Synch to No Gnus 200504221124.

[elisp/gnus.git-] / lisp / mm-util.el

diff --git a/lisp/mm-util.el b/lisp/mm-util.el
index fe7c77c..cee0393 100644 (file)
--- a/lisp/mm-util.el
+++ b/lisp/mm-util.el
@@ -57,7 +57,8 @@
                    mm-mime-mule-charset-alist)
            nil t))))
      (subst-char-in-string
-      . (lambda (from to string &optional inplace) ;; stolen (and renamed) from nnheader.el
+      . (lambda (from to string &optional inplace)
+         ;; stolen (and renamed) from nnheader.el
          "Replace characters in STRING from FROM to TO.
          Unless optional argument INPLACE is non-nil, return a new string."
          (let ((string (if inplace string (copy-sequence string)))
@@ -75,6 +76,24 @@
          (replace-regexp-in-string regexp rep string nil literal)))
      (string-as-unibyte . identity)
      (string-make-unibyte . identity)
+     ;; string-as-multibyte often doesn't really do what you think it does.
+     ;; Example:
+     ;;    (aref (string-as-multibyte "\201") 0) -> 129 (aka ?\201)
+     ;;    (aref (string-as-multibyte "\300") 0) -> 192 (aka ?\300)
+     ;;    (aref (string-as-multibyte "\300\201") 0) -> 192 (aka ?\300)
+     ;;    (aref (string-as-multibyte "\300\201") 1) -> 129 (aka ?\201)
+     ;; but
+     ;;    (aref (string-as-multibyte "\201\300") 0) -> 2240
+     ;;    (aref (string-as-multibyte "\201\300") 1) -> <error>
+     ;; Better use string-to-multibyte or encode-coding-string.
+     ;; If you really need string-as-multibyte somewhere it's usually
+     ;; because you're using the internal emacs-mule representation (maybe
+     ;; because you're using string-as-unibyte somewhere), which is
+     ;; generally a problem in itself.
+     ;; Here is an approximate equivalence table to help think about it:
+     ;; (string-as-multibyte s)   ~= (decode-coding-string s 'emacs-mule)
+     ;; (string-to-multibyte s)   ~= (decode-coding-string s 'binary)
+     ;; (string-make-multibyte s) ~= (decode-coding-string s locale-coding-system)
      (string-as-multibyte . identity)
      (string-to-multibyte
       . (lambda (string)
@@ -138,7 +157,7 @@ In XEmacs, also return non-nil if CS is a coding system object.
 If CS is available, return CS itself in Emacs, and return a coding
 system object in XEmacs."
   (if (fboundp 'find-coding-system)
-      (find-coding-system cs)
+      (and cs (find-coding-system cs))
     (if (fboundp 'coding-system-p)
        (when (coding-system-p cs)
          cs)
@@ -668,7 +687,7 @@ But this is very much a corner case, so don't worry about it."
 
 (defmacro mm-xemacs-find-mime-charset (begin end)
   (when (featurep 'xemacs)
-    `(mm-xemacs-find-mime-charset-1 ,begin ,end)))
+    `(and (featurep 'mule) (mm-xemacs-find-mime-charset-1 ,begin ,end))))
 
 (defun mm-find-mime-charset-region (b e &optional hack-charsets)
   "Return the MIME charsets needed to encode the region between B and E.
@@ -912,7 +931,7 @@ If INHIBIT is non-nil, inhibit `mm-inhibit-file-name-handlers'."
     (defun mm-detect-coding-region (start end)
       "Like `detect-coding-region' except returning the best one."
       (let ((coding-systems
-            (detect-coding-region (point) (point-max))))
+            (detect-coding-region start end)))
        (or (car-safe coding-systems)
            coding-systems)))
   (defun mm-detect-coding-region (start end)