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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__) && defined (USE_PRAGMA_INTERFACE_IMPLEMENTATION) |
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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 "quit.h" |
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32 |
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33 #include "error.h" |
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34 #include "oct-lvalue.h" |
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35 #include "ov.h" |
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36 #include "pt-bp.h" |
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37 #include "pt-cmd.h" |
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38 #include "pt-except.h" |
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39 #include "pt-exp.h" |
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40 #include "pt-jump.h" |
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41 #include "pt-stmt.h" |
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42 #include "pt-walk.h" |
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43 #include "unwind-prot.h" |
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44 #include "variables.h" |
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45 |
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46 // Simple exception handling. |
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47 |
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48 tree_try_catch_command::~tree_try_catch_command (void) |
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49 { |
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50 delete try_code; |
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51 delete catch_code; |
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52 delete lead_comm; |
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53 delete mid_comm; |
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54 delete trail_comm; |
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55 } |
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56 |
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57 static void |
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58 do_catch_code (void *ptr) |
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59 { |
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60 // Is it safe to call OCTAVE_QUIT here? We are already running |
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61 // something on the unwind_protect stack, but the element for this |
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62 // action would have already been popped from the top of the stack, |
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63 // so we should not be attempting to run it again. |
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64 |
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65 OCTAVE_QUIT; |
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66 |
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67 // If we are interrupting immediately, or if an interrupt is in |
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68 // progress (octave_interrupt_state < 0), then we don't want to run |
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69 // the catch code (it should only run on errors, not interrupts). |
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70 |
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71 // If octave_interrupt_state is positive, an interrupt is pending. |
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72 // The only way that could happen would be for the interrupt to |
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73 // come in after the OCTAVE_QUIT above and before the if statement |
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74 // below -- it's possible, but unlikely. In any case, we should |
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75 // probably let the catch code throw the exception because we don't |
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76 // want to skip that and potentially run some other code. For |
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77 // example, an error may have originally brought us here for some |
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78 // cleanup operation and we shouldn't skip that. |
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79 |
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80 if (octave_interrupt_immediately || octave_interrupt_state < 0) |
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81 return; |
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82 |
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83 tree_statement_list *list = static_cast<tree_statement_list *> (ptr); |
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84 |
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85 // Set up for letting the user print any messages from errors that |
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86 // occurred in the body of the try_catch statement. |
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87 |
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88 buffer_error_messages--; |
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89 |
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90 if (list) |
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91 list->eval (); |
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92 } |
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93 |
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94 void |
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95 tree_try_catch_command::eval (void) |
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96 { |
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97 unwind_protect::begin_frame ("tree_try_catch::eval"); |
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98 |
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99 MAYBE_DO_BREAKPOINT; |
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100 |
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101 if (catch_code) |
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102 { |
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103 unwind_protect_int (buffer_error_messages); |
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104 buffer_error_messages++; |
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105 } |
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106 |
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107 unwind_protect::add (do_catch_code, catch_code); |
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108 |
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109 if (try_code) |
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110 try_code->eval (); |
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111 |
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112 if (catch_code && error_state) |
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113 { |
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114 error_state = 0; |
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115 unwind_protect::run_frame ("tree_try_catch::eval"); |
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116 } |
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117 else |
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118 { |
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119 error_state = 0; |
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120 |
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121 // Unwind stack elements must be cleared or run in the reverse |
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122 // order in which they were added to the stack. |
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123 |
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124 // For clearing the do_catch_code cleanup function. |
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125 unwind_protect::discard (); |
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126 |
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127 // For restoring buffer_error_messages. |
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128 if (catch_code) |
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129 unwind_protect::run (); |
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130 |
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131 // Also clear the frame marker. |
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132 unwind_protect::discard (); |
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133 } |
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134 } |
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135 |
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136 void |
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137 tree_try_catch_command::accept (tree_walker& tw) |
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138 { |
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139 tw.visit_try_catch_command (*this); |
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140 } |
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141 |
