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pollen/pollen/decode.rkt

253 lines
15 KiB
Racket

#lang racket/base
(require xml txexpr/base racket/list sugar/list sugar/define sugar/test)
(require "setup.rkt" "private/splice.rkt")
(require "unstable/typography.rkt")
(provide (all-from-out "unstable/typography.rkt")) ; bw compat, includes `whitespace?`
(define (->list/tx x)
;; same as ->list but catches special case of single txexpr,
;; which is itself a list, but in this case should be wrapped into a list,
;; for use with append-map.
(cond
[(txexpr? x) (list x)]
[(list? x) x]
[else (list x)]))
(define decode-proc-output-contract (or/c txexpr-element? txexpr-elements?))
(define identity (λ(x) x))
;; decoder wireframe
(define+provide/contract (decode tx-in
#:txexpr-tag-proc [txexpr-tag-proc identity]
#:txexpr-attrs-proc [txexpr-attrs-proc identity]
#:txexpr-elements-proc [txexpr-elements-proc identity]
#:txexpr-proc [txexpr-proc identity]
#:block-txexpr-proc [block-txexpr-proc identity]
#:inline-txexpr-proc [inline-txexpr-proc identity]
#:string-proc [string-proc identity]
#:entity-proc [entity-proc identity]
#:cdata-proc [cdata-proc identity]
#:exclude-tags [excluded-tags empty]
#:exclude-attrs [excluded-attrs empty])
((xexpr/c)
(#:txexpr-tag-proc (txexpr-tag? . -> . txexpr-tag?)
#:txexpr-attrs-proc (txexpr-attrs? . -> . txexpr-attrs?)
#:txexpr-elements-proc (txexpr-elements? . -> . txexpr-elements?)
#:txexpr-proc (txexpr? . -> . decode-proc-output-contract)
#:block-txexpr-proc (block-txexpr? . -> . decode-proc-output-contract)
#:inline-txexpr-proc (txexpr? . -> . decode-proc-output-contract)
#:string-proc (string? . -> . decode-proc-output-contract)
#:entity-proc ((or/c symbol? valid-char?) . -> . decode-proc-output-contract)
#:cdata-proc (cdata? . -> . decode-proc-output-contract)
#:exclude-tags txexpr-tags?
#:exclude-attrs txexpr-attrs?) . ->* . decode-proc-output-contract)
(let loop ([x tx-in])
(cond
[(txexpr? x) (let-values([(tag attrs elements) (txexpr->values x)])
(if (or (member tag excluded-tags) (ormap (λ(attr) (member attr excluded-attrs)) attrs))
x ; because it's excluded
;; we apply processing here rather than do recursive descent on the pieces
;; because if we send them back through loop, certain element types are ambiguous
;; e.g., ((p "foo")) tests out as both txexpr-attrs and txexpr-elements
(let ([decoded-txexpr
(apply make-txexpr (list (txexpr-tag-proc tag)
(txexpr-attrs-proc attrs)
(txexpr-elements-proc (append-map (compose1 ->list/tx loop) elements))))])
((compose1 txexpr-proc (if (block-txexpr? decoded-txexpr)
block-txexpr-proc
inline-txexpr-proc)) decoded-txexpr))))]
[(string? x) (string-proc x)]
[(or (symbol? x) (valid-char? x)) (entity-proc x)]
[(cdata? x) (cdata-proc x)]
[else (error "decode: can't decode" x)])))
(module-test-external
(require racket/list txexpr racket/function)
(define (doubler x) (list x x))
(define (doubletag x) (txexpr (string->symbol (format "~a~a" (get-tag x) (get-tag x))) (get-attrs x) (get-elements x)))
(check-equal? (decode #:txexpr-elements-proc identity '(p "foo")) '(p "foo"))
;; can't use doubler on txexpr-elements because it needs a list, not list of lists
