/* GNU Objective C Runtime class related functions   Copyright (C) 1993, 1995, 1996, 1997 Free Software Foundation, Inc.   Contributed by Kresten Krab Thorup and Dennis Glatting.This file is part of GNU CC.GNU CC is free software; you can redistribute it and/or modify it under theterms of the GNU General Public License as published by the Free SoftwareFoundation; either version 2, or (at your option) any later version.GNU CC is distributed in the hope that it will be useful, but WITHOUT ANYWARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESSFOR A PARTICULAR PURPOSE.  See the GNU General Public License for moredetails.You should have received a copy of the GNU General Public License along withGNU CC; see the file COPYING.  If not, write to the Free SoftwareFoundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  *//* As a special exception, if you link this library with files compiled with   GCC to produce an executable, this does not cause the resulting executable   to be covered by the GNU General Public License. This exception does not   however invalidate any other reasons why the executable file might be   covered by the GNU General Public License.  */#include "runtime.h"		/* the kitchen sink */#include "sarray.h"/* The table of classname->class.  Used for objc_lookup_class and friends */static cache_ptr __objc_class_hash = 0;                 /* !T:MUTEX *//* This is a hook which is called by objc_get_class and    objc_lookup_class if the runtime is not able to find the class.   This may e.g. try to load in the class using dynamic loading */Class (*_objc_lookup_class)(const char* name) = 0;      /* !T:SAFE *//* True when class links has been resolved */     BOOL __objc_class_links_resolved = NO;                  /* !T:UNUSED *//* Initial number of buckets size of class hash table. */#define CLASS_HASH_SIZE 32void __objc_init_class_tables(){  /* Allocate the class hash table */  if(__objc_class_hash)    return;  objc_mutex_lock(__objc_runtime_mutex);  __objc_class_hash    =  hash_new (CLASS_HASH_SIZE,		 (hash_func_type) hash_string,		 (compare_func_type) compare_strings);  objc_mutex_unlock(__objc_runtime_mutex);}  /* This function adds a class to the class hash table, and assigns the    class a number, unless it's already known */void__objc_add_class_to_hash(Class class){  Class h_class;  objc_mutex_lock(__objc_runtime_mutex);  /* make sure the table is there */  assert(__objc_class_hash);  /* make sure it's not a meta class */    assert(CLS_ISCLASS(class));  /* Check to see if the class is already in the hash table.  */  h_class = hash_value_for_key (__objc_class_hash, class->name);  if (!h_class)    {      /* The class isn't in the hash table.  Add the class and assign a class         number.  */      static unsigned int class_number = 1;      CLS_SETNUMBER(class, class_number);      CLS_SETNUMBER(class->class_pointer, class_number);      ++class_number;      hash_add (&__objc_class_hash, class->name, class);    }  objc_mutex_unlock(__objc_runtime_mutex);}/* Get the class object for the class named NAME.  If NAME does not   identify a known class, the hook _objc_lookup_class is called.  If   this fails, nil is returned */Class objc_lookup_class (const char* name){  Class class;  objc_mutex_lock(__objc_runtime_mutex);  /* Make sure the class hash table exists.  */  assert (__objc_class_hash);  class = hash_value_for_key (__objc_class_hash, name);  objc_mutex_unlock(__objc_runtime_mutex);  if (class)    return class;  if (_objc_lookup_class)    return (*_objc_lookup_class)(name);  else    return 0;}/* Get the class object for the class named NAME.  If NAME does not   identify a known class, the hook _objc_lookup_class is called.  If   this fails,  an error message is issued and the system aborts */Classobjc_get_class (const char *name){  Class class;  objc_mutex_lock(__objc_runtime_mutex);  /* Make sure the class hash table exists.  */  assert (__objc_class_hash);  class = hash_value_for_key (__objc_class_hash, name);  objc_mutex_unlock(__objc_runtime_mutex);  if (class)    return class;  if (_objc_lookup_class)    class = (*_objc_lookup_class)(name);  if(class)    return class;    objc_error(nil, OBJC_ERR_BAD_CLASS, 	     "objc runtime: cannot find class %s\n", name);  return 0;}MetaClassobjc_get_meta_class(const char *name){  return objc_get_class(name)->class_pointer;}/* This function provides a way to enumerate all the classes in the   executable.  Pass *ENUM_STATE == NULL to start the enumeration.  The   function will return 0 when there are no more classes.     For example:        id class;        void *es = NULL;       while ((class = objc_next_class(&es)))         ... do something with class; */Classobjc_next_class(void **enum_state){  objc_mutex_lock(__objc_runtime_mutex);  /* make sure the table is there */  assert(__objc_class_hash);  *(node_ptr*)enum_state =     hash_next(__objc_class_hash, *(node_ptr*)enum_state);  objc_mutex_unlock(__objc_runtime_mutex);  if (*(node_ptr*)enum_state)    return (*(node_ptr*)enum_state)->value;  return (Class)0;}/* Resolve super/subclass links for all classes.  