On Monday, August 19, 2019 at 3:35:00 PM UTC-4, Brian Adkins wrote:
>
> I'm working on a macro to allow the following:
>
> (routes
> ("/foo" foo-handler #:method put)
> ("/bar" bar-handler #:methods (put update))
> ("/baz" baz-handler))
>
> The idea is that you could restrict a route based on the HTTP method
> either for one method using #:method or for a list of methods using
> #:methods. I tried using some ideas from the following examples:
>
> https://docs.racket-lang.org/syntax/Optional_Keyword_Arguments.html
>
> https://docs.racket-lang.org/syntax/More_Keyword_Arguments.html
>
> The attempt below does not work, and from my debugging I think it's
> probably the wrong approach. If there are examples of this sort of thing,
> I'd love to see them.
>
> Thanks,
> Brian Adkins
>
> (define-syntax (routes stx)
> (syntax-parse stx
> [ (routes (route:string
> handler:id
> (~alt (~optional (~or* (~seq #:methods (methods:expr ...))
> (~seq #:method method:expr))
> #:name "#:method, or #:methods option")
> (~optional (~seq #:when guard:expr)
> #:name "#:when option"))
> ...)
> ...)
> (with-syntax ([ name (format-id stx "axio-routes") ])
> #'(define name (list (list route handler 'method (list 'methods
> ...)) ...)))]))
>
>
The following got me over the main hurdle:
(define-syntax (routes stx)
(syntax-parse stx
[ (routes (element ...) ...)
(with-syntax ([ name (format-id stx "axio-routes") ])
#'(define name (list (route-element element ...) ...)))]))
(define-syntax (route-element stx)
(syntax-parse stx
[ (route-element route:string
handler:id
(~alt (~optional (~or* (~seq #:methods (methods:expr
...))
(~seq #:method method:expr))
#:name "#:method, or #:methods
option")
(~optional (~seq #:when guard:expr)
#:name "#:when option"))
...)
(with-syntax ([ m (or (attribute method) #'#f) ]
[ ms (or (attribute methods) #'#f) ])
#'(list route handler 'm 'ms))]))
(routes
("/foo" foo-handler #:method put)
("/bar" bar-handler #:methods (put update))
("/baz" baz-handler))
axio-routes
==> '(("/foo" #<procedure:foo-handler> put #f) ("/bar"
#<procedure:bar-handler> #f (put update)) ("/baz" #<procedure:baz-handler>
#f #f))
Now I just need to normalize to a list of HTTP methods vs. having separate
fields.
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