From: Stephen Gildea <stepheng+emacs@gildea.com>
Date: Wed, 12 Mar 2025 14:02:44 +0000 (-0700)
Subject: time-stamp: optimize resource use
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=cd49d8832ac2874e40c2f6dd2cb4f8f7af28f8dd;p=emacs.git

time-stamp: optimize resource use

* lisp/time-stamp.el (time-stamp-string-preprocess): Replace
n-squared string 'concat' with linear list 'push'.

(cherry picked from commit 6ab65281c54a1fcef90786f9d50142e3427781fb)
---

diff --git a/lisp/time-stamp.el b/lisp/time-stamp.el
index c448e4748fe..43b9f1a0c5d 100644
--- a/lisp/time-stamp.el
+++ b/lisp/time-stamp.el
@@ -535,7 +535,7 @@ and all `time-stamp-format' compatibility."
       ((fmt-len (length format))
        (ind 0)
        cur-char
-       (result "")
+       (result nil)
        (handle-one-conversion
         (lambda ()
 	  (let ((prev-char nil)
@@ -778,17 +778,13 @@ and all `time-stamp-format' compatibility."
     ;; iterate over the format string
     (while (< ind fmt-len)
       (setq cur-char (aref format ind))
-      (setq
-       result
-       (concat
-        result
-        (cond
-         ((eq cur-char ?%)
-          (funcall handle-one-conversion))
-         (t
-	  (char-to-string cur-char)))))
+      (push (cond ((eq cur-char ?%)
+                   (funcall handle-one-conversion))
+                  (t
+                   (char-to-string cur-char)))
+            result)
       (setq ind (1+ ind)))
-    result))
+    (apply #'concat (nreverse result))))
 
 (defun time-stamp-do-letter-case (change-is-downcase
                                   upcase title-case change-case text)