Jaidyn Ann
c8890a1d22
The spec recommends splitting at 75 octets, but that’s hard. We assume that 70 characters is more-or-less 75 octets (even though with UTF-8 chars this might be passed).
391 lines
14 KiB
Scheme
391 lines
14 KiB
Scheme
;; Copyright © 2024 Jaidyn Ann <jadedctrl@posteo.at>
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;;
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;; This program is free software: you can redistribute it and/or
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;; modify it under the terms of the GNU General Public License as
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;; published by the Free Software Foundation, either version 3 of
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;; the License, or (at your option) any later version.
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;;
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;; This program is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;;
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;; You should have received a copy of the GNU General Public License
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;; along with this program. If not, see <https://www.gnu.org/licenses/>.
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(module vcarded
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(read-vcard write-vcard)
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(import
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scheme
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(chicken base)
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(chicken condition)
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(chicken io)
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(chicken irregex)
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(srfi 1)
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(srfi 4)
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(srfi 13)
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(srfi 19)
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(srfi 130)
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(srfi 207)
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(prefix uri-common uri:))
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;;; ~ Macros ~
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;; Ignore whatever conditions the expression might return; just return the
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;; default value in that case.
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;; (ignore-error (+ 1 "seven") 3) → 3
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(define-syntax ignore-error
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(syntax-rules ()
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((ignore-error expr default)
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(condition-case expr (var () default)))))
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;;; ~ Exports ~
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;; Reader thunk. Read/parse an entire vCard into a “vCard alist.”
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;; vCard is read from an optional PORT, defaulting to (current-input-port).
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;; Ignore the IGNORED parameter.
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;;
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;; The format of a cell is:
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;; (PROPERTY-SYMBOL (ATTRIBUTE-STR …) PROPERTY-VALUE)
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;;
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;; PROPERTY-VALUE might be a string, a uri-common URI, an srfi-19 datetime,
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;; an srfi-4 bytevector (u8vector), or a list of values.
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;;
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;; The type of the value follows logically from the vCard specification’s
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;; type for that property — URI properties are a uri-common URI and NICKNAME
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;; is a list of strings, for example.
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;;
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;; But there is one notable exception: `data`-URIs are parsed into bytevectors
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;; for convenience, as these are often used to encode profile pictures.
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;;
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;; Anyway, here is an example vCard alist made by this function:
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;; ((BEGIN () "VCARD")
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;; (VERSION () "3.0")
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;; (FN () "Birdie Johnson")
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;; (NICKNAME () ("Bird" "Gal" "Tweety"))
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;; (TEL ("type=home") #<URI-common: scheme=tel path=("12149989852")>)
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;; (END () "VCARD"))
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(define (read-vcard #!optional (port (current-input-port)) (ignored #t))
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(let* [(first-element? ignored)
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(element (read-vcard-element port first-element?))]
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(if (not (eof-object? (peek-char port)))
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(append (list element) (read-vcard port #f))
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(list element))))
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;; Writes a vCard’s parsed alist to the output port as a string.
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;; Defaults to (current-output-port).
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;;
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;; I wish I had more to say, especially compared to READ-VCARD’s essay-long
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;; description, but unfortunately I’m coming up empty! =w=,
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(define (write-vcard vcard-alist #!optional (port (current-output-port)))
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(for-each (lambda (element)
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(write-folded-line (serialize-vcard-element element)))
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vcard-alist))
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;;; ~ vCard parsing [string→alist] ~
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;; Read a single unfolded line into a vCard “element” list.
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;; The optional FIRST-ELEMENT? argument simply makes sure the next line is a
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;; BEGIN:VCARD element (as the first element in any valid vCard file should
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;; be. It is used internally by READ-VCARD.
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(define (read-vcard-element #!optional (port (current-input-port)) (first-element? #f))
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(let* [(line (read-folded-line (if first-element? 100 #f) port))]
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(cond
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;; Ignore blank lines, they’re not doing anyone any harm!
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[(or (string-null? line)
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(irregex-search "^[[:whitespace:]]+$" line))
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(read-vcard-element port first-element?)]
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;; If we’ve previously established this is a vCard stream we’re dealing
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;; with, just go ahead and parse. If we haven’t established that, make
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;; sure it’s a BEGIN:VCARD line first.
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[(or (not first-element?)
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(and first-element?
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(string-contains line "BEGIN")
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(string-contains line "VCARD")))
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(parse-vcard-line line)]
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;; If we’re still making sure the file is vCard, and the first non-blank
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;; line *isn’t* a BEGIN:VCARD line, then the file probably isn’t a vCard.
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[#t
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(signal
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(condition '(exn location vcarded message
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"Not a valid vCard file.")