(check-equal? (decode #:txexpr-elements-proc (λ(elems) (append elems elems)) '(p "foo")) '(p "foo" "foo"))
(check-equal? (decode #:block-txexpr-proc identity '(p "foo")) '(p "foo"))
(check-equal? (decode #:block-txexpr-proc doubler '(p "foo")) (list '(p "foo") '(p "foo")))
(check-equal? (decode #:block-txexpr-proc doubler '(p "foo")) (list '(p "foo") '(p "foo")))
(check-equal? (decode #:txexpr-proc doubletag '(root (p "foo") (b "bar"))) '(rootroot (pp "foo") (bb "bar")))
(check-equal? (decode #:block-txexpr-proc doubletag '(root (p "foo") (b "bar"))) '(rootroot (pp "foo") (b "bar")))
(check-equal? (decode #:inline-txexpr-proc doubletag '(root (p "foo") (b "bar"))) '(root (p "foo") (bb "bar")))
(check-equal? (decode #:inline-txexpr-proc identity '(p (span "foo"))) '(p (span "foo")))
(check-equal? (decode #:inline-txexpr-proc doubler '(p (span "foo"))) '(p (span "foo") (span "foo")))
(check-equal? (decode #:string-proc identity '(p (span "foo"))) '(p (span "foo")))
(check-equal? (decode #:string-proc doubler '(p (span "foo"))) '(p (span "foo" "foo")))
(check-equal? (decode #:entity-proc identity '(p (span "foo" 'amp))) '(p (span "foo" 'amp)))
(check-equal? (decode #:entity-proc identity '(p 42)) '(p 42))
(check-equal? (decode #:entity-proc doubler '(p 42)) '(p 42 42))
(check-equal? (decode #:entity-proc identity '(p amp)) '(p amp))
;; next text doesn't work because list of symbol elements is ambiguous with tagged X-expression
;; is there a general patch for this? maybe, but for now it's better to not patch selectively
;; otherwise ambiguous expressions will have erratic misbehavior (instead of merely consistent misbehavior)
;;(check-equal? (decode #:entity-proc doubler '(p amp)) '(p amp amp))
(check-equal? (decode-elements #:string-proc identity '("foo")) '("foo"))
(check-equal? (decode-elements #:string-proc doubler '("foo")) '("foo" "foo")))
;; it would be nice to not repeat this, but with all the keywords, it's simpler to repeat than do a macro
(define+provide/contract decode-elements
((txexpr-elements?)
(#:txexpr-tag-proc (txexpr-tag? . -> . txexpr-tag?)
#:txexpr-attrs-proc (txexpr-attrs? . -> . txexpr-attrs?)
#:txexpr-elements-proc (txexpr-elements? . -> . txexpr-elements?)
#:txexpr-proc (txexpr? . -> . decode-proc-output-contract)
#:block-txexpr-proc (block-txexpr? . -> . decode-proc-output-contract)
#:inline-txexpr-proc (txexpr? . -> . decode-proc-output-contract)
#:string-proc (string? . -> . decode-proc-output-contract)
#:entity-proc ((or/c symbol? valid-char?) . -> . decode-proc-output-contract)
#:cdata-proc (cdata? . -> . decode-proc-output-contract)
#:exclude-tags txexpr-tags?
#:exclude-attrs txexpr-attrs?) . ->* . decode-proc-output-contract)
(make-keyword-procedure
(λ (kws kwargs . args)
(define temp-tag (gensym "temp-tag"))
(define elements (car args))
(define decode-result (keyword-apply decode kws kwargs (list (cons temp-tag elements))))
(get-elements decode-result))))
(define+provide/contract (block-txexpr? x)
(any/c . -> . boolean?)
;; Mostly this is used inside `decode`,
;; so rather than test for `txexpr?` at the beginning (which is potentially slow)
;; just look at the tag.
