--- stack/stack.c	2002/01/07 23:35:37	1.4
+++ stack/stack.c	2002/01/31 21:47:20	1.15
@@ -11,7 +11,7 @@
 
 typedef struct stack_item
 {
-  enum {value, string, ref, func, symbol} type;
+  enum {value, string, ref, func, symbol, list} type;
   union {
     void* ptr;
     int val;
@@ -25,6 +25,8 @@
 typedef stackitem* hashtbl[HASHTBLSIZE];
 typedef void (*funcp)(stackitem**);
 
+
+/* Initiates a newly created hash table. */
 void init_hashtbl(hashtbl out_hash)
 {
   long i;
@@ -33,6 +35,7 @@
     out_hash[i]= NULL;
 }
 
+/* Returns a pointer to an element in the hash table. */
 stackitem** hash(hashtbl in_hashtbl, const char* in_string)
 {
   long i= 0;
@@ -61,7 +64,7 @@
   }
 }
 
-
+/* Generic push function. */
 int push(stackitem** stack_head, stackitem* in_item)
 {
   in_item->next= *stack_head;
@@ -69,6 +72,7 @@
   return 1;
 }
 
+/* Push a value on the stack. */
 int push_val(stackitem** stack_head, int in_val) 
 {
   stackitem* new_item= malloc(sizeof(stackitem));
@@ -79,6 +83,7 @@
   return 1;
 }
 
+/* Copy a string onto the stack. */
 int push_cstring(stackitem** stack_head, const char* in_string)
 {
   stackitem* new_item= malloc(sizeof(stackitem));
@@ -90,6 +95,7 @@
   return 1;
 }
 
+/* Create a new hash entry. */
 int mk_hashentry(hashtbl in_hashtbl, stackitem* in_item, const char* id)
 {
   in_item->id= malloc(strlen(id)+1);
@@ -100,6 +106,7 @@
   return 1;
 }
 
+/* Define a function a new function in the hash table. */
 void def_func(hashtbl in_hashtbl, funcp in_func, const char* id)
 {
   stackitem* temp= malloc(sizeof(stackitem));
@@ -110,6 +117,7 @@
   mk_hashentry(in_hashtbl, temp, id);
 }
 
+/* Define a new symbol in the hash table. */
 void def_sym(hashtbl in_hashtbl, const char* id)
 {
   stackitem* temp= malloc(sizeof(stackitem));
@@ -119,17 +127,20 @@
   mk_hashentry(in_hashtbl, temp, id);
 }
 
+/* Push a reference to an entry in the hash table onto the stack. */
 int push_ref(stackitem** stack_head, hashtbl in_hash, const char* in_string)
 {
-  void* handle;
+  static void* handle= NULL;
   void* symbol;
-  
+
   stackitem* new_item= malloc(sizeof(stackitem));
   new_item->content.ptr= *hash(in_hash, in_string);
   new_item->type= ref;
 
   if(new_item->content.ptr==NULL) {
-    handle= dlopen(NULL, RTLD_LAZY);
+    if(handle==NULL)
+      handle= dlopen(NULL, RTLD_LAZY);    
+
     symbol= dlsym(handle, in_string);
     if(dlerror()==NULL) 
       def_func(in_hash, symbol, in_string);
@@ -144,36 +155,69 @@
   return 1;
 }
 
+/* Discard the top element of the stack. */
 extern void toss(stackitem** stack_head)
 {
   stackitem* temp= *stack_head;
 
+  if((*stack_head)==NULL)
+    return;
+  
+  if((*stack_head)->type==string)
+    free((*stack_head)->content.ptr);
+
   *stack_head= (*stack_head)->next;
   free(temp);
 }
 
+/* Print newline. */
+extern void nl()
+{
+  printf("\n");
+}
 
-/* print_stack(stack); */
-void print_st(stackitem* stack_head, long counter)
-{ 
-  if(stack_head->next != NULL)
-    print_st(stack_head->next, counter+1);
+/* Prints the top element of the stack. */
+void print_(stackitem** stack_head)
+{
+  if((*stack_head)==NULL)
+    return;
 
-  switch(stack_head->type){
+  switch((*stack_head)->type) {
   case value:
-    printf("%ld: %d\n", counter, (int)stack_head->content.val);
+    printf("%d", (*stack_head)->content.val);
     break;
   case string:
-    printf("%ld: \"%s\"\n", counter, (char*)stack_head->content.ptr);
+    printf("%s", (char*)(*stack_head)->content.ptr);
     break;
   case ref:
-  case func:
+    printf("%s", ((stackitem*)(*stack_head)->content.ptr)->id);
+    break;
   case symbol:
-    printf("%ld: %p\n", counter, stack_head->content.ptr);
+  default:
+    printf("%p", (*stack_head)->content.ptr);
     break;
   }
 }
 
+/* Prints the top element of the stack and then discards it. */
+extern void print(stackitem** stack_head)
+{
+  print_(stack_head);
+  toss(stack_head);
+}
+
+/* Only to be called by function printstack. */
+void print_st(stackitem* stack_head, long counter)
+{ 
+  if(stack_head->next != NULL)
+    print_st(stack_head->next, counter+1);
+
+  printf("%ld: ", counter);
+  print_(&stack_head);
+  nl();
+}
+
+/* Prints the stack. */
 extern void printstack(stackitem** stack_head)
 {
   if(*stack_head != NULL) {
@@ -182,7 +226,9 @@
   }
 }
 
-
+/* 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. */
 extern void eval(stackitem** stack_head)
 {
   funcp in_func;
@@ -198,6 +244,7 @@
   }
 }
 
+/* Parse input. */
 int stack_read(stackitem** stack_head, hashtbl in_hash, char* in_line) 
 {
   char *temp, *rest;
@@ -208,15 +255,34 @@
   temp= malloc(inlength);
   rest= malloc(inlength);
 
