Relevant things from fields.h, dllist.h, queue.h, stack.h

typedef struct inputstruct {
  char *name;               /* File name */
  FILE *f;                  /* File descriptor */
  int line;                 /* Line number */
  char text1[MAXLEN];       /* The line */
  int NF;                   /* Number of fields */
  char *fields[MAXFIELDS];  /* Pointers to fields */
  ...
} *IS;

extern IS new_inputstruct(/* FILENAME -- NULL for stdin */);
extern int get_line(/* IS */); /* returns NF, or -1 on EOF.  Does not
                                  close the file */
typedef struct dllist {
  struct dllist *flink;
  struct dllist *blink;
  Jval val;
} *Dllist;

extern Dllist new_dllist();
extern void free_dllist(Dllist);

extern void dll_append(Dllist, Jval);
extern void dll_prepend(Dllist, Jval);
extern void dll_insert_b(Dllist, Jval);
extern void dll_insert_a(Dllist, Jval);

extern void dll_delete_node(Dllist);
extern int dll_empty(Dllist);
typedef void *Stack;
Stack new_stack();    /* Create an empty stack */
void stack_push(Stack s, Jval jv);  /* Push an element onto the stack */
Jval stack_pop(Stack s);  /* Pop an element off the stack.  Will exit with an error
                             if the stack is empty */
int stack_empty(Stack s); /* This is a boolean function that returns 1 
                            if there are no elements on the stack, 
                            and 0 if there are elements on the stack.  */
typedef void *Queue;
Queue new_queue();    /* Create an empty queue */
void queue_enqueue(Queue q, Jval jv);  
Jval queue_dequeue(Queue q);  
int queue_empty(Queue q); /* This is a boolean function that returns 1 
                            if there are no elements on the queue, 
                            and 0 if there are elements on the queue.  */
typedef union {
    int i;
    long l;
    ...
    char *s;
    ...
  } Jval;  

extern Jval new_jval_s(char *);