Jaidyn Ann
8e73f121be
Also, now we avoid using regex, which is apparently more efficient, According to TIME.
104 lines
3.6 KiB
Scheme
104 lines
3.6 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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(import
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scheme
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(chicken io)
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(chicken irregex)
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srfi-1
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srfi-130)
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;; Splits a string into a list of CRLF’d lines.
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(define (unlines lines)
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(string-join lines "\r\n"))
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;; Splits a string into a list of CRLF’d lines.
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(define (lines string)
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(remove string-null? (string-split string "\r\n")))
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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 (irregex-extract "(\\\\:|[^:])*" line))]
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(if (>= (length split) 2)
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(cons
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(car split)
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;; Drop the value’s first char (redundant “:”) and concatenate the
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;; rest of the string-parts which were erroneously split along “:”.
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(string-drop (reduce-right
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(lambda (a b) (string-concatenate (list a ":" b)))
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"" (cdr split))
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1))
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#f)))
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;; Splits a key or value-element into its (potentially multiple) parameters.
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;; … basically just splits along non-escaped semi-colons.
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;; "Bird;dad;apple\;mom" → ("Bird" "dad" "apple\;mom")
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(define (split-vcard-element key-or-value)
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(let [(appendee "")]
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(remove
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not
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(map (lambda (str)
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(let [(str (string-concatenate `(,appendee ,str)))]
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(if (and (not (string-null? str))
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(eq? (last (string->list str))
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#\\))
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(and (set! appendee (string-concatenate `(,str ";")))
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#f)
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(and (set! appendee "") str))))
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(string-split key-or-value ";")))))
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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* [(key-value-strings (split-vcard-line line))
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(key-elements (split-vcard-element (car key-value-strings)))
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(value-elements (split-vcard-element (cdr key-value-strings)))]
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(list (string->symbol (car key-elements))
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(car value-elements)
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(cdr key-elements)
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(cdr value-elements))))
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;; Reader thunk. Read/parse an entire vcard into a “vcard alist.”
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(define (read-vcard)
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(let [(element (read-vcard-element))]
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(if (not (eof-object? (peek-char)))
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(append (list element) (read-vcard))
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element)))
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;; Read a single unfolded line into a vcard “element” list.
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(define (read-vcard-element)
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(parse-vcard-line (read-folded-line)))
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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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(define (read-folded-line)
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(let [(line (read-line))]
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(if (eq? (peek-char) #\space)
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(string-concatenate
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(list line
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(string-drop (read-element) 1)))
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line)))
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