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finish "pollen.rkt" comments

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dev-lp
Matthew Butterick 9 years ago
parent dccc9f737b
commit 57641ecc53
1 changed files with 102 additions and 48 deletions
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140
pollen.rkt
Unescape Escape View File

@ -641,9 +641,9 @@ But to be safe, we'll raise an arity error if we get too many arguments.
(module+ test
(check-txexprs-equal? ◊xref{target}
'(a ((class "xref") (href "target.html") (hyphens "none")) "target"))
`(a ((class "xref") (href "target.html") ,no-hyphens-attr) "target"))
(check-txexprs-equal? ◊xref["url"]{target}
'(a ((class "xref") (href "url") (hyphens "none")) "target"))
`(a ((class "xref") (href "url") ,no-hyphens-attr) "target"))
(check-exn exn:fail:contract:arity? (λ _ (xref "url" "target" "spurious-third-argument"))))
@ -705,9 +705,9 @@ with arguments that will be filled in when you invoke the macro.
|#
(define-syntax-rule (define-heading heading-name tag)
; first, heading-name is used as an identifier
(define (heading-name . text-args)
(define heading-name
; then it's used as a symbol that is converted to a string.
(list* tag (list `(class ,(~a 'heading-name)) no-hyphens-attr) text-args)))
(make-default-tag-function tag #:class (symbol->string 'heading-name))))
(define-heading topic 'h3)
(define-heading subhead 'h3)
@ -717,15 +717,15 @@ with arguments that will be filled in when you invoke the macro.
(module+ test
(check-txexprs-equal? ◊topic{foo}
'(h3 ((class "topic") (hyphens "none")) "foo"))
'(h3 ((class "topic")) "foo"))
(check-txexprs-equal? ◊subhead{foo}
'(h3 ((class "subhead") (hyphens "none")) "foo"))
'(h3 ((class "subhead")) "foo"))
(check-txexprs-equal? ◊font-headline{foo}
'(h3 ((class "font-headline") (hyphens "none")) "foo"))
'(h3 ((class "font-headline")) "foo"))
(check-txexprs-equal? ◊section{foo}
'(h2 ((class "section") (hyphens "none")) "foo"))
'(h2 ((class "section")) "foo"))
(check-txexprs-equal? ◊chapter{foo}
'(h1 ((class "chapter") (hyphens "none")) "foo")))
'(h1 ((class "chapter")) "foo")))
#|
`define-heading-from-metas`: macro for defining a function that makes a heading
@ -759,11 +759,11 @@ For fun, I used Pollen notation inside the macro just to show you that it will w
(module+ test
(let ([my-fake-metas (hash 'title "Fake Title" 'white "noise")])
(check-txexprs-equal? ◊topic-from-metas[my-fake-metas]
'(h3 ((class "topic") (hyphens "none")) "Fake Title"))
'(h3 ((class "topic")) "Fake Title"))
(check-txexprs-equal? ◊section-from-metas[my-fake-metas]
'(h2 ((class "section") (hyphens "none")) "Fake Title"))
'(h2 ((class "section")) "Fake Title"))
(check-txexprs-equal? ◊chapter-from-metas[my-fake-metas]
'(h1 ((class "chapter") (hyphens "none")) "Fake Title"))))
'(h1 ((class "chapter")) "Fake Title"))))
#|
`hanging-topic`: convert a topic + subhead into one HTML markup unit
@ -777,8 +777,8 @@ For fun, I used Pollen notation inside the macro just to show you that it will w
(module+ test
(check-txexprs-equal? ◊hanging-topic["Topic name"]{One-line explanation}
'(div ((class "hanging-topic") (hyphens "none")) "Topic name"
(p ((hyphens "none")) "One-line explanation"))))
`(div ((class "hanging-topic") ,no-hyphens-attr) "Topic name"
(p (,no-hyphens-attr) "One-line explanation"))))
#|
@ -848,6 +848,17 @@ You could improve it to fill in blank cells in rows that need them.
(tr (td "five") (td "six")))))
#|
`pdf-thumbnail-link`: create a thumbnail of a PDF that links to the PDF
This function will only work properly if you have `sips` on your system
(command-line image-processing program, included with OS X).
This shows how you can fold other kinds of project housekeeping into Pollen commands.
Here, the function generates the thumbnail it needs when the page is compiled.
One disadvantage of this approach is that the thumbnail will *always* be generated on recompile,
though you could put in some logic to avoid this (e.g., check the modification date of the PDF).
In this case, `sips` is fast enough that it's not bothersome.
|#
(define (pdf-thumbnail-link pdf-pathstring)
@ -856,12 +867,16 @@ You could improve it to fill in blank cells in rows that need them.
(define sips-command
(format "sips -Z 2000 -s format ~a --out '~a' '~a' > /dev/null"
img-extension img-pathstring pdf-pathstring))
(if (system sips-command)
(link pdf-pathstring `(img ((src ,img-pathstring))))
(error 'pdf-thumbnail-link "sips failed")))
◊link[pdf-pathstring]{◊(if (system sips-command)
`(img ((src ,img-pathstring)))
;; usually one would raise an error on the next line,
;; but for instructional purposes, we'll have a graceful fail
"sips not available")})
#|
A few convenience variants of `pdf-thumbnail-link`
|#
(define (pdf-thumbnail-link-from-metas metas)
(define-values (dir fn _) (split-path (add-ext (remove-ext* (hash-ref metas 'here-path)) "pdf")))
(pdf-thumbnail-link (->string fn)))
@ -881,35 +896,71 @@ You could improve it to fill in blank cells in rows that need them.
