--- stack/stack.c	2002/02/17 04:03:57	1.89
+++ stack/stack.c	2002/03/07 01:21:07	1.90
@@ -24,6 +24,8 @@
 
   env->gc_limit= 20;
   env->gc_count= 0;
+  env->gc_ref= NULL;
+  env->gc_protect= NULL;
 
   env->head= NULL;
   for(i= 0; i<HASHTBLSIZE; i++)
@@ -46,12 +48,14 @@
 
   if((env->head)==NULL) {
     printerr("Too Few Arguments");
-    env->err=1;
+    env->err= 1;
     return;
   }
   
   env->head= env->head->next;	/* Remove the top stack item */
   free(temp);			/* Free the old top stack item */
+
+  gc_init(env);
 }
 
 /* Returns a pointer to a pointer to an element in the hash table. */
@@ -88,12 +92,16 @@
   stackitem *nitem= malloc(sizeof(stackitem));
 
   nval->content.ptr= NULL;
+  protect(env, nval);
+
+  gc_init(env);
 
   nitem->item= nval;
   nitem->next= env->gc_ref;
   env->gc_ref= nitem;
 
   env->gc_count++;
+  unprotect(env);
 
   return nval;
 }
@@ -130,6 +138,12 @@
   }
 
   /* Mark */
+  iterator= env->gc_protect;
+  while(iterator!=NULL) {
+    gc_mark(iterator->item);
+    iterator= iterator->next;
+  }
+
   iterator= env->head;
   while(iterator!=NULL) {
     gc_mark(iterator->item);
@@ -148,6 +162,7 @@
 
   /* Sweep */
   while(env->gc_ref!=NULL) {
+
     if(env->gc_ref->item->gc_garb) {
       switch(env->gc_ref->item->type) {
       case string:
@@ -182,6 +197,21 @@
   env->gc_ref= new_head;
 }
 
+void protect(environment *env, value *val)
+{
+  stackitem *new_item= malloc(sizeof(stackitem));
+  new_item->item= val;
+  new_item->next= env->gc_protect;
+  env->gc_protect= new_item;
+}
+
+void unprotect(environment *env)
+{
+  stackitem *temp= env->gc_protect;
+  env->gc_protect= env->gc_protect->next;
+  free(temp);
+}
+
 /* Push a value onto the stack */
 void push_val(environment *env, value *val)
 {
@@ -216,20 +246,19 @@
 
 /* Mangle a symbol name to a valid C identifier name */
 char *mangle_str(const char *old_string){
-  char validchars[]
-    ="0123456789abcdef";
+  char validchars[]= "0123456789abcdef";
   char *new_string, *current;
 
-  new_string=malloc((strlen(old_string)*2)+4);
+  new_string= malloc((strlen(old_string)*2)+4);
   strcpy(new_string, "sx_");	/* Stack eXternal */
-  current=new_string+3;
+  current= new_string+3;
   while(old_string[0] != '\0'){
-    current[0]=validchars[(unsigned char)(old_string[0])/16];
-    current[1]=validchars[(unsigned char)(old_string[0])%16];
-    current+=2;
+    current[0]= validchars[(unsigned char)(old_string[0])/16];
+    current[1]= validchars[(unsigned char)(old_string[0])%16];
+    current+= 2;
     old_string++;
   }
-  current[0]='\0';
+  current[0]= '\0';
 
   return new_string;		/* The caller must free() it */
 }
@@ -239,13 +268,13 @@
 
   if((env->head)==NULL) {
     printerr("Too Few Arguments");
-    env->err=1;
+    env->err= 1;
     return;
   }
 
   if(env->head->item->type!=string) {
     printerr("Bad Argument Type");
-    env->err=2;
+    env->err= 2;
     return;
   }
 
@@ -298,18 +327,18 @@
     if(handle==NULL)		/* If no handle */
       handle= dlopen(NULL, RTLD_LAZY);
 
-    mangled=mangle_str(in_string); /* mangle the name */
+    mangled= mangle_str(in_string); /* mangle the name */
     funcptr= dlsym(handle, mangled); /* and try to find it */
     free(mangled);
-    dlerr=dlerror();
+    dlerr= dlerror();
     if(dlerr != NULL) {		/* If no function was found */
       funcptr= dlsym(handle, in_string); /* Get function pointer */
-      dlerr=dlerror();
+      dlerr= dlerror();
     }
     if(dlerr==NULL) {		/* If a function was found */
       new_fvalue= new_val(env); /* Create a new value */
-      new_fvalue->type=func;	/* The new value is a function pointer */
-      new_fvalue->content.ptr=funcptr; /* Store function pointer */
+      new_fvalue->type= func;	/* The new value is a function pointer */
+      new_fvalue->content.ptr= funcptr; /* Store function pointer */
       (*new_symbol)->val= new_fvalue; /* Bind the symbol to the new
                                          function value */
     }
@@ -497,9 +526,11 @@
     env->err=3;
     return;
   }
+  protect(env, val);
   toss(env);		/* toss the symbol */
   if(env->err) return;
   push_val(env, val); /* Return its bound value */
+  unprotect(env);
 }
 
