1 | /* GNU Objective C Runtime class related functions |
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2 | Copyright (C) 1993, 1995 Free Software Foundation, Inc. |
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3 | Contributed by Kresten Krab Thorup and Dennis Glatting. |
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4 | |
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5 | This file is part of GNU CC. |
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6 | |
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7 | GNU CC is free software; you can redistribute it and/or modify it under the |
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8 | terms of the GNU General Public License as published by the Free Software |
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9 | Foundation; either version 2, or (at your option) any later version. |
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10 | |
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11 | GNU CC is distributed in the hope that it will be useful, but WITHOUT ANY |
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12 | WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS |
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13 | FOR A PARTICULAR PURPOSE. See the GNU General Public License for more |
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14 | details. |
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15 | |
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16 | You should have received a copy of the GNU General Public License along with |
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17 | GNU CC; see the file COPYING. If not, write to the Free Software |
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18 | Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ |
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19 | |
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20 | /* As a special exception, if you link this library with files compiled with |
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21 | GCC to produce an executable, this does not cause the resulting executable |
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22 | to be covered by the GNU General Public License. This exception does not |
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23 | however invalidate any other reasons why the executable file might be |
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24 | covered by the GNU General Public License. */ |
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25 | |
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26 | #include "runtime.h" /* the kitchen sink */ |
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27 | #include "sarray.h" |
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28 | |
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29 | /* The table of classname->class. Used for objc_lookup_class and friends */ |
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30 | static cache_ptr __objc_class_hash = 0; |
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31 | |
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32 | /* This is a hook which is called by objc_get_class and |
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33 | objc_lookup_class if the runtime is not able to find the class. |
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34 | This may e.g. try to load in the class using dynamic loading */ |
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35 | Class (*_objc_lookup_class)(const char* name) = 0; |
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36 | |
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37 | |
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38 | /* True when class links has been resolved */ |
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39 | BOOL __objc_class_links_resolved = NO; |
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40 | |
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41 | |
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42 | /* Initial number of buckets size of class hash table. */ |
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43 | #define CLASS_HASH_SIZE 32 |
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44 | |
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45 | void __objc_init_class_tables() |
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46 | { |
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47 | /* Allocate the class hash table */ |
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48 | |
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49 | if(__objc_class_hash) |
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50 | return; |
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51 | |
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52 | __objc_class_hash |
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53 | = hash_new (CLASS_HASH_SIZE, |
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54 | (hash_func_type) hash_string, |
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55 | (compare_func_type) compare_strings); |
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56 | } |
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57 | |
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58 | /* This function adds a class to the class hash table, and assigns the |
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59 | class a number, unless it's already known */ |
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60 | void |
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61 | __objc_add_class_to_hash(Class class) |
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62 | { |
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63 | Class h_class; |
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64 | |
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65 | /* make sure the table is there */ |
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66 | assert(__objc_class_hash); |
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67 | |
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68 | /* make sure it's not a meta class */ |
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69 | assert(CLS_ISCLASS(class)); |
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70 | |
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71 | /* Check to see if the class is already in the hash table. */ |
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72 | h_class = hash_value_for_key (__objc_class_hash, class->name); |
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73 | if (!h_class) |
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74 | { |
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75 | /* The class isn't in the hash table. Add the class and assign a class |
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76 | number. */ |
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77 | static unsigned int class_number = 1; |
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78 | |
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79 | CLS_SETNUMBER(class, class_number); |
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80 | CLS_SETNUMBER(class->class_pointer, class_number); |
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81 | |
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82 | ++class_number; |
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83 | hash_add (&__objc_class_hash, class->name, class); |
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84 | } |
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85 | } |
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86 | |
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87 | /* Get the class object for the class named NAME. If NAME does not |
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88 | identify a known class, the hook _objc_lookup_class is called. If |
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89 | this fails, nil is returned */ |
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90 | Class objc_lookup_class (const char* name) |
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91 | { |
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92 | Class class; |
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93 | |
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94 | /* Make sure the class hash table exists. */ |
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95 | assert (__objc_class_hash); |
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96 | |
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97 | class = hash_value_for_key (__objc_class_hash, name); |
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98 | |
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99 | if (class) |
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100 | return class; |
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101 | |
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102 | if (_objc_lookup_class) |
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103 | return (*_objc_lookup_class)(name); |
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104 | else |
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105 | return 0; |
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106 | } |
