Merge from emacs-24; up to 2012-12-30T19:34:25Z!jan.h.d@swipnet.se
[bpt/emacs.git] / doc / lispref / keymaps.texi
1 @c -*-texinfo-*-
2 @c This is part of the GNU Emacs Lisp Reference Manual.
3 @c Copyright (C) 1990-1994, 1998-2013 Free Software Foundation, Inc.
4 @c See the file elisp.texi for copying conditions.
5 @node Keymaps
6 @chapter Keymaps
7 @cindex keymap
8
9 The command bindings of input events are recorded in data structures
10 called @dfn{keymaps}. Each entry in a keymap associates (or
11 @dfn{binds}) an individual event type, either to another keymap or to
12 a command. When an event type is bound to a keymap, that keymap is
13 used to look up the next input event; this continues until a command
14 is found. The whole process is called @dfn{key lookup}.
15
16 @menu
17 * Key Sequences:: Key sequences as Lisp objects.
18 * Keymap Basics:: Basic concepts of keymaps.
19 * Format of Keymaps:: What a keymap looks like as a Lisp object.
20 * Creating Keymaps:: Functions to create and copy keymaps.
21 * Inheritance and Keymaps:: How one keymap can inherit the bindings
22 of another keymap.
23 * Prefix Keys:: Defining a key with a keymap as its definition.
24 * Active Keymaps:: How Emacs searches the active keymaps
25 for a key binding.
26 * Searching Keymaps:: A pseudo-Lisp summary of searching active maps.
27 * Controlling Active Maps:: Each buffer has a local keymap
28 to override the standard (global) bindings.
29 A minor mode can also override them.
30 * Key Lookup:: Finding a key's binding in one keymap.
31 * Functions for Key Lookup:: How to request key lookup.
32 * Changing Key Bindings:: Redefining a key in a keymap.
33 * Remapping Commands:: A keymap can translate one command to another.
34 * Translation Keymaps:: Keymaps for translating sequences of events.
35 * Key Binding Commands:: Interactive interfaces for redefining keys.
36 * Scanning Keymaps:: Looking through all keymaps, for printing help.
37 * Menu Keymaps:: Defining a menu as a keymap.
38 @end menu
39
40 @node Key Sequences
41 @section Key Sequences
42 @cindex key
43 @cindex keystroke
44 @cindex key sequence
45
46 A @dfn{key sequence}, or @dfn{key} for short, is a sequence of one
47 or more input events that form a unit. Input events include
48 characters, function keys, mouse actions, or system events external to
49 Emacs, such as @code{iconify-frame} (@pxref{Input Events}).
50 The Emacs Lisp representation for a key sequence is a string or
51 vector. Unless otherwise stated, any Emacs Lisp function that accepts
52 a key sequence as an argument can handle both representations.
53
54 In the string representation, alphanumeric characters ordinarily
55 stand for themselves; for example, @code{"a"} represents @kbd{a}
56 and @code{"2"} represents @kbd{2}. Control character events are
57 prefixed by the substring @code{"\C-"}, and meta characters by
58 @code{"\M-"}; for example, @code{"\C-x"} represents the key @kbd{C-x}.
59 In addition, the @key{TAB}, @key{RET}, @key{ESC}, and @key{DEL} events
60 are represented by @code{"\t"}, @code{"\r"}, @code{"\e"}, and
61 @code{"\d"} respectively. The string representation of a complete key
62 sequence is the concatenation of the string representations of the
63 constituent events; thus, @code{"\C-xl"} represents the key sequence
64 @kbd{C-x l}.
65
66 Key sequences containing function keys, mouse button events, system
67 events, or non-@acronym{ASCII} characters such as @kbd{C-=} or
68 @kbd{H-a} cannot be represented as strings; they have to be
69 represented as vectors.
70
71 In the vector representation, each element of the vector represents
72 an input event, in its Lisp form. @xref{Input Events}. For example,
73 the vector @code{[?\C-x ?l]} represents the key sequence @kbd{C-x l}.
74
75 For examples of key sequences written in string and vector
76 representations, @ref{Init Rebinding,,, emacs, The GNU Emacs Manual}.
77
78 @defun kbd keyseq-text
79 This function converts the text @var{keyseq-text} (a string constant)
80 into a key sequence (a string or vector constant). The contents of
81 @var{keyseq-text} should use the same syntax as in the buffer invoked
82 by the @kbd{C-x C-k @key{RET}} (@code{kmacro-edit-macro}) command; in
83 particular, you must surround function key names with
84 @samp{<@dots{}>}. @xref{Edit Keyboard Macro,,, emacs, The GNU Emacs
85 Manual}.
86
87 @example
88 (kbd "C-x") @result{} "\C-x"
89 (kbd "C-x C-f") @result{} "\C-x\C-f"
90 (kbd "C-x 4 C-f") @result{} "\C-x4\C-f"
91 (kbd "X") @result{} "X"
92 (kbd "RET") @result{} "\^M"
93 (kbd "C-c SPC") @result{} "\C-c@ "
94 (kbd "<f1> SPC") @result{} [f1 32]
95 (kbd "C-M-<down>") @result{} [C-M-down]
96 @end example
97 @end defun
98
99 @node Keymap Basics
100 @section Keymap Basics
101 @cindex key binding
102 @cindex binding of a key
103 @cindex complete key
104 @cindex undefined key
105
106 A keymap is a Lisp data structure that specifies @dfn{key bindings}
107 for various key sequences.