 /* If the top element is a symbol, determine if it's bound to a
@@ -539,15 +570,20 @@
     /* If it's a list */
   case list:
     temp_val= env->head->item;
+    protect(env, temp_val);
     toss(env);
     if(env->err) return;
     iterator= (stackitem*)temp_val->content.ptr;
+    unprotect(env);
+    
     while(iterator!=NULL) {
       push_val(env, iterator->item);
+      
       if(env->head->item->type==symb
 	&& strcmp(";", ((symbol*)(env->head->item->content.ptr))->id)==0) {
 	toss(env);
 	if(env->err) return;
+	
 	if(iterator->next == NULL){
 	  goto eval_start;
 	}
@@ -569,25 +605,25 @@
 
   if((env->head)==NULL) {
     printerr("Too Few Arguments");
-    env->err=1;
+    env->err= 1;
     return;
   }
 
   if(env->head->item->type!=list) {
     printerr("Bad Argument Type");
-    env->err=2;
+    env->err= 2;
     return;
   }
 
-  old_head=(stackitem *)(env->head->item->content.ptr);
-  new_head=NULL;
+  old_head= (stackitem *)(env->head->item->content.ptr);
+  new_head= NULL;
   while(old_head != NULL){
-    item=old_head;
-    old_head=old_head->next;
-    item->next=new_head;
-    new_head=item;
+    item= old_head;
+    old_head= old_head->next;
+    item->next= new_head;
+    new_head= item;
   }
-  env->head->item->content.ptr=new_head;
+  env->head->item->content.ptr= new_head;
 }
 
 /* Make a list. */
@@ -636,12 +672,12 @@
   /* Is top element a list? */
   if(env->head==NULL) {
     printerr("Too Few Arguments");
-    env->err=1;
+    env->err= 1;
     return;
   }
   if(env->head->item->type!=list) {
     printerr("Bad Argument Type");
-    env->err=2;
+    env->err= 2;
     return;
   }
 
@@ -673,7 +709,7 @@
 
   if((env->head)==NULL || env->head->next==NULL) {
     printerr("Too Few Arguments");
-    env->err=1;
+    env->err= 1;
     return;
   }
 
@@ -693,13 +729,13 @@
 
   if((env->head)==NULL) {
     printerr("Too Few Arguments");
-    env->err=1;
+    env->err= 1;
     return;
   }
 
   if(env->head->item->type!=integer) {
     printerr("Bad Argument Type");
-    env->err=2;
+    env->err= 2;
     return;
   }
 
@@ -724,20 +760,18 @@
   /* Needs two values on the stack, the top one must be a symbol */
   if(env->head==NULL || env->head->next==NULL) {
     printerr("Too Few Arguments");
-    env->err=1;
+    env->err= 1;
     return;
   }
 
   if(env->head->item->type!=symb) {
     printerr("Bad Argument Type");
-    env->err=2;
+    env->err= 2;
     return;
   }
 
   /* long names are a pain */
-  sym=env->head->item->content.ptr;
-
-  /* if the symbol was bound to something else, throw it away */
+  sym= env->head->item->content.ptr;
 
   /* Bind the symbol to the value */
   sym->val= env->head->next->item;
@@ -760,6 +794,7 @@
     env->symbols[i]= NULL;
   }
 
+  env->gc_limit= 0;
   gc_init(env);
 
   if(env->free_string!=NULL)
@@ -904,7 +939,7 @@
 
   if((env->head)==NULL || env->head->next==NULL) {
     printerr("Too Few Arguments");
-    env->err=1;
+    env->err= 1;
     return;
   }
 
@@ -912,6 +947,7 @@
      && env->head->next->item->type==string) {
     a_val= env->head->item;
     b_val= env->head->next->item;
+    protect(env, a_val); protect(env, b_val);
     toss(env); if(env->err) return;
     toss(env); if(env->err) return;
     len= strlen(a_val->content.ptr)+strlen(b_val->content.ptr)+1;
@@ -919,6 +955,7 @@
     strcpy(new_string, b_val->content.ptr);
     strcat(new_string, a_val->content.ptr);
     push_cstring(env, new_string);
+    unprotect(env); unprotect(env);
     free(new_string);
     return;
   }
@@ -929,10 +966,10 @@
     env->err=2;
     return;
   }
-  a=env->head->item->content.val;
+  a= env->head->item->content.val;
   toss(env); if(env->err) return;
   
-  b=env->head->item->content.val;
+  b= env->head->item->content.val;
   toss(env); if(env->err) return;
   push_int(env, a+b);
 }
@@ -953,6 +990,7 @@
     env->err=2;
     return;
   }
+
   a=env->head->item->content.val;
   toss(env); if(env->err) return;
   b=env->head->item->content.val;
@@ -976,6 +1014,7 @@
     env->err=2;
     return;
   }
+
   a=env->head->item->content.val;
   toss(env); if(env->err) return;
   b=env->head->item->content.val;
@@ -987,42 +1026,46 @@
 value *copy_val(environment *env, value *old_value){
   stackitem *old_item, *new_item, *prev_item;
 
