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@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1998, 1999, 2000, 2001,
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@c   2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
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@c   Free Software Foundation, Inc.
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@c See the file elisp.texi for copying conditions.
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@setfilename ../../info/keymaps
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@node Keymaps, Modes, Command Loop, Top
@chapter Keymaps
@cindex keymap

  The command bindings of input events are recorded in data structures
called @dfn{keymaps}.  Each entry in a keymap associates (or
@dfn{binds}) an individual event type, either to another keymap or to
a command.  When an event type is bound to a keymap, that keymap is
used to look up the next input event; this continues until a command
is found.  The whole process is called @dfn{key lookup}.

@menu
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* Key Sequences::               Key sequences as Lisp objects.
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* Keymap Basics::               Basic concepts of keymaps.
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* Format of Keymaps::           What a keymap looks like as a Lisp object.
* Creating Keymaps::            Functions to create and copy keymaps.
* Inheritance and Keymaps::     How one keymap can inherit the bindings
                                   of another keymap.
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* Prefix Keys::                 Defining a key with a keymap as its definition.
* Active Keymaps::              How Emacs searches the active keymaps
                                   for a key binding.
* Searching Keymaps::           A pseudo-Lisp summary of searching active maps.
* Controlling Active Maps::     Each buffer has a local keymap
                                   to override the standard (global) bindings.
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                                   A minor mode can also override them.
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* Key Lookup::                  Finding a key's binding in one keymap.
* Functions for Key Lookup::    How to request key lookup.
* Changing Key Bindings::       Redefining a key in a keymap.
* Remapping Commands::          A keymap can translate one command to another.
* Translation Keymaps::         Keymaps for translating sequences of events.
* Key Binding Commands::        Interactive interfaces for redefining keys.
* Scanning Keymaps::            Looking through all keymaps, for printing help.
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* Menu Keymaps::                Defining a menu as a keymap.
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@end menu

@node Key Sequences
@section Key Sequences
@cindex key
@cindex keystroke
@cindex key sequence

  A @dfn{key sequence}, or @dfn{key} for short, is a sequence of one
or more input events that form a unit.  Input events include
characters, function keys, and mouse actions (@pxref{Input Events}).
The Emacs Lisp representation for a key sequence is a string or
vector.  Unless otherwise stated, any Emacs Lisp function that accepts
a key sequence as an argument can handle both representations.

  In the string representation, alphanumeric characters ordinarily
stand for themselves; for example, @code{"a"} represents @kbd{a}
and @code{"2"} represents @kbd{2}.  Control character events are
prefixed by the substring @code{"\C-"}, and meta characters by
@code{"\M-"}; for example, @code{"\C-x"} represents the key @kbd{C-x}.
In addition, the @key{TAB}, @key{RET}, @key{ESC}, and @key{DEL} events
are represented by @code{"\t"}, @code{"\r"}, @code{"\e"}, and
@code{"\d"} respectively.  The string representation of a complete key
sequence is the concatenation of the string representations of the
constituent events; thus, @code{"\C-xl"} represents the key sequence
@kbd{C-x l}.

  Key sequences containing function keys, mouse button events, or
non-ASCII characters such as @kbd{C-=} or @kbd{H-a} cannot be
represented as strings; they have to be represented as vectors.

  In the vector representation, each element of the vector represents
an input event, in its Lisp form.  @xref{Input Events}.  For example,
the vector @code{[?\C-x ?l]} represents the key sequence @kbd{C-x l}.

  For examples of key sequences written in string and vector
representations, @ref{Init Rebinding,,, emacs, The GNU Emacs Manual}.

@defmac kbd keyseq-text
This macro converts the text @var{keyseq-text} (a string constant)
into a key sequence (a string or vector constant).  The contents of
@var{keyseq-text} should describe the key sequence using almost the same
syntax used in this manual.  More precisely, it uses the same syntax
that Edit Macro mode uses for editing keyboard macros (@pxref{Edit
Keyboard Macro,,, emacs, The GNU Emacs Manual}); you must surround
function key names with @samp{<@dots{}>}.

@example
(kbd "C-x") @result{} "\C-x"
(kbd "C-x C-f") @result{} "\C-x\C-f"
(kbd "C-x 4 C-f") @result{} "\C-x4\C-f"
(kbd "X") @result{} "X"
(kbd "RET") @result{} "\^M"
(kbd "C-c SPC") @result{} "\C-c@ "
(kbd "<f1> SPC") @result{} [f1 32]
(kbd "C-M-<down>") @result{} [C-M-down]
@end example

This macro is not meant for use with arguments that vary---only
with string constants.
@end defmac

@node Keymap Basics
@section Keymap Basics
@cindex key binding
@cindex binding of a key
@cindex complete key
@cindex undefined key

  A keymap is a Lisp data structure that specifies @dfn{key bindings}
for various key sequences.

  A single keymap directly specifies definitions for individual
events.  When a key sequence consists of a single event, its binding
in a keymap is the keymap's definition for that event.  The binding of
a longer key sequence is found by an iterative process: first find the
definition of the first event (which must itself be a keymap); then
find the second event's definition in that keymap, and so on until all
the events in the key sequence have been processed.

  If the binding of a key sequence is a keymap, we call the key sequence
a @dfn{prefix key}.  Otherwise, we call it a @dfn{complete key} (because
no more events can be added to it).  If the binding is @code{nil},
we call the key @dfn{undefined}.  Examples of prefix keys are @kbd{C-c},
@kbd{C-x}, and @kbd{C-x 4}.  Examples of defined complete keys are
@kbd{X}, @key{RET}, and @kbd{C-x 4 C-f}.  Examples of undefined complete
keys are @kbd{C-x C-g}, and @kbd{C-c 3}.  @xref{Prefix Keys}, for more
details.

  The rule for finding the binding of a key sequence assumes that the
intermediate bindings (found for the events before the last) are all
keymaps; if this is not so, the sequence of events does not form a
unit---it is not really one key sequence.  In other words, removing one
or more events from the end of any valid key sequence must always yield
a prefix key.  For example, @kbd{C-f C-n} is not a key sequence;
@kbd{C-f} is not a prefix key, so a longer sequence starting with
@kbd{C-f} cannot be a key sequence.

  The set of possible multi-event key sequences depends on the bindings
for prefix keys; therefore, it can be different for different keymaps,
and can change when bindings are changed.  However, a one-event sequence
is always a key sequence, because it does not depend on any prefix keys
for its well-formedness.

  At any time, several primary keymaps are @dfn{active}---that is, in
use for finding key bindings.  These are the @dfn{global map}, which is
shared by all buffers; the @dfn{local keymap}, which is usually
associated with a specific major mode; and zero or more @dfn{minor mode
keymaps}, which belong to currently enabled minor modes.  (Not all minor
modes have keymaps.)  The local keymap bindings shadow (i.e., take
precedence over) the corresponding global bindings.  The minor mode
keymaps shadow both local and global keymaps.  @xref{Active Keymaps},
for details.

@node Format of Keymaps
@section Format of Keymaps
@cindex format of keymaps
@cindex keymap format
@cindex full keymap
@cindex sparse keymap

  Each keymap is a list whose @sc{car} is the symbol @code{keymap}.  The
remaining elements of the list define the key bindings of the keymap.
A symbol whose function definition is a keymap is also a keymap.  Use
the function @code{keymapp} (see below) to test whether an object is a
keymap.

  Several kinds of elements may appear in a keymap, after the symbol
@code{keymap} that begins it:

@table @code
@item (@var{type} .@: @var{binding})
This specifies one binding, for events of type @var{type}.  Each
ordinary binding applies to events of a particular @dfn{event type},
which is always a character or a symbol.  @xref{Classifying Events}.
In this kind of binding, @var{binding} is a command.

@item (@var{type} @var{item-name} @r{[}@var{cache}@r{]} .@: @var{binding})
This specifies a binding which is also a simple menu item that
displays as @var{item-name} in the menu.  @var{cache}, if present,
caches certain information for display in the menu.  @xref{Simple Menu
Items}.

@item (@var{type} @var{item-name} @var{help-string} @r{[}@var{cache}@r{]} .@: @var{binding})
This is a simple menu item with help string @var{help-string}.

@item (@var{type} menu-item .@: @var{details})
This specifies a binding which is also an extended menu item.  This
allows use of other features.  @xref{Extended Menu Items}.

@item (t .@: @var{binding})
@cindex default key binding
This specifies a @dfn{default key binding}; any event not bound by other
elements of the keymap is given @var{binding} as its binding.  Default
bindings allow a keymap to bind all possible event types without having
to enumerate all of them.  A keymap that has a default binding
completely masks any lower-precedence keymap, except for events
explicitly bound to @code{nil} (see below).

@item @var{char-table}
If an element of a keymap is a char-table, it counts as holding
bindings for all character events with no modifier bits
(@pxref{modifier bits}): element @var{n} is the binding for the
character with code @var{n}.  This is a compact way to record lots of
bindings.  A keymap with such a char-table is called a @dfn{full
keymap}.  Other keymaps are called @dfn{sparse keymaps}.