,(pdf-thumbnail-link (format "pdf/sample-doc-~a-after-alternate.pdf" base-name))))
#|
`root`: decode page content
In a Pollen markup source, the output is a tagged X-expression that starts with `root`:
(root (div ((class "headline")) "Page title") ...)
(define (root . xs)
;; process paragraphs first so that they're treated as block-txexprs in next phase.
(define elements-with-paragraphs (decode-elements xs #:txexpr-elements-proc detect-paragraphs))
`(div ((id "doc")) ,@(decode-elements elements-with-paragraphs
Recall that every Pollen tag calls a function with the same name (if it exists, otherwise it just
becomes a tag). This is also true of `root`.
`root` has slightly special status inasmuch as it is the top tag of the X-expression,
and thus the last tag function that will get called. Therefore, `root` is a good place to put any
processing that should happen once all the page content has been filled in.
Often, you'll want to use a `decode` function, which can recursively perform different kinds of
processing on different types of page elements.
|#
(define (root . elems)
;; We will do the decoding in two steps.
;; Detect paragraphs first so that they're treated as block-txexprs in next phase.
(define elements-with-paragraphs (decode-elements elems #:txexpr-elements-proc detect-paragraphs))
;; Then do the rest of the decoding normally.
(list* 'div '((id "doc"))
(decode-elements elements-with-paragraphs
#:block-txexpr-proc hyphenate-block
;; `hangable-quotes` doesn't return a string, so do it last
#:string-proc (compose1 hangable-quotes
#:string-proc (compose1 make-quotes-hangable
fix-em-dashes
smart-quotes)
#:exclude-tags '(style script))))
#|
`hyphenate-block`: helper function for root decoder
|#
(define (hyphenate-block block-tx)
;; attach hyphenate as a block processor rather than string processor
;; so that attrs can be inspected for "no-hyphens" flag.
;; The basic `hyphenate` function comes from the `hyphenate` module.
;; We could attach `hyphenate` to our decoder as a string processor rather than block processor.
;; But we want to be able to handle our "no-hyphens" flag (aka `no-hyphens-attr`).
;; So we want to look at blocks, not strings.
(define (no-hyphens? tx)
(or (member (get-tag tx) '(th h1 h2 h3 h4 style script))
(member no-hyphens-attr (get-attrs tx))))
(or (member (get-tag tx) '(th h1 h2 h3 h4 style script)) ; don't hyphenate these, no matter what
(member no-hyphens-attr (get-attrs tx)))) ; also don't hyphenate blocks with `no-hyphens-attr`
(hyphenate block-tx
#:min-left-length 3
#:min-right-length 3
#:omit-txexpr no-hyphens?))
(module+ test
(check-txexprs-equal? (hyphenate-block `(div "snowman" (span (,no-hyphens-attr) "snowman")))
`(div "snow\u00ADman" (span (,no-hyphens-attr) "snowman"))))
(define (hangable-quotes str)
(define strs (regexp-match* #px"\\s?[“‘]" str #:gap-select? #t))
(if (= (length strs) 1) ; no submatches
(car strs)
#|
`make-quotes-hangable`: perform tricky processing on quotation marks.
Because I'm a typography snob I like to push quotation marks into the margin a little bit
when they appear at the left edge of a line (aka "hanging quotes").
This function just wraps left-hand quote marks in two little tags ("push" and "pull")
that I can then manipulate in CSS to get the effect.
|#
(define (make-quotes-hangable str)
;; using `regexp-match*` with #:gap-select? makes it act like a funny kind of string splitter
(define substrs (regexp-match* #px"\\s?[“‘]" str #:gap-select? #t))
(if (= (length substrs) 1) ; no submatches
(car substrs)
(cons 'quo (append-map (λ(str)
(let ([strlen (string-length str)])
(if (> strlen 0)
@ -917,19 +968,27 @@ You could improve it to fill in blank cells in rows that need them.
[("‘") (list '(squo-push) `(squo-pull ,str))]
[("“") (list '(dquo-push) `(dquo-pull ,str))]
[else (list str)])
(list str)))) strs))))
(list str)))) substrs))))
(module+ test
(check-txexprs-equal? (make-quotes-hangable "“Who is it?”")
'(quo "" (dquo-push) (dquo-pull "“") "Who is it?”")))
#|
`fix-em-dashes`: helper function for root decoder
When I type an em dash in my sources, I will often leave a space around it,
but I don't want spaces in the output, so this function removes them.
|#
(define (fix-em-dashes str)
;; remove word spaces around em dashes where necessary.
;; replace with thin spaces.
;; \u00A0 = nbsp, \u2009 = thinsp (neither included in \s)
(let* ([str (regexp-replace* #px"(?<=\\w)[\u00A0\u2009\\s]—" str "—")]
[str (regexp-replace* #px"—[\u00A0\u2009\\s](?=\\w)" str "—")])
str))
(module+ test
(check-equal? (fix-em-dashes "Hey — you!") "Hey—you!")
(check-equal? (fix-em-dashes "Hey—you!") "Hey—you!"))
#|
`capitalize-first-letter`: utility function for use in HTML templates.
@ -974,8 +1033,3 @@ You could improve it to fill in blank cells in rows that need them.
(define (captioned name . xs)
`(table ((class "captioned indented"))
(tr (td ((style "text-align:left")) ,@xs) (td ,(caption name)))))