1 | // -*- C++ -*- |
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2 | /*********************************************************************** |
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3 | * promote.h Arithmetic type promotion trait class |
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4 | * |
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5 | * $Id$ |
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6 | * |
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7 | * Copyright (C) 1997-2011 Todd Veldhuizen <tveldhui@acm.org> |
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8 | * |
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9 | * This file is a part of Blitz. |
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10 | * |
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11 | * Blitz is free software: you can redistribute it and/or modify |
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12 | * it under the terms of the GNU Lesser General Public License |
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13 | * as published by the Free Software Foundation, either version 3 |
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14 | * of the License, or (at your option) any later version. |
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15 | * |
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16 | * Blitz is distributed in the hope that it will be useful, |
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17 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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18 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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19 | * GNU Lesser General Public License for more details. |
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20 | * |
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21 | * You should have received a copy of the GNU Lesser General Public |
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22 | * License along with Blitz. If not, see <http://www.gnu.org/licenses/>. |
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23 | * |
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24 | * Suggestions: blitz-devel@lists.sourceforge.net |
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25 | * Bugs: blitz-support@lists.sourceforge.net |
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26 | * |
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27 | * For more information, please see the Blitz++ Home Page: |
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28 | * https://sourceforge.net/projects/blitz/ |
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29 | * |
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30 | ***************************************************************************/ |
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31 | |
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32 | #ifndef BZ_PROMOTE_H |
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33 | #define BZ_PROMOTE_H |
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34 | |
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35 | #include <blitz/blitz.h> |
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36 | |
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37 | BZ_NAMESPACE(blitz) |
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38 | |
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39 | #ifdef BZ_HAVE_TEMPLATE_QUALIFIED_RETURN_TYPE |
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40 | #define BZ_PROMOTE(A,B) _bz_typename BZ_BLITZ_SCOPE(promote_trait)<A,B>::T_promote |
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41 | #else |
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42 | #define BZ_PROMOTE(A,B) A |
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43 | #endif |
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44 | |
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45 | #if defined(BZ_HAVE_PARTIAL_SPECIALIZATION) && !defined(BZ_DISABLE_NEW_PROMOTE) |
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46 | |
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47 | /* |
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48 | * This compiler supports partial specialization, so type promotion |
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49 | * can be done the elegant way. This implementation is after ideas |
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50 | * by Jean-Louis Leroy. |
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51 | */ |
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52 | |
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53 | template<typename T> |
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54 | struct precision_trait { |
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55 | static const int precisionRank = 0; |
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56 | static const bool knowPrecisionRank = false; |
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57 | }; |
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58 | |
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59 | #define BZ_DECLARE_PRECISION(T,rank) \ |
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60 | template<> \ |
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61 | struct precision_trait< T > { \ |
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62 | static const int precisionRank = rank; \ |
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63 | static const bool knowPrecisionRank = true; \ |
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64 | }; |
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65 | |
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66 | BZ_DECLARE_PRECISION(int,100) |
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67 | BZ_DECLARE_PRECISION(unsigned int,200) |
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68 | BZ_DECLARE_PRECISION(long,300) |
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69 | BZ_DECLARE_PRECISION(unsigned long,400) |
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70 | BZ_DECLARE_PRECISION(float,500) |
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71 | BZ_DECLARE_PRECISION(double,600) |
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72 | BZ_DECLARE_PRECISION(long double,700) |
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73 | |
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74 | #ifdef BZ_HAVE_COMPLEX |
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75 | BZ_DECLARE_PRECISION(complex<float>,800) |
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76 | BZ_DECLARE_PRECISION(complex<double>,900) |
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77 | BZ_DECLARE_PRECISION(complex<long double>,1000) |
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78 | #endif |
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79 | |
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80 | template<typename T> |
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81 | struct autopromote_trait { |
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82 | typedef T T_numtype; |
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83 | }; |
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84 | |
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85 | #define BZ_DECLARE_AUTOPROMOTE(T1,T2) \ |
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86 | template<> \ |
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87 | struct autopromote_trait<T1> { \ |