@item @var{string}
@cindex keymap prompt string
@cindex overall prompt string
@cindex prompt string of keymap
Aside from elements that specify bindings for keys, a keymap can also
have a string as an element.  This is called the @dfn{overall prompt
string} and makes it possible to use the keymap as a menu.
@xref{Defining Menus}.
@end table

When the binding is @code{nil}, it doesn't constitute a definition
but it does take precedence over a default binding or a binding in the
parent keymap.  On the other hand, a binding of @code{nil} does
@emph{not} override lower-precedence keymaps; thus, if the local map
gives a binding of @code{nil}, Emacs uses the binding from the
global map.

@cindex meta characters lookup
  Keymaps do not directly record bindings for the meta characters.
Instead, meta characters are regarded for purposes of key lookup as
sequences of two characters, the first of which is @key{ESC} (or
whatever is currently the value of @code{meta-prefix-char}).  Thus, the
key @kbd{M-a} is internally represented as @kbd{@key{ESC} a}, and its
global binding is found at the slot for @kbd{a} in @code{esc-map}
(@pxref{Prefix Keys}).

  This conversion applies only to characters, not to function keys or
other input events; thus, @kbd{M-@key{end}} has nothing to do with
@kbd{@key{ESC} @key{end}}.

  Here as an example is the local keymap for Lisp mode, a sparse
keymap.  It defines bindings for @key{DEL} and @key{TAB}, plus @kbd{C-c
C-l}, @kbd{M-C-q}, and @kbd{M-C-x}.

@example
@group
lisp-mode-map
@result{}
@end group
@group
(keymap
 (3 keymap
    ;; @kbd{C-c C-z}
    (26 . run-lisp))
@end group
@group
 (27 keymap
     ;; @r{@kbd{M-C-x}, treated as @kbd{@key{ESC} C-x}}
     (24 . lisp-send-defun)
     keymap
     ;; @r{@kbd{M-C-q}, treated as @kbd{@key{ESC} C-q}}
     (17 . indent-sexp))
@end group
@group
 ;; @r{This part is inherited from @code{lisp-mode-shared-map}.}
 keymap
 ;; @key{DEL}
 (127 . backward-delete-char-untabify)
@end group
@group
 (27 keymap
     ;; @r{@kbd{M-C-q}, treated as @kbd{@key{ESC} C-q}}
     (17 . indent-sexp))
 (9 . lisp-indent-line))
@end group
@end example

@defun keymapp object
This function returns @code{t} if @var{object} is a keymap, @code{nil}
otherwise.  More precisely, this function tests for a list whose
@sc{car} is @code{keymap}, or for a symbol whose function definition
satisfies @code{keymapp}.

@example
@group
(keymapp '(keymap))
    @result{} t
@end group
@group
(fset 'foo '(keymap))
(keymapp 'foo)
    @result{} t
@end group
@group
(keymapp (current-global-map))
    @result{} t
@end group
@end example
@end defun

@node Creating Keymaps
@section Creating Keymaps
@cindex creating keymaps

  Here we describe the functions for creating keymaps.

@defun make-sparse-keymap &optional prompt
This function creates and returns a new sparse keymap with no entries.
(A sparse keymap is the kind of keymap you usually want.)  The new
keymap does not contain a char-table, unlike @code{make-keymap}, and
does not bind any events.

@example
@group
(make-sparse-keymap)
    @result{} (keymap)
@end group
@end example

If you specify @var{prompt}, that becomes the overall prompt string
for the keymap.  You should specify this only for menu keymaps
(@pxref{Defining Menus}).  A keymap with an overall prompt string will
always present a mouse menu or a keyboard menu if it is active for
looking up the next input event.  Don't specify an overall prompt string
for the main map of a major or minor mode, because that would cause
the command loop to present a keyboard menu every time.
@end defun

@defun make-keymap &optional prompt
This function creates and returns a new full keymap.  That keymap
contains a char-table (@pxref{Char-Tables}) with slots for all
characters without modifiers.  The new keymap initially binds all
these characters to @code{nil}, and does not bind any other kind of
event.  The argument @var{prompt} specifies a
prompt string, as in @code{make-sparse-keymap}.

@example
@group
(make-keymap)
    @result{} (keymap #^[t nil nil nil @dots{} nil nil keymap])
@end group
@end example

A full keymap is more efficient than a sparse keymap when it holds
lots of bindings; for just a few, the sparse keymap is better.
@end defun

@defun copy-keymap keymap
This function returns a copy of @var{keymap}.  Any keymaps that
appear directly as bindings in @var{keymap} are also copied recursively,
and so on to any number of levels.  However, recursive copying does not
take place when the definition of a character is a symbol whose function
definition is a keymap; the same symbol appears in the new copy.
@c Emacs 19 feature

@example
@group
(setq map (copy-keymap (current-local-map)))
@result{} (keymap
@end group
@group
     ;; @r{(This implements meta characters.)}
     (27 keymap
         (83 . center-paragraph)
         (115 . center-line))
     (9 . tab-to-tab-stop))
@end group

@group
(eq map (current-local-map))
    @result{} nil
@end group
@group
(equal map (current-local-map))
    @result{} t
@end group
@end example
@end defun

@node Inheritance and Keymaps
@section Inheritance and Keymaps
@cindex keymap inheritance
@cindex inheriting a keymap's bindings

  A keymap can inherit the bindings of another keymap, which we call the
@dfn{parent keymap}.  Such a keymap looks like this:

@example
(keymap @var{elements}@dots{} . @var{parent-keymap})
@end example

@noindent
The effect is that this keymap inherits all the bindings of
@var{parent-keymap}, whatever they may be at the time a key is looked up,
but can add to them or override them with @var{elements}.

If you change the bindings in @var{parent-keymap} using
@code{define-key} or other key-binding functions, these changed
bindings are visible in the inheriting keymap, unless shadowed by the
bindings made by @var{elements}.  The converse is not true: if you use
@code{define-key} to change bindings in the inheriting keymap, these
changes are recorded in @var{elements}, but have no effect on
@var{parent-keymap}.

The proper way to construct a keymap with a parent is to use
@code{set-keymap-parent}; if you have code that directly constructs a
keymap with a parent, please convert the program to use
@code{set-keymap-parent} instead.

@defun keymap-parent keymap
This returns the parent keymap of @var{keymap}.  If @var{keymap}
has no parent, @code{keymap-parent} returns @code{nil}.
@end defun

@defun set-keymap-parent keymap parent
This sets the parent keymap of @var{keymap} to @var{parent}, and returns
@var{parent}.  If @var{parent} is @code{nil}, this function gives
@var{keymap} no parent at all.

If @var{keymap} has submaps (bindings for prefix keys), they too receive
new parent keymaps that reflect what @var{parent} specifies for those
prefix keys.
@end defun

   Here is an example showing how to make a keymap that inherits
from @code{text-mode-map}:

@example
(let ((map (make-sparse-keymap)))
  (set-keymap-parent map text-mode-map)
  map)
@end example

  A non-sparse keymap can have a parent too, but this is not very
useful.  A non-sparse keymap always specifies something as the binding
for every numeric character code without modifier bits, even if it is
@code{nil}, so these character's bindings are never inherited from
the parent keymap.

@node Prefix Keys
@section Prefix Keys
@cindex prefix key

  A @dfn{prefix key} is a key sequence whose binding is a keymap.  The
keymap defines what to do with key sequences that extend the prefix key.
For example, @kbd{C-x} is a prefix key, and it uses a keymap that is
also stored in the variable @code{ctl-x-map}.  This keymap defines
bindings for key sequences starting with @kbd{C-x}.

  Some of the standard Emacs prefix keys use keymaps that are
also found in Lisp variables:

@itemize @bullet
@item
@vindex esc-map
@findex ESC-prefix
@code{esc-map} is the global keymap for the @key{ESC} prefix key.  Thus,
the global definitions of all meta characters are actually found here.
This map is also the function definition of @code{ESC-prefix}.

@item
@cindex @kbd{C-h}
@code{help-map} is the global keymap for the @kbd{C-h} prefix key.

@item
@cindex @kbd{C-c}
@vindex mode-specific-map
@code{mode-specific-map} is the global keymap for the prefix key
@kbd{C-c}.  This map is actually global, not mode-specific, but its name
provides useful information about @kbd{C-c} in the output of @kbd{C-h b}
(@code{display-bindings}), since the main use of this prefix key is for
mode-specific bindings.

@item
@cindex @kbd{C-x}
@vindex ctl-x-map
@findex Control-X-prefix
@code{ctl-x-map} is the global keymap used for the @kbd{C-x} prefix key.
This map is found via the function cell of the symbol
@code{Control-X-prefix}.

@item
@cindex @kbd{C-x @key{RET}}
@vindex mule-keymap
@code{mule-keymap} is the global keymap used for the @kbd{C-x @key{RET}}
prefix key.

@item
@cindex @kbd{C-x 4}
@vindex ctl-x-4-map
@code{ctl-x-4-map} is the global keymap used for the @kbd{C-x 4} prefix
key.

@item
@cindex @kbd{C-x 5}
@vindex ctl-x-5-map
@code{ctl-x-5-map} is the global keymap used for the @kbd{C-x 5} prefix
key.

