(subset-p): Renamed from

find-safe-coding-system-list-subset-p.
(find-coding-systems-region, find-coding-systems-string): New
functions.
(find-coding-systems-for-charsets): Renamed from
find-safe-coding-system.  This is now a helper function of the
above two.
(select-safe-coding-system): Adjusted for the above changes.

1 files changed, 50 insertions, 40 deletions

diff --git a/lisp/international/mule-cmds.el b/lisp/international/mule-cmds.el
index 509672cee6d..a6526ff0160 100644
--- a/lisp/international/mule-cmds.el
+++ b/lisp/international/mule-cmds.el
@@ -228,7 +228,7 @@ This also sets the following values:
                  base coding-system))
     (set-default-coding-systems (or base coding-system))))
 
-(defun find-safe-coding-system-list-subset-p (list1 list2)
+(defun subset-p (list1 list2)
   "Return non-nil if all elements in LIST1 are included in LIST2.
 Comparison done with EQ."
   (catch 'tag
@@ -238,50 +238,58 @@ Comparison done with EQ."
       (setq list1 (cdr list1)))
     t))
 
-(defun find-safe-coding-system (from to)
+(defun find-coding-systems-region (from to)
   "Return a list of proper coding systems to encode a text between FROM and TO.
 All coding systems in the list can safely encode any multibyte characters
 in the text.
 
 If the text contains no multibyte charcters, return a list of a single
-element `undecided'.
+element `undecided'."
+  (find-coding-systems-for-charsets (find-charset-region from to)))
 
-Kludgy feature: if FROM is a string, the string is the target text,
-and TO is ignored."
-  (let ((charset-list (if (stringp from) (find-charset-string from)
-                        (find-charset-region from to))))
-    (if (or (null charset-list)
-            (and (= (length charset-list) 1)
-                 (eq 'ascii (car charset-list))))
-        '(undecided)
-      (let ((l coding-system-list)
-            (prefered-codings
-             (mapcar (function
-                      (lambda (x)
-                        (get-charset-property x 'prefered-coding-system)))
-                     charset-list))
-            codings coding safe)
-        (while l
-          (setq coding (car l) l (cdr l))
-          (if (and (eq coding (coding-system-base coding))
-                   (setq safe (coding-system-get coding 'safe-charsets))
-                   (or (eq safe t)
-                       (find-safe-coding-system-list-subset-p
-                        charset-list safe)))
-              ;; We put the higher priority to coding systems included
-              ;; in PREFERED-CODINGS, and within them, put the higher
-              ;; priority to coding systems which support smaller
-              ;; number of charsets.
-              (let ((priority
-                     (logior (if (coding-system-get coding 'mime-charset)
-                                 256 0)
-                             (if (memq coding prefered-codings) 128 0)
-                             (if (> (coding-system-type coding) 0) 64 0)
-                             (if (consp safe) (- 64 (length safe)) 0))))
-                (setq codings (cons (cons priority coding) codings)))))
-        (mapcar 'cdr
-                (sort codings (function (lambda (x y) (> (car x) (car y))))))
-        ))))
+(defun find-coding-systems-string (string)
+  "Return a list of proper coding systems to encode STRING.
+All coding systems in the list can safely encode any multibyte characters
+in STRING.
+
+If STRING contains no multibyte charcters, return a list of a single
+element `undecided'."
+  (find-coding-systems-for-charsets (find-charset-string string)))
+
+(defun find-coding-systems-for-charsets (charsets)
+  "Return a list of proper coding systems to encode characters of CHARSETS.
+CHARSETS is a list of character sets."
+  (if (or (null charsets)
+          (and (= (length charsets) 1)
+               (eq 'ascii (car charsets))))
+      '(undecided)
+    (let ((l coding-system-list)
+          (prefered-codings
+           (mapcar (function
+                    (lambda (x)
+                      (get-charset-property x 'prefered-coding-system)))
+                   charsets))
+          codings coding safe)
+      (while l
+        (setq coding (car l) l (cdr l))
+        (if (and (eq coding (coding-system-base coding))
+                 (setq safe (coding-system-get coding 'safe-charsets))
+                 (or (eq safe t)
+                     (subset-p charsets safe)))
+            ;; We put the higher priority to coding systems included
+            ;; in PREFERED-CODINGS, and within them, put the higher
+            ;; priority to coding systems which support smaller
+            ;; number of charsets.
+            (let ((priority
+                   (logior (if (coding-system-get coding 'mime-charset)
+                               256 0)
+                           (if (memq coding prefered-codings) 128 0)
+                           (if (> (coding-system-type coding) 0) 64 0)
+                           (if (consp safe) (- 64 (length safe)) 0))))
+              (setq codings (cons (cons priority coding) codings)))))
+      (mapcar 'cdr
+              (sort codings (function (lambda (x y) (> (car x) (car y))))))
+      )))
 
 (defun select-safe-coding-system (from to &optional default-coding-system)
   "Ask a user to select a safe coding system from candidates.
@@ -299,7 +307,9 @@ Kludgy feature: if FROM is a string, the string is the target text,
 and TO is ignored."
   (or default-coding-system
       (setq default-coding-system buffer-file-coding-system))
-  (let ((safe-coding-systems (find-safe-coding-system from to)))
+  (let ((safe-coding-systems (if (stringp from)
+                                 (find-coding-systems-string from)
+                               (find-coding-systems-region from to))))
     (if (or (eq (car safe-coding-systems) 'undecided)
             (and default-coding-system
                  (memq (coding-system-base default-coding-system)