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21.16 Scanning Keymaps

This section describes functions used to scan all the current keymaps for the sake of printing help information.

— Function: accessible-keymaps keymap &optional prefix

This function returns a list of all the keymaps that can be reached (via zero or more prefix keys) from keymap. The value is an association list with elements of the form (key . map), where key is a prefix key whose definition in keymap is map.

The elements of the alist are ordered so that the key increases in length. The first element is always ([] . keymap), because the specified keymap is accessible from itself with a prefix of no events.

If prefix is given, it should be a prefix key sequence; then accessible-keymaps includes only the submaps whose prefixes start with prefix. These elements look just as they do in the value of (accessible-keymaps); the only difference is that some elements are omitted.

In the example below, the returned alist indicates that the key <ESC>, which is displayed as ‘^[’, is a prefix key whose definition is the sparse keymap (keymap (83 . center-paragraph) (115 . foo)).

          (accessible-keymaps (current-local-map))
          ⇒(([] keymap
                (27 keymap   ; Note this keymap for <ESC> is repeated below.
                    (83 . center-paragraph)
                    (115 . center-line))
                (9 . tab-to-tab-stop))
             ("^[" keymap
              (83 . center-paragraph)
              (115 . foo)))

In the following example, C-h is a prefix key that uses a sparse keymap starting with (keymap (118 . describe-variable)...). Another prefix, C-x 4, uses a keymap which is also the value of the variable ctl-x-4-map. The event mode-line is one of several dummy events used as prefixes for mouse actions in special parts of a window.

          (accessible-keymaps (current-global-map))
          ⇒ (([] keymap [set-mark-command beginning-of-line ...
              ("^H" keymap (118 . describe-variable) ...
               (8 . help-for-help))
              ("^X" keymap [x-flush-mouse-queue ...
              ("^[" keymap [mark-sexp backward-sexp ...
              ("^X4" keymap (15 . display-buffer) ...)
              ([mode-line] keymap
               (S-mouse-2 . mouse-split-window-horizontally) ...))

These are not all the keymaps you would see in actuality.

— Function: map-keymap function keymap

The function map-keymap calls function once for each binding in keymap. It passes two arguments, the event type and the value of the binding. If keymap has a parent, the parent's bindings are included as well. This works recursively: if the parent has itself a parent, then the grandparent's bindings are also included and so on.

This function is the cleanest way to examine all the bindings in a keymap.

— Function: where-is-internal command &optional keymap firstonly noindirect no-remap

This function is a subroutine used by the where-is command (see Help). It returns a list of all key sequences (of any length) that are bound to command in a set of keymaps.

The argument command can be any object; it is compared with all keymap entries using eq.

If keymap is nil, then the maps used are the current active keymaps, disregarding overriding-local-map (that is, pretending its value is nil). If keymap is a keymap, then the maps searched are keymap and the global keymap. If keymap is a list of keymaps, only those keymaps are searched.

Usually it's best to use overriding-local-map as the expression for keymap. Then where-is-internal searches precisely the keymaps that are active. To search only the global map, pass the value (keymap) (an empty keymap) as keymap.

If firstonly is non-ascii, then the value is a single vector representing the first key sequence found, rather than a list of all possible key sequences. If firstonly is t, then the value is the first key sequence, except that key sequences consisting entirely of ASCII characters (or meta variants of ASCII characters) are preferred to all other key sequences and that the return value can never be a menu binding.

If noindirect is non-nil, where-is-internal doesn't look inside menu-items to find their commands. This makes it possible to search for a menu-item itself.

The fifth argument, no-remap, determines how this function treats command remappings (see Remapping Commands). There are two cases of interest:

If a command other-command is remapped to command:
If no-remap is nil, find the bindings for other-command and treat them as though they are also bindings for command. If no-remap is non-nil, include the vector [remap other-command] in the list of possible key sequences, instead of finding those bindings.
If command is remapped to other-command:
If no-remap is nil, return the bindings for other-command rather than command. If no-remap is non-nil, return the bindings for command, ignoring the fact that it is remapped.

— Command: describe-bindings &optional prefix buffer-or-name

This function creates a listing of all current key bindings, and displays it in a buffer named *Help*. The text is grouped by modes—minor modes first, then the major mode, then global bindings.

If prefix is non-nil, it should be a prefix key; then the listing includes only keys that start with prefix.

When several characters with consecutive ASCII codes have the same definition, they are shown together, as ‘firstchar..lastchar’. In this instance, you need to know the ASCII codes to understand which characters this means. For example, in the default global map, the characters ‘<SPC> .. ~’ are described by a single line. <SPC> is ASCII 32, ~ is ASCII 126, and the characters between them include all the normal printing characters, (e.g., letters, digits, punctuation, etc.); all these characters are bound to self-insert-command.

If buffer-or-name is non-nil, it should be a buffer or a buffer name. Then describe-bindings lists that buffer's bindings, instead of the current buffer's.