(and (pair? x)
(memq (get-tag x) (setup:block-tags))
#t))
(define+provide/contract (decode-linebreaks elems [maybe-linebreak-proc '(br)]
#:separator [newline (setup:linebreak-separator)])
((txexpr-elements?) ((or/c txexpr-element? (txexpr-element? txexpr-element? . -> . txexpr-element?)) #:separator string?) . ->* . txexpr-elements?)
(define linebreak-proc (if (procedure? maybe-linebreak-proc)
maybe-linebreak-proc
(λ (e1 e2) maybe-linebreak-proc)))
(define elems-vec (list->vector elems))
(filter identity
(for/list ([(item i) (in-indexed elems-vec)])
(cond
[(or (= i 0) (= i (sub1 (vector-length elems-vec)))) item] ; pass through first & last items
[(equal? item newline)
(let ([prev (vector-ref elems-vec (sub1 i))]
[next (vector-ref elems-vec (add1 i))])
;; only convert if neither adjacent tag is a block
;; (because blocks automatically force a newline before & after)
(if (or (block-txexpr? prev) (block-txexpr? next))
#f ; flag for filtering
(linebreak-proc prev next)))]
[else item]))))
(module-test-external
(check-equal? (decode-linebreaks '("foo" "\n" "bar")) '("foo" (br) "bar"))
(check-equal? (decode-linebreaks '("\n" "foo" "\n" "bar" "\n")) '("\n" "foo" (br) "bar" "\n"))
(check-equal? (decode-linebreaks '((p "foo") "\n" (p "bar"))) '((p "foo") (p "bar")))
(check-equal? (decode-linebreaks '("foo" "\n" (p "bar"))) '("foo" (p "bar")))
(check-equal? (decode-linebreaks '("foo" "moo" "bar")) '("foo" "moo" "bar"))
(check-equal? (decode-linebreaks '("foo" "moo" "bar") "moo") '("foo" "moo" "bar"))
(check-equal? (decode-linebreaks '("foo" "\n\n" "bar")) '("foo" "\n\n" "bar")))
;; Find adjacent newline characters in a list and merge them into one item
;; Scribble, by default, makes each newline a separate list item.
;; Ignore empty strings.
(define+provide/contract (merge-newlines x)
(txexpr-elements? . -> . txexpr-elements?)
(define newline-pat (regexp (format "^~a+$" (setup:newline))))
(define (newlines? x) (and (string? x) (regexp-match newline-pat x)))
(define (merge-if-newlines xs)
(if (newlines? (car xs))
(list (apply string-append xs))
xs))
(define not-empty-string? (λ(x) (not (and (string? x) (= (string-length x) 0)))))
(let loop ([x x])
(if (and (pair? x) (not (attrs? x)))
(let ([xs (map loop (filter not-empty-string? x))])
(append-map merge-if-newlines (slicef xs newlines?)))
x)))
(module-test-external
(require racket/list)
(check-equal? (merge-newlines empty) empty)
(check-equal? (merge-newlines '((p ((id "")) "\n" "" "\n"))) '((p ((id "")) "\n\n")))
(check-equal? (merge-newlines '((p "\n" "" "\n"))) '((p "\n\n")))
(check-equal? (merge-newlines '(p "\n" "\n" "foo" "\n" "\n\n" "bar" (em "\n" "\n" "\n")))
'(p "\n\n" "foo" "\n\n\n" "bar" (em "\n\n\n"))))
;; detect paragraphs
;; todo: unit tests
(define+provide/contract (decode-paragraphs elements [maybe-wrap-proc 'p]
#:linebreak-proc [linebreak-proc decode-linebreaks]
#:force? [force-paragraph #f])
((txexpr-elements?) ((or/c txexpr-tag? ((listof xexpr?) . -> . txexpr?))
#:linebreak-proc (txexpr-elements? . -> . txexpr-elements?)
#:force? boolean?)
. ->* . txexpr-elements?)
(define (prep-paragraph-flow elems)
(linebreak-proc (merge-newlines (trimf elems whitespace?))))
