; hw4.lisp
; CS 381 homework 4
; Jacob Lundberg

; MY-MEMBER returns a sub-list starting at a member.
(defun MY-MEMBER (mem1 list1)
  (cond ((null list1) nil)
        ((eq mem1 (car list1)) list1)
        (T (MY-MEMBER mem1 (cdr list1)))
  )
)

; MY-SET-UNION returns a set that is the union of two sets, unordered.
; *NOTE* that if you don't give it true sets it may not behave like UNION.
(defun MY-SET-UNION (set1 set2)
  (cond ((null set2) set1)
        ((MY-MEMBER (car set2) set1) (MY-SET-UNION set1 (cdr set2)))
        (T (MY-SET-UNION (cons (car set2) set1) (cdr set2)))
  )
)

; MY-SUB-UNION does the work for MY-UNION, which is a wrapper.
; When list1 comes in, it should be a ((1 2) (3) (3 4 5)) type list.
(defun MY-SUB-UNION (set1 list1)
  (cond ((null list1) set1)
        ((null (car list1)) set1)
        (T (MY-SET-UNION set1 (MY-SUB-UNION (car list1) (cdr list1))))
  )
)

; MY-UNION returns a set that is the union of the given sets, unordered.
; *NOTE* that if you don't give it true sets it may not behave like UNION.
; Not that UNION takes more than two sets anyway.  ;-)
(defun MY-UNION (set1 &rest list1)
  (MY-SUB-UNION set1 list1)
)

; LISTIFY makes a two-level list out of whatever you pass it.
(defun LISTIFY (&rest list1)
  (cons list1 nil)
)

; MY-SUB-COMPILE does the work for MY-COMPILE, which sets up the base case.
; A badly formed btree may cause this to return invalid "machine language".
(defun MY-SUB-COMPILE (btree1 level1)
  (cond ((null btree1) nil)
        ((listp btree1)
         (cond ((eql (car btree1) '+) ; this is the ADD case
                (append (MY-SUB-COMPILE (cadr btree1) level1)
                        (MY-SUB-COMPILE (caddr btree1) (+ level1 1))
                        (LISTIFY 'ADD level1 (+ level1 1))
                ) ; append
               ) ; eql '+ cond line
               ((eql (car btree1) '-) ; this is the SUB case
                (append (MY-SUB-COMPILE (cadr btree1) level1)
                        (MY-SUB-COMPILE (caddr btree1) (+ level1 1))
                        (LISTIFY 'SUB level1 (+ level1 1))
                ) ; append
               ) ; eql '- cond line
               ((eql (car btree1) '*) ; this is the MUL case
                (append (MY-SUB-COMPILE (cadr btree1) level1)
                        (MY-SUB-COMPILE (caddr btree1) (+ level1 1))
                        (LISTIFY 'MUL level1 (+ level1 1))
                ) ; append
               ) ; eql '* cond line
               ((eql (car btree1) '/) ; this is the DIV case
                (append (MY-SUB-COMPILE (cadr btree1) level1)
                        (MY-SUB-COMPILE (caddr btree1) (+ level1 1))
                        (LISTIFY 'DIV level1 (+ level1 1))
                ) ; append
               ) ; eql '/ cond line
         ) ; 2nd level cond
        ) ; listp cond line
        (T (LISTIFY 'MOVE level1 btree1)) ; this is the MOVE case
  ) ; 1st level cond
) ; defun MY-SUB-COMPILE

; MY-COMPILE takes a btree and returns its "machine language" translation.
(defun MY-COMPILE (btree1)
  (MY-SUB-COMPILE btree1 1) ; start processing on level 1
)