@item
@cindex @kbd{C-x 6}
@vindex 2C-mode-map
@code{2C-mode-map} is the global keymap used for the @kbd{C-x 6} prefix
key.

@item
@cindex @kbd{C-x v}
@vindex vc-prefix-map
@code{vc-prefix-map} is the global keymap used for the @kbd{C-x v} prefix
key.

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@item
@cindex @kbd{M-g}
@vindex goto-map
@code{goto-map} is the global keymap used for the @kbd{M-g} prefix
key.

@item
@cindex @kbd{M-s}
@vindex search-map
@code{search-map} is the global keymap used for the @kbd{M-s} prefix
key.

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@item
@cindex @kbd{M-o}
@vindex facemenu-keymap
@code{facemenu-keymap} is the global keymap used for the @kbd{M-o}
prefix key.

@item
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The other Emacs prefix keys are @kbd{C-x @@}, @kbd{C-x a i}, @kbd{C-x
@key{ESC}} and @kbd{@key{ESC} @key{ESC}}.  They use keymaps that have
no special names.
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@end itemize

  The keymap binding of a prefix key is used for looking up the event
that follows the prefix key.  (It may instead be a symbol whose function
definition is a keymap.  The effect is the same, but the symbol serves
as a name for the prefix key.)  Thus, the binding of @kbd{C-x} is the
symbol @code{Control-X-prefix}, whose function cell holds the keymap
for @kbd{C-x} commands.  (The same keymap is also the value of
@code{ctl-x-map}.)

  Prefix key definitions can appear in any active keymap.  The
definitions of @kbd{C-c}, @kbd{C-x}, @kbd{C-h} and @key{ESC} as prefix
keys appear in the global map, so these prefix keys are always
available.  Major and minor modes can redefine a key as a prefix by
putting a prefix key definition for it in the local map or the minor
mode's map.  @xref{Active Keymaps}.

  If a key is defined as a prefix in more than one active map, then its
various definitions are in effect merged: the commands defined in the
minor mode keymaps come first, followed by those in the local map's
prefix definition, and then by those from the global map.

  In the following example, we make @kbd{C-p} a prefix key in the local
keymap, in such a way that @kbd{C-p} is identical to @kbd{C-x}.  Then
the binding for @kbd{C-p C-f} is the function @code{find-file}, just
like @kbd{C-x C-f}.  The key sequence @kbd{C-p 6} is not found in any
active keymap.

@example
@group
(use-local-map (make-sparse-keymap))
    @result{} nil
@end group
@group
(local-set-key "\C-p" ctl-x-map)
    @result{} nil
@end group
@group
(key-binding "\C-p\C-f")
    @result{} find-file
@end group

@group
(key-binding "\C-p6")
    @result{} nil
@end group
@end example

@defun define-prefix-command symbol &optional mapvar prompt
@cindex prefix command
@anchor{Definition of define-prefix-command}
This function prepares @var{symbol} for use as a prefix key's binding:
it creates a sparse keymap and stores it as @var{symbol}'s function
definition.  Subsequently binding a key sequence to @var{symbol} will
make that key sequence into a prefix key.  The return value is @code{symbol}.

This function also sets @var{symbol} as a variable, with the keymap as
its value.  But if @var{mapvar} is non-@code{nil}, it sets @var{mapvar}
as a variable instead.

If @var{prompt} is non-@code{nil}, that becomes the overall prompt
string for the keymap.  The prompt string should be given for menu keymaps
(@pxref{Defining Menus}).
@end defun

@node Active Keymaps
@section Active Keymaps
@cindex active keymap
@cindex global keymap
@cindex local keymap

  Emacs normally contains many keymaps; at any given time, just a few
of them are @dfn{active}, meaning that they participate in the
interpretation of user input.  All the active keymaps are used
together to determine what command to execute when a key is entered.

  Normally the active keymaps are the @code{keymap} property keymap,
the keymaps of any enabled minor modes, the current buffer's local
keymap, and the global keymap, in that order.  Emacs searches for each
input key sequence in all these keymaps.  @xref{Searching Keymaps},
for more details of this procedure.

  When the key sequence starts with a mouse event (optionally preceded
by a symbolic prefix), the active keymaps are determined based on the
position in that event.  If the event happened on a string embedded
with a @code{display}, @code{before-string}, or @code{after-string}
property (@pxref{Special Properties}), the non-@code{nil} map
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properties of the string override those of the buffer (if the
underlying buffer text contains map properties in its text properties
or overlays, they are ignored).
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  The @dfn{global keymap} holds the bindings of keys that are defined
regardless of the current buffer, such as @kbd{C-f}.  The variable
@code{global-map} holds this keymap, which is always active.

  Each buffer may have another keymap, its @dfn{local keymap}, which
may contain new or overriding definitions for keys.  The current
buffer's local keymap is always active except when
@code{overriding-local-map} overrides it.  The @code{local-map} text
or overlay property can specify an alternative local keymap for certain
parts of the buffer; see @ref{Special Properties}.

  Each minor mode can have a keymap; if it does, the keymap is active
when the minor mode is enabled.  Modes for emulation can specify
additional active keymaps through the variable
@code{emulation-mode-map-alists}.

  The highest precedence normal keymap comes from the @code{keymap}
text or overlay property.  If that is non-@code{nil}, it is the first
keymap to be processed, in normal circumstances.

  However, there are also special ways for programs to substitute
other keymaps for some of those.  The variable
@code{overriding-local-map}, if non-@code{nil}, specifies a keymap
that replaces all the usual active keymaps except the global keymap.
Another way to do this is with @code{overriding-terminal-local-map};
it operates on a per-terminal basis.  These variables are documented
below.

@cindex major mode keymap
  Since every buffer that uses the same major mode normally uses the
same local keymap, you can think of the keymap as local to the mode.  A
change to the local keymap of a buffer (using @code{local-set-key}, for
example) is seen also in the other buffers that share that keymap.

  The local keymaps that are used for Lisp mode and some other major
modes exist even if they have not yet been used.  These local keymaps are
the values of variables such as @code{lisp-mode-map}.  For most major
modes, which are less frequently used, the local keymap is constructed
only when the mode is used for the first time in a session.

  The minibuffer has local keymaps, too; they contain various completion
and exit commands.  @xref{Intro to Minibuffers}.

  Emacs has other keymaps that are used in a different way---translating
events within @code{read-key-sequence}.  @xref{Translation Keymaps}.

  @xref{Standard Keymaps}, for a list of standard keymaps.

@defun current-active-maps &optional olp position
This returns the list of active keymaps that would be used by the
command loop in the current circumstances to look up a key sequence.
Normally it ignores @code{overriding-local-map} and
@code{overriding-terminal-local-map}, but if @var{olp} is non-@code{nil}
then it pays attention to them.  @var{position} can optionally be either
an event position as returned by @code{event-start} or a buffer
position, and may change the keymaps as described for
@code{key-binding}.
@end defun

@defun key-binding key &optional accept-defaults no-remap position
This function returns the binding for @var{key} according to the
current active keymaps.  The result is @code{nil} if @var{key} is
undefined in the keymaps.

The argument @var{accept-defaults} controls checking for default
bindings, as in @code{lookup-key} (@pxref{Functions for Key Lookup}).

When commands are remapped (@pxref{Remapping Commands}),
@code{key-binding} normally processes command remappings so as to
returns the remapped command that will actually be executed.  However,
if @var{no-remap} is non-@code{nil}, @code{key-binding} ignores
remappings and returns the binding directly specified for @var{key}.

If @var{key} starts with a mouse event (perhaps following a prefix
event), the maps to be consulted are determined based on the event's
position.  Otherwise, they are determined based on the value of point.
However, you can override either of them by specifying @var{position}.
If @var{position} is non-@code{nil}, it should be either a buffer
position or an event position like the value of @code{event-start}.
Then the maps consulted are determined based on @var{position}.

An error is signaled if @var{key} is not a string or a vector.

@example
@group
(key-binding "\C-x\C-f")
    @result{} find-file
@end group
@end example
@end defun

@node Searching Keymaps
@section Searching the Active Keymaps
@cindex searching active keymaps for keys

  After translation of event subsequences (@pxref{Translation
Keymaps}) Emacs looks for them in the active keymaps.  Here is a
pseudo-Lisp description of the order and conditions for searching
them:

@lisp
(or (if overriding-terminal-local-map
        (@var{find-in} overriding-terminal-local-map)
      (if overriding-local-map
          (@var{find-in} overriding-local-map)
        (or (@var{find-in} (get-char-property (point) 'keymap))
            (@var{find-in-any} emulation-mode-map-alists)
            (@var{find-in-any} minor-mode-overriding-map-alist)
            (@var{find-in-any} minor-mode-map-alist)
            (if (get-text-property (point) 'local-map)
                (@var{find-in} (get-char-property (point) 'local-map))
              (@var{find-in} (current-local-map))))))
    (@var{find-in} (current-global-map)))
@end lisp

@noindent
The @var{find-in} and @var{find-in-any} are pseudo functions that
search in one keymap and in an alist of keymaps, respectively.
(Searching a single keymap for a binding is called @dfn{key lookup};
see @ref{Key Lookup}.)  If the key sequence starts with a mouse event,
or a symbolic prefix event followed by a mouse event, that event's
position is used instead of point and the current buffer.  Mouse
events on an embedded string use non-@code{nil} text properties from
that string instead of the buffer.

