(describe-categories): Display the terse legend at the head.

1 files changed, 40 insertions, 12 deletions

diff --git a/lisp/help-fns.el b/lisp/help-fns.el
index 612b90ff62b..d08c184e1f5 100644
--- a/lisp/help-fns.el
+++ b/lisp/help-fns.el
@@ -780,20 +780,48 @@ BUFFER should be a buffer or a buffer name."
   (setq buffer (or buffer (current-buffer)))
   (help-setup-xref (list #'describe-categories buffer) (interactive-p))
   (with-help-window (help-buffer)
-    (let ((table (with-current-buffer buffer (category-table))))
+    (let* ((table (with-current-buffer buffer (category-table)))
+           (docs (char-table-extra-slot table 0)))
+      (if (or (not (vectorp docs)) (/= (length docs) 95))
+          (error "Invalid first extra slot in this category table\n"))
       (with-current-buffer standard-output
+        (insert "Legend of category mnemonics (see the tail for the longer description)\n")
+        (let ((pos (point)) (items 0) lines n)
+          (dotimes (i 95)
+            (if (aref docs i) (setq items (1+ items))))
+          (setq lines (1+ (/ (1- items) 4)))
+          (setq n 0)
+          (dotimes (i 95)
+            (let ((elt (aref docs i)))
+              (when elt
+                (string-match ".*" elt)
+                (setq elt (match-string 0 elt))
+                (if (>= (length elt) 17)
+                    (setq elt (concat (substring elt 0 14) "...")))
+                (if (< (point) (point-max))
+                    (move-to-column (* 20 (/ n lines)) t))
+                (insert (+ i ?\s) ?: elt)
+                (if (< (point) (point-max))
+                    (forward-line 1)
+                  (insert "\n"))
+                (setq n (1+ n))
+                (if (= (% n lines) 0)
+                    (goto-char pos))))))
+        (goto-char (point-max))
+        (insert "\n"
+                "character(s)\tcategory mnemonics\n"
+                "------------\t------------------")
         (describe-vector table 'help-describe-category-set)
-        (let ((docs (char-table-extra-slot table 0)))
-          (if (or (not (vectorp docs)) (/= (length docs) 95))
-              (insert "Invalid first extra slot in this char table\n")
-            (insert "Meanings of mnemonic characters are:\n")
-            (dotimes (i 95)
-              (let ((elt (aref docs i)))
-                (when elt
-                  (insert (+ i ?\s) ": " elt "\n"))))
-            (while (setq table (char-table-parent table))
-              (insert "\nThe parent category table is:")
-              (describe-vector table 'help-describe-category-set))))))))
+        (insert "Legend of category mnemonics:\n")
+        (dotimes (i 95)
+          (let ((elt (aref docs i)))
+            (when elt
+              (if (string-match "\n" elt)
+                  (setq elt (substring elt (match-end 0))))
+              (insert (+ i ?\s) ": " elt "\n"))))
+        (while (setq table (char-table-parent table))
+          (insert "\nThe parent category table is:")
+          (describe-vector table 'help-describe-category-set))))))
 
 (provide 'help-fns)