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1 // Boost Lambda Library -- switch.hpp ----------------------------------- |
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2 // |
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3 // Copyright (C) 2000 Gary Powell (powellg@amazon.com) |
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4 // Copyright (C) 1999, 2000 Jaakko Järvi (jaakko.jarvi@cs.utu.fi) |
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5 // |
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6 // Distributed under the Boost Software License, Version 1.0. (See |
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7 // accompanying file LICENSE_1_0.txt or copy at |
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8 // http://www.boost.org/LICENSE_1_0.txt) |
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9 // |
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10 // For more information, see www.boost.org |
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11 |
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12 // -------------------------------------------------------------------------- |
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13 |
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14 #if !defined(BOOST_LAMBDA_SWITCH_HPP) |
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15 #define BOOST_LAMBDA_SWITCH_HPP |
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16 |
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17 #include "boost/lambda/core.hpp" |
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18 #include "boost/lambda/detail/control_constructs_common.hpp" |
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19 |
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20 #include "boost/preprocessor/enum_shifted_params.hpp" |
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21 #include "boost/preprocessor/repeat_2nd.hpp" |
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22 #include "boost/preprocessor/tuple.hpp" |
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23 |
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24 namespace boost { |
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25 namespace lambda { |
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26 |
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27 // Switch actions |
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28 template <int N, class Switch1 = null_type, class Switch2 = null_type, |
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29 class Switch3 = null_type, class Switch4 = null_type, |
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30 class Switch5 = null_type, class Switch6 = null_type, |
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31 class Switch7 = null_type, class Switch8 = null_type, |
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32 class Switch9 = null_type> |
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33 struct switch_action {}; |
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34 |
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35 |
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36 namespace detail { |
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37 |
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38 // templates to represent special lambda functors for the cases in |
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39 // switch statements |
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40 |
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41 template <int Value> struct case_label {}; |
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42 struct default_label {}; |
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43 |
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44 template<class Type> struct switch_case_tag {}; |
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45 |
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46 // a normal case is represented as: |
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47 // tagged_lambda_functor<switch_case_tag<case_label<N> > >, LambdaFunctor> |
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48 |
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49 // the default case as: |
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50 // tagged_lambda_functor<switch_case_tag<default_label> >, LambdaFunctor> |
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51 |
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52 |
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53 } // end detail |
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54 |
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55 |
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56 /// create switch_case_tag tagged_lambda_functors |
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57 template <int CaseValue, class Arg> |
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58 inline const |
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59 tagged_lambda_functor< |
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60 detail::switch_case_tag<detail::case_label<CaseValue> >, |
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61 lambda_functor<Arg> |
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62 > |
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63 case_statement(const lambda_functor<Arg>& a) { |
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64 return |
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65 tagged_lambda_functor< |
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66 detail::switch_case_tag<detail::case_label<CaseValue> >, |
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67 lambda_functor<Arg> |
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68 >(a); |
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69 } |
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70 |
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71 // No case body case. |
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72 template <int CaseValue> |
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73 inline const |
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74 tagged_lambda_functor< |
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75 detail::switch_case_tag<detail::case_label<CaseValue> >, |
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76 lambda_functor< |
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77 lambda_functor_base< |
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78 do_nothing_action, |
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79 null_type |
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80 > |
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81 > |
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82 > |
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83 case_statement() { |
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84 return |
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85 tagged_lambda_functor< |
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86 detail::switch_case_tag<detail::case_label<CaseValue> >, |
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87 lambda_functor< |
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88 lambda_functor_base< |
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89 do_nothing_action, |
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90 null_type |
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91 > |
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92 > |
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93 > () ; |
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94 } |
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95 |
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96 // default label |
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97 template <class Arg> |
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98 inline const |
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99 tagged_lambda_functor< |