-  value *new_value=new_val(env);
+  value *new_value= new_val(env);
 
-  new_value->type=old_value->type;
+  protect(env, old_value);
+  new_value->type= old_value->type;
 
   switch(old_value->type){
   case integer:
-    new_value->content.val=old_value->content.val;
+    new_value->content.val= old_value->content.val;
     break;
   case string:
-    (char *)(new_value->content.ptr)
-      = strdup((char *)(old_value->content.ptr));
+    (char *)(new_value->content.ptr)= 
+      strdup((char *)(old_value->content.ptr));
     break;
   case func:
   case symb:
-    new_value->content.ptr=old_value->content.ptr;
+    new_value->content.ptr= old_value->content.ptr;
     break;
   case list:
-    new_value->content.ptr=NULL;
+    new_value->content.ptr= NULL;
 
-    prev_item=NULL;
-    old_item=(stackitem *)(old_value->content.ptr);
+    prev_item= NULL;
+    old_item= (stackitem*)(old_value->content.ptr);
 
     while(old_item != NULL) {	/* While list is not empty */
       new_item= malloc(sizeof(stackitem));
-      new_item->item=copy_val(env, old_item->item); /* recurse */
-      new_item->next=NULL;
+      new_item->item= copy_val(env, old_item->item); /* recurse */
+      new_item->next= NULL;
       if(prev_item != NULL)	/* If this wasn't the first item */
-	prev_item->next=new_item; /* point the previous item to the
+	prev_item->next= new_item; /* point the previous item to the
                                      new item */
       else
-	new_value->content.ptr=new_item;
-      old_item=old_item->next;
-      prev_item=new_item;
+	new_value->content.ptr= new_item;
+      old_item= old_item->next;
+      prev_item= new_item;
     }	  
     break;
   }
+
+  unprotect(env);
+
   return new_value;
 }
 
@@ -1030,7 +1073,7 @@
 extern void sx_647570(environment *env) {
   if((env->head)==NULL) {
     printerr("Too Few Arguments");
-    env->err=1;
+    env->err= 1;
     return;
   }
   push_val(env, copy_val(env, env->head->item));
@@ -1043,7 +1086,7 @@
 
   if((env->head)==NULL || env->head->next==NULL) {
     printerr("Too Few Arguments");
-    env->err=1;
+    env->err= 1;
     return;
   }
 
@@ -1116,9 +1159,11 @@
   }
 
   loop= env->head->item;
+  protect(env, loop);
   toss(env); if(env->err) return;
 
   test= env->head->item;
+  protect(env, test);
   toss(env); if(env->err) return;
 
   do {
@@ -1127,7 +1172,7 @@
     
     if(env->head->item->type != integer) {
       printerr("Bad Argument Type");
-      env->err=2;
+      env->err= 2;
       return;
     }
     
@@ -1142,6 +1187,8 @@
     }
   
   } while(truth);
+
+  unprotect(env); unprotect(env);
 }
 
 
@@ -1165,6 +1212,7 @@
   }
 
   loop= env->head->item;
+  protect(env, loop);
   toss(env); if(env->err) return;
 
   foo2= env->head->item->content.val;
@@ -1188,6 +1236,7 @@
       foo1--;
     }
   }
+  unprotect(env);
 }
 
 /* Variant of for-loop */
@@ -1198,20 +1247,22 @@
   
   if((env->head)==NULL || env->head->next==NULL) {
     printerr("Too Few Arguments");
-    env->err=1;
+    env->err= 1;
     return;
   }
 
   if(env->head->next->item->type != list) {
     printerr("Bad Argument Type");
-    env->err=2;
+    env->err= 2;
     return;
   }
 
   loop= env->head->item;
+  protect(env, loop);
   toss(env); if(env->err) return;
 
   foo= env->head->item;
+  protect(env, foo);
   toss(env); if(env->err) return;
 
   iterator= foo->content.ptr;
@@ -1222,6 +1273,7 @@
     eval(env); if(env->err) return;
     iterator= iterator->next;
   }
+  unprotect(env); unprotect(env);
 }
 
 /* "to" */
@@ -1282,9 +1334,9 @@
   const char strform[]= "\"%[^\"]\"%n";
   const char intform[]= "%i%n";
   const char blankform[]= "%*[ \t]%n";
-  const char ebrackform[]= "%*1[]]%n";
-  const char semicform[]= "%*1[;]%n";
-  const char bbrackform[]= "%*1[[]%n";
+  const char ebrackform[]= "]%n";
+  const char semicform[]= ";%n";
+  const char bbrackform[]= "[%n";
 
   int itemp, readlength= -1;
   static int depth= 0;