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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2018 Mathieu Othacehe <m.othacehe@gmail.com>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
(define-module (gnu installer timezone)
#:use-module (gnu installer utils)
#:use-module (guix i18n)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-26)
#:use-module (srfi srfi-34)
#:use-module (srfi srfi-35)
#:use-module (ice-9 match)
#:use-module (ice-9 receive)
#:export (locate-children
timezone->posix-tz
timezone-has-child?
zonetab->timezone-tree
posix-tz->configuration))
(define %not-blank
(char-set-complement char-set:blank))
(define (posix-tz->timezone tz)
"Convert given TZ in Posix format like \"Europe/Paris\" into a list like
(\"Europe\" \"Paris\")."
(string-split tz #\/))
(define (timezone->posix-tz timezone)
"Convert given TIMEZONE like (\"Europe\" \"Paris\") into a Posix timezone
like \"Europe/Paris\"."
(string-join timezone "/"))
(define (zonetab->timezones zonetab)
"Parse ZONETAB file and return the corresponding list of timezones."
(define (zonetab-line->posix-tz line)
(let ((tokens (string-tokenize line %not-blank)))
(match tokens
((code coordinates tz _ ...)
tz))))
(call-with-input-file zonetab
(lambda (port)
(let* ((lines (read-lines port))
;; Filter comment lines starting with '#' character.
(tz-lines (filter (lambda (line)
(not (eq? (string-ref line 0)
#\#)))
lines)))
(map (lambda (line)
(posix-tz->timezone
(zonetab-line->posix-tz line)))
tz-lines)))))
(define (timezones->timezone-tree timezones)
"Convert the list of timezones, TIMEZONES into a tree under the form:
(\"America\" (\"North_Dakota\" \"New_Salem\" \"Center\"))
representing America/North_Dakota/New_Salem and America/North_Dakota/Center
timezones."
(define (remove-first lists)
"Remove the first element of every sublists in the argument LISTS."
(map (lambda (list)
(if (null? list) list (cdr list)))
lists))
(let loop ((cur-timezones timezones))
(match cur-timezones
(() '())
(((region . rest-region) . rest-timezones)
(if (null? rest-region)
(cons (list region) (loop rest-timezones))
(receive (same-region other-region)
(partition (lambda (timezone)
(string=? (car timezone) region))
cur-timezones)
(acons region
(loop (remove-first same-region))
(loop other-region))))))))
(define (locate-children tree path)
"Return the children of the timezone indicated by PATH in the given
TREE. Raise a condition if the PATH could not be found."
(let ((extract-proc (cut map car <>)))
(match path
(() (sort (extract-proc tree) string<?))
((region . rest)
(or (and=> (assoc-ref tree region)
(cut locate-children <> rest))
(raise
(condition
(&message
(message
(format #f (G_ "Unable to locate path: ~a.") path))))))))))
(define (timezone-has-child? tree timezone)
"Return #t if the given TIMEZONE any child in TREE and #f otherwise."
(not (null? (locate-children tree timezone))))
(define* (zonetab->timezone-tree zonetab)
"Return the timezone tree corresponding to the given ZONETAB file."
(timezones->timezone-tree (zonetab->timezones zonetab)))
;;;
;;; Configuration formatter.
;;;
(define (posix-tz->configuration timezone)
"Return the configuration field for TIMEZONE."
`((timezone ,timezone)))
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