emacs: help: remove duplicate bindings

If the user (or a mode) overrides a keybinding from the common keymap
in one of the modes then both help lines appear in the help screen
even though only one of them is applicable.

Fix this by checking if we already have that key binding. We do this
by constructing an list of (key . docstring) pairs so it is easy to
check if we have already had that binding. Then the actual print help
routine changes these pairs into strings "key \t docstring"

1 files changed, 24 insertions, 17 deletions

diff --git a/emacs/notmuch-lib.el b/emacs/notmuch-lib.el
index 623f4fad..0242edb7 100644
--- a/emacs/notmuch-lib.el
+++ b/emacs/notmuch-lib.el
@@ -237,11 +237,12 @@ This is basically just `format-kbd-macro' but we also convert ESC to M-."
       (concat desc " "))))
 
 (defun notmuch-describe-keymap (keymap ua-keys &optional prefix tail)
-  "Return a list of strings, each describing one binding in KEYMAP.
+  "Return a list of cons cells, each describing one binding in KEYMAP.
 
-Each string gives a human-readable description of the key and a
-one-line description of the bound function.  See `notmuch-help'
-for an overview of how this documentation is extracted.
+Each cons cell consists of a string giving a human-readable
+description of the key, and a one-line description of the bound
+function.  See `notmuch-help' for an overview of how this
+documentation is extracted.
 
 UA-KEYS should be a key sequence bound to `universal-argument'.
 It will be used to describe bindings of commands that support a
@@ -254,18 +255,23 @@ prefix argument.  PREFIX and TAIL are used internally."
 		  (notmuch-describe-keymap
 		   binding ua-keys (notmuch-prefix-key-description key) tail)))
 	   (binding
-	    (when (and ua-keys (symbolp binding)
-		       (get binding 'notmuch-prefix-doc))
-	      ;; Documentation for prefixed command
-	      (let ((ua-desc (key-description ua-keys)))
-		(push (concat ua-desc " " prefix (format-kbd-macro (vector key))
-			      "\t" (get binding 'notmuch-prefix-doc))
-		      tail)))
-	    ;; Documentation for command
-	    (push (concat prefix (format-kbd-macro (vector key)) "\t"
-			  (or (and (symbolp binding) (get binding 'notmuch-doc))
-			      (notmuch-documentation-first-line binding)))
-		  tail))))
+	    (let ((key-string (concat prefix (format-kbd-macro (vector key)))))
+	      ;; We don't include documentation if the key-binding is
+	      ;; over-ridden. Note, over-riding a binding
+	      ;; automatically hides the prefixed version too.
+	      (unless (assoc key-string tail)
+		(when (and ua-keys (symbolp binding)
+			   (get binding 'notmuch-prefix-doc))
+		  ;; Documentation for prefixed command
+		  (let ((ua-desc (key-description ua-keys)))
+		    (push (cons (concat ua-desc " " prefix (format-kbd-macro (vector key)))
+				(get binding 'notmuch-prefix-doc))
+			  tail)))
+		;; Documentation for command
+		(push (cons key-string
+			    (or (and (symbolp binding) (get binding 'notmuch-doc))
+				(notmuch-documentation-first-line binding)))
+		      tail))))))
    keymap)
   tail)
 
@@ -278,7 +284,8 @@ prefix argument.  PREFIX and TAIL are used internally."
 	       (let* ((keymap-name (substring doc (match-beginning 1) (match-end 1)))
 		      (keymap (symbol-value (intern keymap-name)))
 		      (ua-keys (where-is-internal 'universal-argument keymap t))
-		      (desc-list (notmuch-describe-keymap keymap ua-keys)))
+		      (desc-alist (notmuch-describe-keymap keymap ua-keys))
+		      (desc-list (mapcar (lambda (arg) (concat (car arg) "\t" (cdr arg))) desc-alist)))
 		 (mapconcat #'identity desc-list "\n")))))
 	(setq doc (replace-match desc 1 1 doc)))
       (setq beg (match-end 0)))