racket/collects/syntax/module-reader.ss

104 lines
4.5 KiB
Scheme

(module module-reader scheme/base
(provide (rename-out [provide-module-reader #%module-begin]
[wrap wrap-read-all])
(except-out (all-from-out scheme/base) #%module-begin))
(require (for-syntax scheme/base))
(define-syntax (provide-module-reader stx)
(syntax-case stx ()
[(_ lib body ...)
(let ([key-args '()])
(define (err str [sub #f])
(raise-syntax-error 'syntax/module-reader str sub))
(define -body
(let loop ([body (syntax->list #'(body ...))])
(if (not (and (pair? body)
(pair? (cdr body))
(keyword? (syntax-e (car body)))))
(datum->syntax stx body stx)
(let* ([k (car body)] [k* (syntax-e k)] [v (cadr body)])
(cond
[(assq k* key-args) (err (format "got two ~s keywords" k*) k)]
[(not (memq k* '(#:read #:read-syntax #:wrapper1 #:wrapper2
#:whole-body-readers?)))
(err "got an unknown keyword" (car body))]
[else (set! key-args (cons (cons k* v) key-args))
(loop (cddr body))])))))
(define (get kwd [dflt #f])
(cond [(assq kwd key-args) => cdr] [else dflt]))
(unless (equal? (and (assq '#:read key-args) #t)
(and (assq '#:read-syntax key-args) #t))
(err "must specify either both #:read and #:read-syntax, or none"))
(when (and (assq '#:whole-body-readers? key-args)
(not (assq '#:read key-args)))
(err "got a #:whole-body-readers? without #:read and #:read-syntax"))
(quasisyntax/loc stx
(#%module-begin
#,@-body
(#%provide (rename *read read) (rename *read-syntax read-syntax))
(define-values (*read *read-syntax)
(let* ([rd #,(get '#:read #'read)]
[rds #,(get '#:read-syntax #'read-syntax)]
[w1 #,(get '#:wrapper1 #'#f)]
[w2 #,(get '#:wrapper2 #'#f)]
[w2 (cond [(not w2) (lambda (in r _) (r in))]
[(procedure-arity-includes? w2 3) w2]
[else (lambda (in r _) (w2 in r))])]
[base 'lib]
[whole? #,(get '#:whole-body-readers? #'#f)])
(values
(lambda (in modpath line col pos)
(w2 in
(lambda (in)
(wrap-internal base in rd whole?
w1 #f modpath #f line col pos))
#f))
(lambda (src in modpath line col pos)
(w2 in
(lambda (in)
(wrap-internal
base in (lambda (in) (rds src in)) whole?
w1 #t modpath src line col pos))
#t))))))))]))
(define (wrap-internal lib port read whole? wrapper stx?
modpath src line col pos)
(let* ([body (lambda ()
(if whole?
(read port)
(let loop ([a null])
(let ([v (read port)])
(if (eof-object? v) (reverse a) (loop (cons v a)))))))]
[body (cond [(not wrapper) (body)]
[(procedure-arity-includes? wrapper 2) (wrapper body stx?)]
[else (wrapper body)])]
[all-loc (vector src line col pos
(let-values ([(l c p) (port-next-location port)])
(and p (- p pos))))]
[body (if (and stx? (not (syntax? body)))
(datum->syntax #f body all-loc)
body)]
[p-name (object-name port)]
[name (if (path? p-name)
(let-values ([(base name dir?) (split-path p-name)])
(string->symbol
(path->string (path-replace-suffix name #""))))
'page)]
[tag-src (lambda (v)
(if stx?
(datum->syntax
#f v (vector src line col pos
(- (or (syntax-position modpath) (add1 pos))
pos)))
v))]
[lib (if stx? (datum->syntax #f lib modpath modpath) lib)]
[r `(,(tag-src 'module) ,(tag-src name) ,lib . ,body)])
(if stx? (datum->syntax #f r all-loc) r)))
(define (wrap lib port read modpath src line col pos)
(wrap-internal lib port read #f #f #f modpath src line col pos))
)