+(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 t))
+ (goto-char (point-min))
+ (let ((beg (point)))
+ (end-of-line)
+ (buffer-substring beg (point))))
+ "")))
+
+(defun notmuch-prefix-key-description (key)
+ "Given a prefix key code, return a human-readable string representation.
+
+This is basically just `format-kbd-macro' but we also convert ESC to M-."
+ (let ((desc (format-kbd-macro (vector key))))
+ (if (string= desc "ESC")
+ "M-"
+ (concat desc " "))))
+
+; I would think that emacs would have code handy for walking a keymap
+; and generating strings for each key, and I would prefer to just call
+; that. But I couldn't find any (could be all implemented in C I
+; suppose), so I wrote my own here.
+(defun notmuch-substitute-one-command-key-with-prefix (prefix binding)
+ "For a key binding, return a string showing a human-readable
+representation of the prefixed key as well as the first line of
+documentation from the bound function.
+
+For a mouse binding, return nil."
+ (let ((key (car binding))
+ (action (cdr binding)))
+ (if (mouse-event-p key)
+ nil
+ (if (keymapp action)
+ (let ((substitute (apply-partially 'notmuch-substitute-one-command-key-with-prefix (notmuch-prefix-key-description key)))
+ (as-list))
+ (map-keymap (lambda (a b)
+ (push (cons a b) as-list))
+ action)
+ (mapconcat substitute as-list "\n"))
+ (concat prefix (format-kbd-macro (vector key))
+ "\t"
+ (notmuch-documentation-first-line action))))))
+
+(defalias 'notmuch-substitute-one-command-key
+ (apply-partially 'notmuch-substitute-one-command-key-with-prefix nil))
+
+(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)
+ (doc (substitute-command-keys (notmuch-substitute-command-keys (documentation mode t)))))
+ (with-current-buffer (generate-new-buffer "*notmuch-help*")
+ (insert doc)
+ (goto-char (point-min))
+ (set-buffer-modified-p nil)
+ (view-buffer (current-buffer) 'kill-buffer-if-not-modified))))
+