* rfc2047.el (rfc2047-decode-string): Don't cons a string

unnecessarily.

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index a17db77..99042af 100644 (file)
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,5 +1,8 @@
 2004-01-12  Jesper Harder  <harder@ifa.au.dk>
 
+       * rfc2047.el (rfc2047-decode-string): Don't cons a string
+       unnecessarily.
+
        * mm-util.el (mm-replace-chars-in-string): Remove.
 
        * rfc2047.el (rfc2047-decode): Use mm-subst-char-in-string instead

diff --git a/lisp/rfc2047.el b/lisp/rfc2047.el
index 32842f5..9d05c08 100644 (file)
--- a/lisp/rfc2047.el
+++ b/lisp/rfc2047.el
@@ -668,7 +668,20 @@ By default, the region is treated as containing addresses (see
               mail-parse-charset
               (not (eq mail-parse-charset 'us-ascii))
               (not (eq mail-parse-charset 'gnus-decoded)))
-         (mm-decode-coding-string string mail-parse-charset)
+         ;; `decode-coding-string' in Emacs offers a third optional
+         ;; arg NOCOPY to avoid consing a new string if the decoding
+         ;; is "trivial".  Unfortunately it currently doesn't
+         ;; consider anything else than a `nil' coding system
+         ;; trivial.
+         ;; `rfc2047-decode-string' is called multiple times for each
+         ;; article during summary buffer generation, and we really
+         ;; want to avoid unnecessary consing.  So we bypass
+         ;; `decode-coding-string' if the string is purely ASCII.
+         (if (and (fboundp 'detect-coding-string)
+                  ;; string is purely ASCII
+                  (eq (detect-coding-string string t) 'undecided))
+             string
+           (mm-decode-coding-string string mail-parse-charset))
        (mm-string-as-multibyte string)))))
 
 (defun rfc2047-parse-and-decode (word)