@enumerate
@item
The function finally found may be remapped
(@pxref{Remapping Commands}).

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@item
Characters that are bound to @code{self-insert-command} are translated
according to @code{translation-table-for-input} before insertion.

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@item
@code{current-active-maps} returns a list of the
currently active keymaps at point.

@item
When a match is found (@pxref{Key Lookup}), if the binding in the
keymap is a function, the search is over.  However if the keymap entry
is a symbol with a value or a string, Emacs replaces the input key
sequences with the variable's value or the string, and restarts the
search of the active keymaps.
@end enumerate

@node Controlling Active Maps
@section Controlling the Active Keymaps

@defvar global-map
This variable contains the default global keymap that maps Emacs
keyboard input to commands.  The global keymap is normally this
keymap.  The default global keymap is a full keymap that binds
@code{self-insert-command} to all of the printing characters.

It is normal practice to change the bindings in the global keymap, but you
should not assign this variable any value other than the keymap it starts
out with.
@end defvar

@defun current-global-map
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This function returns the current global keymap.  This is the same as
the value of @code{global-map} unless you change one or the other.
The return value is a reference, not a copy; if you use
@code{define-key} or other functions on it you will alter global
bindings.
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@example
@group
(current-global-map)
@result{} (keymap [set-mark-command beginning-of-line @dots{}
            delete-backward-char])
@end group
@end example
@end defun

@defun current-local-map
This function returns the current buffer's local keymap, or @code{nil}
if it has none.  In the following example, the keymap for the
@samp{*scratch*} buffer (using Lisp Interaction mode) is a sparse keymap
in which the entry for @key{ESC}, @acronym{ASCII} code 27, is another sparse
keymap.

@example
@group
(current-local-map)
@result{} (keymap
    (10 . eval-print-last-sexp)
    (9 . lisp-indent-line)
    (127 . backward-delete-char-untabify)
@end group
@group
    (27 keymap
        (24 . eval-defun)
        (17 . indent-sexp)))
@end group
@end example
@end defun

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@code{current-local-map} returns a reference to the local keymap, not
a copy of it; if you use @code{define-key} or other functions on it 
you will alter local bindings.

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@defun current-minor-mode-maps
This function returns a list of the keymaps of currently enabled minor modes.
@end defun

@defun use-global-map keymap
This function makes @var{keymap} the new current global keymap.  It
returns @code{nil}.

It is very unusual to change the global keymap.
@end defun

@defun use-local-map keymap
This function makes @var{keymap} the new local keymap of the current
buffer.  If @var{keymap} is @code{nil}, then the buffer has no local
keymap.  @code{use-local-map} returns @code{nil}.  Most major mode
commands use this function.
@end defun

@c Emacs 19 feature
@defvar minor-mode-map-alist
@anchor{Definition of minor-mode-map-alist}
This variable is an alist describing keymaps that may or may not be
active according to the values of certain variables.  Its elements look
like this:

@example
(@var{variable} . @var{keymap})
@end example

The keymap @var{keymap} is active whenever @var{variable} has a
non-@code{nil} value.  Typically @var{variable} is the variable that
enables or disables a minor mode.  @xref{Keymaps and Minor Modes}.

Note that elements of @code{minor-mode-map-alist} do not have the same
structure as elements of @code{minor-mode-alist}.  The map must be the
@sc{cdr} of the element; a list with the map as the second element will
not do.  The @sc{cdr} can be either a keymap (a list) or a symbol whose
function definition is a keymap.

When more than one minor mode keymap is active, the earlier one in
@code{minor-mode-map-alist} takes priority.  But you should design
minor modes so that they don't interfere with each other.  If you do
this properly, the order will not matter.

See @ref{Keymaps and Minor Modes}, for more information about minor
modes.  See also @code{minor-mode-key-binding} (@pxref{Functions for Key
Lookup}).
@end defvar

@defvar minor-mode-overriding-map-alist
This variable allows major modes to override the key bindings for
particular minor modes.  The elements of this alist look like the
elements of @code{minor-mode-map-alist}: @code{(@var{variable}
. @var{keymap})}.

If a variable appears as an element of
@code{minor-mode-overriding-map-alist}, the map specified by that
element totally replaces any map specified for the same variable in
@code{minor-mode-map-alist}.

@code{minor-mode-overriding-map-alist} is automatically buffer-local in
all buffers.
@end defvar

@defvar overriding-local-map
If non-@code{nil}, this variable holds a keymap to use instead of the
buffer's local keymap, any text property or overlay keymaps, and any
minor mode keymaps.  This keymap, if specified, overrides all other
maps that would have been active, except for the current global map.
@end defvar

@defvar overriding-terminal-local-map
If non-@code{nil}, this variable holds a keymap to use instead of
@code{overriding-local-map}, the buffer's local keymap, text property
or overlay keymaps, and all the minor mode keymaps.

This variable is always local to the current terminal and cannot be
902
buffer-local.  @xref{Multiple Terminals}.  It is used to implement
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incremental search mode.
@end defvar

@defvar overriding-local-map-menu-flag
If this variable is non-@code{nil}, the value of
@code{overriding-local-map} or @code{overriding-terminal-local-map} can
affect the display of the menu bar.  The default value is @code{nil}, so
those map variables have no effect on the menu bar.

Note that these two map variables do affect the execution of key
sequences entered using the menu bar, even if they do not affect the
menu bar display.  So if a menu bar key sequence comes in, you should
clear the variables before looking up and executing that key sequence.
Modes that use the variables would typically do this anyway; normally
they respond to events that they do not handle by ``unreading'' them and
exiting.
@end defvar

@defvar special-event-map
This variable holds a keymap for special events.  If an event type has a
binding in this keymap, then it is special, and the binding for the
event is run directly by @code{read-event}.  @xref{Special Events}.
@end defvar

@defvar emulation-mode-map-alists
This variable holds a list of keymap alists to use for emulations
modes.  It is intended for modes or packages using multiple minor-mode
keymaps.  Each element is a keymap alist which has the same format and
meaning as @code{minor-mode-map-alist}, or a symbol with a variable
binding which is such an alist.  The ``active'' keymaps in each alist
are used before @code{minor-mode-map-alist} and
@code{minor-mode-overriding-map-alist}.
@end defvar

@node Key Lookup
@section Key Lookup
@cindex key lookup
@cindex keymap entry

  @dfn{Key lookup} is the process of finding the binding of a key
sequence from a given keymap.  The execution or use of the binding is
not part of key lookup.

  Key lookup uses just the event type of each event in the key sequence;
the rest of the event is ignored.  In fact, a key sequence used for key
lookup may designate a mouse event with just its types (a symbol)
instead of the entire event (a list).  @xref{Input Events}.  Such
a ``key sequence'' is insufficient for @code{command-execute} to run,
but it is sufficient for looking up or rebinding a key.

  When the key sequence consists of multiple events, key lookup
processes the events sequentially: the binding of the first event is
found, and must be a keymap; then the second event's binding is found in
that keymap, and so on until all the events in the key sequence are used
up.  (The binding thus found for the last event may or may not be a
keymap.)  Thus, the process of key lookup is defined in terms of a
simpler process for looking up a single event in a keymap.  How that is
done depends on the type of object associated with the event in that
keymap.

  Let's use the term @dfn{keymap entry} to describe the value found by
looking up an event type in a keymap.  (This doesn't include the item
string and other extra elements in a keymap element for a menu item, because
@code{lookup-key} and other key lookup functions don't include them in
the returned value.)  While any Lisp object may be stored in a keymap
as a keymap entry, not all make sense for key lookup.  Here is a table
of the meaningful types of keymap entries:

@table @asis
@item @code{nil}
@cindex @code{nil} in keymap
@code{nil} means that the events used so far in the lookup form an
undefined key.  When a keymap fails to mention an event type at all, and
has no default binding, that is equivalent to a binding of @code{nil}
for that event type.

@item @var{command}
@cindex command in keymap
The events used so far in the lookup form a complete key,
and @var{command} is its binding.  @xref{What Is a Function}.

@item @var{array}
@cindex string in keymap
The array (either a string or a vector) is a keyboard macro.  The events
used so far in the lookup form a complete key, and the array is its
binding.  See @ref{Keyboard Macros}, for more information.

@item @var{keymap}
@cindex keymap in keymap
The events used so far in the lookup form a prefix key.  The next
event of the key sequence is looked up in @var{keymap}.

@item @var{list}
@cindex list in keymap
The meaning of a list depends on what it contains:

@itemize @bullet
@item
If the @sc{car} of @var{list} is the symbol @code{keymap}, then the list
is a keymap, and is treated as a keymap (see above).

@item
@cindex @code{lambda} in keymap
If the @sc{car} of @var{list} is @code{lambda}, then the list is a
lambda expression.  This is presumed to be a function, and is treated
as such (see above).  In order to execute properly as a key binding,
this function must be a command---it must have an @code{interactive}
specification.  @xref{Defining Commands}.

