From: Daniel Mendler <mail@daniel-mendler.de>
To: 47712@debbugs.gnu.org
Subject: bug#47712: 27.1; Provide `string-display-width` function, which takes properties into account, `substring-width`
Date: Sun, 11 Apr 2021 23:16:13 +0200 [thread overview]
Message-ID: <642c8a37-31c7-2723-12af-06cd7f120c2f@daniel-mendler.de> (raw)
Provide a `string-display-width' function, which computes the
`string-width', but takes invisible display properties into account.
This function is often needed by packages.
For example my Consult package (https://github.com/minad/consult) has a
crude (non-recursive) version of that function. Then the Embark package
has (https://github.com/oantolin/embark) has a similar function. Last
but not least, the function already exists in Org under the name
`org-string-width'.
It is reasonable to implement this function in Elisp. But all the
implementations have to use `string-width' for measuring the parts which
make up the actual string. Unfortunately this requires allocations for
the substrings. A possible solution to this problem is to implement a
primitive function `substring-width' and implement `string-width' in
terms of that function.
(defun consult--display-width (string)
"Compute width of STRING taking display and invisible properties into
account."
(let ((pos 0) (width 0) (end (length string)))
(while (< pos end)
(let ((nextd (next-single-property-change
pos 'display string end))
(display (get-text-property
pos 'display string)))
(if (stringp display)
(setq width (+ width (string-width display))
pos nextd)
(while (< pos nextd)
(let ((nexti (next-single-property-change
pos 'invisible string nextd)))
(unless (get-text-property
pos 'invisible string)
(setq width
(+ width
(string-width
;; Avoid allocation for the full string.
;; There should be a `substring-width'
;; provided by Emacs. TODO: Propose
;; upstream? Alternatively propose this
;; whole `display-width' function to
;; upstream.
(if (and (= pos 0) (= nexti end))
string
(substring-no-properties
string pos nexti))))))
(setq pos nexti))))))
width))
next reply other threads:[~2021-04-11 21:16 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-11 21:16 Daniel Mendler [this message]
2021-04-12 2:26 ` bug#47712: 27.1; Provide `string-display-width` function, which takes properties into account, `substring-width` Eli Zaretskii
2021-04-12 8:45 ` Daniel Mendler
2021-04-12 8:53 ` Lars Ingebrigtsen
2021-04-12 9:08 ` Daniel Mendler
2021-04-13 8:01 ` Lars Ingebrigtsen
2021-04-13 12:00 ` Eli Zaretskii
2021-04-13 12:25 ` Daniel Mendler
2021-04-14 8:50 ` Eli Zaretskii
2021-04-14 10:49 ` Daniel Mendler
2021-04-14 11:38 ` Eli Zaretskii
2021-04-12 12:21 ` Eli Zaretskii
2021-04-12 12:50 ` Daniel Mendler
2021-04-12 13:21 ` Eli Zaretskii
2021-04-12 13:32 ` Daniel Mendler
2021-04-12 13:40 ` Eli Zaretskii
2021-04-12 14:05 ` Daniel Mendler
2021-04-12 14:15 ` Eli Zaretskii
2021-04-12 14:32 ` Eli Zaretskii
2021-04-12 14:38 ` Daniel Mendler
2021-04-12 17:01 ` Eli Zaretskii
2021-04-12 17:18 ` Daniel Mendler
2021-04-13 7:06 ` martin rudalics
2021-04-13 12:23 ` Eli Zaretskii
2021-04-12 14:36 ` Daniel Mendler
2021-04-12 17:09 ` Eli Zaretskii
2021-04-12 17:13 ` Daniel Mendler
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