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100 detail::switch_case_tag<detail::default_label>, |
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101 lambda_functor<Arg> |
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102 > |
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103 default_statement(const lambda_functor<Arg>& a) { |
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104 return |
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105 tagged_lambda_functor< |
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106 detail::switch_case_tag<detail::default_label>, |
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107 lambda_functor<Arg> |
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108 >(a); |
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109 } |
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110 |
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111 // default lable, no case body case. |
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112 inline const |
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113 tagged_lambda_functor< |
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114 detail::switch_case_tag<detail::default_label>, |
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115 lambda_functor< |
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116 lambda_functor_base< |
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117 do_nothing_action, |
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118 null_type |
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119 > |
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120 > |
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121 > |
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122 default_statement() { |
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123 return |
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124 lambda_functor_base< |
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125 do_nothing_action, |
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126 null_type |
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127 > () ; |
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128 } |
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129 |
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130 |
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131 // Specializations for lambda_functor_base of case_statement ----------------- |
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132 |
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133 // 0 case type: |
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134 // useless (just the condition part) but provided for completeness. |
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135 template<class Args> |
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136 class |
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137 lambda_functor_base< |
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138 switch_action<1>, |
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139 Args |
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140 > |
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141 { |
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142 public: |
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143 Args args; |
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144 template <class SigArgs> struct sig { typedef void type; }; |
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145 public: |
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146 explicit lambda_functor_base(const Args& a) : args(a) {} |
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147 |
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148 template<class RET, CALL_TEMPLATE_ARGS> |
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149 RET call(CALL_FORMAL_ARGS) const { |
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150 detail::select(::boost::tuples::get<1>(args), CALL_ACTUAL_ARGS); |
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151 } |
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152 }; |
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153 |
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154 // 1 case type: |
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155 // template<class Args, int Case1> |
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156 // class |
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157 // lambda_functor_base< |
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158 // action< |
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159 // 2, |
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160 // return_void_action<switch_action<detail::case_label<Case1> > > |
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161 // >, |
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162 // Args |
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163 // > |
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164 // { |
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165 // Args args; |
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166 // public: |
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167 // explicit lambda_functor_base(const Args& a) : args(a) {} |
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168 |
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169 // template<class RET, class A, class B, class C> |
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170 // RET call(A& a, B& b, C& c) const { |
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171 // switch( detail::select(::boost::tuples::get<0>(args), a, b, c) ) |
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172 // { |
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173 // case Case1: |
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174 // detail::select(::boost::tuples::get<1>(args), a, b, c); |
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175 // break; |
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176 // } |
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177 // } |
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178 // }; |
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179 |
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180 // switch with default being the sole label - doesn't make much sense but |
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181 // it is there for completeness |
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182 // template<class Args> |
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183 // class |
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184 // lambda_functor_base< |
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185 // action< |
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186 // 2, |
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187 // return_void_action<switch_action<detail::default_label> > |
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188 // >, |
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189 // Args |
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190 // > |
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191 // { |
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192 // Args args; |
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193 // public: |
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194 // explicit lambda_functor_base(const Args& a) : args(a) {} |
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195 // |
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196 // template<class RET, class A, class B, class C> |
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197 // RET call(A& a, B& b, C& c) const { |
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198 // switch( detail::select(::boost::tuples::get<0>(args), a, b, c) ) |
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199 // { |
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200 // default: |
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201 // detail::select(::boost::tuples::get<1>(args), a, b, c); |
