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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, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
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20 02110-1301, USA. |
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21 |
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22 */ |
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23 |
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24 #ifdef HAVE_CONFIG_H |
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25 #include <config.h> |
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26 #endif |
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27 |
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28 #include "quit.h" |
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29 |
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30 #include "error.h" |
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31 #include "oct-lvalue.h" |
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32 #include "ov.h" |
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33 #include "pt-bp.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 // Is it safe to call OCTAVE_QUIT here? We are already running |
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58 // something on the unwind_protect stack, but the element for this |
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59 // action would have already been popped from the top of the stack, |
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60 // so we should not be attempting to run it again. |
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61 |
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62 OCTAVE_QUIT; |
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63 |
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64 // If we are interrupting immediately, or if an interrupt is in |
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65 // progress (octave_interrupt_state < 0), then we don't want to run |
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66 // the catch code (it should only run on errors, not interrupts). |
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67 |
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68 // If octave_interrupt_state is positive, an interrupt is pending. |
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69 // The only way that could happen would be for the interrupt to |
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70 // come in after the OCTAVE_QUIT above and before the if statement |
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71 // below -- it's possible, but unlikely. In any case, we should |
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72 // probably let the catch code throw the exception because we don't |
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73 // want to skip that and potentially run some other code. For |
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74 // example, an error may have originally brought us here for some |
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75 // cleanup operation and we shouldn't skip that. |
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76 |
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77 if (octave_interrupt_immediately || octave_interrupt_state < 0) |
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78 return; |
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79 |
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80 tree_statement_list *list = static_cast<tree_statement_list *> (ptr); |
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81 |
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82 // Set up for letting the user print any messages from errors that |
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83 // occurred in the body of the try_catch statement. |
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84 |
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85 buffer_error_messages--; |
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86 |
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87 if (list) |
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88 list->eval (); |
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89 } |
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90 |
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91 void |
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92 tree_try_catch_command::eval (void) |
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93 { |
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94 unwind_protect::begin_frame ("tree_try_catch::eval"); |
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95 |
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96 MAYBE_DO_BREAKPOINT; |
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97 |
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98 unwind_protect_int (buffer_error_messages); |
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99 buffer_error_messages++; |
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100 |
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101 unwind_protect::add (do_catch_code, catch_code); |
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102 |
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103 if (try_code) |
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104 try_code->eval (); |
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105 |
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106 if (catch_code && error_state) |
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107 { |
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108 error_state = 0; |
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109 unwind_protect::run_frame ("tree_try_catch::eval"); |
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110 } |
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111 else |
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112 { |
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113 error_state = 0; |
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114 |
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115 // Unwind stack elements must be cleared or run in the reverse |
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116 // order in which they were added to the stack. |
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117 |
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118 // For clearing the do_catch_code cleanup function. |
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119 unwind_protect::discard (); |
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120 |
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121 // For restoring buffer_error_messages. |
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122 unwind_protect::run (); |
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123 |
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124 // Also clear the frame marker. |
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125 unwind_protect::discard (); |
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126 } |
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127 } |
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128 |
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129 void |
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130 tree_try_catch_command::accept (tree_walker& tw) |
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131 { |
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132 tw.visit_try_catch_command (*this); |
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133 } |
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134 |
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135 // Simple exception handling. |
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136 |
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137 tree_unwind_protect_command::~tree_unwind_protect_command (void) |
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138 { |
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139 delete unwind_protect_code; |
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140 delete cleanup_code; |
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141 delete lead_comm; |
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142 delete mid_comm; |
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143 delete trail_comm; |
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144 } |
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145 |
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146 static void |
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147 do_unwind_protect_cleanup_code (void *ptr) |
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148 { |
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149 tree_statement_list *list = static_cast<tree_statement_list *> (ptr); |
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150 |
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151 // We want to run the cleanup code without error_state being set, |
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152 // but we need to restore its value, so that any errors encountered |
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153 // in the first part of the unwind_protect are not completely |
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154 // ignored. |
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155 |
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156 unwind_protect_int (error_state); |
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157 error_state = 0; |
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158 |
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159 // Similarly, if we have seen a return or break statement, allow all |
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160 // the cleanup code to run before returning or handling the break. |
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161 // We don't have to worry about continue statements because they can |
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162 // only occur in loops. |
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163 |
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164 unwind_protect_int (tree_return_command::returning); |
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165 tree_return_command::returning = 0; |
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166 |
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167 unwind_protect_int (tree_break_command::breaking); |
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168 tree_break_command::breaking = 0; |
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169 |
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170 if (list) |
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171 list->eval (); |
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172 |
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173 // The unwind_protects are popped off the stack in the reverse of |
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174 // the order they are pushed on. |
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175 |
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176 // XXX FIXME XXX -- these statements say that if we see a break or |
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177 // return statement in the cleanup block, that we want to use the |
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178 // new value of the breaking or returning flag instead of restoring |
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179 // the previous value. Is that the right thing to do? I think so. |
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180 // Consider the case of |
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181 // |
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182 // function foo () |
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183 // unwind_protect |
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184 // stderr << "1: this should always be executed\n"; |
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185 // break; |
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186 // stderr << "1: this should never be executed\n"; |
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187 // unwind_protect_cleanup |
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188 // stderr << "2: this should always be executed\n"; |
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189 // return; |
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190 // stderr << "2: this should never be executed\n"; |
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191 // end_unwind_protect |
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192 // endfunction |
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193 // |
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194 // If we reset the value of the breaking flag, both the returning |
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195 // flag and the breaking flag will be set, and we shouldn't have |
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196 // both. So, use the most recent one. If there is no return or |
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197 // break in the cleanup block, the values should be reset to |
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198 // whatever they were when the cleanup block was entered. |
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199 |
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200 if (tree_break_command::breaking || tree_return_command::returning) |
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201 { |
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202 unwind_protect::discard (); |
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203 unwind_protect::discard (); |
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204 } |
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205 else |
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206 { |
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207 unwind_protect::run (); |
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208 unwind_protect::run (); |
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209 } |
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210 |
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211 // We don't want to ignore errors that occur in the cleanup code, so |
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212 // if an error is encountered there, leave error_state alone. |
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213 // Otherwise, set it back to what it was before. |
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214 |
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215 if (error_state) |
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216 unwind_protect::discard (); |
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217 else |
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218 unwind_protect::run (); |
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219 } |
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220 |
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221 void |
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222 tree_unwind_protect_command::eval (void) |
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223 { |
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224 unwind_protect::add (do_unwind_protect_cleanup_code, cleanup_code); |
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225 |
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226 MAYBE_DO_BREAKPOINT; |
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227 |
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228 if (unwind_protect_code) |
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229 unwind_protect_code->eval (); |
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230 |
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231 unwind_protect::run (); |
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232 } |
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233 |
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234 void |
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235 tree_unwind_protect_command::accept (tree_walker& tw) |
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236 { |
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237 tw.visit_unwind_protect_command (*this); |
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238 } |
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239 |
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240 /* |
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241 ;;; Local Variables: *** |
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242 ;;; mode: C++ *** |
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243 ;;; End: *** |
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244 */ |
