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pollen/decode/fast.rkt

64 lines
2.5 KiB
Racket

#lang racket/base
(require racket/match xml)
11 years ago
(require "../tools.rkt" "../predicates.rkt" txexpr "typography-fast.rkt")
(provide (all-defined-out) (all-from-out "typography-fast.rkt"))
;; general way of coercing to string
(define (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
;; this function is among the predicates because it alters a predicate globally.
(define (register-block-tag tag)
(append-block-tag tag))
;; decoder wireframe
(define (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)])
(when (not (txexpr? nx))
(error (format "decode: ~v not a full txexpr" nx)))
(define (&decode x)
(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 &decode (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 &decode (xexpr-elements-proc x))]
[(string? x) (string-proc x)]
;; if something has made it through undecoded, that's a problem
[else (error "Can't decode" x)]))
(&decode nx))