@item
If the @sc{car} of @var{list} is a keymap and the @sc{cdr} is an event
type, then this is an @dfn{indirect entry}:

@example
(@var{othermap} . @var{othertype})
@end example

When key lookup encounters an indirect entry, it looks up instead the
binding of @var{othertype} in @var{othermap} and uses that.

This feature permits you to define one key as an alias for another key.
For example, an entry whose @sc{car} is the keymap called @code{esc-map}
and whose @sc{cdr} is 32 (the code for @key{SPC}) means, ``Use the global
binding of @kbd{Meta-@key{SPC}}, whatever that may be.''
@end itemize

@item @var{symbol}
@cindex symbol in keymap
The function definition of @var{symbol} is used in place of
@var{symbol}.  If that too is a symbol, then this process is repeated,
any number of times.  Ultimately this should lead to an object that is
a keymap, a command, or a keyboard macro.  A list is allowed if it is a
keymap or a command, but indirect entries are not understood when found
via symbols.

Note that keymaps and keyboard macros (strings and vectors) are not
valid functions, so a symbol with a keymap, string, or vector as its
function definition is invalid as a function.  It is, however, valid as
a key binding.  If the definition is a keyboard macro, then the symbol
is also valid as an argument to @code{command-execute}
(@pxref{Interactive Call}).

@cindex @code{undefined} in keymap
The symbol @code{undefined} is worth special mention: it means to treat
the key as undefined.  Strictly speaking, the key is defined, and its
binding is the command @code{undefined}; but that command does the same
thing that is done automatically for an undefined key: it rings the bell
(by calling @code{ding}) but does not signal an error.

@cindex preventing prefix key
@code{undefined} is used in local keymaps to override a global key
binding and make the key ``undefined'' locally.  A local binding of
@code{nil} would fail to do this because it would not override the
global binding.

@item @var{anything else}
If any other type of object is found, the events used so far in the
lookup form a complete key, and the object is its binding, but the
binding is not executable as a command.
@end table

  In short, a keymap entry may be a keymap, a command, a keyboard macro,
a symbol that leads to one of them, or an indirection or @code{nil}.
Here is an example of a sparse keymap with two characters bound to
commands and one bound to another keymap.  This map is the normal value
of @code{emacs-lisp-mode-map}.  Note that 9 is the code for @key{TAB},
127 for @key{DEL}, 27 for @key{ESC}, 17 for @kbd{C-q} and 24 for
@kbd{C-x}.

@example
@group
(keymap (9 . lisp-indent-line)
        (127 . backward-delete-char-untabify)
        (27 keymap (17 . indent-sexp) (24 . eval-defun)))
@end group
@end example

@node Functions for Key Lookup
@section Functions for Key Lookup

  Here are the functions and variables pertaining to key lookup.

@defun lookup-key keymap key &optional accept-defaults
This function returns the definition of @var{key} in @var{keymap}.  All
the other functions described in this chapter that look up keys use
@code{lookup-key}.  Here are examples:

@example
@group
(lookup-key (current-global-map) "\C-x\C-f")
    @result{} find-file
@end group
@group
(lookup-key (current-global-map) (kbd "C-x C-f"))
    @result{} find-file
@end group
@group
(lookup-key (current-global-map) "\C-x\C-f12345")
    @result{} 2
@end group
@end example

If the string or vector @var{key} is not a valid key sequence according
to the prefix keys specified in @var{keymap}, it must be ``too long''
and have extra events at the end that do not fit into a single key
sequence.  Then the value is a number, the number of events at the front
of @var{key} that compose a complete key.

@c Emacs 19 feature
If @var{accept-defaults} is non-@code{nil}, then @code{lookup-key}
considers default bindings as well as bindings for the specific events
in @var{key}.  Otherwise, @code{lookup-key} reports only bindings for
the specific sequence @var{key}, ignoring default bindings except when
you explicitly ask about them.  (To do this, supply @code{t} as an
element of @var{key}; see @ref{Format of Keymaps}.)

If @var{key} contains a meta character (not a function key), that
character is implicitly replaced by a two-character sequence: the value
of @code{meta-prefix-char}, followed by the corresponding non-meta
character.  Thus, the first example below is handled by conversion into
the second example.

@example
@group
(lookup-key (current-global-map) "\M-f")
    @result{} forward-word
@end group
@group
(lookup-key (current-global-map) "\ef")
    @result{} forward-word
@end group
@end example

Unlike @code{read-key-sequence}, this function does not modify the
specified events in ways that discard information (@pxref{Key Sequence
Input}).  In particular, it does not convert letters to lower case and
it does not change drag events to clicks.
@end defun

@deffn Command undefined
Used in keymaps to undefine keys.  It calls @code{ding}, but does
not cause an error.
@end deffn

@defun local-key-binding key &optional accept-defaults
This function returns the binding for @var{key} in the current
local keymap, or @code{nil} if it is undefined there.

@c Emacs 19 feature
The argument @var{accept-defaults} controls checking for default bindings,
as in @code{lookup-key} (above).
@end defun

@defun global-key-binding key &optional accept-defaults
This function returns the binding for command @var{key} in the
current global keymap, or @code{nil} if it is undefined there.

@c Emacs 19 feature
The argument @var{accept-defaults} controls checking for default bindings,
as in @code{lookup-key} (above).
@end defun

@c Emacs 19 feature
@defun minor-mode-key-binding key &optional accept-defaults
This function returns a list of all the active minor mode bindings of
@var{key}.  More precisely, it returns an alist of pairs
@code{(@var{modename} . @var{binding})}, where @var{modename} is the
variable that enables the minor mode, and @var{binding} is @var{key}'s
binding in that mode.  If @var{key} has no minor-mode bindings, the
value is @code{nil}.

If the first binding found is not a prefix definition (a keymap or a
symbol defined as a keymap), all subsequent bindings from other minor
modes are omitted, since they would be completely shadowed.  Similarly,
the list omits non-prefix bindings that follow prefix bindings.

The argument @var{accept-defaults} controls checking for default
bindings, as in @code{lookup-key} (above).
@end defun

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@defopt meta-prefix-char
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@cindex @key{ESC}
This variable is the meta-prefix character code.  It is used for
translating a meta character to a two-character sequence so it can be
looked up in a keymap.  For useful results, the value should be a
prefix event (@pxref{Prefix Keys}).  The default value is 27, which is
the @acronym{ASCII} code for @key{ESC}.

As long as the value of @code{meta-prefix-char} remains 27, key lookup
translates @kbd{M-b} into @kbd{@key{ESC} b}, which is normally defined
as the @code{backward-word} command.  However, if you were to set
@code{meta-prefix-char} to 24, the code for @kbd{C-x}, then Emacs will
translate @kbd{M-b} into @kbd{C-x b}, whose standard binding is the
@code{switch-to-buffer} command.  (Don't actually do this!)  Here is an
illustration of what would happen:

@smallexample
@group
meta-prefix-char                    ; @r{The default value.}
     @result{} 27
@end group
@group
(key-binding "\M-b")
     @result{} backward-word
@end group
@group
?\C-x                               ; @r{The print representation}
     @result{} 24                          ;   @r{of a character.}
@end group
@group
(setq meta-prefix-char 24)
     @result{} 24
@end group
@group
(key-binding "\M-b")
     @result{} switch-to-buffer            ; @r{Now, typing @kbd{M-b} is}
                                    ;   @r{like typing @kbd{C-x b}.}

(setq meta-prefix-char 27)          ; @r{Avoid confusion!}
     @result{} 27                          ; @r{Restore the default value!}
@end group
@end smallexample

This translation of one event into two happens only for characters, not
for other kinds of input events.  Thus, @kbd{M-@key{F1}}, a function
key, is not converted into @kbd{@key{ESC} @key{F1}}.
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@end defopt
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@node Changing Key Bindings
@section Changing Key Bindings
@cindex changing key bindings
@cindex rebinding

  The way to rebind a key is to change its entry in a keymap.  If you
change a binding in the global keymap, the change is effective in all
buffers (though it has no direct effect in buffers that shadow the
global binding with a local one).  If you change the current buffer's
local map, that usually affects all buffers using the same major mode.
The @code{global-set-key} and @code{local-set-key} functions are
convenient interfaces for these operations (@pxref{Key Binding
Commands}).  You can also use @code{define-key}, a more general
function; then you must specify explicitly the map to change.

  When choosing the key sequences for Lisp programs to rebind, please
follow the Emacs conventions for use of various keys (@pxref{Key
Binding Conventions}).

@cindex meta character key constants
@cindex control character key constants
  In writing the key sequence to rebind, it is good to use the special
escape sequences for control and meta characters (@pxref{String Type}).
The syntax @samp{\C-} means that the following character is a control
character and @samp{\M-} means that the following character is a meta
character.  Thus, the string @code{"\M-x"} is read as containing a
single @kbd{M-x}, @code{"\C-f"} is read as containing a single
@kbd{C-f}, and @code{"\M-\C-x"} and @code{"\C-\M-x"} are both read as
containing a single @kbd{C-M-x}.  You can also use this escape syntax in
vectors, as well as others that aren't allowed in strings; one example
is @samp{[?\C-\H-x home]}.  @xref{Character Type}.

