--- stack/stack.c	2002/01/31 21:47:20	1.15
+++ stack/stack.c	2002/01/31 22:32:59	1.16
@@ -11,19 +11,27 @@
 
 typedef struct stack_item
 {
-  enum {value, string, ref, func, symbol, list} type;
+  enum {
+    value,			/* Integer */
+    string, 
+    ref,	    /* Reference (to an element in the hash table) */ 
+    func,			/* Function pointer */
+    symbol, 
+    list
+  } type;			/* Tells what kind of stack element */
+  
   union {
-    void* ptr;
-    int val;
-  } content;
+    void* ptr;			/* Pointer to the content */
+    int val;			/* ...or an integer */
+  } content;			/* Stores a pointer or an integer */
 
-  char* id;
-  struct stack_item* next;
+  char* id;			/* Symbol name */
+  struct stack_item* next;	/* Next element */
 } stackitem;
 
 
-typedef stackitem* hashtbl[HASHTBLSIZE];
-typedef void (*funcp)(stackitem**);
+typedef stackitem* hashtbl[HASHTBLSIZE]; /* Hash table declaration */
+typedef void (*funcp)(stackitem**); /* Function pointer declaration */
 
 
 /* Initiates a newly created hash table. */
@@ -43,7 +51,7 @@
   char key= 0;
   stackitem** position;
   
-  while(1){
+  while(1){			/* Hash in_string */
     key= in_string[i++];
     if(key=='\0')
       break;
@@ -53,14 +61,14 @@
   out_hash= out_hash%HASHTBLSIZE;
   position= &(in_hashtbl[out_hash]);
 
-  while(1){
+  while(1){			/* Return position if empty */
     if(*position==NULL)
       return position;
     
-    if(strcmp(in_string, (*position)->id)==0)
+    if(strcmp(in_string, (*position)->id)==0) /* Return position if match */
       return position;
 
-    position= &((*position)->next);
+    position= &((*position)->next); /* Try next */
   }
 }
 
@@ -123,7 +131,6 @@
   stackitem* temp= malloc(sizeof(stackitem));
   
   temp->type= symbol;
-
   mk_hashentry(in_hashtbl, temp, id);
 }
 
@@ -137,17 +144,17 @@
   new_item->content.ptr= *hash(in_hash, in_string);
   new_item->type= ref;
 
-  if(new_item->content.ptr==NULL) {
-    if(handle==NULL)
+  if(new_item->content.ptr==NULL) { /* If hash entry empty */
+    if(handle==NULL)		/* If no handle */
       handle= dlopen(NULL, RTLD_LAZY);    
 
-    symbol= dlsym(handle, in_string);
-    if(dlerror()==NULL) 
-      def_func(in_hash, symbol, in_string);
+    symbol= dlsym(handle, in_string); /* Get function pointer */
+    if(dlerror()==NULL) 	/* If existing function pointer */
+      def_func(in_hash, symbol, in_string); /* Store function pointer */
     else
-      def_sym(in_hash, in_string);
+      def_sym(in_hash, in_string); /* Make symbol */
       
-    new_item->content.ptr= *hash(in_hash, in_string);
+    new_item->content.ptr= *hash(in_hash, in_string); /* XXX */
     new_item->type= ref;
   }
 
@@ -227,8 +234,7 @@
 }
 
 /* If the top element is a reference, determine if it's a reference to a
-   function, and if it is execute and pop the reference and execute the
-   function. */
+   function, and if it is, toss the reference and execute the function. */
 extern void eval(stackitem** stack_head)
 {
   funcp in_func;
@@ -256,29 +262,30 @@
   rest= malloc(inlength);
 
   do {
+    /* If string */
     if((convert= sscanf(in_line, "\"%[^\"\n\r]\" %[^\n\r]", temp, rest))) {
       push_cstring(stack_head, temp);
       break;
     }
- 
+    /* If value */
     if((convert= sscanf(in_line, "%d %[^\n\r]", &itemp, rest))) {
       push_val(stack_head, itemp);
       break;
     }
- 
+    /* Escape ';' with '\' */
     if((convert= sscanf(in_line, "\\%c%[^\n\r]", temp, rest))) {
       temp[1]= '\0'; 
       push_ref(stack_head, in_hash, temp);
       break;
     } 
-      
+    /* If symbol */
     if((convert= sscanf(in_line, "%[^ ;\n\r]%[^\n\r]", temp, rest))) {
 	push_ref(stack_head, in_hash, temp);
 	break;
     }
-  
+    /* If ';' */
     if((convert= sscanf(in_line, "%c%[^\n\r]", temp, rest)) && *temp==';') {
-      eval(stack_head);
+      eval(stack_head);		/* Evaluate top element */
       break;
     }
   } while(0);
@@ -303,17 +310,19 @@
   void* delimiter;
   stackitem *iterator, *temp, *pack;
 
-  if((*stack_head)==NULL)
+  if((*stack_head)==NULL)	/* No delimiter */
     return;
 
-  delimiter= (*stack_head)->content.ptr;
+  delimiter= (*stack_head)->content.ptr; /* Get delimiter */
   toss(stack_head);
 
   iterator= *stack_head;
 
+  /* Search for first delimiter */
   while(iterator->next!=NULL && iterator->next->content.ptr!=delimiter)
     iterator= iterator->next;
 
+  /* Extract list */
   temp= *stack_head;
   *stack_head= iterator->next;
   iterator->next= NULL;
@@ -321,6 +330,7 @@
   if(*stack_head!=NULL && (*stack_head)->content.ptr==delimiter)
     toss(stack_head);
 
+  /* Push list */
   pack= malloc(sizeof(stackitem));
   pack->type= list;
   pack->content.ptr= temp;
@@ -328,22 +338,26 @@
   push(stack_head, pack);
 }
 
-/* Push elements of the list on the stack. */
+/* Relocate elements of the list on the stack. */
 extern void expand(stackitem** stack_head)
 {
   stackitem *temp, *new_head;
 
+  /* Is top element a list? */
   if((*stack_head)==NULL || (*stack_head)->type!=list)
     return;
 
+  /* The first list element is the new stack head */
   new_head= temp= (*stack_head)->content.ptr;
   toss(stack_head);
 
+  /* Search the end of the list */
   while(temp->next!=NULL)
     temp= temp->next;
 
+  /* Connect the the tail of the list with the old stack head */
   temp->next= *stack_head;
-  *stack_head= new_head;
+  *stack_head= new_head;	/* ...and voila! */
 }
 
 /* Swap the two top elements on the stack. */
@@ -382,7 +396,7 @@
 {
   int value;
 
-  if((*stack_head)==NULL)
+  if((*stack_head)==NULL || (*stack_head)->type!=value)
     return;
 
   value= (*stack_head)->content.val;