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utils: Add a procedure for pretty printing tabular data.

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* guix/utils.scm (pretty-print-table): New procedure.

Co-authored-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>
Signed-off-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>
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Steve Sprang 2018-01-09 14:00:11 -08:00 committed by Maxim Cournoyer
parent a49c5488bd
commit b73b9aae0d
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1 changed files with 32 additions and 1 deletions
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guix/utils.scm
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@ -10,6 +10,8 @@
;;; Copyright © 2020 Efraim Flashner <efraim@flashner.co.il>
;;; Copyright © 2021 Simon Tournier <zimon.toutoune@gmail.com>
;;; Copyright © 2021 Chris Marusich <cmmarusich@gmail.com>
;;; Copyright © 2018 Steve Sprang <scs@stevesprang.com>
;;; Copyright © 2021 Maxim Cournoyer <maxim.cournoyer@gmail.com>
;;;
;;; This file is part of GNU Guix.
;;;
@ -123,7 +125,9 @@
canonical-newline-port
string-distance
string-closest))
string-closest
pretty-print-table))
;;;
@ -935,6 +939,33 @@ according to THRESHOLD, then #f is returned."
#f +inf.0
tests)))
;;;
;;; Prettified output.
;;;
(define* (pretty-print-table rows #:key (max-column-width 20))
"Print ROWS in neat columns. All rows should be lists of strings and each
row should have the same length. The columns are separated by a tab
character, and aligned using spaces. The maximum width of each column is
bound by MAX-COLUMN-WIDTH."
(let* ((number-of-columns-to-pad (if (null? rows)
0
(1- (length (first rows)))))
;; Ignore the last column as it is left aligned and doesn't need
;; padding; this prevents printing extraneous trailing spaces.
(column-widths (fold (lambda (row maximums)
(map max (map string-length row) maximums))
;; Initial max width is 0 for each column.
(make-list number-of-columns-to-pad 0)
(map (cut drop-right <> 1) rows)))
(column-formats (map (cut format #f "~~~da" <>)
(map (cut min <> max-column-width)
column-widths)))
(fmt (string-append (string-join column-formats "\t") "\t~a")))
(setvbuf (current-output-port) 'block) ;for better performance
(for-each (cut format #t "~?~%" fmt <>) rows)))
;;; Local Variables:
;;; eval: (put 'call-with-progress-reporter 'scheme-indent-function 1)
;;; End: