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pollen/pollen/tag.rkt

99 lines
6.2 KiB
Racket

#lang pollen/mode racket/base
(require (for-syntax racket/base))
(require txexpr racket/string racket/match)
(provide default-tag-function make-default-tag-function define-tag-function)
(define first car)
(define second cadr)
(define default-tag-function
(make-keyword-procedure
(λ (outer-kws outer-kw-args . ids)
(define (make-one-tag id)
(make-keyword-procedure
(λ (inner-kws inner-kw-args . attrs+xs)
;; Three possible sources of attrs:
;; 1) normal attrs, in a list at the front of the args
;; 2) colon args, using special 'key: "value" syntax, also at the front of the args
;; 3) keyword args.
(define-values (leading-attrs xs) (if (and (pair? attrs+xs) (txexpr-attrs? (car attrs+xs)))
(values (car attrs+xs) (cdr attrs+xs))
(values null attrs+xs)))
(define-values (kws kw-args) (values (append outer-kws inner-kws) (append outer-kw-args inner-kw-args)))
(match-define (list colon-attrs ... body) (let parse-one-colon-attr ([xs xs])
(define (colon-attr-name? x) (let ([result (regexp-match #rx".*?(?=:$)" (symbol->string x))])
(and result (string->symbol (car result))))) ; return name or #f
(define maybe-attr-name (and (>= (length xs) 2)
(symbol? (first xs))
(string? (second xs)) ; accept strings only as attr value
(colon-attr-name? (first xs))))
(if maybe-attr-name
(let ([attr-name maybe-attr-name][attr-value (second xs)])
(cons (list attr-name attr-value) (parse-one-colon-attr (cddr xs))))
(list xs))))
(define kw-symbols (map (λ(kw) (string->symbol (string-trim (keyword->string kw) "#:"))) kws))
(define attrs (append (map list kw-symbols kw-args) colon-attrs leading-attrs))
;; construct the xexpr result "manually" (i.e., not with `make-txexpr` because it may not be a legit txexpr for now
;; (but it may become one through further processing, so no need to be finicky)
;; however, don't show empty attrs.
(list* id (if (null? attrs)
body
(list* attrs body))))))
(let ([tag-proc (apply compose1 (map make-one-tag ids))]
[tag-proc-name (string->symbol (format "pollen-tag:~a" (string-join (map symbol->string ids) "+")))])
(procedure-rename tag-proc tag-proc-name)))))
(define make-default-tag-function default-tag-function) ; bw compat
(module+ test
(require rackunit)
(define outerdiv (default-tag-function 'div #:class "outer" #:style "outer"))
(check-txexprs-equal? (outerdiv "foo") '(div ((class "outer") (style "outer")) "foo"))
(check-txexprs-equal? (outerdiv) '(div ((class "outer") (style "outer"))))
(check-txexprs-equal? (outerdiv #:class "inner") '(div ((class "outer") (style "outer") (class "inner"))))
(check-txexprs-equal? (outerdiv #:class "inner" "foo") '(div ((class "outer") (style "outer") (class "inner")) "foo"))
(check-txexprs-equal? (outerdiv #:field "greens" #:id "shazbot" "foo") '(div ((class "outer") (style "outer") (field "greens") (id "shazbot")) "foo"))
(check-txexprs-equal? (outerdiv 'id: "shazbot" "foo") '(div ((class "outer") (style "outer") (id "shazbot")) "foo"))
(check-txexprs-equal? (outerdiv '((id "shazbot")) "foo") '(div ((class "outer") (style "outer") (id "shazbot")) "foo"))
(check-txexprs-equal? (outerdiv 'id: "shazbot" 'class: "inner" "foo") '(div ((class "outer") (style "outer") (id "shazbot") (class "inner")) "foo"))
;; (outerdiv 'id: "shazbot" '((class "inner")) "foo") won't work because colon attrs supplant conventional attrs (docs concur)
(check-txexprs-equal? (outerdiv 'id: "shazbot" #:class "inner" "foo") '(div ((class "outer") (style "outer") (class "inner") (id "shazbot")) "foo")))
(define-syntax (define-tag-function stx)
(syntax-case stx (λ)
[(_ (ID ARG ...) EXPR ...)
#'(define-tag-function ID (λ (ARG ...) EXPR ...))]
[(_ ID (λ (ATTRS ELEMS) EXPR0 EXPR ...))
#'(define ID
(make-keyword-procedure
(λ (kws kwargs . args)
(define tx-proc (keyword-apply default-tag-function kws kwargs (list 'ID)))
(define tx (apply tx-proc args))
(define-values (_ ATTRS ELEMS) (txexpr->values tx))
EXPR0 EXPR ...)))]
[(_ ID (λ (ATTRS ELEMS)))
(raise-syntax-error 'define-tag-function (format "bad syntax (no expressions for procedure body) in ~a" (syntax->datum stx)))]
[(_ ID (λ (ARG ...) EXPR ...)) (raise-syntax-error 'define-tag-function (format "bad syntax (arity must be exactly 2 positional arguments) in ~a" (cadr (syntax->datum stx))))]))
(module+ test
(require rackunit)
(define foo2 (default-tag-function 'foo))
(define-tag-function (foo attrs elems)
`(foo ,(reverse attrs) ,@elems))
(check-txexprs-equal? ◊foo[#:zim "zam"]{hello} ◊foo2[#:zim "zam"]{hello})
(check-txexprs-equal? ◊foo[#:ding "dong" '((zim "zam"))]{hello} ◊foo2[#:ding "dong" '((zim "zam"))]{hello})
(check-txexprs-equal? ◊foo['zim: "zam" #:ding "dong" ]{hello} ◊foo2['zim: "zam" #:ding "dong" ]{hello})
(define-tag-function foolam (λ (attrs elems)
`(foo ,(reverse attrs) ,@elems)))
(check-txexprs-equal? ◊foolam[#:zim "zam"]{hello} ◊foo2[#:zim "zam"]{hello})
(check-txexprs-equal? ◊foolam[#:ding "dong" '((zim "zam"))]{hello} ◊foo2[#:ding "dong" '((zim "zam"))]{hello})
(check-txexprs-equal? ◊foolam['zim: "zam" #:ding "dong" ]{hello} ◊foo2['zim: "zam" #:ding "dong" ]{hello}))