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delete superfluity

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Matthew Butterick 11 years ago
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decode-tools.rkt
Unescape Escape View File

@ -1,264 +0,0 @@
#lang racket/base
(require racket/contract racket/list racket/string racket/match)
(require sugar "../predicates.rkt" "../tools.rkt")
(module+ test (require rackunit))
(provide (all-defined-out))
;; This module is a library of functions to be used in building pollen decoders.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Typography
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; insert typographic niceties
;; ligatures are handled in css
(define (typogrify str)
(string? . -> . string?)
;; make set of functions for replacers
(define (make-replacer query replacement)
(λ(str) (regexp-replace* query str replacement)))
;; just store the query strings + replacement strings
(define dashes
;; fix em dashes first, else they'll be mistaken for en dashes
;; [\\s ] is whitespace + nonbreaking space
'((#px"[\\s ]*(---|—)[\\s ]*" "—") ; em dash
(#px"[\\s ]*(--|–)[\\s ]*" "–"))) ; en dash
(define smart-quotes
'((#px"(?<=\\w)'(?=\\w)" "’") ; apostrophe
(#px"(?<!\\w)'(?=\\w)" "‘") ; single_at_beginning
(#px"(?<=\\S)'(?!\\w)" "’") ; single_at_end
(#px"(?<!\\w)\"(?=\\w)" "“") ; double_at_beginning
(#px"(?<=\\S)\"(?!\\w)" "”"))) ; double_at_end
;; put replacers in desired order here
(let* ([typogrifiers (append dashes smart-quotes)]
[queries (map first typogrifiers)]
[replacements (map second typogrifiers)])
(define replacers (map make-replacer queries replacements))
;; compose goes from last to first, so reverse order
((apply compose1 (reverse replacers)) str)))
(module+ test
(check-equal? (typogrify "I had --- maybe 13 -- 20 --- hob-nobs.") "I had—maybe 13–20—hob-nobs.")
(check-equal? (typogrify "\"Why,\" she could've asked, \"are we in O‘ahu watching 'Mame'?\"")
"“Why,” she could’ve asked, “are we in O‘ahu watching ‘Mame’?”"))
;; insert nbsp between last two words
(define/contract (nonbreaking-last-space x
#:nbsp [nbsp (->string #\u00A0)]
#:minimum-word-length [minimum-word-length 6])
((tagged-xexpr?) (#:nbsp string? #:minimum-word-length integer?) . ->* . tagged-xexpr?)
;; todo: parameterize this, as it will be different for each project
(define tags-to-pay-attention-to '(p aside)) ; only apply to paragraphs
(define (replace-last-space str)
(if (#\space . in? . str)
(let ([reversed-str-list (reverse (string->list str))]
[reversed-nbsp (reverse (string->list nbsp))])
(define-values (last-word-chars other-chars)
(splitf-at reversed-str-list (λ(i) (not (eq? i #\space)))))
(list->string (reverse (append last-word-chars
; OK for long words to be on their own line.
(if (< (len last-word-chars) minimum-word-length)
; first char of other-chars will be the space, so use cdr
(append reversed-nbsp (cdr other-chars))
other-chars)))))
str))
(define (find-last-word-space x) ; recursively traverse xexpr
(cond
[(string? x) (replace-last-space x)]
[(tagged-xexpr? x)
(let-values([(tag attr elements) (break-tagged-xexpr x)])
(if (> (length elements) 0) ; elements is list of xexprs
(let-values ([(all-but-last last) (split-at elements (sub1 (length elements)))])
(make-tagged-xexpr tag attr `(,@all-but-last ,(find-last-word-space (car last)))))
x))]
[else x]))
(if ((car x) . in? . tags-to-pay-attention-to)
(find-last-word-space x)
x))
;; todo: make some tougher tests, it gets flaky with edge cases
(module+ test
(check-equal? (nonbreaking-last-space '(p "Hi there")) '(p "Hi there")) ; nbsp in between last two words
(check-equal? (nonbreaking-last-space '(p "Hi there") #:nbsp "Ø") '(p "HiØthere")) ; but let's make it visible
(check-equal? (nonbreaking-last-space '(p "Hi there") #:nbsp "_up_") '(p "Hi_up_there"))
(check-equal? (nonbreaking-last-space '(p "Hi there") #:nbsp "_up_" #:minimum-word-length 3)
'(p "Hi there"))
(check-equal? (nonbreaking-last-space '(p "Hi here" (em "ho there")) #:nbsp "Ø") '(p "Hi here" (em "hoØthere"))))
; wrap initial quotes for hanging punctuation
; todo: improve this
; does not handle <p>“<em>thing</em> properly
(define/contract (wrap-hanging-quotes nx
#:single-prepend [single-pp '(squo)]
#:double-prepend [double-pp '(dquo)])
((tagged-xexpr?) (#:single-prepend list? #:double-prepend list?) . ->* . tagged-xexpr?)
