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1 /* |
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2 |
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3 Copyright (C) 1996, 1997 John W. Eaton |
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4 |
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5 This file is part of Octave. |
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6 |
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7 Octave is free software; you can redistribute it and/or modify it |
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8 under the terms of the GNU General Public License as published by the |
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9 Free Software Foundation; either version 2, or (at your option) any |
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10 later version. |
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11 |
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12 Octave is distributed in the hope that it will be useful, but WITHOUT |
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13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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15 for more details. |
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16 |
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17 You should have received a copy of the GNU General Public License |
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18 along with Octave; see the file COPYING. If not, write to the Free |
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19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
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20 |
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21 */ |
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22 |
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23 #if defined (__GNUG__) |
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24 #pragma implementation |
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25 #endif |
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26 |
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27 #ifdef HAVE_CONFIG_H |
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28 #include <config.h> |
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29 #endif |
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30 |
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31 #include "error.h" |
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32 #include "oct-lvalue.h" |
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33 #include "ov.h" |
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34 #include "pt-cmd.h" |
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35 #include "pt-except.h" |
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36 #include "pt-exp.h" |
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37 #include "pt-jump.h" |
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38 #include "pt-stmt.h" |
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39 #include "pt-walk.h" |
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40 #include "unwind-prot.h" |
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41 #include "variables.h" |
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42 |
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43 // Simple exception handling. |
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44 |
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45 tree_try_catch_command::~tree_try_catch_command (void) |
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46 { |
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47 delete try_code; |
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48 delete catch_code; |
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49 delete lead_comm; |
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50 delete mid_comm; |
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51 delete trail_comm; |
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52 } |
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53 |
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54 static void |
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55 do_catch_code (void *ptr) |
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56 { |
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57 tree_statement_list *list = static_cast<tree_statement_list *> (ptr); |
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58 |
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59 unwind_protect::begin_frame ("do_catch_code"); |
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60 |
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61 // Set up for letting the user print any messages from errors that |
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62 // occurred in the body of the try_catch statement. |
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63 |
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64 unwind_protect_bool (buffer_error_messages); |
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65 buffer_error_messages = false; |
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66 |
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67 bind_global_error_variable (); |
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68 |
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69 unwind_protect::add (clear_global_error_variable, 0); |
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70 |
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71 if (list) |
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72 list->eval (); |
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73 |
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74 unwind_protect::run_frame ("do_catch_code"); |
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75 } |
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76 |
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77 void |
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78 tree_try_catch_command::eval (void) |
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79 { |
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80 unwind_protect::begin_frame ("tree_try_catch::eval"); |
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81 |
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82 if (catch_code) |
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83 { |
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84 unwind_protect_bool (buffer_error_messages); |
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85 buffer_error_messages = true; |
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86 } |
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87 |
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88 unwind_protect::add (do_catch_code, catch_code); |
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89 |
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90 if (try_code) |
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91 try_code->eval (); |
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92 |
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93 if (catch_code && error_state) |
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94 { |
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95 error_state = 0; |
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96 unwind_protect::run_frame ("tree_try_catch::eval"); |
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97 } |
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98 else |
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99 { |
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100 error_state = 0; |
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101 |
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102 // For clearing the do_catch_code cleanup function. |
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103 unwind_protect::discard (); |
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104 |
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105 // For restoring buffer_error_messages. |
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106 if (catch_code) |
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107 unwind_protect::run (); |
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108 |
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109 // Also clear the frame marker. |
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110 unwind_protect::discard (); |
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111 } |
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112 } |
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113 |
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114 void |
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115 tree_try_catch_command::accept (tree_walker& tw) |
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116 { |
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117 tw.visit_try_catch_command (*this); |
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118 } |
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119 |
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120 // Simple exception handling. |
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121 |
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122 tree_unwind_protect_command::~tree_unwind_protect_command (void) |
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123 { |
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124 delete unwind_protect_code; |
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125 delete cleanup_code; |
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126 delete lead_comm; |
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127 delete mid_comm; |
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128 delete trail_comm; |
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129 } |
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130 |
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131 static void |
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132 do_unwind_protect_cleanup_code (void *ptr) |
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133 { |
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134 tree_statement_list *list = static_cast<tree_statement_list *> (ptr); |
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135 |
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136 // We want to run the cleanup code without error_state being set, |
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137 // but we need to restore its value, so that any errors encountered |
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138 // in the first part of the unwind_protect are not completely |
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139 // ignored. |
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140 |
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141 unwind_protect_int (error_state); |
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142 error_state = 0; |
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143 |
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144 // Similarly, if we have seen a return or break statement, allow all |
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145 // the cleanup code to run before returning or handling the break. |
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146 // We don't have to worry about continue statements because they can |
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147 // only occur in loops. |
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148 |
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149 unwind_protect_int (tree_return_command::returning); |
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150 tree_return_command::returning = 0; |
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151 |
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152 unwind_protect_int (tree_break_command::breaking); |
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153 tree_break_command::breaking = 0; |
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154 |
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155 if (list) |
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156 list->eval (); |
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157 |
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158 // The unwind_protects are popped off the stack in the reverse of |
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159 // the order they are pushed on. |
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160 |
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161 // XXX FIXME XXX -- these statements say that if we see a break or |
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162 // return statement in the cleanup block, that we want to use the |
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163 // new value of the breaking or returning flag instead of restoring |
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164 // the previous value. Is that the right thing to do? I think so. |
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165 // Consider the case of |
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166 // |
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167 // function foo () |
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168 // unwind_protect |
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169 // stderr << "1: this should always be executed\n"; |
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170 // break; |
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171 // stderr << "1: this should never be executed\n"; |
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172 // unwind_protect_cleanup |
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173 // stderr << "2: this should always be executed\n"; |
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174 // return; |
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175 // stderr << "2: this should never be executed\n"; |
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176 // end_unwind_protect |
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177 // endfunction |
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178 // |
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179 // If we reset the value of the breaking flag, both the returning |
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180 // flag and the breaking flag will be set, and we shouldn't have |
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181 // both. So, use the most recent one. If there is no return or |
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182 // break in the cleanup block, the values should be reset to |
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183 // whatever they were when the cleanup block was entered. |
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184 |
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185 if (tree_break_command::breaking || tree_return_command::returning) |
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186 { |
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187 unwind_protect::discard (); |
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188 unwind_protect::discard (); |
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189 } |
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190 else |
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191 { |
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192 unwind_protect::run (); |
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193 unwind_protect::run (); |
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194 } |
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195 |
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196 // We don't want to ignore errors that occur in the cleanup code, so |
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197 // if an error is encountered there, leave error_state alone. |
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198 // Otherwise, set it back to what it was before. |
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199 |
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200 if (error_state) |
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201 unwind_protect::discard (); |
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202 else |
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203 unwind_protect::run (); |
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204 } |
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205 |
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206 void |
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207 tree_unwind_protect_command::eval (void) |
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208 { |
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209 unwind_protect::add (do_unwind_protect_cleanup_code, cleanup_code); |
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210 |
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211 if (unwind_protect_code) |
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212 unwind_protect_code->eval (); |
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213 |
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214 unwind_protect::run (); |
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215 } |
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216 |
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217 void |
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218 tree_unwind_protect_command::accept (tree_walker& tw) |
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219 { |
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220 tw.visit_unwind_protect_command (*this); |
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221 } |
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222 |
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223 /* |
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224 ;;; Local Variables: *** |
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225 ;;; mode: C++ *** |
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226 ;;; End: *** |
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227 */ |