  The key definition and lookup functions accept an alternate syntax for
event types in a key sequence that is a vector: you can use a list
containing modifier names plus one base event (a character or function
key name).  For example, @code{(control ?a)} is equivalent to
@code{?\C-a} and @code{(hyper control left)} is equivalent to
@code{C-H-left}.  One advantage of such lists is that the precise
numeric codes for the modifier bits don't appear in compiled files.

  The functions below signal an error if @var{keymap} is not a keymap,
or if @var{key} is not a string or vector representing a key sequence.
You can use event types (symbols) as shorthand for events that are
lists.  The @code{kbd} macro (@pxref{Key Sequences}) is a convenient
way to specify the key sequence.

@defun define-key keymap key binding
This function sets the binding for @var{key} in @var{keymap}.  (If
@var{key} is more than one event long, the change is actually made
in another keymap reached from @var{keymap}.)  The argument
@var{binding} can be any Lisp object, but only certain types are
meaningful.  (For a list of meaningful types, see @ref{Key Lookup}.)
The value returned by @code{define-key} is @var{binding}.

If @var{key} is @code{[t]}, this sets the default binding in
@var{keymap}.  When an event has no binding of its own, the Emacs
command loop uses the keymap's default binding, if there is one.

@cindex invalid prefix key error
@cindex key sequence error
Every prefix of @var{key} must be a prefix key (i.e., bound to a keymap)
or undefined; otherwise an error is signaled.  If some prefix of
@var{key} is undefined, then @code{define-key} defines it as a prefix
key so that the rest of @var{key} can be defined as specified.

If there was previously no binding for @var{key} in @var{keymap}, the
new binding is added at the beginning of @var{keymap}.  The order of
bindings in a keymap makes no difference for keyboard input, but it
does matter for menu keymaps (@pxref{Menu Keymaps}).
@end defun

  This example creates a sparse keymap and makes a number of
bindings in it:

@smallexample
@group
(setq map (make-sparse-keymap))
    @result{} (keymap)
@end group
@group
(define-key map "\C-f" 'forward-char)
    @result{} forward-char
@end group
@group
map
    @result{} (keymap (6 . forward-char))
@end group

@group
;; @r{Build sparse submap for @kbd{C-x} and bind @kbd{f} in that.}
(define-key map (kbd "C-x f") 'forward-word)
    @result{} forward-word
@end group
@group
map
@result{} (keymap
    (24 keymap                ; @kbd{C-x}
        (102 . forward-word)) ;      @kbd{f}
    (6 . forward-char))       ; @kbd{C-f}
@end group

@group
;; @r{Bind @kbd{C-p} to the @code{ctl-x-map}.}
(define-key map (kbd "C-p") ctl-x-map)
;; @code{ctl-x-map}
@result{} [nil @dots{} find-file @dots{} backward-kill-sentence]
@end group

@group
;; @r{Bind @kbd{C-f} to @code{foo} in the @code{ctl-x-map}.}
(define-key map (kbd "C-p C-f") 'foo)
@result{} 'foo
@end group
@group
map
@result{} (keymap     ; @r{Note @code{foo} in @code{ctl-x-map}.}
    (16 keymap [nil @dots{} foo @dots{} backward-kill-sentence])
    (24 keymap
        (102 . forward-word))
    (6 . forward-char))
@end group
@end smallexample

@noindent
Note that storing a new binding for @kbd{C-p C-f} actually works by
changing an entry in @code{ctl-x-map}, and this has the effect of
changing the bindings of both @kbd{C-p C-f} and @kbd{C-x C-f} in the
default global map.

  The function @code{substitute-key-definition} scans a keymap for
keys that have a certain binding and rebinds them with a different
binding.  Another feature which is cleaner and can often produce the
same results to remap one command into another (@pxref{Remapping
Commands}).

@defun substitute-key-definition olddef newdef keymap &optional oldmap
@cindex replace bindings
This function replaces @var{olddef} with @var{newdef} for any keys in
@var{keymap} that were bound to @var{olddef}.  In other words,
@var{olddef} is replaced with @var{newdef} wherever it appears.  The
function returns @code{nil}.

For example, this redefines @kbd{C-x C-f}, if you do it in an Emacs with
standard bindings:

@smallexample
@group
(substitute-key-definition
 'find-file 'find-file-read-only (current-global-map))
@end group
@end smallexample

@c Emacs 19 feature
If @var{oldmap} is non-@code{nil}, that changes the behavior of
@code{substitute-key-definition}: the bindings in @var{oldmap} determine
which keys to rebind.  The rebindings still happen in @var{keymap}, not
in @var{oldmap}.  Thus, you can change one map under the control of the
bindings in another.  For example,

@smallexample
(substitute-key-definition
  'delete-backward-char 'my-funny-delete
  my-map global-map)
@end smallexample

@noindent
puts the special deletion command in @code{my-map} for whichever keys
are globally bound to the standard deletion command.

Here is an example showing a keymap before and after substitution:

@smallexample
@group
(setq map '(keymap
            (?1 . olddef-1)
            (?2 . olddef-2)
            (?3 . olddef-1)))
@result{} (keymap (49 . olddef-1) (50 . olddef-2) (51 . olddef-1))
@end group

@group
(substitute-key-definition 'olddef-1 'newdef map)
@result{} nil
@end group
@group
map
@result{} (keymap (49 . newdef) (50 . olddef-2) (51 . newdef))
@end group
@end smallexample
@end defun

@defun suppress-keymap keymap &optional nodigits
@cindex @code{self-insert-command} override
This function changes the contents of the full keymap @var{keymap} by
remapping @code{self-insert-command} to the command @code{undefined}
(@pxref{Remapping Commands}).  This has the effect of undefining all
printing characters, thus making ordinary insertion of text impossible.
@code{suppress-keymap} returns @code{nil}.

If @var{nodigits} is @code{nil}, then @code{suppress-keymap} defines
digits to run @code{digit-argument}, and @kbd{-} to run
@code{negative-argument}.  Otherwise it makes them undefined like the
rest of the printing characters.

@cindex yank suppression
@cindex @code{quoted-insert} suppression
The @code{suppress-keymap} function does not make it impossible to
modify a buffer, as it does not suppress commands such as @code{yank}
and @code{quoted-insert}.  To prevent any modification of a buffer, make
it read-only (@pxref{Read Only Buffers}).

Since this function modifies @var{keymap}, you would normally use it
on a newly created keymap.  Operating on an existing keymap
that is used for some other purpose is likely to cause trouble; for
example, suppressing @code{global-map} would make it impossible to use
most of Emacs.

Most often, @code{suppress-keymap} is used to initialize local
keymaps of modes such as Rmail and Dired where insertion of text is not
desirable and the buffer is read-only.  Here is an example taken from
the file @file{emacs/lisp/dired.el}, showing how the local keymap for
Dired mode is set up:

@smallexample
@group
(setq dired-mode-map (make-keymap))
(suppress-keymap dired-mode-map)
(define-key dired-mode-map "r" 'dired-rename-file)
(define-key dired-mode-map "\C-d" 'dired-flag-file-deleted)
(define-key dired-mode-map "d" 'dired-flag-file-deleted)
(define-key dired-mode-map "v" 'dired-view-file)
(define-key dired-mode-map "e" 'dired-find-file)
(define-key dired-mode-map "f" 'dired-find-file)
@dots{}
@end group
@end smallexample
@end defun

@node Remapping Commands
@section Remapping Commands
@cindex remapping commands

  A special kind of key binding, using a special ``key sequence''
which includes a command name, has the effect of @dfn{remapping} that
command into another.  Here's how it works.  You make a key binding
for a key sequence that starts with the dummy event @code{remap},
followed by the command name you want to remap.  Specify the remapped
definition as the definition in this binding.  The remapped definition
is usually a command name, but it can be any valid definition for
a key binding.

  Here's an example.  Suppose that My mode uses special commands
@code{my-kill-line} and @code{my-kill-word}, which should be invoked
instead of @code{kill-line} and @code{kill-word}.  It can establish
this by making these two command-remapping bindings in its keymap:

@smallexample
(define-key my-mode-map [remap kill-line] 'my-kill-line)
(define-key my-mode-map [remap kill-word] 'my-kill-word)
@end smallexample

Whenever @code{my-mode-map} is an active keymap, if the user types
@kbd{C-k}, Emacs will find the standard global binding of
@code{kill-line} (assuming nobody has changed it).  But
@code{my-mode-map} remaps @code{kill-line} to @code{my-kill-line},
so instead of running @code{kill-line}, Emacs runs
@code{my-kill-line}.

Remapping only works through a single level.  In other words,

@smallexample
(define-key my-mode-map [remap kill-line] 'my-kill-line)
(define-key my-mode-map [remap my-kill-line] 'my-other-kill-line)
@end smallexample

@noindent
does not have the effect of remapping @code{kill-line} into
@code{my-other-kill-line}.  If an ordinary key binding specifies
@code{kill-line}, this keymap will remap it to @code{my-kill-line};
if an ordinary binding specifies @code{my-kill-line}, this keymap will
remap it to @code{my-other-kill-line}.

