Remove trailing space and (- x x) matching

This commit is contained in:
Enrico Lumetti 2021-05-01 00:11:54 +02:00
parent 866af9c2b5
commit 4c67b0f18d
3 changed files with 75 additions and 77 deletions

73
c1.scm
View File

@ -9,54 +9,54 @@
(let ([r (read)])
(cond
[(fixnum? r) r]
[else (error "invalid fixnum in input: " r)]
)))
[else (error "invalid fixnum in input: " r)])))
(define (interp-exp sexp)
(match sexp
[(? fixnum?) sexp]
[`(read) (read-fixnum)]
[`(- ,e) (fx- 0 (interp-exp e))]
[`(+ ,e1 ,e2) (fx+ (interp-exp e1) (interp-exp e2))]
))
[`(+ ,e1 ,e2) (fx+ (interp-exp e1) (interp-exp e2))]))
(define (interp-R0 p)
(match p
[`(program ,e) (interp-exp e)]
))
[`(program ,e) (interp-exp e)]))
(define (pe-arith p)
(match p
[`(program ,e) (pe-exp e)]
))
[`(program ,e) (pe-exp e)]))
(define (pe-exp exp)
(pe-remove-node-labels (pe-fold-right-constants (pe-move-reads-left (pe-do-negate exp))))
)
(pe-remove-node-labels (pe-fold-right-constants (pe-move-reads-left (pe-do-negate exp)))))
; removes R/C/S labels from a tree
(define (pe-remove-node-labels tree)
(match tree
[`((+ ,e1 ,e2) ,_) `(+ ,(pe-remove-node-labels e1) ,(pe-remove-node-labels e2))]
[`(,e C) e]
[`(,e R) e]
))
[`(,e R) e]))
; partially evaluates an S/R/C-tree
(define (pe-fold-right-constants exp)
(match exp
[`(,_ S) (make-S-node (node-S-left exp) `(,(pe-fold-constants (node-S-right exp)) C))]
[`(,_ C) `(,(pe-fold-constants exp) C)]
[`(,_ R) exp]
))
[`(,_ R) exp]))
; evaluates a C-tree and returns the integer result
(define (pe-fold-constants c-tree)
(match c-tree
[`((+ ,e1 ,e2) C) (fx+ (pe-fold-constants e1) (pe-fold-constants e2))]
[`(,e C) e]
))
[`(,e C) e]))
; pushes down negation to literals, inside additions and elides multiple consecutive negations
(define (pe-do-negate exp)
@ -65,8 +65,8 @@
[`(- (+ ,e1 ,e2)) (pe-do-negate `(+ (- ,e1) (- ,e2)))]
[`(+ ,e1 ,e2) `(+ ,(pe-do-negate e1) ,(pe-do-negate e2))]
[`(- ,e) (if (fixnum? e) (fx- 0 e) `(- ,(pe-do-negate e)))]
[_ exp]
))
[_ exp]))
; takes an exepression and transforms it in an equivalent form such that it is either
; - a tree of C nodes
@ -84,9 +84,9 @@
[`(+ ,e1 ,e2)
(let ([e1-rl (pe-move-reads-left e1)]
[e2-rl (pe-move-reads-left e2)])
(pe-join-subtrees e1-rl e2-rl)
)]
))
(pe-join-subtrees e1-rl e2-rl))]))
; join two subtrees and forms either a new C-tree, a new R-tree or a new S-tree
(define (pe-join-subtrees e1-rl e2-rl)
@ -105,41 +105,41 @@
(node-S-right e1-rl))]
[(node-is-S e2-rl) (make-S-node
(make-R-node (node-S-left e1-rl) (node-S-left e2-rl))
(make-C-node (node-S-right e1-rl) (node-S-right e2-rl)))]
)]
[(node-is-S e2-rl) (pe-join-subtrees e2-rl e1-rl)]
)
)
(make-C-node (node-S-right e1-rl) (node-S-right e2-rl)))])]
[(node-is-S e2-rl) (pe-join-subtrees e2-rl e1-rl)]))
(define (node-is-C n)
(match n
[`(,_ C) #t]
[_ #f]
))
[_ #f]))
(define (node-is-R n)
(match n
[`(,_ R) #t]
[_ #f]
))
[_ #f]))
(define (node-is-S n)
(match n
[`(,_ S) #t]
[_ #f]
))
[_ #f]))
(define (node-S-left n)
(match n
[`((+ ,e1 ,_) S) e1]
[_ (error "cannot be here! (S left)")]
))
[_ (error "cannot be here! (S left)")]))
(define (node-S-right n)
(match n
[`((+ ,_ ,e2) S) e2]
[_ (error "cannot be here! (S right)")]
))
[_ (error "cannot be here! (S right)")]))
(define (make-S-node r c)
`((+ ,r ,c) S))
@ -180,4 +180,3 @@
(test-eq (pe-remove-node-labels `((+ ((- (read)) R) (-2 C)) S) ) `(+ (- (read)) -2))
(test-eq (pe-exp `(+ (- (+ (read) 9)) (+ (+ (read) 1) 5)) ) `(+ (+ (- (read)) (read)) -3))

View File

@ -41,13 +41,12 @@
(begin
(define-values (new-exp assoc-list new-tmpcount) (rco-arg e tmpcount))
(values (wrap-associations assoc-list `(- ,new-exp)) new-tmpcount))]
[`(,op ,e1 ,e2)
#:when (or (eq? op `+) (eq? op `-))
[`(+ ,e1 ,e2)
(begin
(define-values (new-exp1 assoc-list1 new-tmpcount1) (rco-arg e1 tmpcount))
(define-values (new-exp2 assoc-list2 new-tmpcount) (rco-arg e2 new-tmpcount1))
(values (wrap-associations (append assoc-list1 assoc-list2)
`(,op ,new-exp1 ,new-exp2)) new-tmpcount))]
`(+ ,new-exp1 ,new-exp2)) new-tmpcount))]
[`(let ([,var ,e]) ,body)
(begin
(define-values (exp-tmp exp-tmpcount) (rco-exp e tmpcount))