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hopefully better algorithm

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svn: r17118
This commit is contained in:
Jon Rafkind 2009-11-30 22:37:33 +00:00
parent aee5ba80d7
commit f01aa1161a
1 changed files with 58 additions and 2 deletions
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60
collects/honu/private/macro.ss
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@ -162,7 +162,56 @@
(define wrapped #f)
(define unwrap #f)
(define-for-syntax (pull stx)
(define (reverse-syntax stx)
(with-syntax ([(x ...) (reverse (syntax->list stx))])
#'(x ...)))
(define-syntax-class stop-class
(pattern x:id #:when (or (free-identifier=? #'x #'(... ...))
(free-identifier=? #'x #'\;))))
(define (do-ellipses stx)
(let loop ([ellipses '()]
[body '()]
[stx stx])
(cond
[(null? stx) (values (with-syntax ([(ellipses ...) ellipses]
[(body ...) body])
#'(ellipses ... body ...))
stx)]
[(and (identifier? (car stx))
(free-identifier=? (car stx) #'(... ...)))
(loop (cons #'(... ...) ellipses) body (cdr stx))]
[(and (identifier? (car stx))
(free-identifier=? (car stx) #'\;))
;; (printf "Found a ; in ~a\n" (syntax->datum stx))
(with-syntax ([all (cdr stx)])
;; (printf "Found a ; -- ~a\n" (syntax->datum #'all))
(syntax-parse #'all
[((~and x (~not _:stop-class)) ... stop:stop-class y ...)
(with-syntax ([(ellipses ...) ellipses]
[(x* ...) (reverse-syntax #'(x ...))])
(values #'(ellipses ... (wrapped x* ... \;) unwrap)
#'(stop y ...)))]
[else (with-syntax ([(f ...) (reverse-syntax #'all)]
[(ellipses ...) ellipses])
(values #'(ellipses ... (wrapped f ... \;) unwrap)
#'()))]))])))
(let loop ([all '()]
[stx (reverse (syntax->list stx))])
(if (null? stx)
(with-syntax ([x all])
#'x)
(let ([head (car stx)]
[tail (cdr stx)])
(cond
[(and (identifier? head)
(free-identifier=? head #'(... ...)))
(let-values ([(wrapped rest) (do-ellipses (cons head tail))])
(loop (cons (reverse-syntax wrapped) all) (syntax->list rest)))]
[else (loop (cons head all) tail)])))))
;; rename this to wrap
#;
(define-for-syntax (pull stx)
(define (reverse-syntax stx)
(with-syntax ([(x ...) (reverse (syntax->list stx))])
@ -171,6 +220,8 @@
(pattern x:id #:when (delimiter? #'x)))
(define-syntax-class ellipses-class
(pattern x:id #:when (free-identifier=? #'x #'(... ...))))
(define-syntax-class not-ellipses-class
(pattern x:id #:when (not (free-identifier=? #'x #'(... ...)))))
;; use this if you are defining your own ellipses identifier
#;
(define-syntax-class ellipses-class
@ -183,7 +234,7 @@
;; (printf "stx is ~a\n" stx)
;; (printf "... = ~a\n" (free-identifier=? #'(... ...) (stx-car stx)))
(syntax-parse stx
[(ellipses1:ellipses-class ellipses:ellipses-class ... delimiter:delimiter-class x ...)
[(before:not-ellipses-class ... ellipses1:ellipses-class ellipses:ellipses-class ... delimiter:delimiter-class x ...)
(with-syntax ([(x* ...) (reverse-syntax (pull #'(delimiter x ...)))])
(reverse-syntax
(with-syntax ([wrapped #'wrapped]
@ -192,7 +243,7 @@
#'((... ...) (... ...)))
(syntax->list #'(ellipses1 ellipses ...)))]
[(x-new ...) (generate-temporaries #'(delimiter x ...))])
(reverse-syntax #'(ellipses* ... x-new ...)))]
(reverse-syntax #'(before ... ellipses* ... x-new ...)))]
#;
[original (syntax->datum (reverse-syntax #'(ellipses1 ellipses ... x ...)))])
#'(ellipses1 ellipses ... (wrapped x* ...) unwrap))))]
@ -219,8 +270,13 @@
(pattern x:id #:when (free-identifier=? #'x #'(... ...))))
(define-syntax-class delimiter-class
(pattern x:id #:when (delimiter? #'x)))
;; (printf "unpull ~a\n" (syntax->datum stx))
(syntax-parse stx
#:literals (wrapped unwrap)
[((~and z (~not (unwrap _ ...))) ... (unwrap (wrapped x ... delimiter:delimiter-class) ...) rest ...)
(with-syntax ([(x1 ...) (apply append (map syntax->list (syntax->list #'((x ... delimiter) ...))))]
[(rest* ...) (unpull #'(rest ...))])
#'(z ... x1 ... rest* ...))]
[(unwrap (wrapped x ... delimiter:delimiter-class) ...)
(with-syntax ([(x1 ...) (apply append (map syntax->list (syntax->list #'((x ... delimiter) ...))))])
#'(x1 ...))]