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202 // break; |
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203 // } |
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204 // } |
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205 // }; |
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206 |
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207 |
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208 |
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209 // // 2 case type: |
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210 // The different specializations are generated with Vesa Karvonen's |
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211 // preprocessor library. |
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212 |
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213 // This is just a comment to show what the generated classes look like |
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214 |
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215 // template<class Args, int Case1, int Case2> |
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216 // class |
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217 // lambda_functor_base< |
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218 // action<3, |
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219 // return_void_action< |
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220 // switch_action< |
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221 // detail::case_label<Case1>, |
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222 // detail::case_label<Case2> |
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223 // > |
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224 // > |
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225 // >, |
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226 // Args |
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227 // > |
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228 // { |
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229 // Args args; |
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230 // public: |
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231 // explicit lambda_functor_base(const Args& a) : args(a) {} |
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232 |
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233 // template<class RET, class A, class B, class C> |
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234 // RET call(A& a, B& b, C& c) const { |
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235 // switch( detail::select(::boost::tuples::get<0>(args), a, b, c) ) |
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236 // { |
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237 // case Case1: |
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238 // detail::select(::boost::tuples::get<1>(args), a, b, c); |
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239 // break; |
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240 // case Case2: |
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241 // detail::select(::boost::tuples::get<2>(args), a, b, c); |
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242 // break; |
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243 // } |
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244 // } |
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245 // }; |
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246 |
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247 // template<class Args, int Case1> |
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248 // class |
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249 // lambda_functor_base< |
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250 // action<3, |
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251 // return_void_action< |
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252 // switch_action< |
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253 // detail::case_label<Case1>, |
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254 // detail::default_label |
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255 // > |
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256 // > |
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257 // >, |
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258 // Args |
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259 // > |
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260 // { |
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261 // Args args; |
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262 // public: |
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263 // explicit lambda_functor_base(const Args& a) : args(a) {} |
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264 |
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265 // template<class RET, class A, class B, class C> |
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266 // RET call(A& a, B& b, C& c) const { |
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267 // switch( detail::select(::boost::tuples::get<0>(args), a, b, c) ) |
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268 // { |
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269 // case Case1: |
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270 // detail::select(::boost::tuples::get<1>(args), a, b, c); |
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271 // break; |
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272 // default: |
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273 // detail::select(::boost::tuples::get<2>(args), a, b, c); |
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274 // break; |
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275 // } |
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276 // } |
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277 // }; |
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278 // ------------------------- |
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279 |
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280 // Some helper preprocessor macros --------------------------------- |
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281 |
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282 // BOOST_LAMBDA_A_I_LIST(N, X) is a list of form X0, X1, ..., XN |
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283 // BOOST_LAMBDA_A_I_B_LIST(N, X, Y) is a list of form X0 Y, X1 Y, ..., XN Y |
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284 |
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285 #define BOOST_LAMBDA_A_I(z, i, A) \ |
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286 BOOST_PP_COMMA_IF(i) BOOST_PP_CAT(A,i) |
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287 |
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288 #define BOOST_LAMBDA_A_I_B(z, i, T) \ |
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289 BOOST_PP_COMMA_IF(i) BOOST_PP_CAT(BOOST_PP_TUPLE_ELEM(2,0,T),i) BOOST_PP_TUPLE_ELEM(2,1,T) |
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290 |
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291 #define BOOST_LAMBDA_A_I_LIST(i, A) \ |
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292 BOOST_PP_REPEAT(i,BOOST_LAMBDA_A_I, A) |
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293 |
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294 #define BOOST_LAMBDA_A_I_B_LIST(i, A, B) \ |
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295 BOOST_PP_REPEAT(i,BOOST_LAMBDA_A_I_B, (A,B)) |
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296 |
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297 |
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298 // Switch related macros ------------------------------------------- |
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299 #define BOOST_LAMBDA_SWITCH_CASE_BLOCK(z, N, A) \ |
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300 case Case##N: \ |
