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touchup

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Matthew Butterick 6 years ago
parent b94c278f4b
commit 426125c093
1 changed files with 73 additions and 47 deletions
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120
csp/hacs.rkt
Unescape Escape View File

@ -10,6 +10,12 @@
(struct $avar $var () #:transparent)
(struct inconsistency-signal (csp) #:transparent)
(define current-select-variable (make-parameter #f))
(define current-order-values (make-parameter #f))
(define current-inference (make-parameter #f))
(define current-solver (make-parameter #f))
(define/contract (check-name-in-csp! caller csp name)
(symbol? $csp? $var-name? . -> . void?)
(define names (map $var-name ($csp-vars csp)))
@ -29,7 +35,8 @@
($var-vals ($csp-var csp name)))
(define order-domain-values values)
(define (assign-val csp name val)
(define/contract (assign-val csp name val)
($csp? $var-name? any/c . -> . $csp?)
($csp
(for/list ([var ($csp-vars csp)])
(if (eq? name ($var-name var))
@ -37,49 +44,52 @@
var))
($csp-constraints csp)))
(define current-select-variable (make-parameter #f))
(define current-order-values (make-parameter #f))
(define current-inference (make-parameter #f))
(define (first-unassigned-variable csp)
(for/first ([var ($csp-vars csp)]
(define/contract (first-unassigned-variable csp)
($csp? . -> . (or/c #false (and/c $var? (not/c $avar?))))
(for/first ([var (in-list ($csp-vars csp))]
#: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)) ($var 'b (range 3)))
(check-equal? (first-unassigned-variable ($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)
(define (no-inference csp name) csp)
(define (forward-check csp aname)
(define/contract (relating constraints names)
((listof $constraint?) (listof $var-name?) . -> . (listof $constraint?))
(for*/list ([constraint (in-list constraints)]
[cnames (in-value ($constraint-names constraint))]
#:when (for/and ([name (in-list names)])
(memq name cnames)))
constraint))
(define/contract (forward-check csp aname)
($csp? $var-name? . -> . $csp?)
(define aval (first ($csp-vals csp aname)))
(define (filter-vals var)
(match-define ($var name vals) var)
(define new-vals
(match (for*/list ([constraint (in-list ($csp-constraints csp))]
[cnames (in-value ($constraint-names constraint))]
#:when (and (memq aname cnames) (memq name cnames)))
constraint)
[(list) vals]
(match (($csp-constraints csp) . relating . (list aname name))
[(? empty?) vals]
[constraints
(for*/list ([val (in-list vals)]
[constraint (in-list constraints)]
[cnames (in-value ($constraint-names constraint))]
#:when (cond
[(eq? (first cnames) name)
(($constraint-proc constraint) val aval)]
[(eq? (second cnames) name)
(($constraint-proc constraint) aval val)]
[else #true]))
(for/list ([val (in-list vals)]
#:when (for/and ([constraint (in-list constraints)])
(let ([proc ($constraint-proc constraint)])
(if (eq? name (first ($constraint-names constraint)))
(proc val aval)
(proc aval val)))))
val)]))
(unless (pair? new-vals) (raise (inconsistency-signal csp)))
(unless (pair? new-vals)
(raise (inconsistency-signal csp)))
new-vals)
($csp
(for/list ([var ($csp-vars csp)])
(for/list ([var (in-list ($csp-vars csp))])
(if ($avar? var)
var
($var ($var-name var) (filter-vals var))))
@ -90,14 +100,14 @@
(list ($avar 'a '(1)) ($var 'b '(0 1))))
(check-equal?
;; no inconsistency because b≠c not checked (because fc is relative to a)
;; no inconsistency: b≠c not checked when fc is relative to a
($csp-vars (forward-check ($csp (list ($avar 'a '(1)) ($var 'b (range 2)) ($var 'c '(0)))
(list ($constraint '(a b) (negate =))
($constraint '(b c) (negate =)))) 'a))
(list ($avar 'a '(1)) ($var 'b '(0)) ($var 'c '(0))))
(check-equal?
;; no inconsistency because a≠b not checked (because fc ignores a, which is already assigned)
;; no inconsistency: a≠b not checked when fc ignores a, which is already assigned
($csp-vars (forward-check ($csp (list ($avar 'a '(1)) ($avar 'b '(1)) ($var 'c (range 2)))
(list ($constraint '(a b) (negate =))
($constraint '(b c) (negate =)))) 'b))
@ -108,11 +118,21 @@
($var 'b '(1)))
(list ($constraint '(a b) (negate =)))) 'a))))
(define/contract (backtrack-solution-generator csp
[select-unassigned-variable (or (current-select-variable) first-unassigned-variable)]
[order-domain-values (or (current-order-values) first-domain-value)]
[inference (or (current-inference) no-inference)])
(($csp?) (procedure? procedure? procedure?) . ->* . generator?)
(check-equal? ($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))))
(define/contract (backtracking-solver
csp
#:select-variable [select-unassigned-variable (or (current-select-variable) first-unassigned-variable)]
#:order-values [order-domain-values (or (current-order-values) first-domain-value)]
#:inference [inference (or (current-inference) no-inference)])
(($csp?) (#:select-variable procedure? #:order-values procedure? #:inference procedure?) . ->* . generator?)
(generator ()
(let backtrack ([csp csp])
(match (select-unassigned-variable csp)
@ -124,28 +144,34 @@
[csp (inference csp name)])
(backtrack csp))))]))))
(define/contract (solve* csp [finish-proc $csp-vars][solution-limit +inf.0])
(($csp?) (procedure? integer?) . ->* . (listof any/c))
(for/list ([solution (in-producer (backtrack-solution-generator csp) (void))]
[idx (in-range solution-limit)])
(define/contract (solve* csp
#:finish-proc [finish-proc $csp-vars]
#:solver [solver (or (current-solver) backtracking-solver)]
#:count [max-solutions +inf.0])
(($csp?) (#:finish-proc procedure? #:solver generator? #:count integer?) . ->* . (listof any/c))
(for/list ([solution (in-producer (solver csp) (void))]
[idx (in-range max-solutions)])
(finish-proc solution)))
(define/contract (solve csp [finish-proc $csp-vars])
(($csp?) (procedure?) . ->* . (or/c #false any/c))
(match (solve* csp finish-proc 1)
(define/contract (solve csp
#:finish-proc [finish-proc $csp-vars]
#:solver [solver (or (current-solver) backtracking-solver)])
(($csp?) (#:finish-proc procedure? #:solver generator?) . ->* . (or/c #false any/c))
(match (solve* csp #:finish-proc finish-proc #:solver solver #:count 1)
[(list solution) solution]
[else #false]))
(define (<> a b) (not (= a b)))
(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)))
(list ($constraint '(a b) <>)
($constraint '(a c) <>)
($constraint '(b c) <>))))))
#;(parameterize ([current-inference forward-check])
(time (solve* ($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))))

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