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142 // Simple exception handling. |
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143 |
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144 tree_unwind_protect_command::~tree_unwind_protect_command (void) |
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145 { |
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146 delete unwind_protect_code; |
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147 delete cleanup_code; |
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148 delete lead_comm; |
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149 delete mid_comm; |
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150 delete trail_comm; |
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151 } |
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152 |
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153 static void |
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154 do_unwind_protect_cleanup_code (void *ptr) |
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155 { |
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156 tree_statement_list *list = static_cast<tree_statement_list *> (ptr); |
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157 |
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158 // We want to run the cleanup code without error_state being set, |
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159 // but we need to restore its value, so that any errors encountered |
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160 // in the first part of the unwind_protect are not completely |
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161 // ignored. |
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162 |
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163 unwind_protect_int (error_state); |
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164 error_state = 0; |
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165 |
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166 // Similarly, if we have seen a return or break statement, allow all |
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167 // the cleanup code to run before returning or handling the break. |
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168 // We don't have to worry about continue statements because they can |
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169 // only occur in loops. |
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170 |
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171 unwind_protect_int (tree_return_command::returning); |
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172 tree_return_command::returning = 0; |
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173 |
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174 unwind_protect_int (tree_break_command::breaking); |
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175 tree_break_command::breaking = 0; |
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176 |
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177 if (list) |
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178 list->eval (); |
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179 |
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180 // The unwind_protects are popped off the stack in the reverse of |
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181 // the order they are pushed on. |
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182 |
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183 // XXX FIXME XXX -- these statements say that if we see a break or |
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184 // return statement in the cleanup block, that we want to use the |
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185 // new value of the breaking or returning flag instead of restoring |
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186 // the previous value. Is that the right thing to do? I think so. |
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187 // Consider the case of |
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188 // |
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189 // function foo () |
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190 // unwind_protect |
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191 // stderr << "1: this should always be executed\n"; |
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192 // break; |
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193 // stderr << "1: this should never be executed\n"; |
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194 // unwind_protect_cleanup |
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195 // stderr << "2: this should always be executed\n"; |
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196 // return; |
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197 // stderr << "2: this should never be executed\n"; |
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198 // end_unwind_protect |
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199 // endfunction |
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200 // |
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201 // If we reset the value of the breaking flag, both the returning |
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202 // flag and the breaking flag will be set, and we shouldn't have |
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203 // both. So, use the most recent one. If there is no return or |
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204 // break in the cleanup block, the values should be reset to |
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205 // whatever they were when the cleanup block was entered. |
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206 |
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207 if (tree_break_command::breaking || tree_return_command::returning) |
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208 { |
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209 unwind_protect::discard (); |
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210 unwind_protect::discard (); |
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211 } |
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212 else |
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213 { |
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214 unwind_protect::run (); |
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215 unwind_protect::run (); |
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216 } |
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217 |
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218 // We don't want to ignore errors that occur in the cleanup code, so |
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219 // if an error is encountered there, leave error_state alone. |
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220 // Otherwise, set it back to what it was before. |
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221 |
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222 if (error_state) |
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223 unwind_protect::discard (); |
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224 else |
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225 unwind_protect::run (); |
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226 } |
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227 |
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228 void |
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229 tree_unwind_protect_command::eval (void) |
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230 { |
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231 unwind_protect::add (do_unwind_protect_cleanup_code, cleanup_code); |
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232 |
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233 MAYBE_DO_BREAKPOINT; |
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234 |
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235 if (unwind_protect_code) |
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236 unwind_protect_code->eval (); |
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237 |
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238 unwind_protect::run (); |
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239 } |
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240 |
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241 void |
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242 tree_unwind_protect_command::accept (tree_walker& tw) |
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243 { |
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244 tw.visit_unwind_protect_command (*this); |
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245 } |
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246 |
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247 /* |
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248 ;;; Local Variables: *** |
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249 ;;; mode: C++ *** |
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250 ;;; End: *** |
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251 */ |