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To undo the remapping of a command, remap it to @code{nil}; e.g.

@smallexample
(define-key my-mode-map [remap kill-line] nil)
@end smallexample

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@defun command-remapping command &optional position keymaps
This function returns the remapping for @var{command} (a symbol),
given the current active keymaps.  If @var{command} is not remapped
(which is the usual situation), or not a symbol, the function returns
@code{nil}.  @code{position} can optionally specify a buffer position
or an event position to determine the keymaps to use, as in
@code{key-binding}.

If the optional argument @code{keymaps} is non-@code{nil}, it
specifies a list of keymaps to search in.  This argument is ignored if
@code{position} is non-@code{nil}.
@end defun

@node Translation Keymaps
@section Keymaps for Translating Sequences of Events
@cindex keymaps for translating events

  This section describes keymaps that are used during reading a key
sequence, to translate certain event sequences into others.
@code{read-key-sequence} checks every subsequence of the key sequence
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being read, as it is read, against @code{input-decode-map}, then
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@code{local-function-key-map}, and then against @code{key-translation-map}.
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@defvar input-decode-map
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This variable holds a keymap that describes the character sequences sent
by function keys on an ordinary character terminal.  This keymap has the
same structure as other keymaps, but is used differently: it specifies
translations to make while reading key sequences, rather than bindings
for key sequences.

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If @code{input-decode-map} ``binds'' a key sequence @var{k} to a vector
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@var{v}, then when @var{k} appears as a subsequence @emph{anywhere} in a
key sequence, it is replaced with the events in @var{v}.

For example, VT100 terminals send @kbd{@key{ESC} O P} when the
keypad @key{PF1} key is pressed.  Therefore, we want Emacs to translate
that sequence of events into the single event @code{pf1}.  We accomplish
this by ``binding'' @kbd{@key{ESC} O P} to @code{[pf1]} in
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@code{input-decode-map}, when using a VT100.
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Thus, typing @kbd{C-c @key{PF1}} sends the character sequence @kbd{C-c
@key{ESC} O P}; later the function @code{read-key-sequence} translates
this back into @kbd{C-c @key{PF1}}, which it returns as the vector
@code{[?\C-c pf1]}.

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The value of @code{input-decode-map} is usually set up automatically
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according to the terminal's Terminfo or Termcap entry, but sometimes
those need help from terminal-specific Lisp files.  Emacs comes with
terminal-specific files for many common terminals; their main purpose is
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to make entries in @code{input-decode-map} beyond those that can be
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deduced from Termcap and Terminfo.  @xref{Terminal-Specific}.
@end defvar

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@defvar local-function-key-map
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This variable holds a keymap similar to @code{input-decode-map} except
that it describes key sequences which should be translated to
alternative interpretations that are usually preferred.  It applies
after @code{input-decode-map} and before @code{key-translation-map}.
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Entries in @code{local-function-key-map} are ignored if they conflict
with bindings made in the minor mode, local, or global keymaps.  I.e.
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the remapping only applies if the original key sequence would
otherwise not have any binding.
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@code{local-function-key-map} inherits from @code{function-key-map},
but the latter should not be used directly.
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@end defvar
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@defvar key-translation-map
This variable is another keymap used just like @code{input-decode-map}
to translate input events into other events.  It differs from
@code{input-decode-map} in that it goes to work after
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@code{local-function-key-map} is finished rather than before; it
receives the results of translation by @code{local-function-key-map}.

Just like @code{input-decode-map}, but unlike
@code{local-function-key-map}, this keymap is applied regardless of
whether the input key-sequence has a normal binding.  Note however
that actual key bindings can have an effect on
@code{key-translation-map}, even though they are overridden by it.
Indeed, actual key bindings override @code{local-function-key-map} and
thus may alter the key sequence that @code{key-translation-map}
receives.  Clearly, it is better to avoid this type of situation.
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The intent of @code{key-translation-map} is for users to map one
character set to another, including ordinary characters normally bound
to @code{self-insert-command}.
@end defvar

@cindex key translation function
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You can use @code{input-decode-map}, @code{local-function-key-map}, or
@code{key-translation-map} for more than simple aliases, by using a
function, instead of a key sequence, as the ``translation'' of a key.
Then this function is called to compute the translation of that key.
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The key translation function receives one argument, which is the prompt
that was specified in @code{read-key-sequence}---or @code{nil} if the
key sequence is being read by the editor command loop.  In most cases
you can ignore the prompt value.

If the function reads input itself, it can have the effect of altering
the event that follows.  For example, here's how to define @kbd{C-c h}
to turn the character that follows into a Hyper character:

@example
@group
(defun hyperify (prompt)
  (let ((e (read-event)))
    (vector (if (numberp e)
                (logior (lsh 1 24) e)
              (if (memq 'hyper (event-modifiers e))
                  e
                (add-event-modifier "H-" e))))))

(defun add-event-modifier (string e)
  (let ((symbol (if (symbolp e) e (car e))))
    (setq symbol (intern (concat string
                                 (symbol-name symbol))))
@end group
@group
    (if (symbolp e)
        symbol
      (cons symbol (cdr e)))))

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(define-key local-function-key-map "\C-ch" 'hyperify)
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@end group
@end example

  If you have enabled keyboard character set decoding using
@code{set-keyboard-coding-system}, decoding is done after the
translations listed above.  @xref{Terminal I/O Encoding}.  However, in
future Emacs versions, character set decoding may be done at an
earlier stage.

@node Key Binding Commands
@section Commands for Binding Keys

  This section describes some convenient interactive interfaces for
changing key bindings.  They work by calling @code{define-key}.

  People often use @code{global-set-key} in their init files
(@pxref{Init File}) for simple customization.  For example,

@smallexample
(global-set-key (kbd "C-x C-\\") 'next-line)
@end smallexample

@noindent
or

@smallexample
(global-set-key [?\C-x ?\C-\\] 'next-line)
@end smallexample

@noindent
or

@smallexample
(global-set-key [(control ?x) (control ?\\)] 'next-line)
@end smallexample

@noindent
redefines @kbd{C-x C-\} to move down a line.

@smallexample
(global-set-key [M-mouse-1] 'mouse-set-point)
@end smallexample

@noindent
redefines the first (leftmost) mouse button, entered with the Meta key, to
set point where you click.

@cindex non-@acronym{ASCII} text in keybindings
  Be careful when using non-@acronym{ASCII} text characters in Lisp
specifications of keys to bind.  If these are read as multibyte text, as
they usually will be in a Lisp file (@pxref{Loading Non-ASCII}), you
must type the keys as multibyte too.  For instance, if you use this:

@smallexample
(global-set-key "@"o" 'my-function) ; bind o-umlaut
@end smallexample

@noindent
or

@smallexample
(global-set-key ?@"o 'my-function) ; bind o-umlaut
@end smallexample

@noindent
and your language environment is multibyte Latin-1, these commands
1710 1711 1712 1713 1714
actually bind the multibyte character with code 246, not the byte
code 246 (@kbd{M-v}) sent by a Latin-1 terminal.  In order to use this
binding, you need to teach Emacs how to decode the keyboard by using an
appropriate input method (@pxref{Input Methods, , Input Methods, emacs, The GNU
Emacs Manual}).
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@deffn Command global-set-key key binding
This function sets the binding of @var{key} in the current global map
to @var{binding}.

@smallexample
@group
(global-set-key @var{key} @var{binding})
@equiv{}
(define-key (current-global-map) @var{key} @var{binding})
@end group
@end smallexample
@end deffn

@deffn Command global-unset-key key
@cindex unbinding keys
This function removes the binding of @var{key} from the current
global map.

One use of this function is in preparation for defining a longer key
that uses @var{key} as a prefix---which would not be allowed if
@var{key} has a non-prefix binding.  For example:

@smallexample
@group
(global-unset-key "\C-l")
    @result{} nil
@end group
@group
(global-set-key "\C-l\C-l" 'redraw-display)
    @result{} nil
@end group
@end smallexample

This function is implemented simply using @code{define-key}:

@smallexample
@group
(global-unset-key @var{key})
@equiv{}
(define-key (current-global-map) @var{key} nil)
@end group
@end smallexample
@end deffn

@deffn Command local-set-key key binding
This function sets the binding of @var{key} in the current local
keymap to @var{binding}.

@smallexample
@group
(local-set-key @var{key} @var{binding})
@equiv{}
(define-key (current-local-map) @var{key} @var{binding})
@end group
@end smallexample
@end deffn

@deffn Command local-unset-key key
This function removes the binding of @var{key} from the current
local map.

@smallexample
@group
(local-unset-key @var{key})
@equiv{}
(define-key (current-local-map) @var{key} nil)
@end group
@end smallexample
@end deffn

@node Scanning Keymaps
@section Scanning Keymaps

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

@defun 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 @var{keymap}.  The value is an
association list with elements of the form @code{(@var{key} .@:
@var{map})}, where @var{key} is a prefix key whose definition in
@var{keymap} is @var{map}.