The only thing we    can be sure of is that the class_pointer for class objects point    to the right meta class objects */void __objc_resolve_class_links(){  node_ptr node;  Class object_class = objc_get_class ("Object");  assert(object_class);  objc_mutex_lock(__objc_runtime_mutex);  /* Assign subclass links */  for (node = hash_next (__objc_class_hash, NULL); node;       node = hash_next (__objc_class_hash, node))    {      Class class1 = node->value;      /* Make sure we have what we think we have.  */      assert (CLS_ISCLASS(class1));      assert (CLS_ISMETA(class1->class_pointer));      /* The class_pointer of all meta classes point to Object's meta class. */      class1->class_pointer->class_pointer = object_class->class_pointer;      if (!(CLS_ISRESOLV(class1)))        {          CLS_SETRESOLV(class1);          CLS_SETRESOLV(class1->class_pointer);                        if(class1->super_class)            {                 Class a_super_class                 = objc_get_class ((char *) class1->super_class);                            assert (a_super_class);                            DEBUG_PRINTF ("making class connections for: %s\n",                            class1->name);                            /* assign subclass links for superclass */              class1->sibling_class = a_super_class->subclass_list;              a_super_class->subclass_list = class1;                            /* Assign subclass links for meta class of superclass */              if (a_super_class->class_pointer)                {                  class1->class_pointer->sibling_class                    = a_super_class->class_pointer->subclass_list;                  a_super_class->class_pointer->subclass_list                     = class1->class_pointer;                }            }          else                  /* a root class, make its meta object */                                /* be a subclass of Object */            {              class1->class_pointer->sibling_class                 = object_class->subclass_list;              object_class->subclass_list = class1->class_pointer;            }        }    }  /* Assign superclass links */  for (node = hash_next (__objc_class_hash, NULL); node;       node = hash_next (__objc_class_hash, node))    {      Class class1 = node->value;      Class sub_class;      for (sub_class = class1->subclass_list; sub_class;           sub_class = sub_class->sibling_class)        {          sub_class->super_class = class1;          if(CLS_ISCLASS(sub_class))            sub_class->class_pointer->super_class = class1->class_pointer;        }    }  objc_mutex_unlock(__objc_runtime_mutex);}#define CLASSOF(c) ((c)->class_pointer)Classclass_pose_as (Class impostor, Class super_class){  node_ptr node;  Class class1;  if (!CLS_ISRESOLV (impostor))    __objc_resolve_class_links ();  /* preconditions */  assert (impostor);  assert (super_class);  assert (impostor->super_class == super_class);  assert (CLS_ISCLASS (impostor));  assert (CLS_ISCLASS (super_class));  assert (impostor->instance_size == super_class->instance_size);  {    Class *subclass = &(super_class->subclass_list);    /* move subclasses of super_class to impostor */    while (*subclass)      {	Class nextSub = (*subclass)->sibling_class;	if (*subclass != impostor)	  {	    Class sub = *subclass;	    /* classes */	    sub->sibling_class = impostor->subclass_list;	    sub->super_class = impostor;	    impostor->subclass_list = sub;	    /* It will happen that SUB is not a class object if it is 	       the top of the meta class hierarchy chain.  (root	       meta-class objects inherit their class object)  If that is	       the case... don't mess with the meta-meta class. */ 	    if (CLS_ISCLASS (sub))	      {		/* meta classes */		CLASSOF (sub)->sibling_class = 		  CLASSOF (impostor)->subclass_list;		CLASSOF (sub)->super_class = CLASSOF (impostor);		CLASSOF (impostor)->subclass_list = CLASSOF (sub);	      }	  }	*subclass = nextSub;      }    /* set subclasses of superclass to be impostor only */    super_class->subclass_list = impostor;    CLASSOF (super_class)->subclass_list = CLASSOF (impostor);        /* set impostor to have no sibling classes */    impostor->sibling_class = 0;    CLASSOF (impostor)->sibling_class = 0;  }    /* check relationship of impostor and super_class is kept. */  assert (impostor->super_class == super_class);  assert (CLASSOF (impostor)->super_class == CLASSOF (super_class));  /* This is how to update the lookup table. Regardless of     what the keys of the hashtable is, change all values that are     superclass into impostor. */  objc_mutex_lock(__objc_runtime_mutex);  for (node = hash_next (__objc_class_hash, NULL); node;       node = hash_next (__objc_class_hash, node))    {      class1 = (Class)node->value;      if (class1 == super_class)	{	  node->value = impostor; /* change hash table value */	}    }        objc_mutex_unlock(__objc_runtime_mutex);  /* next, we update the dispatch tables... */  __objc_update_dispatch_table_for_class (CLASSOF (impostor));  __objc_update_dispatch_table_for_class (impostor);  return impostor;}