guix-devel/guix/import/utils.scm

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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2012, 2013 Ludovic Courtès <ludo@gnu.org>
;;;
;;; 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 (guix import utils)
#:use-module (ice-9 match)
#:use-module (ice-9 regex)
#:use-module (srfi srfi-1)
#:export (factorize-uri))
(define (factorize-uri uri version)
"Factorize URI, a package tarball URI as a string, such that any occurrences
of the string VERSION is replaced by the symbol 'version."
(let ((version-rx (make-regexp (regexp-quote version))))
(match (regexp-exec version-rx uri)
(#f
uri)
(_
(let ((indices (fold-matches version-rx uri
'((0))
(lambda (m result)
(match result
(((start) rest ...)
`((,(match:end m))
(,start . ,(match:start m))
,@rest)))))))
(fold (lambda (index result)
(match index
((start)
(cons (substring uri start)
result))
((start . end)
(cons* (substring uri start end)
'version
result))))
'()
indices))))))