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107 | |
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108 | /* Get the class object for the class named NAME. If NAME does not |
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109 | identify a known class, the hook _objc_lookup_class is called. If |
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110 | this fails, an error message is issued and the system aborts */ |
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111 | Class |
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112 | objc_get_class (const char *name) |
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113 | { |
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114 | Class class; |
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115 | |
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116 | /* Make sure the class hash table exists. */ |
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117 | assert (__objc_class_hash); |
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118 | |
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119 | class = hash_value_for_key (__objc_class_hash, name); |
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120 | |
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121 | if (class) |
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122 | return class; |
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123 | |
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124 | if (_objc_lookup_class) |
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125 | class = (*_objc_lookup_class)(name); |
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126 | |
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127 | if(class) |
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128 | return class; |
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129 | |
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130 | fprintf(stderr, "objc runtime: cannot find class %s\n", name); |
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131 | abort(); |
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132 | } |
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133 | |
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134 | MetaClass |
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135 | objc_get_meta_class(const char *name) |
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136 | { |
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137 | return objc_get_class(name)->class_pointer; |
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138 | } |
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139 | |
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140 | /* This function provides a way to enumerate all the classes in the |
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141 | executable. Pass *ENUM_STATE == NULL to start the enumeration. The |
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142 | function will return 0 when there are no more classes. |
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143 | For example: |
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144 | id class; |
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145 | void *es = NULL; |
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146 | while ((class = objc_next_class(&es))) |
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147 | ... do something with class; |
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148 | */ |
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149 | Class |
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150 | objc_next_class(void **enum_state) |
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151 | { |
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152 | /* make sure the table is there */ |
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153 | assert(__objc_class_hash); |
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154 | |
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155 | *(node_ptr*)enum_state = |
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156 | hash_next(__objc_class_hash, *(node_ptr*)enum_state); |
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157 | if (*(node_ptr*)enum_state) |
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158 | return (*(node_ptr*)enum_state)->value; |
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159 | return (Class)0; |
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160 | } |
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161 | |
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162 | /* Resolve super/subclass links for all classes. The only thing we |
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163 | can be sure of is that the class_pointer for class objects point |
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164 | to the right meta class objects */ |
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165 | void __objc_resolve_class_links() |
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166 | { |
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167 | node_ptr node; |
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168 | Class object_class = objc_get_class ("Object"); |
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169 | |
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170 | assert(object_class); |
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171 | |
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172 | /* Assign subclass links */ |
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173 | for (node = hash_next (__objc_class_hash, NULL); node; |
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174 | node = hash_next (__objc_class_hash, node)) |
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175 | { |
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176 | Class class1 = node->value; |
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177 | |
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178 | /* Make sure we have what we think we have. */ |
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179 | assert (CLS_ISCLASS(class1)); |
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180 | assert (CLS_ISMETA(class1->class_pointer)); |
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181 | |
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182 | /* The class_pointer of all meta classes point to Object's meta class. */ |
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183 | class1->class_pointer->class_pointer = object_class->class_pointer; |
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184 | |
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185 | if (!(CLS_ISRESOLV(class1))) |
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186 | { |
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187 | CLS_SETRESOLV(class1); |
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188 | CLS_SETRESOLV(class1->class_pointer); |
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189 | |
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190 | if(class1->super_class) |
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191 | { |
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192 | Class a_super_class |
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193 | = objc_get_class ((char *) class1->super_class); |
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194 | |
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195 | assert (a_super_class); |
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196 | |
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197 | DEBUG_PRINTF ("making class connections for: %s\n", |
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198 | class1->name); |
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199 | |
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200 | /* assign subclass links for superclass */ |
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201 | class1->sibling_class = a_super_class->subclass_list; |
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202 | a_super_class->subclass_list = class1; |
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203 | |
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204 | /* Assign subclass links for meta class of superclass */ |
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205 | if (a_super_class->class_pointer) |
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206 | { |
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207 | class1->class_pointer->sibling_class |
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208 | = a_super_class->class_pointer->subclass_list; |
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209 | a_super_class->class_pointer->subclass_list |
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210 | = class1->class_pointer; |
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211 | } |
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212 | } |
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213 | else /* a root class, make its meta object */ |
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214 | /* be a subclass of Object */ |
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215 | { |
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216 | class1->class_pointer->sibling_class |
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217 | = object_class->subclass_list; |
