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pollen/decode.rkt

62 lines
2.6 KiB
Racket

#lang racket/base
(require xml txexpr sugar/define)
(require "predicates.rkt" "decode/typography.rkt")
(provide (all-from-out "decode/typography.rkt"))
(define+provide (to-string x)
(if (string? x)
x ; fast exit for strings
(with-handlers ([exn:fail? (λ(exn) (error (format "Pollen parser: can't convert ~v to ~a" x 'string)))])
(cond
[(equal? '() x) ""]
[(symbol? x) (symbol->string x)]
[(number? x) (number->string x)]
[(path? x) (path->string x)]
[(char? x) (format "~a" x)]
[else (error)])))) ; put this last so other xexprish things don't get caught
;; add a block tag to the list
(define+provide/contract (register-block-tag tag)
(symbol? . -> . void?)
(append-block-tag tag))
;; decoder wireframe
(define+provide/contract (decode nx
#:exclude-xexpr-tags [excluded-xexpr-tags '()]
#:xexpr-tag-proc [xexpr-tag-proc (λ(x)x)]
#:xexpr-attrs-proc [xexpr-attrs-proc (λ(x)x)]
#:xexpr-elements-proc [xexpr-elements-proc (λ(x)x)]
#:block-xexpr-proc [block-xexpr-proc (λ(x)x)]
#:inline-xexpr-proc [inline-xexpr-proc (λ(x)x)]
#:string-proc [string-proc (λ(x)x)])
((xexpr/c)
(#:exclude-xexpr-tags list?
#:xexpr-tag-proc procedure?
#:xexpr-attrs-proc procedure?
#:xexpr-elements-proc procedure?
#:block-xexpr-proc procedure?
#:inline-xexpr-proc procedure?
#:string-proc procedure?) . ->* . txexpr?)
(let loop ([x (validate-txexpr? nx)])
(cond
[(txexpr? x) (let-values([(tag attr elements) (txexpr->values x)])
(if (member tag excluded-xexpr-tags)
x ; let x pass through untouched
(let ([decoded-xexpr (apply make-txexpr (map loop (list tag attr elements)))])
((if (block-xexpr? decoded-xexpr)
block-xexpr-proc
inline-xexpr-proc) decoded-xexpr))))]
[(txexpr-tag? x) (xexpr-tag-proc x)]
[(txexpr-attrs? x) (xexpr-attrs-proc x)]
;; need this for operations that may depend on context in list
[(txexpr-elements? x) (map loop (xexpr-elements-proc x))]
[(string? x) (string-proc x)]
;; if something has made it through undecoded, that's a problem
[else (error "decode: can't decode" x)])))