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utils: 'edit-expression' reads and conses less when not modifying.

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* guix/utils.scm (edit-expression): Delay call to 'get-bytevector-all'
until after (string=? str* str).
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Ludovic Courtès 2022-01-08 17:29:12 +01:00
parent b77b788421
commit a74d0cc209
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1 changed files with 16 additions and 16 deletions
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32
guix/utils.scm
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@ -1,5 +1,5 @@
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2012-2022 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2013, 2014, 2015 Mark H Weaver <mhw@netris.org>
;;; Copyright © 2014 Eric Bavier <bavier@member.fsf.org>
;;; Copyright © 2014 Ian Denhardt <ian@zenhack.net>
@ -454,27 +454,27 @@ This procedure returns #t on success."
(str (iconv:bytevector->string
(get-bytevector-n in (- end start))
(port-encoding in)))
(post-bv (get-bytevector-all in))
(str* (proc str)))
;; Modify FILE only if there are changes.
(unless (string=? str* str)
;; Verify the edited expression is still a scheme expression.
(call-with-input-string str* read)
;; Update the file with edited expression.
(with-atomic-file-output file
(lambda (out)
(put-bytevector out pre-bv)
(display str* out)
;; post-bv maybe the end-of-file object.
(when (not (eof-object? post-bv))
(put-bytevector out post-bv))
#t))
;; Due to 'with-atomic-file-output', IN and FILE no longer share
;; the same inode, but we can reassign the source map up to LINE
;; to the new file.
(move-source-location-map! (stat in) (stat file)
(+ 1 line)))))))))
(let ((post-bv (get-bytevector-all in)))
;; Update the file with edited expression.
(with-atomic-file-output file
(lambda (out)
(put-bytevector out pre-bv)
(display str* out)
(unless (eof-object? post-bv)
;; Copy everything that came after STR.
(put-bytevector out post-bv))))
;; Due to 'with-atomic-file-output', IN and FILE no longer
;; share the same inode, but we can reassign the source map up
;; to LINE to the new file.
(move-source-location-map! (stat in) (stat file)
(+ 1 line))))))))))
;;;