-  if((convert= sscanf(in_line, "\"%[^\"\n\r]\" %[^\n\r]", temp, rest)) >= 1)
-    push_cstring(stack_head, temp);
-  else if((convert= sscanf(in_line, "%d %[^\n\r]", &itemp, rest)) >= 1)
-    push_val(stack_head, itemp);
-  else if((convert= sscanf(in_line, "%[^ ;\n\r]%[^\n\r]", temp, rest)) >= 1) 
-    push_ref(stack_head, in_hash, temp);
-  else if((convert= sscanf(in_line, "%c%[^\n\r]", temp, rest)) >= 1)
-    if(*temp==';')
+  do {
+    if((convert= sscanf(in_line, "\"%[^\"\n\r]\" %[^\n\r]", temp, rest))) {
+      push_cstring(stack_head, temp);
+      break;
+    }
+ 
+    if((convert= sscanf(in_line, "%d %[^\n\r]", &itemp, rest))) {
+      push_val(stack_head, itemp);
+      break;
+    }
+ 
+    if((convert= sscanf(in_line, "\\%c%[^\n\r]", temp, rest))) {
+      temp[1]= '\0'; 
+      push_ref(stack_head, in_hash, temp);
+      break;
+    } 
+      
+    if((convert= sscanf(in_line, "%[^ ;\n\r]%[^\n\r]", temp, rest))) {
+	push_ref(stack_head, in_hash, temp);
+	break;
+    }
+  
+    if((convert= sscanf(in_line, "%c%[^\n\r]", temp, rest)) && *temp==';') {
       eval(stack_head);
+      break;
+    }
+  } while(0);
+
 
   free(temp);
 
@@ -231,24 +297,129 @@
   return 1;
 }
 
-extern void print(stackitem** stack_head)
+/* Make a list. */
+extern void pack(stackitem** stack_head)
 {
+  void* delimiter;
+  stackitem *iterator, *temp, *pack;
+
   if((*stack_head)==NULL)
     return;
 
-  if((*stack_head)->type==value)
-    printf("%d", (*stack_head)->content.val);
-  else if((*stack_head)->type==string)
-    printf("%s", (char*)(*stack_head)->content.ptr);
-  else
-    printf("%p", (*stack_head)->content.ptr);
+  delimiter= (*stack_head)->content.ptr;
+  toss(stack_head);
+
+  iterator= *stack_head;
+
+  while(iterator->next!=NULL && iterator->next->content.ptr!=delimiter)
+    iterator= iterator->next;
+
+  temp= *stack_head;
+  *stack_head= iterator->next;
+  iterator->next= NULL;
+  
+  if(*stack_head!=NULL && (*stack_head)->content.ptr==delimiter)
+    toss(stack_head);
+
+  pack= malloc(sizeof(stackitem));
+  pack->type= list;
+  pack->content.ptr= temp;
+
+  push(stack_head, pack);
+}
+
+/* Push elements of the list on the stack. */
+extern void expand(stackitem** stack_head)
+{
+  stackitem *temp, *new_head;
+
+  if((*stack_head)==NULL || (*stack_head)->type!=list)
+    return;
 
+  new_head= temp= (*stack_head)->content.ptr;
   toss(stack_head);
+
+  while(temp->next!=NULL)
+    temp= temp->next;
+
+  temp->next= *stack_head;
+  *stack_head= new_head;
 }
 
-extern void nl()
+/* Swap the two top elements on the stack. */
+extern void swap(stackitem** stack_head)
 {
-  printf("\n");
+  stackitem* temp= (*stack_head);
+  
+  if((*stack_head)==NULL || (*stack_head)->next==NULL)
+    return;
+
+  *stack_head= (*stack_head)->next;
+  temp->next= (*stack_head)->next;
+  (*stack_head)->next= temp;
+} 
+
+/* Compares two elements by reference. */
+extern void eq(stackitem** stack_head)
+{
+  void *left, *right;
+  int result;
+
+  if((*stack_head)==NULL || (*stack_head)->next==NULL)
+    return;
+
+  left= (*stack_head)->content.ptr;
+  swap(stack_head);
+  right= (*stack_head)->content.ptr;
+  result= (left==right);
+  
+  toss(stack_head); toss(stack_head);
+  push_val(stack_head, (left==right));
+}
+
+/* Negates the top element on the stack. */
+extern void not(stackitem** stack_head)
+{
+  int value;
+
+  if((*stack_head)==NULL)
+    return;
+
+  value= (*stack_head)->content.val;
+  toss(stack_head);
+  push_val(stack_head, !value);
+}
+
+/* Compares the two top elements on the stack and return 0 if they're the
+   same. */
+extern void neq(stackitem** stack_head)
+{
+  eq(stack_head);
+  not(stack_head);
+}
+
+/* Give a symbol some content. */
+extern void def(stackitem** stack_head)
+{
+  stackitem *temp, *value;
+
+  if(*stack_head==NULL || (*stack_head)->next==NULL 
+     || (*stack_head)->type!=ref)
+    return;
+
+  temp= (*stack_head)->content.ptr;
+  value= (*stack_head)->next;
+  temp->content= value->content;
+  value->content.ptr=NULL;
+  temp->type= value->type;
+
+  toss(stack_head); toss(stack_head);
+} 
+
+/* Quit stack. */
+extern void quit()
+{
+  exit(EXIT_SUCCESS);
 }
 
 int main()
@@ -266,8 +437,7 @@
     printf("okidok\n ");
   }
 
-
-  return EXIT_SUCCESS;
+  exit(EXIT_SUCCESS);
 }
 
 /* Local Variables: */