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s/s/d tail call optimization

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svn: r1389
This commit is contained in:
Jay McCarthy 2005-11-24 06:05:59 +00:00
parent 06c60a7f18
commit c478a29110
1 changed files with 20 additions and 13 deletions
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9
collects/web-server/servlet.ss
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@ -122,11 +122,18 @@
;; send/back a response generated from a procedure that may convert ;; send/back a response generated from a procedure that may convert
;; procedures to continuation urls ;; procedures to continuation urls
(define (send/suspend/dispatch response-generator) (define (send/suspend/dispatch response-generator)
; This restores the tail position.
; Note: Herman's syntactic strategy would fail without the new-request capture.
; (Moving this to the tail-position is not possible anyway, by the way.)
(let ([thunk
(let/ec k0 (let/ec k0
(send/back (send/back
(response-generator (response-generator
(opt-lambda (proc [expiration-handler (current-servlet-continuation-expiration-handler)]) (opt-lambda (proc [expiration-handler (current-servlet-continuation-expiration-handler)])
(let/ec k1 (k0 (proc (send/suspend k1 expiration-handler))))))))) (let/ec k1
(let ([new-request (send/suspend k1 expiration-handler)])
(k0 (lambda () (proc new-request)))))))))])
(thunk)))
;; send/suspend/callback : xexpr/callback? -> void ;; send/suspend/callback : xexpr/callback? -> void
;; send/back a response with callbacks in it; send/suspend those callbacks. ;; send/back a response with callbacks in it; send/suspend those callbacks.