212 lines
7.8 KiB
Racket
212 lines
7.8 KiB
Racket
#lang racket/base
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(require (only-in "stxloc.rkt" syntax-case)
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stxparse-info/current-pvars
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(for-syntax racket/base
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racket/private/sc))
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(provide define/with-syntax
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current-recorded-disappeared-uses
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with-disappeared-uses
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syntax-local-value/record
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record-disappeared-uses
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format-symbol
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format-id
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current-syntax-context
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wrong-syntax
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generate-temporary
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internal-definition-context-apply
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syntax-local-eval
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with-syntax*)
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;; == Defining pattern variables ==
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(define-syntax (define/with-syntax stx)
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(syntax-case stx ()
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[(define/with-syntax pattern rhs)
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(let* ([pvar-env (get-match-vars #'define/with-syntax
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stx
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#'pattern
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'())]
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[depthmap (for/list ([x pvar-env])
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(let loop ([x x] [d 0])
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(if (pair? x)
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(loop (car x) (add1 d))
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(cons x d))))]
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[pvars (map car depthmap)]
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[depths (map cdr depthmap)]
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[mark (make-syntax-introducer)])
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(with-syntax ([(pvar ...) pvars]
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[(depth ...) depths]
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[(valvar ...) (generate-temporaries pvars)])
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#'(begin (define-values (valvar ...)
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(with-syntax ([pattern rhs])
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(values (pvar-value pvar) ...)))
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(define-syntax pvar
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(make-syntax-mapping 'depth (quote-syntax valvar)))
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...
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(define-pvars (pvar ...)))))]))
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;; Ryan: alternative name: define/syntax-pattern ??
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;; auxiliary macro
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(define-syntax (pvar-value stx)
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(syntax-case stx ()
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[(_ pvar)
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(identifier? #'pvar)
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(let ([mapping (syntax-local-value #'pvar)])
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(unless (syntax-pattern-variable? mapping)
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(raise-syntax-error #f "not a pattern variable" #'pvar))
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(syntax-mapping-valvar mapping))]))
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;; == Disappeared uses ==
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(define current-recorded-disappeared-uses (make-parameter #f))
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(define-syntax-rule (with-disappeared-uses body-expr ... stx-expr)
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(let-values ([(stx disappeared-uses)
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(parameterize ((current-recorded-disappeared-uses null))
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(let ([result (let () body-expr ... stx-expr)])
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(values result (current-recorded-disappeared-uses))))])
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(syntax-property stx
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'disappeared-use
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(append (or (syntax-property stx 'disappeared-use) null)
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disappeared-uses))))
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(define (syntax-local-value/record id pred)
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(unless (identifier? id)
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(raise-argument-error 'syntax-local-value/record
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"identifier?"
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0 id pred))
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(unless (and (procedure? pred)
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(procedure-arity-includes? pred 1))
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(raise-argument-error 'syntax-local-value/record
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"(-> any/c boolean?)"
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1 id pred))
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(let ([value (syntax-local-value id (lambda () #f))])
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(and (pred value)
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(begin (record-disappeared-uses (list id))
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value))))
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(define (record-disappeared-uses ids)
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(cond
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[(identifier? ids) (record-disappeared-uses (list ids))]
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[(and (list? ids) (andmap identifier? ids))
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(let ([uses (current-recorded-disappeared-uses)])
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(when uses
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(current-recorded-disappeared-uses
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(append
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(if (syntax-transforming?)
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(map syntax-local-introduce ids)
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ids)
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uses))))]
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[else (raise-argument-error 'record-disappeared-uses
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"(or/c identifier? (listof identifier?))"
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ids)]))
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;; == Identifier formatting ==
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(define (format-id lctx
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#:source [src #f]
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#:props [props #f]
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#:cert [cert #f]
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fmt . args)
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(define (convert x) (->atom x 'format-id))
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(check-restricted-format-string 'format-id fmt)
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(let* ([args (map convert args)]
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[str (apply format fmt args)]
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[sym (string->symbol str)])
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(datum->syntax lctx sym src props cert)))
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;; Eli: This looks very *useful*, but I'd like to see it more convenient to
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;; "preserve everything". Maybe add a keyword argument that when #t makes
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;; all the others use values lctx, and when syntax makes the others use that
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;; syntax?
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;; Finally, if you get to add this, then another useful utility in the same
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;; spirit is one that concatenates symbols and/or strings and/or identifiers
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;; into a new identifier. I considered something like that, which expects a
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;; single syntax among its inputs, and will use it for the context etc, or
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;; throw an error if there's more or less than 1.
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(define (format-symbol fmt . args)
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(define (convert x) (->atom x 'format-symbol))
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(check-restricted-format-string 'format-symbol fmt)
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(let ([args (map convert args)])
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(string->symbol (apply format fmt args))))
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(define (restricted-format-string? fmt)
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(regexp-match? #rx"^(?:[^~]|~[aAn~%])*$" fmt))
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(define (check-restricted-format-string who fmt)
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(unless (restricted-format-string? fmt)
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(raise-arguments-error who
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(format "format string should have ~a placeholders"
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fmt)
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"format string" fmt)))
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(define (->atom x err)
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(cond [(string? x) x]
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[(symbol? x) x]
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[(identifier? x) (syntax-e x)]
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[(keyword? x) (keyword->string x)]
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[(number? x) x]
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[(char? x) x]
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[else (raise-argument-error err
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"(or/c string? symbol? identifier? keyword? char? number?)"
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x)]))
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;; == Error reporting ==
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(define current-syntax-context
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(make-parameter #f
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(lambda (new-value)
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(unless (or (syntax? new-value) (eq? new-value #f))
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(raise-argument-error 'current-syntax-context
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"(or/c syntax? #f)"
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new-value))
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new-value)))
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(define (wrong-syntax stx #:extra [extras null] format-string . args)
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(unless (or (eq? stx #f) (syntax? stx))
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(raise-argument-error 'wrong-syntax "(or/c syntax? #f)" 0 (list* stx format-string args)))
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(let* ([ctx (current-syntax-context)]
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[blame (and (syntax? ctx) (syntax-property ctx 'report-error-as))])
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(raise-syntax-error (if (symbol? blame) blame #f)
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(apply format format-string args)
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ctx
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stx
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extras)))
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;; Eli: The `report-error-as' thing seems arbitrary to me.
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;; == Other utilities ==
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;; generate-temporary : any -> identifier
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(define (generate-temporary [stx 'g])
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(car (generate-temporaries (list stx))))
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;; Applies the renaming of intdefs to stx.
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(define (internal-definition-context-apply intdefs stx)
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(let ([qastx (local-expand #`(quote #,stx) 'expression (list #'quote) intdefs)])
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(with-syntax ([(q astx) qastx]) #'astx)))
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(define (syntax-local-eval stx [intdef0 #f])
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(let* ([name (generate-temporary)]
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[intdefs (syntax-local-make-definition-context intdef0)])
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(syntax-local-bind-syntaxes (list name)
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#`(call-with-values (lambda () #,stx) list)
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intdefs)
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(internal-definition-context-seal intdefs)
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(apply values
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(syntax-local-value (internal-definition-context-apply intdefs name)
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#f intdefs))))
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(define-syntax (with-syntax* stx)
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(syntax-case stx ()
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[(_ (cl) body ...) #'(with-syntax (cl) body ...)]
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[(_ (cl cls ...) body ...)
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#'(with-syntax (cl) (with-syntax* (cls ...) body ...))]))
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