Doc fixes.

(map-charset-chars): New function.
(register-char-codings): Use it to cope with generic chars in
safe-chars.

1 files changed, 73 insertions, 13 deletions

diff --git a/lisp/international/mule.el b/lisp/international/mule.el
index 84701b4841e..9ffc9dc54e7 100644
--- a/lisp/international/mule.el
+++ b/lisp/international/mule.el
@@ -269,7 +269,11 @@ don't have corresponding generic characters.  If CHARSET is one of
 them and you don't supply CODE1, return the character of the smallest
 code in CHARSET.
 
-If CODE1 or CODE2 are invalid (out of range), this function signals an error."
+If CODE1 or CODE2 are invalid (out of range), this function signals an
+error.  However, the eighth bit of both CODE1 and CODE2 is zeroed
+before they are used to index CHARSET.  Thus you may use, say, the
+actual ISO 8859 character code rather than subtracting 128, as you
+would need to index the corresponding Emacs charset."
   (make-char-internal (charset-id charset) code1 code2))
 
 (put 'make-char 'byte-compile
@@ -536,21 +540,77 @@ formats (e.g. iso-latin-1-unix, koi8-r-dos)."
           (setq tail (cdr tail)))))
     codings))
 
+(defun map-charset-chars (func charset)
+  "Use FUNC to map over all characters in CHARSET for side effects.
+FUNC is a function of two args, the start and end (inclusive) of a
+character code range.  Thus FUNC should iterate over [START, END]."
+  (let* ((dim (charset-dimension charset))
+         (chars (charset-chars charset))
+         (start (if (= chars 94)
+                    33
+                  32)))
+    (if (= dim 1)
+        (funcall func
+                 (make-char charset start)
+                 (make-char charset (+ start chars -1)))
+      (dotimes (i chars)
+        (funcall func
+                 (make-char charset (+ i start) start)
+                 (make-char charset (+ i start) (+ start chars -1)))))))
+
 (defun register-char-codings (coding-system safe-chars)
-  (let ((general (char-table-extra-slot char-coding-system-table 0)))
+  "Add entries for CODING-SYSTEM to `char-coding-system-table'.
+If SAFE-CHARS is a char-table, its non-nil entries specify characters
+which CODING-SYSTEM encodes safely.  If SAFE-CHARS is t, register
+CODING-SYSTEM as a general one which can encode all characters."
+  (let ((general (char-table-extra-slot char-coding-system-table 0))
+        ;; Charsets which have some members in the table, but not all
+        ;; of them (i.e. not just a generic character):
+        (partials (char-table-extra-slot char-coding-system-table 1)))
     (if (eq safe-chars t)
         (or (memq coding-system general)
             (set-char-table-extra-slot char-coding-system-table 0
                                        (cons coding-system general)))
       (map-char-table
-       (function
-        (lambda (key val)
-          (if (and (>= key 128) val)
-              (let ((codings (aref char-coding-system-table key)))
-                (or (memq coding-system codings)
-                    (aset char-coding-system-table key
-                          (cons coding-system codings)))))))
-       safe-chars))))
+       (lambda (key val)
+         (if (and (>= key 128) val)
+             (let ((codings (aref char-coding-system-table key))
+                   (charset (char-charset key)))
+               (unless (memq coding-system codings)
+                 (if (and (generic-char-p key)
+                          (memq charset partials))
+                     ;; The generic char would clobber individual
+                     ;; entries already in the table.  First save the
+                     ;; separate existing entries for all chars of the
+                     ;; charset (with the generic entry added, if
+                     ;; necessary).
+                     (let (entry existing)
+                       (map-charset-chars
+                        (lambda (start end)
+                          (while (<= start end)
+                            (setq entry (aref char-coding-system-table start))
+                            (when entry
+                              (push (cons
+                                     start
+                                     (if (memq coding-system entry)
+                                         entry
+                                       (cons coding-system entry)))
+                                    existing))
+                            (setq start (1+ start))))
+                        charset)
+                       ;; Update the generic entry.
+                       (aset char-coding-system-table key
+                             (cons coding-system codings))
+                       ;; Override with the saved entries.
+                       (dolist (elt existing)
+                         (aset char-coding-system-table (car elt) (cdr elt))))
+                   (aset char-coding-system-table key
+                         (cons coding-system codings))
+                   (unless (or (memq charset partials)
+                               (generic-char-p key))
+                     (push charset partials)))))))
+       safe-chars)
+      (set-char-table-extra-slot char-coding-system-table 1 partials))))
 
 
 (defun make-subsidiary-coding-system (coding-system)
@@ -770,7 +830,7 @@ following properties are recognized:
   The value is a list to indicate valid byte ranges of the encoded
   file.  Each element of the list is an integer or a cons of integer.
   In the former case, the integer value is a valid byte code.  In the
-  latter case, the integers specifies the range of valid byte codes.
+  latter case, the integers specify the range of valid byte codes.
 
 These properties are set in PLIST, a property list.  This function
 also sets properties `coding-category' and `alias-coding-systems'
@@ -1330,8 +1390,8 @@ function by default."
           (if (and pos
                    (= (char-after head-start) ?#)
                    (= (char-after (1+ head-start)) ?!))
-             ;; If the file begins with "#!" (exec interpreter magic),
-          ;; look for coding frobs in the first two lines.  You cannot
+              ;; If the file begins with "#!" (exec interpreter magic),
+              ;; look for coding frobs in the first two lines.  You cannot
               ;; necessarily put them in the first line of such a file
               ;; without screwing up the interpreter invocation.
               (setq pos (search-forward "\n" head-end t)))