notmuch.el: Implement our own notmuch-help instead of describe-mode.

This gives somewhat friendlier output for the '?' binding than we had
previously with `describe-mode'. First, we no longer have the various
minor modes cluttering up the output. Second the display of the
binding table uses the first line of documentation for the bound
function rather than the function name.

diff --git a/notmuch.el b/notmuch.el
index b99ca02effade25fbaf8d12c45816c33e242e6cb..6e548f10f022a4f243bb0d3f3252b9b869780fff 100644 (file)
--- a/notmuch.el
+++ b/notmuch.el
@@ -81,7 +81,7 @@
     (define-key map (kbd "DEL") 'notmuch-show-rewind)
     (define-key map " " 'notmuch-show-advance-marking-read-and-archiving)
     (define-key map "|" 'notmuch-show-pipe-message)
-    (define-key map "?" 'describe-mode)
+    (define-key map "?" 'notmuch-help)
     (define-key map (kbd "TAB") 'notmuch-show-next-button)
     (define-key map (kbd "M-TAB") 'notmuch-show-previous-button)
     map)
@@ -775,6 +775,42 @@ which this thread was originally shown."
       (notmuch-show-markup-message)))
   (notmuch-show-hide-markers))
 
+(defun notmuch-documentation-first-line (symbol)
+  "Return the first line of the documentation string for SYMBOL."
+  (let ((doc (documentation symbol)))
+    (if doc
+       (with-temp-buffer
+         (insert (documentation symbol))
+         (goto-char (point-min))
+         (let ((beg (point)))
+           (end-of-line)
+           (buffer-substring beg (point))))
+      "")))
+
+(defun notmuch-substitute-one-command-key (binding)
+  "For a key binding, return a string showing a human-readable representation
+of the key as well as the first line of documentation from the bound function."
+  (concat (format-kbd-macro (vector (car binding)))
+         "\t"
+         (notmuch-documentation-first-line (cdr binding))))
+
+(defun notmuch-substitute-command-keys (doc)
+  "Like `substitute-command-keys' but with documentation, not function names."
+  (let ((beg 0))
+    (while (string-match "\\\\{\\([^}[:space:]]*\\)}" doc beg)
+      (let ((map (substring doc (match-beginning 1) (match-end 1))))
+       (setq doc (replace-match (mapconcat 'notmuch-substitute-one-command-key
+                                           (cdr (symbol-value (intern map))) "\n") 1 1 doc)))
+      (setq beg (match-end 0)))
+    doc))
+
+(defun notmuch-help ()
+  "Display help for the current notmuch mode."
+  (interactive)
+  (let ((mode major-mode))
+    (with-help-window (help-buffer)
+      (princ (notmuch-substitute-command-keys (documentation mode t))))))
+
 ;;;###autoload
 (defun notmuch-show-mode ()
   "Major mode for viewing a thread with notmuch.
@@ -909,7 +945,7 @@ thread from that buffer can be show when done with this one)."
     (define-key map "\M->" 'notmuch-search-goto-last-thread)
     (define-key map " " 'notmuch-search-scroll-up)
     (define-key map (kbd "<DEL>") 'notmuch-search-scroll-down)
-    (define-key map "?" 'describe-mode)
+    (define-key map "?" 'notmuch-help)
     map)
   "Keymap for \"notmuch search\" buffers.")
 (fset 'notmuch-search-mode-map notmuch-search-mode-map)
@@ -977,8 +1013,8 @@ keys can be used to add or remove tags from a thread. The 'a' key
 is a convenience key for archiving a thread (removing the
 \"inbox\" tag).
 
-Other useful commands are `notmuch-search-filter' for filtering
-the current search based on an additional query string,
+Other useful commands are `notmuch-search-filter' for
+filtering the current search based on an additional query string,
 `notmuch-search-filter-by-tag' for filtering to include only
 messages with a given tag, and `notmuch-search' to execute a new,
 global search.
@@ -1258,7 +1294,7 @@ current search results AND that are tagged with the given tag."
     (define-key map (kbd "RET") 'notmuch-folder-show-search)
     (define-key map "<" 'beginning-of-buffer)
     (define-key map "=" 'notmuch-folder)
-    (define-key map "?" 'describe-mode)
+    (define-key map "?" 'notmuch-help)
     (define-key map [mouse-1] 'notmuch-folder-show-search)
     map)
   "Keymap for \"notmuch folder\" buffers.")