309 lines
8.9 KiB
Scheme
309 lines
8.9 KiB
Scheme
#lang scheme/base
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(provide contract?
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contract-name contract-syntax
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contract-arbitrary set-contract-arbitrary!
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contract-violation-proc
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call-with-contract-violation-proc
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make-delayed-contract
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make-property-contract
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make-predicate-contract
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make-type-variable-contract
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make-list-contract
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make-mixed-contract
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make-combined-contract
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make-case-contract
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make-procedure-contract
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contract-update-syntax
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apply-contract apply-contract/blame)
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(require scheme/promise
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(for-syntax scheme/base)
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(for-syntax stepper/private/shared))
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(require deinprogramm/quickcheck/quickcheck)
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; name may be #f
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; enforcer: contract val -> val
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;
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; syntax: syntax data from where the contract was defined
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(define-struct contract (name enforcer syntax (arbitrary-promise #:mutable)))
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(define (contract-arbitrary ctr)
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(force (contract-arbitrary-promise ctr)))
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(define (set-contract-arbitrary! ctr arb)
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(set-contract-arbitrary-promise! ctr (delay arb)))
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(define (contract-update-syntax ctr stx)
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(struct-copy contract ctr (syntax stx)))
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; message may be #f
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(define contract-violation-proc (make-parameter (lambda (obj contract message blame)
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(raise (make-exn:fail:contract (or message
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(format "got ~e" obj))
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(current-continuation-marks))))))
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(define (contract-violation obj contract msg blame)
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((contract-violation-proc) obj contract msg blame))
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(define (call-with-contract-violation-proc proc thunk)
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(parameterize ((contract-violation-proc proc))
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(thunk)))
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(define (make-delayed-contract name promise syntax)
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(make-contract name
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(lambda (self obj)
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((contract-enforcer (force promise)) self obj))
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syntax
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(delay
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(force (contract-arbitrary-promise (force promise))))))
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(define (make-property-contract name access contract syntax)
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(let ((enforce (contract-enforcer contract)))
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(make-contract name
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(lambda (self obj)
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(enforce self (access obj)) ; #### problematic: enforcement doesn't stick
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obj)
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syntax
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#f)))
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(define (make-predicate-contract name predicate-promise syntax)
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(make-contract
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name
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(lambda (self obj) ; dynamic binding because of syntax remapping via `contract-update-syntax'
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(if ((force predicate-promise) obj)
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obj
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(begin
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(contract-violation obj self #f #f)
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obj)))
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syntax
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#f))
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(define (make-type-variable-contract name syntax)
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(make-predicate-contract name (lambda (obj) #t) syntax))
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; maps lists to pairs of contract, enforced value
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(define lists-table (make-weak-hasheq))
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(define (make-list-contract name arg-contract syntax)
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(make-contract
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name
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(lambda (self obj)
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;;(write (list 'list obj) (current-error-port)) (newline (current-error-port))
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(let recur ((l obj))
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(define (go-on)
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(let ((enforced (cons (apply-contract arg-contract (car l))
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(recur (cdr l)))))
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(hash-set! lists-table l (cons self enforced))
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(hash-set! lists-table enforced (cons self enforced))
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enforced))
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(cond
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((null? l)
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l)
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((not (pair? l))
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(contract-violation obj self #f #f)
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obj)
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((hash-ref lists-table l #f)
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=> (lambda (seen)
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;;(write (list 'seen seen (eq? self (car seen))) (current-error-port)) (newline (current-error-port))
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(if (eq? self (car seen))
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(cdr seen)
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(go-on))))
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(else
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(go-on)))))
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syntax
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(delay
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(lift->arbitrary arbitrary-list arg-contract))))
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(define (lift->arbitrary proc . contracts)
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(let ((arbitraries (map force (map contract-arbitrary-promise contracts))))
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(if (andmap values arbitraries)
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(apply proc arbitraries)
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#f)))
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(define (make-mixed-contract name alternative-contracts syntax)
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(make-contract
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name
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(lambda (self obj)
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(let loop ((alternative-contracts alternative-contracts))
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(cond
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((null? alternative-contracts)
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(contract-violation obj self #f #f)
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obj)
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((eq? (car alternative-contracts) self)
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(raise
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(make-exn:fail:contract
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(string->immutable-string
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(if name
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(format "rekursiver Vertrag: ~a" name)
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"rekursiver Vertrag"))
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(current-continuation-marks))))
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(else
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(check-contract (car alternative-contracts)
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obj
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values
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(lambda () (loop (cdr alternative-contracts))))))))
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syntax
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(delay
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(let ((arbitraries (map force (map contract-arbitrary-promise alternative-contracts))))
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(if (andmap values arbitraries)
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(arbitrary-mixed
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(map (lambda (ctr arb)
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(cons (contract->predicate ctr)
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arb))
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alternative-contracts arbitraries))
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#f)))))
