racket/collects/racket/contract/private/struct.rkt

230 lines
11 KiB
Racket

#lang racket/base
(require (for-syntax racket/base
racket/list
racket/struct-info)
racket/list
"guts.rkt"
"blame.rkt"
"prop.rkt"
"misc.rkt")
(provide struct/c)
(define-syntax (struct/c stx)
(syntax-case stx ()
[(_ . args)
(with-syntax ([x (syntax/loc stx (do-struct/c . args))])
(syntax/loc stx (#%expression x)))]))
;; name is symbol
;; predicate is (-> any bool)
;; immutables is (listof (list natural contract selector-proc))
;; mutables is (listof (list natural contract selector-proc mutator-proc))
(define-struct base-struct/c (name predicate immutables mutables))
(define (struct/c-name ctc)
(let ([ctcs (map second
(sort (append (base-struct/c-immutables ctc) (base-struct/c-mutables ctc))
< #:key first))])
(apply build-compound-type-name 'struct/c (base-struct/c-name ctc) ctcs)))
(define (check-struct/c ctc)
(let ([name (base-struct/c-name ctc)]
[pred? (base-struct/c-predicate ctc)]
[ctc/ref-pairs (map (λ (l) (cons (second l) (third l)))
(append (base-struct/c-immutables ctc) (base-struct/c-mutables ctc)))])
(λ (val fail [first-order? #f])
(unless (pred? val)
(fail "expected <~s>, got ~e" name val))
(when first-order?
(for ([p (in-list ctc/ref-pairs)])
(let ([c (car p)] [v ((cdr p) val)])
(unless (contract-first-order-passes? c v)
(fail "expected <~s>, got ~e" (contract-name c) v)))))
#t)))
(define (struct/c-first-order ctc)
(let ([f (check-struct/c ctc)])
(λ (val)
(let/ec fail
(f val (λ args (fail #f)) #t)))))
(define (flat-struct/c-proj ctc)
(let ([checker (check-struct/c ctc)]
[name (base-struct/c-name ctc)]
[pred (base-struct/c-predicate ctc)]
[projs (map contract-projection (map second (base-struct/c-immutables ctc)))]
[refs (map third (base-struct/c-immutables ctc))])
(λ (blame)
(let ([pos-projs (map (λ (f) (f blame)) projs)])
(λ (val)
(checker val (λ args (apply raise-blame-error blame val args)))
(for ([p (in-list pos-projs)] [ref (in-list refs)])
(p (ref val)))
val)))))
(define-struct (flat-struct/c base-struct/c) ()
#:property prop:flat-contract
(build-flat-contract-property
#:name struct/c-name
#:first-order struct/c-first-order
#:projection flat-struct/c-proj))
(define (chaperone-struct/c-proj ctc)
(let-values ([(flat-imms chap-imms)
(partition (λ (l) (flat-contract? (second l))) (base-struct/c-immutables ctc))])
(let ([checker (check-struct/c ctc)]
[name (base-struct/c-name ctc)]
[pred (base-struct/c-predicate ctc)]
[flat-imm-projs (map (compose contract-projection second) flat-imms)]
[flat-imm-refs (map third flat-imms)]
[chap-imm-projs (map (compose contract-projection second) chap-imms)]
[chap-imm-refs (map third chap-imms)]
[mut-projs (map (compose contract-projection second) (base-struct/c-mutables ctc))]
[mut-refs (map third (base-struct/c-mutables ctc))]
[mut-sets (map fourth (base-struct/c-mutables ctc))])
(λ (blame)
(let* ([swapped-blame (blame-swap blame)]
[flat-imm-pos-projs (map (λ (f) (f blame)) flat-imm-projs)]
[chap-imm-pos-projs (map (λ (f) (f blame)) chap-imm-projs)]
[mut-pos-projs (map (λ (f) (f blame)) mut-projs)]
[mut-neg-projs (map (λ (f) (f swapped-blame)) mut-projs)])
(λ (val)
(checker val (λ args (apply raise-blame-error blame val args)))
(for ([p (in-list flat-imm-pos-projs)]
[ref (in-list flat-imm-refs)])
(p (ref val)))
;; While gathering up the selectors and the appropriate projections,
;; we go ahead and apply the projection to check the first order properties.