(define two-or-more-char-string? (λ(i) (and (string? i) (>= (len i) 2))))
(define-values (tag attr elements) (break-tagged-xexpr nx))
(make-tagged-xexpr tag attr
(if (and (list? elements) (not (empty? elements)))
(let ([new-car-elements (match (car elements)
[(? two-or-more-char-string? tcs)
(define str-first (get tcs 0))
(define str-rest (get tcs 1 'end))
(cond
[(str-first . in? . '("\"" "“"))
;; can wrap with any inline tag
;; so that linebreak detection etc still works
`(,@double-pp ,(->string #\“) ,str-rest)]
[(str-first . in? . '("\'" "‘"))
`(,@single-pp ,(->string #\‘) ,str-rest)]
[else tcs])]
[(? tagged-xexpr? nx) (wrap-hanging-quotes nx)]
[else (car elements)])])
(cons new-car-elements (cdr elements)))
elements)))
(module+ test
(check-equal? (wrap-hanging-quotes '(p "\"Hi\" there")) '(p (dquo "“" "Hi\" there")))
(check-equal? (wrap-hanging-quotes '(p "'Hi' there")) '(p (squo "‘" "Hi' there")))
(check-equal? (wrap-hanging-quotes '(p "'Hi' there") #:single-prepend '(foo ((bar "ino"))))
'(p (foo ((bar "ino")) "‘" "Hi' there")))
;; make sure tagged-xexpr without elements passes through unscathed
(check-equal? (wrap-hanging-quotes '(div ((style "height:2em")))) '(div ((style "height:2em")))))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Lines, blocks, paragraphs
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; turn the right items into <br> tags
(define/contract (convert-linebreaks xc #:newline [newline "\n"])
((xexpr-elements?) (#:newline string?) . ->* . xexpr-elements?)
;; todo: should this test be not block + not whitespace?
(define not-block? (λ(i) (not (block-xexpr? i))))
(filter-not empty?
(for/list ([i (len xc)])
(let ([item (get xc i)])
(cond
;; skip first and last
[(or (= i 0) (= i (sub1 (len xc)))) item]
[(equal? item newline)
(match (get xc (- i 1) (+ i 2)) ; a three-element slice with x[i] in the middle
;; only convert if neither adjacent tag is a block
;; (because blocks automatically force a newline before & after)
[(list (? not-block?) newline (? not-block?)) '(br)]
[else empty])] ; otherwise delete
[else item])))))
(module+ test
(check-equal? (convert-linebreaks '("foo" "\n" "bar")) '("foo" (br) "bar"))
(check-equal? (convert-linebreaks '("\n" "foo" "\n" "bar" "\n")) '("\n" "foo" (br) "bar" "\n"))
(check-equal? (convert-linebreaks '((p "foo") "\n" (p "bar"))) '((p "foo") (p "bar")))
(check-equal? (convert-linebreaks '("foo" "\n" (p "bar"))) '("foo" (p "bar")))
(check-equal? (convert-linebreaks '("foo" "moo" "bar")) '("foo" "moo" "bar"))
(check-equal? (convert-linebreaks '("foo" "moo" "bar") #:newline "moo") '("foo" (br) "bar"))
(check-equal? (convert-linebreaks '("foo" "\n\n" "bar")) '("foo" "\n\n" "bar")))
;; is x a paragraph break?