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'(file)
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'(vcard)))])))
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;; Parse a line of a vcard file into an alist-friendly format:
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;; (KEY ("keyprop1=d" "keyprop2=b") "VALUE" ("valprop1=a" "valprop2=b"))
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(define (parse-vcard-line line)
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(let* [(prop-value-strings (split-vcard-line line))
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(prop-elements (string-split-unescaped (car prop-value-strings) ";"))
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(value-elements (cdr prop-value-strings))
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(property (string->symbol (string-upcase (car prop-elements))))]
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(append (parse-vcard-property property (cdr prop-elements))
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(parse-vcard-value property value-elements))))
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;; Splits a line into a cons of the property-string and value-string.
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;; … basically splits the string along the first unescaped colon (:).
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;; "apple\:berry:mom:dad" → ("apple\:berry" . "mom:dad")
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(define (split-vcard-line line)
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(let [(split (string-split-unescaped line ":"))]
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(cons (car split)
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(string-join (cdr split) ":"))))
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;; Given a vCard property and its values (e.g., “VERSION” and “3.0”),
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;; parse them into a list.
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;; "EMAIL;TYPE=home" "mom@dad.com" → '(EMAIL ("TYPE=home") "mom@dad.com")
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(define (parse-vcard-property property elements)
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(append (list property)
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(list elements)))
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;; Given the value(s) of a vCard element’s value string(s), returned a
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;; parsed object.
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;; 'BIRTHDAY "2024-01-02T00:00:00" → #@2024-01-02T00:00:00-0600
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(define (parse-vcard-value prop elements)
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(let [(parser-and-unparser-funcs (alist-ref prop vcard-value-parsers))]
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(if parser-and-unparser-funcs
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(list (ignore-error (apply (car parser-and-unparser-funcs)
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(list elements))
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elements))
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(list elements))))
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;;; ~ vCard serialization [alist→string] ~
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;; With an element of a parsed vCard alist, serialize it (back) into a
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;; string.
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(define (serialize-vcard-element element)
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(let [(property (string-join
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(append (list (symbol->string (car element)))
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(second element)) ";"))
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(value (serialize-vcard-value (car element) (last element)))]
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(string-join (list property value) ":")))
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;; Serialize the value of a vCard property (from a parsed vCard alist)
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;; into a string.
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(define (serialize-vcard-value prop value)
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(let [(parser-and-unparser-funcs (alist-ref prop vcard-value-parsers))]
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(if parser-and-unparser-funcs
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(apply (cadr parser-and-unparser-funcs) (list value))
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value)))
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;;; ~ Property-value parsers/serializers ~
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;; List of all properties with semicoloned-structured strings.
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(define vcard-semicoloned-properties
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'(ADR CLIENTPIDMAP GENDER N))
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;; List of all properties with datetime values.
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(define vcard-datetime-properties
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'(ANNIVERSARY BDAY REV))
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;; List of all properties with multiple comma-separated values.
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(define vcard-csv-properties
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'(CATEGORIES NICKNAME))
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;; List of all URL-type vcard properties.
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(define vcard-url-properties
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'(CALADRURI CALURI FBURL GEO IMPP
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KEY LOGO MEMBER PHOTO RELATED
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SOUND SOURCE TEL UID URL))
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;; Should parse any truncated & reduced-accuracy ISO 8601 datetime.
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;; … right now, it only parses a few possibilities.
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(define (string->any-date str)
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(let* [(ymd "~Y~m~d")
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(hms "~H~M~S")
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(ymd-hms (string-join (list ymd hms) "T"))]
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(or (ignore-error (string->date str ymd-hms) #f)
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(ignore-error (string->date str ymd) #f)
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(ignore-error (string->date str hms) #f))))
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;; Parse a string into a URI object.
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(define (string->uri string)
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(uri:uri-reference string))
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;; Parse a data URI’s contents into a list containing the mimetype (string)
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;; and bytevector contents (u8vector).
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;; "data:text/plain;base64,ZGFk" → ("text/plain;base64" #u8(100 97 100))
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(define (data-uri-str->bytevector uri)
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(let* [(str (string-drop uri (string-length "data:")))
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(split (string-split str ","))
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(mimetype (car split))
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(contents (string-join (cdr split) ","))]
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(list
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mimetype
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(if (string-contains mimetype "base64")
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(base64->bytevector contents)
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(list->u8vector
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(map char->integer
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(string->list contents)))))))
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;; Given a bytevector and according mimetype, return the associated
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;; data-URI.
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;; "text/plain;base64" #u8(100 97 100) → "data:text/plain;base64,ZGFk"
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(define (bytevector->data-uri-str mimetype bytevector)
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(string-concatenate
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(list
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"data:"
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mimetype
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","
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(if (string-contains mimetype "base64")
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(bytevector->base64 bytevector)
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(list->string
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(map integer->char
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(u8vector->list bytevector)))))))
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;; Given a URI property’s value string(s) (like PHOTO or URL), return either
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;; a URI (if URI is valid), string (if invalid), or u8vector/bytevector (if
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;; data-URI).