(let ([combined-imm-refs
(for/list ([p (in-list chap-imm-pos-projs)]
[ref (in-list chap-imm-refs)])
(p (ref val))
(list ref (λ (s v) (p v))))]
[combined-mut-refs
(for/list ([p (in-list mut-pos-projs)]
[ref (in-list mut-refs)])
(p (ref val))
(list ref (λ (s v) (p v))))]
[combined-mut-sets
(for/list ([p (in-list mut-neg-projs)]
[set (in-list mut-sets)])
(list set (λ (s v) (p v))))])
(apply chaperone-struct val
(flatten (list combined-imm-refs combined-mut-refs combined-mut-sets
impersonator-prop:contracted ctc))))))))))
(define-struct (chaperone-struct/c base-struct/c) ()
#:property prop:chaperone-contract
(build-chaperone-contract-property
#:name struct/c-name
#:first-order struct/c-first-order
#:projection chaperone-struct/c-proj))
(define (impersonator-struct/c-proj ctc)
(let-values ([(flat-imms chap-imms)
(partition (λ (l) (flat-contract? (second l))) (base-struct/c-immutables ctc))])
(let ([checker (check-struct/c ctc)]
[name (base-struct/c-name ctc)]
[pred (base-struct/c-predicate ctc)]
[flat-imm-projs (map (compose contract-projection second) flat-imms)]
[flat-imm-refs (map third flat-imms)]
[chap-imm-projs (map (compose contract-projection second) chap-imms)]
[chap-imm-refs (map third chap-imms)]
[mut-projs (map (compose contract-projection second) (base-struct/c-mutables ctc))]
[mut-refs (map third (base-struct/c-mutables ctc))]
[mut-sets (map fourth (base-struct/c-mutables ctc))])
(λ (blame)
(let* ([swapped-blame (blame-swap blame)]
[flat-imm-pos-projs (map (λ (f) (f blame)) flat-imm-projs)]
[chap-imm-pos-projs (map (λ (f) (f blame)) chap-imm-projs)]
[mut-pos-projs (map (λ (f) (f blame)) mut-projs)]
[mut-neg-projs (map (λ (f) (f swapped-blame)) mut-projs)])
(λ (val)
(checker val (λ args (apply raise-blame-error blame val args)))
(for ([p (in-list flat-imm-pos-projs)]
[ref (in-list flat-imm-refs)])
(p (ref val)))
;; While gathering up the selectors and the appropriate projections,
;; we go ahead and apply the projection to check the first order properties.
(let ([combined-imm-refs
(for/list ([p (in-list chap-imm-pos-projs)]
[ref (in-list chap-imm-refs)])
(p (ref val))
(list ref (λ (s v) (p v))))]
[combined-mut-refs
(for/list ([p (in-list mut-pos-projs)]
[ref (in-list mut-refs)])
(p (ref val))
(list ref (λ (s v) (p v))))]
[combined-mut-sets
(for/list ([p (in-list mut-neg-projs)]
[set (in-list mut-sets)])
(list set (λ (s v) (p v))))])
(apply impersonate-struct
(apply chaperone-struct val
combined-imm-refs)
(flatten (list combined-mut-refs combined-mut-sets
impersonator-prop:contracted ctc))))))))))
(define-struct (impersonator-struct/c base-struct/c) ()
#:property prop:contract
(build-contract-property
#:name struct/c-name
#:first-order struct/c-first-order
#:projection impersonator-struct/c-proj))
(define-syntax (do-struct/c stx)
(syntax-case stx ()
[(_ struct-name args ...)
(and (identifier? (syntax struct-name))
(struct-info? (syntax-local-value (syntax struct-name) (λ () #f))))
(let* ([si (extract-struct-info (syntax-local-value (syntax struct-name)))]
[predicate-id (third si)]
[selector-ids (reverse (fourth si))]
[mutator-ids (reverse (fifth si))]
[ctcs (syntax->list #'(args ...))]
[ctc-names (generate-temporaries #'(args ...))])
(unless (= (length selector-ids) (length ctcs))
(raise-syntax-error 'struct/c
(format "expected ~a contracts because struct ~a has ~a fields"
(length selector-ids)
(syntax-e #'struct-name)
(length selector-ids))
stx))
(unless predicate-id
(error 'struct/c "could not determine predicate for ~s" 'struct-name))
(unless (andmap values selector-ids)
(error 'struct/c "could not determine selectors for ~s" 'struct-name))
(let ([combined-ids (for/list ([n (in-naturals)]
[ctc-name (in-list ctc-names)]
[ref-name (in-list selector-ids)]
[mut-name (in-list mutator-ids)])
(list n ctc-name ref-name mut-name))])
(let-values ([(mutables immutables) (partition (λ (l) (fourth l)) combined-ids)])
(with-syntax ([(ctc-x ...) ctc-names]
[predicate-id predicate-id]
[((imm-count imm-ctc-x imm-ref _) ...) immutables]
[((mut-count mut-ctc-x mut-ref mut-set) ...) mutables])
(syntax
(let ([ctc-x (coerce-contract 'struct/c args)] ...)
(unless (chaperone-contract? imm-ctc-x)
(error 'struct/c "expected a chaperone contract for immutable field ~v, got ~e"
imm-count imm-ctc-x))
...
(let ([immutables (list (list imm-count imm-ctc-x imm-ref) ...)]
[mutables (list (list mut-count mut-ctc-x mut-ref mut-set) ...)])
(cond
[(and (null? mutables) (andmap (λ (l) (flat-contract? (second l))) immutables))
(make-flat-struct/c 'struct-name predicate-id immutables mutables)]
[(andmap (λ (l) (chaperone-contract? (second l))) mutables)
(make-chaperone-struct/c 'struct-name predicate-id immutables mutables)]
[else
(make-impersonator-struct/c 'struct-name predicate-id immutables mutables)]))))))))]
[(_ struct-name anything ...)
(raise-syntax-error 'struct/c "expected a struct identifier" stx (syntax struct-name))]))