(define/contract (paragraph-break? x #:pattern [paragraph-pattern #px"^\n\n+$"])
((any/c) (#:pattern pregexp?) . ->* . boolean?)
(and (string? x) (->boolean (regexp-match paragraph-pattern x))))
(module+ test
(check-false (paragraph-break? "foo"))
(check-false (paragraph-break? "\n"))
(check-false (paragraph-break? "\n \n"))
(check-true (paragraph-break? "\n \n" #:pattern #px"^\n \n$"))
(check-true (paragraph-break? "\n\n"))
(check-true (paragraph-break? "\n\n\n")))
;; Find adjacent newline characters in a list and merge them into one item
;; Scribble, by default, makes each newline a separate list item
;; In practice, this is worthless.
(define/contract (merge-newlines x)
(list? . -> . list?)
(define (newline? x)
(and (string? x) (equal? "\n" x)))
(define (not-newline? x)
(not (newline? x)))
(define (really-merge-newlines xs [acc '()])
(if (empty? xs)
acc
;; Try to peel the newlines off the front.
(let-values ([(leading-newlines remainder) (splitf-at xs newline?)])
(if (not (empty? leading-newlines)) ; if you got newlines ...
;; combine them into a string and append them to the accumulator,
;; and recurse on the rest
(really-merge-newlines remainder (append acc (list (string-join leading-newlines ""))))
;; otherwise peel off elements up to the next newline, append them to accumulator,
;; and recurse on the rest
(really-merge-newlines (dropf remainder not-newline?)
(append acc (takef remainder not-newline?)))))))
(cond
[(list? x) (really-merge-newlines (map merge-newlines x))]
[else x]))
(module+ test
(check-equal? (merge-newlines '(p "\n" "foo" "\n" "\n" "bar" (em "\n" "\n" "\n")))
'(p "\n" "foo" "\n\n" "bar" (em "\n\n\n"))))
;; todo: add native support for list-xexpr
;; decode triple newlines to list items
;; prepare elements for paragraph testing
(define/contract (prep-paragraph-flow xc)
(xexpr-elements? . -> . xexpr-elements?)
(convert-linebreaks (merge-newlines (trim xc whitespace?))))
(module+ test
(check-equal? (prep-paragraph-flow '("\n" "foo" "\n" "\n" "bar" "\n" "ino" "\n"))
'("foo" "\n\n" "bar" (br) "ino")))
;; apply paragraph tag
(define/contract (wrap-paragraph xc #:tag [tag 'p])
((xexpr-elements?) (#:tag symbol?) . ->* . block-xexpr?)
(match xc
[(list (? block-xexpr? bx)) bx] ; leave a single block xexpr alone
[else (make-tagged-xexpr tag empty xc)])) ; otherwise wrap in p tag
(module+ test
(check-equal? (wrap-paragraph '("foo" "bar")) '(p "foo" "bar"))
(check-equal? (begin (append-block-tag 'para) (wrap-paragraph #:tag 'para '("foo" "bar")))
'(para "foo" "bar"))
(check-equal? (wrap-paragraph '((p "bar" "foo"))) '(p "bar" "foo"))
(check-equal? (wrap-paragraph '((div "bar" "foo") "Hi" )) '(p (div "bar" "foo") "Hi")))
;; detect paragraphs
;; todo: unit tests
(define/contract (detect-paragraphs elements)
(xexpr-elements? . -> . xexpr-elements?)
(let ([elements (prep-paragraph-flow elements)])
(if (ormap paragraph-break? elements) ; need this condition to prevent infinite recursion
(map wrap-paragraph (splitf-at* elements paragraph-break?)) ; split into ¶¶
elements)))
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