(define (paragraph-break? x)
(define paragraph-separator (setup:paragraph-separator))
(define paragraph-pattern (pregexp (format "^~a+$" paragraph-separator)))
(and (string? x) (regexp-match paragraph-pattern x)))
(define (explicit-or-implicit-paragraph-break? x)
(or (paragraph-break? x) (block-txexpr? x)))
(define wrap-proc (if (procedure? maybe-wrap-proc)
maybe-wrap-proc
(λ(elems) (list* maybe-wrap-proc elems))))
(define (wrap-paragraph elems)
(if (andmap block-txexpr? elems)
elems ; leave a series of block xexprs alone
(list (wrap-proc elems)))) ; otherwise wrap in p tag
(let ([elements (prep-paragraph-flow elements)])
(if (ormap explicit-or-implicit-paragraph-break? elements) ; need this condition to prevent infinite recursion
;; use append-map on wrap-paragraph rather than map to permit return of multiple elements
(append-map wrap-paragraph (append-map (λ(es) (filter-split es paragraph-break?)) (slicef elements block-txexpr?))) ; split into ¶¶, using both implied and explicit paragraph breaks
(if force-paragraph
(append-map wrap-paragraph (slicef elements block-txexpr?)) ; upconverts non-block elements to paragraphs
elements))))
(module-test-external
(check-equal? (decode-paragraphs '("First para" "\n\n" "Second para"))
'((p "First para") (p "Second para")))
(check-equal? (decode-paragraphs '("First para" "\n\n" "Second para" "\n" "Second line"))
'((p "First para") (p "Second para" (br) "Second line")))
(check-equal? (decode-paragraphs '("First para" "\n\n" (div "Second block")))
'((p "First para") (div "Second block")))
(check-equal? (decode-paragraphs '((div "First block") "\n\n" (div "Second block")))
'((div "First block") (div "Second block")))
(check-equal? (decode-paragraphs '("First para" "\n\n" "Second para") 'ns:p)
'((ns:p "First para") (ns:p "Second para")))
(check-equal? (decode-paragraphs '("First para" "\n\n" "Second para" "\n" "Second line")
#:linebreak-proc (λ(x) (decode-linebreaks x '(newline))))
'((p "First para") (p "Second para" (newline) "Second line")))
(check-equal? (decode-paragraphs '("foo" "\n\n" (div "bar") (div "zam")))
'((p "foo") (div "bar") (div "zam")))
(check-equal? (decode-paragraphs '("foo" "\n\n" (div "bar") "\n\n" (div "zam")))
'((p "foo") (div "bar") (div "zam")))
(check-equal? (decode-paragraphs '("foo")) '("foo"))
(check-equal? (decode-paragraphs '("foo") #:force? #t) '((p "foo")))
(check-equal? (decode-paragraphs '((div "foo"))) '((div "foo")))
(check-equal? (decode-paragraphs '((div "foo")) #:force? #t) '((div "foo")))
(check-equal? (decode-paragraphs '("foo" "\n\n" (div "bar"))) '((p "foo") (div "bar")))
(check-equal? (decode-paragraphs '("foo" (div "bar"))) '((p "foo") (div "bar")))
(check-equal? (decode-paragraphs '("foo" (div "bar")) #:force? #t) '((p "foo") (div "bar")))
(check-equal? (decode-paragraphs '("foo" (div "bar") "zam")) '((p "foo") (div "bar") (p "zam")))
(check-equal? (decode-paragraphs '("foo" (span "zing") (div "bar") "zam")) '((p "foo" (span "zing")) (div "bar") (p "zam")))
(check-equal? (decode-paragraphs '("foo" (span "zing") (div "bar") "zam") #:force? #t) '((p "foo" (span "zing")) (div "bar") (p "zam"))))
(define+provide detect-paragraphs decode-paragraphs) ; bw compat
(define+provide detect-linebreaks decode-linebreaks) ; bw compat