(charset-multibyte-form-string): New function.

(list-character-sets-1): Use charset-multibyte-form-string.
(describe-character-set): New function.
(describe-coding-system): Hyperlinks to safe character sets.

1 files changed, 69 insertions, 26 deletions

diff --git a/lisp/international/mule-diag.el b/lisp/international/mule-diag.el
index b723e5fc977..370dda98469 100644
--- a/lisp/international/mule-diag.el
+++ b/lisp/international/mule-diag.el
@@ -120,6 +120,24 @@ but still shows the full information."
           (list-character-sets-1 sort-key)
           (help-setup-xref (list #'list-character-sets nil) t)))))
 
+(defun charset-multibyte-form-string (charset)
+  (let ((info (charset-info charset)))
+    (cond ((eq charset 'ascii)
+           "xx")
+          ((eq charset 'eight-bit-control)
+           (format "%2X Xx" (aref info 6)))
+          ((eq charset 'eight-bit-graphic)
+           "XX")
+          (t
+           (let ((str (format "%2X" (aref info 6))))
+             (if (> (aref info 7) 0)
+                 (setq str (format "%s %2X"
+                                   str (aref info 7))))
+             (setq str (concat str " XX"))
+             (if (> (aref info 2) 1)
+                 (setq str (concat str " XX")))
+             str)))))
+
 ;; Insert a list of character sets sorted by SORT-KEY.  SORT-KEY
 ;; should be one of `id', `name', and `iso-spec'.  If SORT-KEY is nil,
 ;; it defaults to `id'.
@@ -141,21 +159,7 @@ but still shows the full information."
       (setq charset-info-list
             (cons (list (charset-id charset)    ; ID-NUM
                         charset                 ; CHARSET-NAME
-                        (cond ((eq charset 'ascii) ; MULTIBYTE-FORM
-                               "xx")
-                              ((eq charset 'eight-bit-control)
-                               (format "%2X Xx" (aref info 6)))
-                              ((eq charset 'eight-bit-graphic)
-                               "XX")
-                              (t
-                               (let ((str (format "%2X" (aref info 6))))
-                                 (if (> (aref info 7) 0)
-                                     (setq str (format "%s %2X"
-                                                       str (aref info 7))))
-                                 (setq str (concat str " XX"))
-                                 (if (> (aref info 2) 1)
-                                     (setq str (concat str " XX")))
-                                 str)))
+                        (charset-multibyte-form-string charset); MULTIBYTE-FORM
                         (aref info 2)           ; DIMENSION
                         (aref info 3)           ; CHARS
                         (aref info 8)           ; FINAL-CHAR
@@ -470,6 +474,42 @@ detailed meanings of these arguments."
 
 
 ;;;###autoload
+(defun describe-character-set (charset)
+  "Display information about character set CHARSET."
+  (interactive (list (let ((non-iso-charset-alist nil))
+                       (read-charset "Charset: "))))
+  (or (charsetp charset)
+      (error "Invalid charset: %S" charset))
+  (let ((info (charset-info charset)))
+    (with-output-to-temp-buffer "*Help*"
+      (save-excursion
+        (set-buffer standard-output)
+        (insert "Character set: " (symbol-name charset)
+                (format " (ID:%d)\n\n" (aref info 0)))
+        (insert (aref info 13) "\n\n")  ; description
+        (insert "number of contained characters: "
+                (if (= (aref info 2) 1)
+                    (format "%d\n" (aref info 3))
+                  (format "%dx%d\n" (aref info 3) (aref info 3))))
+        (insert "the final char of ISO2022's desgination sequence: ")
+        (if (aref info 8)
+            (insert (format "`%c'\n" (aref info 8)))
+          (insert "not assigned\n"))
+        (insert (format "width (how many columns on screen): %d\n"
+                        (aref info 4)))
+        (insert (format "internal multibyte sequence: %s\n"
+                        (charset-multibyte-form-string charset)))
+        (let ((coding (plist-get (aref info 14) 'preferred-coding-system)))
+          (when coding
+            (insert (format "prefered coding system: %s\n" coding))
+            (search-backward (symbol-name coding))
+            (help-xref-button 0 #'describe-coding-system coding
+                              "mouse-2, RET: describe this coding system")))
+        (help-setup-xref (list #'describe-character-set charset)
+                         (interactive-p))
+        ))))
+
+;;;###autoload
 (defun describe-char-after (&optional pos)
   "Display information of in current buffer at position POS.
 The information includes character code, charset and code points in it,
@@ -683,19 +723,22 @@ which font is being used for displaying the character."
           (princ "\n  ")
           (princ prewrite)
           (princ "\n")))
-      (let ((charsets (coding-system-get coding-system 'safe-charsets)))
-        (when charsets
-          (if (eq charsets t)
-              (princ "This coding system can encode all charsets.\n")
-            (princ "This coding system encode the following charsets:\n")
-            (princ " ")
-            (while charsets
-              (princ " ")
-              (princ (car charsets))
-              (setq charsets (cdr charsets))))))
       (save-excursion
         (set-buffer standard-output)
-        (help-mode)))))
+        (let ((charsets (coding-system-get coding-system 'safe-charsets)))
+          (when charsets
+            (if (eq charsets t)
+                (insert "This coding system can encode all charsets.\n")
+              (insert "This coding system encode the following charsets:\n ")
+              (while charsets
+                (insert " " (symbol-name (car charsets)))
+                (search-backward (symbol-name (car charsets)))
+                (help-xref-button 0 #'describe-character-set (car charsets))
+                (goto-char (point-max))
+                (setq charsets (cdr charsets))))))
+        (help-setup-xref (list #'describe-coding-system coding-system)
+                         (interactive-p))))))
+
 
 ;;;###autoload
 (defun describe-current-coding-system-briefly ()