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301 detail::select(::boost::tuples::get<BOOST_PP_INC(N)>(args), CALL_ACTUAL_ARGS); \ |
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302 break; |
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303 |
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304 #define BOOST_LAMBDA_SWITCH_CASE_BLOCK_LIST(N) \ |
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305 BOOST_PP_REPEAT(N, BOOST_LAMBDA_SWITCH_CASE_BLOCK, FOO) |
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306 // 2 case type: |
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307 |
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308 #define BOOST_LAMBDA_SWITCH_NO_DEFAULT_CASE(N) \ |
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309 template<class Args, BOOST_LAMBDA_A_I_LIST(N, int Case)> \ |
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310 class \ |
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311 lambda_functor_base< \ |
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312 switch_action<BOOST_PP_INC(N), \ |
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313 BOOST_LAMBDA_A_I_B_LIST(N, detail::case_label<Case,>) \ |
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314 >, \ |
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315 Args \ |
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316 > \ |
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317 { \ |
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318 public: \ |
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319 Args args; \ |
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320 template <class SigArgs> struct sig { typedef void type; }; \ |
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321 public: \ |
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322 explicit lambda_functor_base(const Args& a) : args(a) {} \ |
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323 \ |
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324 template<class RET, CALL_TEMPLATE_ARGS> \ |
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325 RET call(CALL_FORMAL_ARGS) const { \ |
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326 switch( detail::select(::boost::tuples::get<0>(args), CALL_ACTUAL_ARGS) ) \ |
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327 { \ |
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328 BOOST_LAMBDA_SWITCH_CASE_BLOCK_LIST(N) \ |
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329 } \ |
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330 } \ |
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331 }; |
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332 |
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333 |
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334 |
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335 #define BOOST_LAMBDA_SWITCH_WITH_DEFAULT_CASE(N) \ |
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336 template< \ |
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337 class Args BOOST_PP_COMMA_IF(BOOST_PP_DEC(N)) \ |
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338 BOOST_LAMBDA_A_I_LIST(BOOST_PP_DEC(N), int Case) \ |
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339 > \ |
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340 class \ |
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341 lambda_functor_base< \ |
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342 switch_action<BOOST_PP_INC(N), \ |
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343 BOOST_LAMBDA_A_I_B_LIST(BOOST_PP_DEC(N), \ |
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344 detail::case_label<Case, >) \ |
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345 BOOST_PP_COMMA_IF(BOOST_PP_DEC(N)) \ |
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346 detail::default_label \ |
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347 >, \ |
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348 Args \ |
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349 > \ |
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350 { \ |
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351 public: \ |
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352 Args args; \ |
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353 template <class SigArgs> struct sig { typedef void type; }; \ |
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354 public: \ |
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355 explicit lambda_functor_base(const Args& a) : args(a) {} \ |
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356 \ |
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357 template<class RET, CALL_TEMPLATE_ARGS> \ |
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358 RET call(CALL_FORMAL_ARGS) const { \ |
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359 switch( detail::select(::boost::tuples::get<0>(args), CALL_ACTUAL_ARGS) ) \ |
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360 { \ |
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361 BOOST_LAMBDA_SWITCH_CASE_BLOCK_LIST(BOOST_PP_DEC(N)) \ |
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362 default: \ |
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363 detail::select(::boost::tuples::get<N>(args), CALL_ACTUAL_ARGS); \ |
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364 break; \ |
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365 } \ |
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366 } \ |
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367 }; |
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368 |
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369 |
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370 |
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371 |
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372 |
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373 |
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374 // switch_statement bind functions ------------------------------------- |
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375 |
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376 // The zero argument case, for completeness sake |
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377 inline const |
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378 lambda_functor< |
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379 lambda_functor_base< |
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380 do_nothing_action, |
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381 null_type |
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382 > |
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383 > |
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384 switch_statement() { |
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385 return |
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386 lambda_functor_base< |
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387 do_nothing_action, |
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388 null_type |
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389 > |
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390 (); |
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391 } |
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392 |
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393 // 1 argument case, this is useless as well, just the condition part |
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394 template <class TestArg> |
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395 inline const |
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396 lambda_functor< |
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397 lambda_functor_base< |
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398 switch_action<1>, |
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399 tuple<lambda_functor<TestArg> > |
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400 > |
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401 > |
