter;
 107
 108     /* Deduce the final type: */
 109     typedef typename select_if<
 110         same_type<float_filter,void>::is_true,
 111         int_filter, float_filter>::result         type;
 112 };
 113
 114 } // namespace et
 115 } // namespace cml
 116
 117 #endif
 118
 119 // -------------------------------------------------------------------------
 120 // vim:ft=cpp