196 lines
7.1 KiB
Racket
196 lines
7.1 KiB
Racket
#lang racket/base
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;; HLL pattern analysis & processing
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(provide (for-syntax analyze-pattern)
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(struct-out predicate-match)
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match-value/captures
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?
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)
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(require (for-syntax racket/base))
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(require (for-syntax racket/match))
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(require (for-syntax syntax/parse))
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(require racket/match)
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(require "support/struct.rkt")
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(require "treap.rkt")
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(require "core.rkt")
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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(struct predicate-match (predicate sub-pattern) #:transparent)
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;; Value Projection -> (Option (Listof Value))
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;; Match a single value against a projection, returning a list of
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;; captured values.
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(define (match-value/captures v p)
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(define (walk v p captures-rev)
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(match* (v p)
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[(_ (capture sub))
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(match (walk v sub '())
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[#f #f]
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['() (cons v captures-rev)]
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[_ (error 'match-value/captures "Bindings in capture sub-patterns not supported")])]
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[(_ (predicate-match pred? sub)) #:when (pred? v)
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(walk v sub captures-rev)]
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[((== ?) _)
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captures-rev]
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[(_ (== ?))
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captures-rev]
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[((cons v1 v2) (cons p1 p2))
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(match (walk v1 p1 captures-rev)
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[#f #f]
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[c (walk v2 p2 c)])]
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[((? vector? v) (? vector? p)) #:when (= (vector-length v) (vector-length p))
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(define limit (vector-length v))
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(do ((c captures-rev (walk (vector-ref v i) (vector-ref p i) c))
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(i 0 (+ i 1)))
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((or (= i limit) (not c)) c))]
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[(_ _) #:when (or (treap? v) (treap? p))
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(error 'match-value/captures "Cannot match on treaps at present")]
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[((? non-object-struct?) (? non-object-struct?))
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#:when (eq? (struct->struct-type v) (struct->struct-type p))
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(walk (struct->vector v) (struct->vector p) captures-rev)]
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[(_ _) #:when (equal? v p)
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captures-rev]
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[(_ _)
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#f]))
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(define captures-rev (walk v p '()))
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(and captures-rev (reverse captures-rev)))
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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(begin-for-syntax
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(define (dollar-id? stx)
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(and (identifier? stx)
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(char=? (string-ref (symbol->string (syntax-e stx)) 0) #\$)))
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(define (undollar stx)
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(and (dollar-id? stx)
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(datum->syntax stx (string->symbol (substring (symbol->string (syntax-e stx)) 1)))))
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;; Syntax -> (Values Projection AssertionSetPattern (ListOf Identifier) Syntax)
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(define (analyze-pattern outer-expr-stx pat-stx0)
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(let walk ((pat-stx pat-stx0))
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(syntax-case pat-stx ($ ? quasiquote unquote quote)
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;; Extremely limited support for quasiquoting and quoting
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[(quasiquote (unquote p)) (walk #'p)]
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[(quasiquote (p ...)) (walk #'(list (quasiquote p) ...))]
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[(quasiquote p) (values #''p #''p '() #''p)]
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[(quote p) (values #''p #''p '() #''p)]
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[$v
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(dollar-id? #'$v)
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(with-syntax [(v (undollar #'$v))]
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(values #'(?!)
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#'?
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(list #'v)
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#'v))]
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[($ v p)
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(let ()
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(define-values (pr g bs _ins) (walk #'p))
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(when (not (null? bs))
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(raise-syntax-error #f "nested bindings not supported" outer-expr-stx pat-stx))
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(values #`(?! #,pr)
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g
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(list #'v)
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#'v))]
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[(? pred? p)
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;; TODO: support pred? in asserted/retracted as well as message events
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(let ()
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(syntax-parse outer-expr-stx
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#:literals [message]
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[(message _ ...) 'ok]
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[_ (raise-syntax-error #f
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"Predicate '?' matching only supported in message events"
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outer-expr-stx
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pat-stx)])
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(define-values (pr g bs ins) (walk #'p))
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(values #`(predicate-match pred? #,pr)
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g
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bs
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ins))]
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[(ctor p ...)
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(let ()
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(define parts (if (identifier? #'ctor) #'(p ...) #'(ctor p ...)))
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(define-values (pr g bs ins)
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(for/fold [(pr '()) (g '()) (bs '()) (ins '())] [(p (syntax->list parts))]
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(define-values (pr1 g1 bs1 ins1) (walk p))
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(values (cons pr1 pr)
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(cons g1 g)
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(append bs bs1)
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(cons ins1 ins))))
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(if (identifier? #'ctor)
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(values (cons #'ctor (reverse pr))
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(cons #'ctor (reverse g))
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bs
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(cons #'ctor (reverse ins)))
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(values (reverse pr)
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(reverse g)
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bs
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(reverse ins))))]
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[?
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(raise-syntax-error #f
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"Invalid use of '?' in pattern; use '_' instead"
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outer-expr-stx
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pat-stx)]
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[non-pair
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(if (and (identifier? #'non-pair)
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(free-identifier=? #'non-pair #'_))
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(values #'?
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#'?
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'()
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#'?)
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(values #'non-pair
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#'non-pair
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'()
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#'non-pair))]))))
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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(module+ test
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(require rackunit)
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(check-equal? (match-value/captures (list 1 2 3)
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(list 1 2 3))
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'())
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(check-equal? (match-value/captures (list 1 2 3)
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(list 1 22 3))
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#f)
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(check-equal? (match-value/captures (list 1 2 3)
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(list (?!) (?!) (?!)))
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(list 1 2 3))
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(check-equal? (match-value/captures (list 1 2 3)
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(list (?!) 2 (?!)))
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(list 1 3))
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(check-equal? (match-value/captures (list 1 2 3)
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(list (?!) ? (?!)))
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(list 1 3))
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(check-equal? (match-value/captures (list 1 2 3)
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(list (?!) (?! 2) (?!)))
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(list 1 2 3))
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(check-equal? (match-value/captures (list 1 2 3)
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(list (?!) (?! 22) (?!)))
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#f)
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(struct x (a b) #:prefab)
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(struct y (z w) #:prefab)
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(check-equal? (match-value/captures (x 1 2) (x 1 2)) '())
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(check-equal? (match-value/captures (x 1 22) (x 1 2)) #f)
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(check-equal? (match-value/captures (x 1 2) (x 1 22)) #f)
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(check-equal? (match-value/captures (x 1 2) (?! (x ? ?))) (list (x 1 2)))
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(check-equal? (match-value/captures (x 1 2) (?! (x ? 2))) (list (x 1 2)))
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(check-equal? (match-value/captures (x 1 2) (?! (x ? 22))) #f)
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(check-equal? (match-value/captures 123 (predicate-match even? ?)) #f)
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(check-equal? (match-value/captures 124 (predicate-match even? ?)) '())
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(check-equal? (match-value/captures (list 123) (list (predicate-match even? ?))) #f)
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(check-equal? (match-value/captures (list 124) (list (predicate-match even? ?))) '())
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(check-equal? (match-value/captures (list 124) (?! (list (predicate-match even? ?)))) '((124))))
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