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1 | /* GNU Objective C Runtime class related functions |
2 | Copyright (C) 1993, 1995, 1996, 1997 Free Software Foundation, Inc. | |
3 | Contributed by Kresten Krab Thorup and Dennis Glatting. | |
4 | ||
5 | This file is part of GNU CC. | |
6 | ||
7 | GNU CC is free software; you can redistribute it and/or modify it under the | |
8 | terms of the GNU General Public License as published by the Free Software | |
9 | Foundation; either version 2, or (at your option) any later version. | |
10 | ||
11 | GNU CC is distributed in the hope that it will be useful, but WITHOUT ANY | |
12 | WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS | |
13 | FOR A PARTICULAR PURPOSE. See the GNU General Public License for more | |
14 | details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License along with | |
17 | GNU CC; see the file COPYING. If not, write to the Free Software | |
18 | Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ | |
19 | ||
20 | /* As a special exception, if you link this library with files compiled with | |
21 | GCC to produce an executable, this does not cause the resulting executable | |
22 | to be covered by the GNU General Public License. This exception does not | |
23 | however invalidate any other reasons why the executable file might be | |
24 | covered by the GNU General Public License. */ | |
25 | ||
26 | #include "runtime.h" /* the kitchen sink */ | |
27 | #include "sarray.h" | |
28 | ||
29 | /* The table of classname->class. Used for objc_lookup_class and friends */ | |
30 | static cache_ptr __objc_class_hash = 0; /* !T:MUTEX */ | |
31 | ||
32 | /* This is a hook which is called by objc_get_class and | |
33 | objc_lookup_class if the runtime is not able to find the class. | |
34 | This may e.g. try to load in the class using dynamic loading */ | |
35 | Class (*_objc_lookup_class)(const char* name) = 0; /* !T:SAFE */ | |
36 | ||
37 | ||
38 | /* True when class links has been resolved */ | |
39 | BOOL __objc_class_links_resolved = NO; /* !T:UNUSED */ | |
40 | ||
41 | ||
42 | /* Initial number of buckets size of class hash table. */ | |
43 | #define CLASS_HASH_SIZE 32 | |
44 | ||
45 | void __objc_init_class_tables() | |
46 | { | |
47 | /* Allocate the class hash table */ | |
48 | ||
49 | if(__objc_class_hash) | |
50 | return; | |
51 | ||
52 | objc_mutex_lock(__objc_runtime_mutex); | |
53 | ||
54 | __objc_class_hash | |
55 | = hash_new (CLASS_HASH_SIZE, | |
56 | (hash_func_type) hash_string, | |
57 | (compare_func_type) compare_strings); | |
58 | ||
59 | objc_mutex_unlock(__objc_runtime_mutex); | |
60 | } | |
61 | ||
62 | /* This function adds a class to the class hash table, and assigns the | |
63 | class a number, unless it's already known */ | |
64 | void | |
65 | __objc_add_class_to_hash(Class class) | |
66 | { | |
67 | Class h_class; | |
68 | ||
69 | objc_mutex_lock(__objc_runtime_mutex); | |
70 | ||
71 | /* make sure the table is there */ | |
72 | assert(__objc_class_hash); | |
73 | ||
74 | /* make sure it's not a meta class */ | |
75 | assert(CLS_ISCLASS(class)); | |
76 | ||
77 | /* Check to see if the class is already in the hash table. */ | |
78 | h_class = hash_value_for_key (__objc_class_hash, class->name); | |
79 | if (!h_class) | |
80 | { | |
81 | /* The class isn't in the hash table. Add the class and assign a class | |
82 | number. */ | |
83 | static unsigned int class_number = 1; | |
84 | ||
85 | CLS_SETNUMBER(class, class_number); | |
86 | CLS_SETNUMBER(class->class_pointer, class_number); | |
87 | ||
88 | ++class_number; | |
89 | hash_add (&__objc_class_hash, class->name, class); | |
90 | } | |
91 | ||
92 | objc_mutex_unlock(__objc_runtime_mutex); | |
93 | } | |
94 | ||
95 | /* Get the class object for the class named NAME. If NAME does not | |
96 | identify a known class, the hook _objc_lookup_class is called. If | |
97 | this fails, nil is returned */ | |
98 | Class objc_lookup_class (const char* name) | |
99 | { | |
100 | Class class; | |
101 | ||
102 | objc_mutex_lock(__objc_runtime_mutex); | |
103 | ||
104 | /* Make sure the class hash table exists. */ | |
105 | assert (__objc_class_hash); | |
106 | ||