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(define (parse-uri-prop-value . strings)
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(let* [(str (string-join strings ";"))
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;; We parse data URIs ourselves; so let’s not be redundant.
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(uri (if (not (string-prefix? "data:" str))
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(string->uri str)))]
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(cond
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[(string-prefix? "data:" str)
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(data-uri-str->bytevector str)]
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[(not (uri:uri? uri))
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str]
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[#t
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uri])))
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;; Given a parsed URI property’s value, serialize back into the original
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;; string-form… as best we can.
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(define (serialize-uri-prop-value value)
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(cond [(uri:uri? value)
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(irregex-replace
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":./"
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(uri:uri->string value)
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":")] ;; Some URIs have “./” mistakenly prepended.
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[(list? value)
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(bytevector->data-uri-str (car value) (cadr value))]
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[(string? value)
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value]
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[#t
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""]))
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;; A list of the parser/serializer functions for each vcard property.
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;; ((TEL #<procedure> #<procedure>)
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;; (ADR #<procedure> #<procedure>)
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;; …)
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;; TODO: Add a parser for the TZ [timezone] property.
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(define vcard-value-parsers
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(append
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(map (lambda (uri-prop)
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(list uri-prop
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parse-uri-prop-value
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serialize-uri-prop-value))
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vcard-url-properties)
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(map (lambda (date-prop)
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(list date-prop
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string->any-date
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(lambda (datetime)
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(if (date? datetime)
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(date->string datetime "~Y~m~dT~H~M~S~z")
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datetime))))
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vcard-datetime-properties)
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(map (lambda (csv-prop)
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(list csv-prop
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(lambda (str) (string-split-unescaped str ",")
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(lambda (csv-list) (string-join csv-list ",")))))
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vcard-csv-properties)
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(map (lambda (semicolon-prop)
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(list semicolon-prop
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(lambda (str) (string-split-unescaped str ";"))
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(lambda (sc-list) (string-join sc-list ";"))))
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vcard-semicoloned-properties)))
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;;; ~ General utilities ~ ^^
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;; Reader-thunk. Read a “logical” folded-line, where a line beginning with a
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;; space is a continuation of the previous line — like with vcards.
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;; LIMIT is the maximum amount of characters it will read before giving up
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;; on finding a newline.
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;; It will default to (current-input-port) as the PORT.
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(define (read-folded-line #!optional (limit #f) (port (current-input-port)))
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(let [(port (or port (current-input-port)))]
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(if (not (eof-object? (peek-char port)))
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(let [(line (read-line port limit))]
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(if (or (eq? (peek-char port) #\space)
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(eq? (peek-char port) #\tab))
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(string-concatenate
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(list line
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(string-drop (read-folded-line limit port) 1)))
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line))
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"")))
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;; Write a line to a port as a “logical” folded-line string, in the style of
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;; vCard and vCalendar. If the line is too long (passed FOLD-LENGTH [70]), it
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;; will be written as several lines of FOLD-LENGTH, with each such line
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;; prepended by the CREASE-CHAR (#\tab).
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;; It will default to (current-output-port), if PORT is #f or unspecified.
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(define (write-folded-line string #!optional
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(port (current-output-port))
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(fold-length 70)
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(crease-char #\tab))
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(write-string
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(string-concatenate
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(list (string-join (string-split-by-lengths string fold-length)
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(list->string (list #\return #\newline crease-char)))
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(list->string '(#\return #\newline))))
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#f (or port (current-output-port))))
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;; Split a STRING into strings of a size of (at most) LENGTH signs.
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;; ("ÁPPLE" 2) → '("ÁP" "PL" "E")
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(define (string-split-by-lengths string length)
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(append (list (if (<= (string-length string) length)
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string
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(substring string 0 length)))
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(if (<= (string-length string) length)
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'()
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(string-split-by-lengths (substring string length) length))))
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;; Splits a string along a delimiter; while not splitting along
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;; backslash-escaped delimiters. With “;” as the delimiter:
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;; "Bird;dad;apple\;mom" → ("Bird" "dad" "apple\;mom")
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(define (string-split-unescaped string delimiter)
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(let [(appendee "")]
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(remove
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not
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(map (lambda (substr)
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(let [(substr (string-concatenate (list appendee substr)))]
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(if (and (not (string-null? substr))
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(eq? (last (string->list substr))
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#\\))
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(and (set! appendee
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(string-concatenate (list substr delimiter)))
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#f)
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(and (set! appendee "") substr))))
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(string-split string delimiter))))))
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