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

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

In the example below, the returned alist indicates that the key
@key{ESC}, which is displayed as @samp{^[}, is a prefix key whose
definition is the sparse keymap @code{(keymap (83 .@: center-paragraph)
(115 .@: foo))}.

@smallexample
@group
(accessible-keymaps (current-local-map))
@result{}(([] keymap
      (27 keymap   ; @r{Note this keymap for @key{ESC} is repeated below.}
          (83 . center-paragraph)
          (115 . center-line))
      (9 . tab-to-tab-stop))
@end group

@group
   ("^[" keymap
    (83 . center-paragraph)
    (115 . foo)))
@end group
@end smallexample

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

@smallexample
@group
(accessible-keymaps (current-global-map))
@result{} (([] keymap [set-mark-command beginning-of-line @dots{}
                   delete-backward-char])
@end group
@group
    ("^H" keymap (118 . describe-variable) @dots{}
     (8 . help-for-help))
@end group
@group
    ("^X" keymap [x-flush-mouse-queue @dots{}
     backward-kill-sentence])
@end group
@group
    ("^[" keymap [mark-sexp backward-sexp @dots{}
     backward-kill-word])
@end group
    ("^X4" keymap (15 . display-buffer) @dots{})
@group
    ([mode-line] keymap
     (S-mouse-2 . mouse-split-window-horizontally) @dots{}))
@end group
@end smallexample

@noindent
These are not all the keymaps you would see in actuality.
@end defun

@defun map-keymap function keymap
The function @code{map-keymap} calls @var{function} once
for each binding in @var{keymap}.  It passes two arguments,
the event type and the value of the binding.  If @var{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.
@end defun

@defun where-is-internal command &optional keymap firstonly noindirect no-remap
This function is a subroutine used by the @code{where-is} command
(@pxref{Help, , Help, emacs,The GNU Emacs Manual}).  It returns a list
of all key sequences (of any length) that are bound to @var{command} in a
set of keymaps.

The argument @var{command} can be any object; it is compared with all
keymap entries using @code{eq}.

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

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

If @var{firstonly} is @code{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 @var{firstonly} is @code{t}, then the
value is the first key sequence, except that key sequences consisting
entirely of @acronym{ASCII} characters (or meta variants of @acronym{ASCII}
characters) are preferred to all other key sequences and that the
return value can never be a menu binding.

If @var{noindirect} is non-@code{nil}, @code{where-is-internal} doesn't
follow indirect keymap bindings.  This makes it possible to search for
an indirect definition itself.

When command remapping is in effect (@pxref{Remapping Commands}),
@code{where-is-internal} figures out when a command will be run due to
remapping and reports keys accordingly.  It also returns @code{nil} if
@var{command} won't really be run because it has been remapped to some
other command.  However, if @var{no-remap} is non-@code{nil}.
@code{where-is-internal} ignores remappings.

@smallexample
@group
(where-is-internal 'describe-function)
    @result{} ([8 102] [f1 102] [help 102]
         [menu-bar help-menu describe describe-function])
@end group
@end smallexample
@end defun

@deffn 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 @samp{*Help*}.  The text is grouped by
modes---minor modes first, then the major mode, then global bindings.

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

The listing describes meta characters as @key{ESC} followed by the
corresponding non-meta character.

When several characters with consecutive @acronym{ASCII} codes have the
same definition, they are shown together, as
@samp{@var{firstchar}..@var{lastchar}}.  In this instance, you need to
know the @acronym{ASCII} codes to understand which characters this means.
For example, in the default global map, the characters @samp{@key{SPC}
..@: ~} are described by a single line.  @key{SPC} is @acronym{ASCII} 32,
@kbd{~} is @acronym{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 @code{self-insert-command}.

If @var{buffer-or-name} is non-@code{nil}, it should be a buffer or a
buffer name.  Then @code{describe-bindings} lists that buffer's bindings,
instead of the current buffer's.
@end deffn

@node Menu Keymaps
@section Menu Keymaps
@cindex menu keymaps

A keymap can operate as a menu as well as defining bindings for
keyboard keys and mouse buttons.  Menus are usually actuated with the
mouse, but they can function with the keyboard also.  If a menu keymap
is active for the next input event, that activates the keyboard menu
feature.

@menu
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* Defining Menus::              How to make a keymap that defines a menu.
* Mouse Menus::                 How users actuate the menu with the mouse.
* Keyboard Menus::              How users actuate the menu with the keyboard.
* Menu Example::                Making a simple menu.
* Menu Bar::                    How to customize the menu bar.
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* Tool Bar::                    A tool bar is a row of images.
* Modifying Menus::             How to add new items to a menu.
@end menu

@node Defining Menus
@subsection Defining Menus
@cindex defining menus
@cindex menu prompt string
@cindex prompt string (of menu)
1979
@cindex menu item
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A keymap acts as a menu if it has an @dfn{overall prompt string},
which is a string that appears as an element of the keymap.
(@xref{Format of Keymaps}.)  The string should describe the purpose of
the menu's commands.  Emacs displays the overall prompt string as the
menu title in some cases, depending on the toolkit (if any) used for
displaying menus.@footnote{It is required for menus which do not use a
toolkit, e.g.@: under MS-DOS.}  Keyboard menus also display the
overall prompt string.

The easiest way to construct a keymap with a prompt string is to
specify the string as an argument when you call @code{make-keymap},
@code{make-sparse-keymap} (@pxref{Creating Keymaps}), or
@code{define-prefix-command} (@pxref{Definition of
define-prefix-command}).  If you do not want the keymap to operate as
a menu, don't specify a prompt string for it.

@defun keymap-prompt keymap
This function returns the overall prompt string of @var{keymap},
or @code{nil} if it has none.
@end defun

The menu's items are the bindings in the keymap.  Each binding
associates an event type to a definition, but the event types have no
significance for the menu appearance.  (Usually we use pseudo-events,
symbols that the keyboard cannot generate, as the event types for menu
item bindings.)  The menu is generated entirely from the bindings that
correspond in the keymap to these events.

The order of items in the menu is the same as the order of bindings in
the keymap.  Since @code{define-key} puts new bindings at the front, you
should define the menu items starting at the bottom of the menu and
moving to the top, if you care about the order.  When you add an item to
an existing menu, you can specify its position in the menu using
@code{define-key-after} (@pxref{Modifying Menus}).

@menu
* Simple Menu Items::       A simple kind of menu key binding,
                              limited in capabilities.
* Extended Menu Items::     More powerful menu item definitions
                              let you specify keywords to enable
                              various features.
* Menu Separators::         Drawing a horizontal line through a menu.
* Alias Menu Items::        Using command aliases in menu items.
@end menu

@node Simple Menu Items
@subsubsection Simple Menu Items

  The simpler (and original) way to define a menu item is to bind some
event type (it doesn't matter what event type) to a binding like this:

@example
(@var{item-string} . @var{real-binding})
@end example

@noindent
The @sc{car}, @var{item-string}, is the string to be displayed in the
menu.  It should be short---preferably one to three words.  It should
describe the action of the command it corresponds to.  Note that it is
not generally possible to display non-@acronym{ASCII} text in menus.  It will
work for keyboard menus and will work to a large extent when Emacs is
built with the Gtk+ toolkit.@footnote{In this case, the text is first
encoded using the @code{utf-8} coding system and then rendered by the
toolkit as it sees fit.}

  You can also supply a second string, called the help string, as follows:

@example
(@var{item-string} @var{help} . @var{real-binding})
@end example

@noindent
@var{help} specifies a ``help-echo'' string to display while the mouse
is on that item in the same way as @code{help-echo} text properties
(@pxref{Help display}).

  As far as @code{define-key} is concerned, @var{item-string} and
@var{help-string} are part of the event's binding.  However,
@code{lookup-key} returns just @var{real-binding}, and only
@var{real-binding} is used for executing the key.

  If @var{real-binding} is @code{nil}, then @var{item-string} appears in
the menu but cannot be selected.

  If @var{real-binding} is a symbol and has a non-@code{nil}
@code{menu-enable} property, that property is an expression that
controls whether the menu item is enabled.  Every time the keymap is
used to display a menu, Emacs evaluates the expression, and it enables
the menu item only if the expression's value is non-@code{nil}.  When a
menu item is disabled, it is displayed in a ``fuzzy'' fashion, and
cannot be selected.

  The menu bar does not recalculate which items are enabled every time you
look at a menu.  This is because the X toolkit requires the whole tree
of menus in advance.  To force recalculation of the menu bar, call
@code{force-mode-line-update} (@pxref{Mode Line Format}).

  You've probably noticed that menu items show the equivalent keyboard key
sequence (if any) to invoke the same command.  To save time on
recalculation, menu display caches this information in a sublist in the
binding, like this:

@c This line is not too long--rms.
@example
(@var{item-string} @r{[}@var{help}@r{]} (@var{key-binding-data}) . @var{real-binding})
@end example

@noindent
Don't put these sublists in the menu item yourself; menu display
calculates them automatically.  Don't mention keyboard equivalents in
the item strings themselves, since that is redundant.

@node Extended Menu Items
@subsubsection Extended Menu Items
@kindex menu-item
2096
@cindex extended menu item
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