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Matthew Butterick 6 years ago
parent 426125c093
commit 2ef93b91a1
1 changed files with 38 additions and 33 deletions
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71
csp/hacs.rkt
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@ -5,9 +5,14 @@
(struct $csp ([vars #:mutable]
[constraints #:mutable]) #:transparent)
(struct $constraint (names proc) #:transparent)
(struct $var (name vals) #:transparent)
(struct $var (name vals past conflicts) #:transparent)
(define (+$var name vals [past null] [conflicts null])
($var name vals past conflicts))
(define $var-name? symbol?)
(struct $avar $var () #:transparent)
(define (+$avar name vals [past null] [conflicts null])
($avar name vals past conflicts))
(struct inconsistency-signal (csp) #:transparent)
(define current-select-variable (make-parameter #f))
@ -40,7 +45,7 @@
($csp
(for/list ([var ($csp-vars csp)])
(if (eq? name ($var-name var))
($avar name (list val))
(+$avar name (list val))
var))
($csp-constraints csp)))
@ -50,11 +55,11 @@
#:unless ($avar? var))
var))
(check-equal? (first-unassigned-variable ($csp (list ($var 'a (range 3)) ($var 'b (range 3))) null))
($var 'a (range 3)))
(check-equal? (first-unassigned-variable ($csp (list ($avar 'a (range 3)) ($var 'b (range 3))) null))
($var 'b (range 3)))
(check-false (first-unassigned-variable ($csp (list ($avar 'a (range 3)) ($avar 'b (range 3))) null)))
(check-equal? (first-unassigned-variable ($csp (list (+$var 'a (range 3)) (+$var 'b (range 3))) null))
(+$var 'a (range 3)))
(check-equal? (first-unassigned-variable ($csp (list (+$avar 'a (range 3)) (+$var 'b (range 3))) null))
(+$var 'b (range 3)))
(check-false (first-unassigned-variable ($csp (list (+$avar 'a (range 3)) (+$avar 'b (range 3))) null)))
(define first-domain-value values)
@ -72,59 +77,59 @@
($csp? $var-name? . -> . $csp?)
(define aval (first ($csp-vals csp aname)))
(define (filter-vals var)
(match-define ($var name vals) var)
(define new-vals
(match (($csp-constraints csp) . relating . (list aname name))
[(? empty?) vals]
[constraints
(match-define ($var name vals _ _) var)
(match (($csp-constraints csp) . relating . (list aname name))
[(? empty?) var]
[constraints
(define new-vals
(for/list ([val (in-list vals)]
#:when (for/and ([constraint (in-list constraints)])
(let ([proc ($constraint-proc constraint)])
(if (eq? name (first ($constraint-names constraint)))
(proc val aval)
(proc aval val)))))
val)]))
(unless (pair? new-vals)
(raise (inconsistency-signal csp)))
new-vals)
val))
(unless (pair? new-vals)
(raise (inconsistency-signal csp)))
(+$var name new-vals (cons aname ($var-past var)) ($var-conflicts var))]))
($csp
(for/list ([var (in-list ($csp-vars csp))])
(if ($avar? var)
var
($var ($var-name var) (filter-vals var))))
(filter-vals var)))
($csp-constraints csp)))
(check-equal?
($csp-vars (forward-check ($csp (list ($avar 'a '(1)) ($var 'b (range 2))) null) 'a))
(list ($avar 'a '(1)) ($var 'b '(0 1))))
($csp-vars (forward-check ($csp (list (+$avar 'a '(1)) (+$var 'b (range 2))) null) 'a))
(list (+$avar 'a '(1)) (+$var 'b '(0 1))))
(check-equal?
;; no inconsistency: b≠c not checked when fc is relative to a
($csp-vars (forward-check ($csp (list ($avar 'a '(1)) ($var 'b (range 2)) ($var 'c '(0)))
($csp-vars (forward-check ($csp (list (+$avar 'a '(1)) (+$var 'b (range 2)) (+$var 'c '(0)))
(list ($constraint '(a b) (negate =))
($constraint '(b c) (negate =)))) 'a))
(list ($avar 'a '(1)) ($var 'b '(0)) ($var 'c '(0))))
(list (+$avar 'a '(1)) (+$var 'b '(0) '(a)) (+$var 'c '(0))))
(check-equal?
;; no inconsistency: a≠b not checked when fc ignores a, which is already assigned
($csp-vars (forward-check ($csp (list ($avar 'a '(1)) ($avar 'b '(1)) ($var 'c (range 2)))
($csp-vars (forward-check ($csp (list (+$avar 'a '(1)) (+$avar 'b '(1)) (+$var 'c (range 2)))
(list ($constraint '(a b) (negate =))
($constraint '(b c) (negate =)))) 'b))
(list ($avar 'a '(1)) ($avar 'b '(1)) ($var 'c '(0))))
(list (+$avar 'a '(1)) (+$avar 'b '(1)) (+$var 'c '(0) '(b))))
(check-exn inconsistency-signal?
(λ () ($csp-vars (forward-check ($csp (list ($avar 'a '(1))
($var 'b '(1)))
(λ () ($csp-vars (forward-check ($csp (list (+$avar 'a '(1))
(+$var 'b '(1)))
(list ($constraint '(a b) (negate =)))) 'a))))
(check-equal? ($csp-vars (forward-check ($csp (list ($avar 'a (range 3))
($var 'b (range 3)))
(check-equal? ($csp-vars (forward-check ($csp (list (+$avar 'a (range 3))
(+$var 'b (range 3)))
(list ($constraint '(a b) <)
($constraint '(a b) <)
($constraint '(a b) <))) 'a))
(list ($avar 'a '(0 1 2)) ($var 'b '(1 2))))
(list (+$avar 'a '(0 1 2)) (+$var 'b '(1 2) '(a))))
(define/contract (backtracking-solver
@ -137,7 +142,7 @@
(let backtrack ([csp csp])
(match (select-unassigned-variable csp)
[#false (yield csp)]
[($var name vals)
[($var name vals _ _)
(for ([val (in-list (order-domain-values vals))])
(with-handlers ([inconsistency-signal? void])
(let* ([csp (assign-val csp name val)]
@ -165,16 +170,16 @@
(define (neq? a b) (not (eq? a b)))
#;(parameterize ([current-inference forward-check])
(time (solve* ($csp (list ($var 'a (range 3))
($var 'b (range 3))
($var 'c (range 3)))
(time (solve* ($csp (list (+$var 'a (range 3))
(+$var 'b (range 3))
(+$var 'c (range 3)))
(list ($constraint '(a b) <>)
($constraint '(a c) <>)
($constraint '(b c) <>))))))
(parameterize ([current-inference forward-check])
(define vds (for/list ([k '(wa nsw t q nt v sa)])
($var k '(red green blue))))
(+$var k '(red green blue))))
(define cs (list
($constraint '(wa nt) neq?)
($constraint '(wa sa) neq?)

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