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Add invert-filter and use it in -imp.

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This commit is contained in:
Eric Dobson 2014-03-26 09:14:43 -07:00
parent 2fda610c54
commit a662f72c9e
2 changed files with 16 additions and 2 deletions
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16
pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/types/filter-ops.rkt
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@ -110,14 +110,26 @@
(loop (cdr props) others)] (loop (cdr props) others)]
[p (loop (cdr props) (cons p others))])))) [p (loop (cdr props) (cons p others))]))))
;; invert-filter: Filter/c -> Filter/c
;; Logically inverts a filter.
(define (invert-filter p)
(match p
[(Bot:) -top]
[(Top:) -bot]
[(TypeFilter: t p o) (-not-filter t o p)]
[(NotTypeFilter: t p o) (-filter t o p)]
[(AndFilter: fs) (apply -or (map invert-filter fs))]
[(OrFilter: fs) (apply -and (map invert-filter fs))]
[(ImpFilter: f1 f2) (-and f1 (invert-filter f2))]))
;; -imp: Filter/c Filter/c -> Filter/c
;; Smart constructor for make-ImpFilter
(define (-imp p1 p2) (define (-imp p1 p2)
(match* (p1 p2) (match* (p1 p2)
[((Bot:) _) -top] [((Bot:) _) -top]
[(_ (Top:)) -top] [(_ (Top:)) -top]
[((Top:) _) p2] [((Top:) _) p2]
[((TypeFilter: t p o) (Bot:)) (-not-filter t o p)] [(_ (Bot:)) (invert-filter p1)]
[((NotTypeFilter: t p o) (Bot:)) (-filter t o p)]
[(_ _) (make-ImpFilter p1 p2)])) [(_ _) (make-ImpFilter p1 p2)]))
(define (-or . args) (define (-or . args)

2
pkgs/typed-racket-pkgs/typed-racket-test/tests/typed-racket/unit-tests/filter-tests.rkt
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@ -111,6 +111,8 @@
(check-equal? (-imp (-filter -Symbol #'x) -top) -top) (check-equal? (-imp (-filter -Symbol #'x) -top) -top)
(check-equal? (-imp (-filter -Symbol #'x) -bot) (-not-filter -Symbol #'x)) (check-equal? (-imp (-filter -Symbol #'x) -bot) (-not-filter -Symbol #'x))
(check-equal? (-imp (-not-filter -Symbol #'x) -bot) (-filter -Symbol #'x)) (check-equal? (-imp (-not-filter -Symbol #'x) -bot) (-filter -Symbol #'x))
(check-equal? (-imp (-imp (-not-filter -Symbol #'x) (-not-filter -Symbol #'y)) -bot)
(-and (-not-filter -Symbol #'x) (-filter -Symbol #'y)))
(check-equal? (check-equal?
(-imp (-not-filter -Symbol #'x) (-imp (-not-filter -Symbol #'x)
(-not-filter -Symbol #'y)) (-not-filter -Symbol #'y))