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218 | object_class->subclass_list = class1->class_pointer; |
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219 | } |
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220 | } |
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221 | } |
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222 | |
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223 | /* Assign superclass links */ |
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224 | for (node = hash_next (__objc_class_hash, NULL); node; |
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225 | node = hash_next (__objc_class_hash, node)) |
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226 | { |
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227 | Class class1 = node->value; |
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228 | Class sub_class; |
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229 | for (sub_class = class1->subclass_list; sub_class; |
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230 | sub_class = sub_class->sibling_class) |
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231 | { |
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232 | sub_class->super_class = class1; |
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233 | if(CLS_ISCLASS(sub_class)) |
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234 | sub_class->class_pointer->super_class = class1->class_pointer; |
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235 | } |
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236 | } |
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237 | } |
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238 | |
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239 | |
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240 | |
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241 | #define CLASSOF(c) ((c)->class_pointer) |
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242 | |
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243 | Class |
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244 | class_pose_as (Class impostor, Class super_class) |
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245 | { |
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246 | node_ptr node; |
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247 | Class class1; |
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248 | |
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249 | if (!CLS_ISRESOLV (impostor)) |
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250 | __objc_resolve_class_links (); |
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251 | |
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252 | /* preconditions */ |
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253 | assert (impostor); |
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254 | assert (super_class); |
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255 | assert (impostor->super_class == super_class); |
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256 | assert (CLS_ISCLASS (impostor)); |
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257 | assert (CLS_ISCLASS (super_class)); |
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258 | assert (impostor->instance_size == super_class->instance_size); |
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259 | |
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260 | { |
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261 | Class *subclass = &(super_class->subclass_list); |
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262 | |
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263 | /* move subclasses of super_class to impostor */ |
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264 | while (*subclass) |
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265 | { |
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266 | Class nextSub = (*subclass)->sibling_class; |
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267 | |
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268 | if (*subclass != impostor) |
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269 | { |
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270 | Class sub = *subclass; |
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271 | |
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272 | /* classes */ |
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273 | sub->sibling_class = impostor->subclass_list; |
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274 | sub->super_class = impostor; |
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275 | impostor->subclass_list = sub; |
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276 | |
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277 | /* It will happen that SUB is not a class object if it is |
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278 | the top of the meta class hierarchy chain. (root |
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279 | meta-class objects inherit their class object) If that is |
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280 | the case... don't mess with the meta-meta class. */ |
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281 | if (CLS_ISCLASS (sub)) |
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282 | { |
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283 | /* meta classes */ |
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284 | CLASSOF (sub)->sibling_class = CLASSOF (impostor)->subclass_list; |
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285 | CLASSOF (sub)->super_class = CLASSOF (impostor); |
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286 | CLASSOF (impostor)->subclass_list = CLASSOF (sub); |
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287 | } |
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288 | } |
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289 | |
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290 | *subclass = nextSub; |
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291 | } |
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292 | |
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293 | /* set subclasses of superclass to be impostor only */ |
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294 | super_class->subclass_list = impostor; |
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295 | CLASSOF (super_class)->subclass_list = CLASSOF (impostor); |
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296 | |
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297 | /* set impostor to have no sibling classes */ |
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298 | impostor->sibling_class = 0; |
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299 | CLASSOF (impostor)->sibling_class = 0; |
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300 | } |
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301 | |
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302 | /* check relationship of impostor and super_class is kept. */ |
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303 | assert (impostor->super_class == super_class); |
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304 | assert (CLASSOF (impostor)->super_class == CLASSOF (super_class)); |
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305 | |
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306 | /* This is how to update the lookup table. Regardless of |
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307 | what the keys of the hashtable is, change all values that are |
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308 | superclass into impostor. */ |
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309 | |
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310 | for (node = hash_next (__objc_class_hash, NULL); node; |
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311 | node = hash_next (__objc_class_hash, node)) |
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312 | { |
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313 | class1 = (Class)node->value; |
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314 | if (class1 == super_class) |
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315 | { |
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316 | node->value = impostor; /* change hash table value */ |
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317 | } |
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318 | } |
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319 | |
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320 | /* next, we update the dispatch tables... */ |
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321 | __objc_update_dispatch_table_for_class (CLASSOF (impostor)); |
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322 | __objc_update_dispatch_table_for_class (impostor); |
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323 | |
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324 | return impostor; |
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325 | } |
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326 | |
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327 | |
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