107 | class = hash_value_for_key (__objc_class_hash, name); | |
108 | ||
109 | objc_mutex_unlock(__objc_runtime_mutex); | |
110 | ||
111 | if (class) | |
112 | return class; | |
113 | ||
114 | if (_objc_lookup_class) | |
115 | return (*_objc_lookup_class)(name); | |
116 | else | |
117 | return 0; | |
118 | } | |
119 | ||
120 | /* Get the class object for the class named NAME. If NAME does not | |
121 | identify a known class, the hook _objc_lookup_class is called. If | |
122 | this fails, an error message is issued and the system aborts */ | |
123 | Class | |
124 | objc_get_class (const char *name) | |
125 | { | |
126 | Class class; | |
127 | ||
128 | objc_mutex_lock(__objc_runtime_mutex); | |
129 | ||
130 | /* Make sure the class hash table exists. */ | |
131 | assert (__objc_class_hash); | |
132 | ||
133 | class = hash_value_for_key (__objc_class_hash, name); | |
134 | ||
135 | objc_mutex_unlock(__objc_runtime_mutex); | |
136 | ||
137 | if (class) | |
138 | return class; | |
139 | ||
140 | if (_objc_lookup_class) | |
141 | class = (*_objc_lookup_class)(name); | |
142 | ||
143 | if(class) | |
144 | return class; | |
145 | ||
146 | objc_error(nil, OBJC_ERR_BAD_CLASS, | |
147 | "objc runtime: cannot find class %s\n", name); | |
148 | return 0; | |
149 | } | |
150 | ||
151 | MetaClass | |
152 | objc_get_meta_class(const char *name) | |
153 | { | |
154 | return objc_get_class(name)->class_pointer; | |
155 | } | |
156 | ||
157 | /* This function provides a way to enumerate all the classes in the | |
158 | executable. Pass *ENUM_STATE == NULL to start the enumeration. The | |
159 | function will return 0 when there are no more classes. | |
160 | For example: | |
161 | id class; | |
162 | void *es = NULL; | |
163 | while ((class = objc_next_class(&es))) | |
164 | ... do something with class; | |
165 | */ | |
166 | Class | |
167 | objc_next_class(void **enum_state) | |
168 | { | |
169 | objc_mutex_lock(__objc_runtime_mutex); | |
170 | ||
171 | /* make sure the table is there */ | |
172 | assert(__objc_class_hash); | |
173 | ||
174 | *(node_ptr*)enum_state = | |
175 | hash_next(__objc_class_hash, *(node_ptr*)enum_state); | |
176 | ||
177 | objc_mutex_unlock(__objc_runtime_mutex); | |
178 | ||
179 | if (*(node_ptr*)enum_state) | |
180 | return (*(node_ptr*)enum_state)->value; | |
181 | return (Class)0; | |
182 | } | |
183 | ||
184 | /* Resolve super/subclass links for all classes. The only thing we | |
185 | can be sure of is that the class_pointer for class objects point | |
186 | to the right meta class objects */ | |
187 | void __objc_resolve_class_links() | |
188 | { | |
189 | node_ptr node; | |
190 | Class object_class = objc_get_class ("Object"); | |
191 | ||
192 | assert(object_class); | |
193 | ||
194 | objc_mutex_lock(__objc_runtime_mutex); | |
195 | ||
196 | /* Assign subclass links */ | |
197 | for (node = hash_next (__objc_class_hash, NULL); node; | |
198 | node = hash_next (__objc_class_hash, node)) | |
199 | { | |
200 | Class class1 = node->value; | |
201 | ||
202 | /* Make sure we have what we think we have. */ | |
203 | assert (CLS_ISCLASS(class1)); | |
204 | assert (CLS_ISMETA(class1->class_pointer)); | |
205 | ||
206 | /* The class_pointer of all meta classes point to Object's meta class. */ | |
207 | class1->class_pointer->class_pointer = object_class->class_pointer; | |
208 | ||
209 | if (!(CLS_ISRESOLV(class1))) | |
210 | { | |
211 | CLS_SETRESOLV(class1); | |
212 | CLS_SETRESOLV(class1->class_pointer); | |
213 | ||
214 | if(class1->super_class) | |
215 | { | |
216 | Class a_super_class | |
217 | = objc_get_class ((char *) class1->super_class); | |
218 | ||
219 | assert (a_super_class); | |
220 | ||
221 | DEBUG_PRINTF ("making class connections for: %s\n", | |
222 | class1->name); | |
223 | ||
224 | /* assign subclass links for superclass */ | |
225 | class1->sibling_class = a_super_class->subclass_list; | |
226 | a_super_class->subclass_list = class1; | |
227 | ||
228 | /* Assign subclass links for meta class of superclass */ | |
229 | if (a_super_class->class_pointer) | |
230 | { | |
231 | class1->class_pointer->sibling_class | |
232 | = a_super_class->class_pointer->subclass_list; | |
233 | a_super_class->class_pointer->subclass_list | |
