sunet/scheme/httpd/surflets/surflet-sxml.scm

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(define url-rule
`(url *preorder*
. ,(lambda (tag uri . maybe-text)
(surflet-sxml->low-level-sxml
`(a (@ (href ,uri))
,(if (null? maybe-text)
uri
maybe-text))))))
(define plain-html-rule
`(plain-html
*preorder*
. ,(lambda (tag . text) text)))
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(define nbsp-rule
`(nbsp . ,(lambda (_) " ")))
(define comment-rule
`(*COMMENT* *preorder*
. ,(lambda (tag . elems)
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`("<!-- " ,@elems "-->"))))
(define default-rules
`(,attribute-rule
,default-rule
,text-rule
,comment-rule
,url-rule
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,plain-html-rule
,nbsp-rule))
(define surflet-form-rule
`(surflet-form
;; Must do something to prevent the k-url string to be HTML
;; escaped.
*preorder*
. ,(lambda (trigger k-url . args)
(receive (parameters elems)
(optionals-first (list symbol? sxml-attribute?) args)
(make-surflet-form k-url ; k-url
(car parameters) ; POST, GET or #f=GET
(cadr parameters); attributes
elems)))))
(define (make-surflet-form k-url method attributes elems)
(let ((real-method (case method
((get GET) "GET")
((post POST) "POST")
((#f) "GET")
(else
(error "invalid method type" method)))))
(surflet-sxml->low-level-sxml
`(form (@ ((method ,real-method)
(action ,k-url)
,@(if attributes (cdr attributes) '())))
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;; cdr == sxml-attribute-attributes
,@elems))))
(define input-field-rule
`(,*input-field-trigger*
*preorder*
. ,(lambda input-field
(surflet-sxml->low-level-sxml
(input-field-html-tree input-field)))))
(define surflet-sxml-rules
`(,@default-rules
;; form contents:
,input-field-rule
,surflet-form-rule))
;; Low-Level-SXML is a list that can be understood by
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;; display-low-level-sxml. In contains only characters, strings, and
;; thunks.
(define (surflet-sxml->low-level-sxml sxml-tree)
(sxml->low-level-sxml sxml-tree surflet-sxml-rules))
;;; Helping funtion for surflet-sxml-rule
;; PRED-LIST contains list of predicates that recognizes optional
;; leading parameters. FURTHER-ATTRIBUTES is the optional parameter
;; list as got by procedure call. TYPED-OPTIONALS returns two values:
;; a list of the same length as PRED-LIST and a list containing the
;; left arguments that did not fit the predicates.
;;
;; With the help of OPTIONALS-FIRST you can define a function
;; like `make-submit-button [string] [further-attributes]' this way:
;; (define (make-submit-button . args)
;; (receive (params rest-args)
;; (prefix-optionals (list string? xml-attribute?) args)
;; (if (pair? rest-args)
;; (error "too many arguments to make-submit-button))
;; (let ((value (first params))
;; (attributes (second params)))
;; ...))))
;;
(define (optionals-first pred-list args)
(let loop ((results '())
(pred-list pred-list)
(args args))
(cond
((null? pred-list)
(values (reverse results) args))
((null? args)
(values (rev-append results (make-list (length pred-list) #f)) '()))
(((car pred-list) (car args))
(loop (cons (car args) results)
(cdr pred-list)
(cdr args)))
(else
(loop (cons #f results)
(cdr pred-list)
args)))))