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402 switch_statement(const lambda_functor<TestArg>& a1) { |
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403 return |
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404 lambda_functor_base< |
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405 switch_action<1>, |
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406 tuple< lambda_functor<TestArg> > |
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407 > |
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408 ( tuple<lambda_functor<TestArg> >(a1)); |
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409 } |
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410 |
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411 |
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412 #define HELPER(z, N, FOO) \ |
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413 BOOST_PP_COMMA_IF(N) \ |
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414 BOOST_PP_CAT( \ |
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415 const tagged_lambda_functor<detail::switch_case_tag<TagData, \ |
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416 N>) \ |
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417 BOOST_PP_COMMA() Arg##N>& a##N |
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418 |
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419 #define HELPER_LIST(N) BOOST_PP_REPEAT(N, HELPER, FOO) |
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420 |
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421 |
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422 #define BOOST_LAMBDA_SWITCH_STATEMENT(N) \ |
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423 template <class TestArg, \ |
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424 BOOST_LAMBDA_A_I_LIST(N, class TagData), \ |
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425 BOOST_LAMBDA_A_I_LIST(N, class Arg)> \ |
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426 inline const \ |
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427 lambda_functor< \ |
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428 lambda_functor_base< \ |
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429 switch_action<BOOST_PP_INC(N), \ |
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430 BOOST_LAMBDA_A_I_LIST(N, TagData) \ |
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431 >, \ |
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432 tuple<lambda_functor<TestArg>, BOOST_LAMBDA_A_I_LIST(N, Arg)> \ |
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433 > \ |
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434 > \ |
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435 switch_statement( \ |
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436 const lambda_functor<TestArg>& ta, \ |
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437 HELPER_LIST(N) \ |
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438 ) \ |
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439 { \ |
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440 return \ |
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441 lambda_functor_base< \ |
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442 switch_action<BOOST_PP_INC(N), \ |
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443 BOOST_LAMBDA_A_I_LIST(N, TagData) \ |
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444 >, \ |
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445 tuple<lambda_functor<TestArg>, BOOST_LAMBDA_A_I_LIST(N, Arg)> \ |
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446 > \ |
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447 ( tuple<lambda_functor<TestArg>, BOOST_LAMBDA_A_I_LIST(N, Arg)> \ |
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448 (ta, BOOST_LAMBDA_A_I_LIST(N, a) )); \ |
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449 } |
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450 |
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451 |
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452 |
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453 |
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454 // Here's the actual generation |
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455 |
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456 #define BOOST_LAMBDA_SWITCH(N) \ |
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457 BOOST_LAMBDA_SWITCH_NO_DEFAULT_CASE(N) \ |
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458 BOOST_LAMBDA_SWITCH_WITH_DEFAULT_CASE(N) |
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459 |
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460 // Use this to avoid case 0, these macros work only from case 1 upwards |
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461 #define BOOST_LAMBDA_SWITCH_HELPER(z, N, A) \ |
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462 BOOST_LAMBDA_SWITCH( BOOST_PP_INC(N) ) |
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463 |
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464 // Use this to avoid cases 0 and 1, these macros work only from case 2 upwards |
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465 #define BOOST_LAMBDA_SWITCH_STATEMENT_HELPER(z, N, A) \ |
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466 BOOST_LAMBDA_SWITCH_STATEMENT(BOOST_PP_INC(N)) |
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467 |
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468 |
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469 |
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470 // up to 9 cases supported (counting default:) |
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471 BOOST_PP_REPEAT_2ND(9,BOOST_LAMBDA_SWITCH_HELPER,FOO) |
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472 BOOST_PP_REPEAT_2ND(9,BOOST_LAMBDA_SWITCH_STATEMENT_HELPER,FOO) |
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473 |
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474 |
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475 } // namespace lambda |
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476 } // namespace boost |
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477 |
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478 |
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479 #undef HELPER |
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480 #undef HELPER_LIST |
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481 |
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482 #undef BOOST_LAMBDA_SWITCH_HELPER |
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483 #undef BOOST_LAMBDA_SWITCH |
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484 #undef BOOST_LAMBDA_SWITCH_NO_DEFAULT_CASE |
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485 #undef BOOST_LAMBDA_SWITCH_WITH_DEFAULT_CASE |
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486 |
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487 #undef BOOST_LAMBDA_SWITCH_CASE_BLOCK |
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488 #undef BOOST_LAMBDA_SWITCH_CASE_BLOCK_LIST |
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489 |
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490 #undef BOOST_LAMBDA_SWITCH_STATEMENT |
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491 #undef BOOST_LAMBDA_SWITCH_STATEMENT_HELPER |
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492 |
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493 |
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494 |
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495 #endif |
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496 |
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497 |
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498 |
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499 |
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500 |
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501 |
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502 |