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(define (check-contract ctr val success fail)
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((let/ec exit
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(let ((enforced
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(call-with-contract-violation-proc
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(lambda (contract syntax msg blame)
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(exit fail))
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(lambda ()
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(apply-contract ctr val)))))
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(lambda () (success enforced))))))
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(define (contract->predicate ctr)
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(lambda (val)
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(check-contract ctr val (lambda (_) #t) (lambda () #f))))
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(define (make-combined-contract name contracts syntax)
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(make-contract
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name
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(lambda (self obj)
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(let ((old-violation-proc (contract-violation-proc)))
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((let/ec exit
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(call-with-contract-violation-proc
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(lambda (contract syntax msg blame)
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(exit
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(lambda ()
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(old-violation-proc contract syntax msg blame)
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obj)))
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(lambda ()
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(let loop ((contracts contracts)
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(obj obj))
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(if (null? contracts)
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(lambda () obj)
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(loop (cdr contracts)
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(apply-contract (car contracts) obj))))))))))
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syntax
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#f))
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(define (make-case-contract name cases =? syntax)
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(make-contract
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name
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(lambda (self obj)
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(let loop ((cases cases))
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(cond
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((null? cases)
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(contract-violation obj self #f #f)
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obj)
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((=? (car cases) obj)
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obj)
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(else
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(loop (cdr cases))))))
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syntax
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(delay (apply arbitrary-one-of =? cases))))
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(define-struct procedure-to-blame (proc syntax))
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(define contract-key (gensym 'contract-key))
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(define (make-procedure-contract name arg-contracts return-contract syntax)
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(let ((arg-count (length arg-contracts)))
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(make-contract
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name
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(lambda (self thing)
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(let-values (((proc blame-syntax)
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(if (procedure-to-blame? thing)
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(values (procedure-to-blame-proc thing)
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(procedure-to-blame-syntax thing))
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(values thing #f))))
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(cond
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((not (procedure? proc))
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(contract-violation proc self #f #f))
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((not (procedure-arity-includes? proc arg-count)) ; #### variable arity
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(contract-violation proc self "falsche Anzahl von Parametern" #f)))
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(attach-name
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(object-name proc)
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(procedure-reduce-arity
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(lambda args
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(call-with-immediate-continuation-mark
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contract-key
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(lambda (maybe)
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(if (not (= (length args) arg-count))
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(begin
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(contract-violation proc self "falsche Anzahl von Argumenten" #f)
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(apply-contract return-contract (apply proc args)))
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(let* ((old-violation-proc (contract-violation-proc))
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(arg-violation? #f)
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(args
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(call-with-contract-violation-proc
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(lambda (obj contract message blame)
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(set! arg-violation? #t)
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(old-violation-proc obj contract message blame))
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(lambda ()
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(map apply-contract arg-contracts args)))))
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(if (eq? maybe return-contract)
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(apply proc args)
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(let ((retval
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(with-continuation-mark
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contract-key return-contract
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(apply proc args))))
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(if arg-violation?
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retval
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(call-with-contract-violation-proc
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(lambda (obj contract message _)
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;; blame the procedure
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(old-violation-proc obj contract message blame-syntax))
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(lambda ()
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(apply-contract return-contract retval)))))))))))
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(procedure-arity proc)))))
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syntax
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(delay
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(apply lift->arbitrary arbitrary-procedure return-contract arg-contracts)))))
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;; Matthew has promised a better way of doing this in the future.
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(define (attach-name name thing)
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(if (and (procedure? thing)
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(symbol? name))
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(procedure-rename thing name)
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thing))
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; like apply-contract, but can track more precise blame into the contract itself
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(define-syntax apply-contract/blame
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(lambda (stx)
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(syntax-case stx ()
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((_ ?cnt-exp ?val-exp)
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(syntax-case (local-expand #'?val-exp 'expression #f) (lambda #%plain-lambda)
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((lambda ?params ?body0 ?body1 ...)
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(stepper-syntax-property
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;; remember there's an implicit #%app
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#'(apply-contract ?cnt-exp
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(make-procedure-to-blame ?val-exp
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#'?val-exp))
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'stepper-skipto/discard
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'(syntax-e cdr syntax-e cdr cdr car
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syntax-e cdr syntax-e cdr car)))
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((#%plain-lambda ?params ?body0 ?body1 ...)
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(stepper-syntax-property
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#'(apply-contract ?cnt-exp
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(make-procedure-to-blame ?val-exp
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#'?val-exp))
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'stepper-skipto/discard
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'(syntax-e cdr syntax-e cdr cdr car
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syntax-e cdr syntax-e cdr car)))
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(_
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(stepper-syntax-property
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#'(apply-contract ?cnt-exp ?val-exp)
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'stepper-skipto/discard
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'(syntax-e cdr syntax-e cdr cdr car))))))))
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(define (apply-contract contract val)
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((contract-enforcer contract) contract val))
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