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88 | typedef T2 T_numtype; \ |
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89 | }; |
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90 | |
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91 | // These are the odd cases where small integer types |
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92 | // are automatically promoted to int or unsigned int for |
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93 | // arithmetic. |
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94 | BZ_DECLARE_AUTOPROMOTE(bool, int) |
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95 | BZ_DECLARE_AUTOPROMOTE(char, int) |
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96 | BZ_DECLARE_AUTOPROMOTE(unsigned char, int) |
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97 | BZ_DECLARE_AUTOPROMOTE(short int, int) |
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98 | BZ_DECLARE_AUTOPROMOTE(short unsigned int, unsigned int) |
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99 | |
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100 | template<typename T1, typename T2, bool promoteToT1> |
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101 | struct _bz_promote2 { |
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102 | typedef T1 T_promote; |
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103 | }; |
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104 | |
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105 | template<typename T1, typename T2> |
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106 | struct _bz_promote2<T1,T2,false> { |
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107 | typedef T2 T_promote; |
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108 | }; |
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109 | |
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110 | template<typename T1_orig, typename T2_orig> |
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111 | struct promote_trait { |
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112 | // Handle promotion of small integers to int/unsigned int |
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113 | typedef _bz_typename autopromote_trait<T1_orig>::T_numtype T1; |
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114 | typedef _bz_typename autopromote_trait<T2_orig>::T_numtype T2; |
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115 | |
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116 | // True if T1 is higher ranked |
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117 | static const bool |
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118 | T1IsBetter = |
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119 | precision_trait<T1>::precisionRank > |
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120 | precision_trait<T2>::precisionRank; |
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121 | |
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122 | // True if we know ranks for both T1 and T2 |
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123 | static const bool |
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124 | knowBothRanks = |
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125 | precision_trait<T1>::knowPrecisionRank && |
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126 | precision_trait<T2>::knowPrecisionRank; |
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127 | |
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128 | // True if we know T1 but not T2 |
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129 | static const bool |
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130 | knowT1butNotT2 = |
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131 | precision_trait<T1>::knowPrecisionRank && |
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132 | !precision_trait<T2>::knowPrecisionRank; |
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133 | |
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134 | // True if we know T2 but not T1 |
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135 | static const bool |
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136 | knowT2butNotT1 = |
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137 | precision_trait<T2>::knowPrecisionRank && |
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138 | !precision_trait<T1>::knowPrecisionRank; |
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139 | |
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140 | // True if T1 is bigger than T2 |
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141 | static const bool |
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142 | T1IsLarger = sizeof(T1) >= sizeof(T2); |
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143 | |
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144 | // We know T1 but not T2: false |
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145 | // We know T2 but not T1: true |
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146 | // Otherwise, if T1 is bigger than T2: true |
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147 | // static const bool |
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148 | // defaultPromotion = knowT1butNotT2 ? false : |
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149 | // (knowT2butNotT1 ? true : T1IsLarger); |
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150 | |
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151 | // If we have both ranks, then use them. |
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152 | // If we have only one rank, then use the unknown type. |
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153 | // If we have neither rank, then promote to the larger type. |
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154 | static const bool |
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155 | promoteToT1 = knowBothRanks ? T1IsBetter : (knowT1butNotT2 ? false : |
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156 | (knowT2butNotT1 ? true : T1IsLarger)); |
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157 | // static const bool |
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158 | // promoteToT1 = knowBothRanks ? T1IsBetter : defaultPromotion; |
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159 | |
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160 | typedef _bz_typename _bz_promote2<T1,T2,promoteToT1>::T_promote T_promote; |
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161 | }; |
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162 | |
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163 | #else // !BZ_HAVE_PARTIAL_SPECIALIZATION |
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164 | |
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165 | // No partial specialization -- have to do it the ugly way. |
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166 | #include <blitz/promote-old.h> |
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167 | |
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168 | #endif // !BZ_HAVE_PARTIAL_SPECIALIZATION |
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169 | |
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170 | BZ_NAMESPACE_END |
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171 | |
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172 | #endif // BZ_PROMOTE_H |
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