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Add apply-patch! to diff.rkt

This commit is contained in:
Tony Garnock-Jones 2014-12-26 18:05:21 -05:00
parent 4dc90fb218
commit 2c21bcd58a
1 changed files with 21 additions and 1 deletions
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22
rmacs/diff.rkt
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@ -5,7 +5,8 @@
;; comparison, Bell Telephone Laboratories CSTR #41 (1976) ;; comparison, Bell Telephone Laboratories CSTR #41 (1976)
;; http://www.cs.dartmouth.edu/~doug/ ;; http://www.cs.dartmouth.edu/~doug/
(provide diff-indices) (provide diff-indices
apply-patch!)
(require racket/set) (require racket/set)
(require racket/match) (require racket/match)
@ -69,6 +70,25 @@
(cons (list (+ i 1) li (+ j 1) lj) (loop mi mj rest)) (cons (list (+ i 1) li (+ j 1) lj) (loop mi mj rest))
(loop mi mj rest))]))) (loop mi mj rest))])))
;; patch-indices is a result from a call to diff-indices
(define (apply-patch! patch-indices ;; DiffIndices
remove-elements! ;; Nat Nat -> Void
insert-elements! ;; Nat Nat Nat -> Void
)
(for/fold [(skew 0)] [(patch patch-indices)]
(match-define (list old-i old-n new-i new-n) patch)
(define delta (- new-n old-n))
(if (negative? delta)
(begin (remove-elements! (+ old-i skew) (- delta))
(+ skew delta))
skew))
(for/fold [(skew 0)] [(patch patch-indices)]
(match-define (list old-i old-n new-i new-n) patch)
(define delta (- new-n old-n))
(insert-elements! (+ old-i skew) (max 0 delta) new-n)
(+ skew delta))
(void))
(module+ test (module+ test
(require rackunit) (require rackunit)