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pollen/tag.rkt

38 lines
2.0 KiB
Racket

#lang racket/base
(require txexpr sugar/define racket/string)
(define/contract+provide (make-default-tag-function . ids)
(() #:rest txexpr-tags? . ->* . procedure?)
(define (make-one-tag id)
(λ x
(define reversed-pieces ; list of attribute pairs, and last element holds a list of everything else, then reversed
(reverse (let chomp ([x x])
(define result+regexp (and ((length x) . >= . 2)
(symbol? (car x))
;; accept strings only
;; numbers are difficult because they don't parse as cleanly.
;; string will read as a string even if there's no space to the left.
(or (string? (cadr x)))
;; Looking for symbol ending with a colon
(regexp-match #rx"^(.*?):$" (symbol->string (car x)))))
(if result+regexp
; reuse result value. cadr is first group in match.
(cons (list (string->symbol (cadr result+regexp))(cadr x)) (chomp (cddr x)))
(list x)))))
(define-values (body attrs) (if (equal? null reversed-pieces)
(values null null)
(values (car reversed-pieces) (cdr reversed-pieces))))
`(,id ,@(if (equal? attrs null) null (list (reverse attrs))) ,@body)))
(procedure-rename (apply compose1 (map make-one-tag ids)) (string->symbol (format "pollen-tag:~a" (string-join (map symbol->string ids) "+")))))
(define/contract+provide (split-attributes parts)
(list? . -> . (values txexpr-attrs? txexpr-elements?))
(define dummy-tag (gensym))
(define dummy-txexpr (apply (make-default-tag-function dummy-tag) parts))
(define-values (tag attrs elements) (txexpr->values dummy-txexpr))
(values attrs elements))