gcc/objc/class.c

   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 }
 149
 150 MetaClass
 151 objc_get_meta_class(const char *name)
 152 {
 153   return objc_get_class(name)->class_pointer;
 154 }
 155
 156 /* This function provides a way to enumerate all the classes in the
 157    executable.  Pass *ENUM_STATE == NULL to start the enumeration.  The
 158    function will return 0 when there are no more classes.
 159    For example:
 160        id class;
 161        void *es = NULL;
 162        while ((class = objc_next_class(&es)))
 163          ... do something with class;
 164 */
 165 Class
 166 objc_next_class(void **enum_state)
 167 {
 168   objc_mutex_lock(__objc_runtime_mutex);
 169
 170   /* make sure the table is there */
 171   assert(__objc_class_hash);
 172
 173   *(node_ptr*)enum_state =
 174     hash_next(__objc_class_hash, *(node_ptr*)enum_state);
 175
 176   objc_mutex_unlock(__objc_runtime_mutex);
 177
 178   if (*(node_ptr*)enum_state)
 179     return (*(node_ptr*)enum_state)->value;
 180   return (Class)0;
 181 }
 182
 183 /* Resolve super/subclass links for all classes.  The only thing we
 184    can be sure of is that the class_pointer for class objects point
 185    to the right meta class objects */
 186 void __objc_resolve_class_links()
 187 {
 188   node_ptr node;
 189   Class object_class = objc_get_class ("Object");
 190
 191   assert(object_class);
 192
 193   objc_mutex_lock(__objc_runtime_mutex);
 194
 195   /* Assign subclass links */
 196   for (node = hash_next (__objc_class_hash, NULL); node;
 197        node = hash_next (__objc_class_hash, node))
 198     {
 199       Class class1 = node->value;
 200
 201       /* Make sure we have what we think we have.  */
 202       assert (CLS_ISCLASS(class1));
 203       assert (CLS_ISMETA(class1->class_pointer));
 204
 205       /* The class_pointer of all meta classes point to Object's meta class. */
 206       class1->class_pointer->class_pointer = object_class->class_pointer;
 207
 208       if (!(CLS_ISRESOLV(class1)))
 209         {
 210           CLS_SETRESOLV(class1);
 211           CLS_SETRESOLV(class1->class_pointer);
 212
 213           if(class1->super_class)
 214             {
 215               Class a_super_class
 216                 = objc_get_class ((char *) class1->super_class);
 217
 218               assert (a_super_class);
 219
 220               DEBUG_PRINTF ("making class connections for: %s\n",
 221                             class1->name);
 222
 223               /* assign subclass links for superclass */
 224               class1->sibling_class = a_super_class->subclass_list;
 225               a_super_class->subclass_list = class1;
 226
 227               /* Assign subclass links for meta class of superclass */
 228               if (a_super_class->class_pointer)
 229                 {
 230                   class1->class_pointer->sibling_class
 231                     = a_super_class->class_pointer->subclass_list;
 232                   a_super_class->class_pointer->subclass_list
 233                     = class1->class_pointer;
 234                 }
 235             }
 236           else                  /* a root class, make its meta object */
 237                                 /* be a subclass of Object */
 238             {
 239               class1->class_pointer->sibling_class
 240                 = object_class->subclass_list;
 241               object_class->subclass_list = class1->class_pointer;
 242             }
 243         }
 244     }
 245
 246   /* Assign superclass links */
 247   for (node = hash_next (__objc_class_hash, NULL); node;
 248        node = hash_next (__objc_class_hash, node))
 249     {
 250       Class class1 = node->value;
 251       Class sub_class;
 252       for (sub_class = class1->subclass_list; sub_class;
 253            sub_class = sub_class->sibling_class)
 254         {
 255           sub_class->super_class = class1;
 256           if(CLS_ISCLASS(sub_class))
 257             sub_class->class_pointer->super_class = class1->class_pointer;
 258         }
 259     }
 260
 261   objc_mutex_unlock(__objc_runtime_mutex);
 262 }
 263
 264
 265
 266 #define CLASSOF(c) ((c)->class_pointer)
 267
 268 Class
 269 class_pose_as (Class impostor, Class super_class)
 270 {
 271   node_ptr node;
 272   Class class1;
 273
 274   if (!CLS_ISRESOLV (impostor))
 275     __objc_resolve_class_links ();
 276
 277   /* preconditions */
 278   assert (impostor);
 279   assert (super_class);
 280   assert (impostor->super_class == super_class);
 281   assert (CLS_ISCLASS (impostor));
 282   assert (CLS_ISCLASS (super_class));
 283   assert (impostor->instance_size == super_class->instance_size);
 284
 285   {
 286     Class *subclass = &(super_class->subclass_list);
 287
 288     /* move subclasses of super_class to impostor */
 289     while (*subclass)
 290       {
 291         Class nextSub = (*subclass)->sibling_class;
 292
 293         if (*subclass != impostor)
 294           {
 295             Class sub = *subclass;
 296
 297             /* classes */
 298             sub->sibling_class = impostor->subclass_list;
 299             sub->super_class = impostor;
 300             impostor->subclass_list = sub;
 301
 302             /* It will happen that SUB is not a class object if it is
 303                the top of the meta class hierarchy chain.  (root
 304                meta-class objects inherit their class object)  If that is
 305                the case... don't mess with the meta-meta class. */
 306             if (CLS_ISCLASS (sub))
 307               {
 308                 /* meta classes */
 309                 CLASSOF (sub)->sibling_class =
 310                   CLASSOF (impostor)->subclass_list;
 311                 CLASSOF (sub)->super_class = CLASSOF (impostor);
 312                 CLASSOF (impostor)->subclass_list = CLASSOF (sub);
 313               }
 314           }
 315
 316         *subclass = nextSub;
 317       }
 318
 319     /* set subclasses of superclass to be impostor only */
 320     super_class->subclass_list = impostor;
 321     CLASSOF (super_class)->subclass_list = CLASSOF (impostor);
 322
 323     /* set impostor to have no sibling classes */
 324     impostor->sibling_class = 0;
 325     CLASSOF (impostor)->sibling_class = 0;
 326   }
 327
 328   /* check relationship of impostor and super_class is kept. */
 329   assert (impostor->super_class == super_class);
 330   assert (CLASSOF (impostor)->super_class == CLASSOF (super_class));
 331
 332   /* This is how to update the lookup table. Regardless of
 333      what the keys of the hashtable is, change all values that are
 334      superclass into impostor. */
 335
 336   objc_mutex_lock(__objc_runtime_mutex);
 337
 338   for (node = hash_next (__objc_class_hash, NULL); node;
 339        node = hash_next (__objc_class_hash, node))
 340     {
 341       class1 = (Class)node->value;
 342       if (class1 == super_class)
 343         {
 344           node->value = impostor; /* change hash table value */
 345         }
 346     }
 347
 348   objc_mutex_unlock(__objc_runtime_mutex);
 349
 350   /* next, we update the dispatch tables... */
 351   __objc_update_dispatch_table_for_class (CLASSOF (impostor));
 352   __objc_update_dispatch_table_for_class (impostor);
 353
 354   return impostor;
 355 }
 356
 357