234 | = class1->class_pointer; | |
235 | } | |
236 | } | |
237 | else /* a root class, make its meta object */ | |
238 | /* be a subclass of Object */ | |
239 | { | |
240 | class1->class_pointer->sibling_class | |
241 | = object_class->subclass_list; | |
242 | object_class->subclass_list = class1->class_pointer; | |
243 | } | |
244 | } | |
245 | } | |
246 | ||
247 | /* Assign superclass links */ | |
248 | for (node = hash_next (__objc_class_hash, NULL); node; | |
249 | node = hash_next (__objc_class_hash, node)) | |
250 | { | |
251 | Class class1 = node->value; | |
252 | Class sub_class; | |
253 | for (sub_class = class1->subclass_list; sub_class; | |
254 | sub_class = sub_class->sibling_class) | |
255 | { | |
256 | sub_class->super_class = class1; | |
257 | if(CLS_ISCLASS(sub_class)) | |
258 | sub_class->class_pointer->super_class = class1->class_pointer; | |
259 | } | |
260 | } | |
261 | ||
262 | objc_mutex_unlock(__objc_runtime_mutex); | |
263 | } | |
264 | ||
265 | ||
266 | ||
267 | #define CLASSOF(c) ((c)->class_pointer) | |
268 | ||
269 | Class | |
270 | class_pose_as (Class impostor, Class super_class) | |
271 | { | |
272 | node_ptr node; | |
273 | Class class1; | |
274 | ||
275 | if (!CLS_ISRESOLV (impostor)) | |
276 | __objc_resolve_class_links (); | |
277 | ||
278 | /* preconditions */ | |
279 | assert (impostor); | |
280 | assert (super_class); | |
281 | assert (impostor->super_class == super_class); | |
282 | assert (CLS_ISCLASS (impostor)); | |
283 | assert (CLS_ISCLASS (super_class)); | |
284 | assert (impostor->instance_size == super_class->instance_size); | |
285 | ||
286 | { | |
287 | Class *subclass = &(super_class->subclass_list); | |
288 | ||
289 | /* move subclasses of super_class to impostor */ | |
290 | while (*subclass) | |
291 | { | |
292 | Class nextSub = (*subclass)->sibling_class; | |
293 | ||
294 | if (*subclass != impostor) | |
295 | { | |
296 | Class sub = *subclass; | |
297 | ||
298 | /* classes */ | |
299 | sub->sibling_class = impostor->subclass_list; | |
300 | sub->super_class = impostor; | |
301 | impostor->subclass_list = sub; | |
302 | ||
303 | /* It will happen that SUB is not a class object if it is | |
304 | the top of the meta class hierarchy chain. (root | |
305 | meta-class objects inherit their class object) If that is | |
306 | the case... don't mess with the meta-meta class. */ | |
307 | if (CLS_ISCLASS (sub)) | |
308 | { | |
309 | /* meta classes */ | |
310 | CLASSOF (sub)->sibling_class = | |
311 | CLASSOF (impostor)->subclass_list; | |
312 | CLASSOF (sub)->super_class = CLASSOF (impostor); | |
313 | CLASSOF (impostor)->subclass_list = CLASSOF (sub); | |
314 | } | |
315 | } | |
316 | ||
317 | *subclass = nextSub; | |
318 | } | |
319 | ||
320 | /* set subclasses of superclass to be impostor only */ | |
321 | super_class->subclass_list = impostor; | |
322 | CLASSOF (super_class)->subclass_list = CLASSOF (impostor); | |
323 | ||
324 | /* set impostor to have no sibling classes */ | |
325 | impostor->sibling_class = 0; | |
326 | CLASSOF (impostor)->sibling_class = 0; | |
327 | } | |
328 | ||
329 | /* check relationship of impostor and super_class is kept. */ | |
330 | assert (impostor->super_class == super_class); | |
331 | assert (CLASSOF (impostor)->super_class == CLASSOF (super_class)); | |
332 | ||
333 | /* This is how to update the lookup table. Regardless of | |
334 | what the keys of the hashtable is, change all values that are | |
335 | superclass into impostor. */ | |
336 | ||
337 | objc_mutex_lock(__objc_runtime_mutex); | |
338 | ||
339 | for (node = hash_next (__objc_class_hash, NULL); node; | |
340 | node = hash_next (__objc_class_hash, node)) | |
341 | { | |
342 | class1 = (Class)node->value; | |
343 | if (class1 == super_class) | |
344 | { | |
345 | node->value = impostor; /* change hash table value */ | |
346 | } | |
347 | } | |
348 | ||
349 | objc_mutex_unlock(__objc_runtime_mutex); | |
350 | ||
351 | /* next, we update the dispatch tables... */ | |
352 | __objc_update_dispatch_table_for_class (CLASSOF (impostor)); | |
353 | __objc_update_dispatch_table_for_class (impostor); | |
354 | ||
355 | return impostor; | |
356 | } | |
357 | ||
358 |