108
109 A single keymap directly specifies definitions for individual
110 events. When a key sequence consists of a single event, its binding
111 in a keymap is the keymap's definition for that event. The binding of
112 a longer key sequence is found by an iterative process: first find the
113 definition of the first event (which must itself be a keymap); then
114 find the second event's definition in that keymap, and so on until all
115 the events in the key sequence have been processed.
116
117 If the binding of a key sequence is a keymap, we call the key sequence
118 a @dfn{prefix key}. Otherwise, we call it a @dfn{complete key} (because
119 no more events can be added to it). If the binding is @code{nil},
120 we call the key @dfn{undefined}. Examples of prefix keys are @kbd{C-c},
121 @kbd{C-x}, and @kbd{C-x 4}. Examples of defined complete keys are
122 @kbd{X}, @key{RET}, and @kbd{C-x 4 C-f}. Examples of undefined complete
123 keys are @kbd{C-x C-g}, and @kbd{C-c 3}. @xref{Prefix Keys}, for more
124 details.
125
126 The rule for finding the binding of a key sequence assumes that the
127 intermediate bindings (found for the events before the last) are all
128 keymaps; if this is not so, the sequence of events does not form a
129 unit---it is not really one key sequence. In other words, removing one
130 or more events from the end of any valid key sequence must always yield
131 a prefix key. For example, @kbd{C-f C-n} is not a key sequence;
132 @kbd{C-f} is not a prefix key, so a longer sequence starting with
133 @kbd{C-f} cannot be a key sequence.
134
135 The set of possible multi-event key sequences depends on the bindings
136 for prefix keys; therefore, it can be different for different keymaps,
137 and can change when bindings are changed. However, a one-event sequence
138 is always a key sequence, because it does not depend on any prefix keys
139 for its well-formedness.
140
141 At any time, several primary keymaps are @dfn{active}---that is, in
142 use for finding key bindings. These are the @dfn{global map}, which is
143 shared by all buffers; the @dfn{local keymap}, which is usually
144 associated with a specific major mode; and zero or more @dfn{minor mode
145 keymaps}, which belong to currently enabled minor modes. (Not all minor
146 modes have keymaps.) The local keymap bindings shadow (i.e., take
147 precedence over) the corresponding global bindings. The minor mode
148 keymaps shadow both local and global keymaps. @xref{Active Keymaps},
149 for details.
150
151 @node Format of Keymaps
152 @section Format of Keymaps
153 @cindex format of keymaps
154 @cindex keymap format
155 @cindex full keymap
156 @cindex sparse keymap
157
158 Each keymap is a list whose @sc{car} is the symbol @code{keymap}. The
159 remaining elements of the list define the key bindings of the keymap.
160 A symbol whose function definition is a keymap is also a keymap. Use
161 the function @code{keymapp} (see below) to test whether an object is a
162 keymap.
163
164 Several kinds of elements may appear in a keymap, after the symbol
165 @code{keymap} that begins it:
166
167 @table @code
168 @item (@var{type} .@: @var{binding})
169 This specifies one binding, for events of type @var{type}. Each
170 ordinary binding applies to events of a particular @dfn{event type},
171 which is always a character or a symbol. @xref{Classifying Events}.
172 In this kind of binding, @var{binding} is a command.
173
174 @item (@var{type} @var{item-name} .@: @var{binding})
175 This specifies a binding which is also a simple menu item that
176 displays as @var{item-name} in the menu. @xref{Simple Menu Items}.
177
178 @item (@var{type} @var{item-name} @var{help-string} .@: @var{binding})
179 This is a simple menu item with help string @var{help-string}.
180
181 @item (@var{type} menu-item .@: @var{details})
182 This specifies a binding which is also an extended menu item. This
183 allows use of other features. @xref{Extended Menu Items}.
184
185 @item (t .@: @var{binding})
186 @cindex default key binding
187 This specifies a @dfn{default key binding}; any event not bound by other
188 elements of the keymap is given @var{binding} as its binding. Default
189 bindings allow a keymap to bind all possible event types without having
190 to enumerate all of them. A keymap that has a default binding
191 completely masks any lower-precedence keymap, except for events
192 explicitly bound to @code{nil} (see below).
193
194 @item @var{char-table}
195 If an element of a keymap is a char-table, it counts as holding
196 bindings for all character events with no modifier bits
197 (@pxref{modifier bits}): element @var{n} is the binding for the
198 character with code @var{n}. This is a compact way to record lots of
199 bindings. A keymap with such a char-table is called a @dfn{full
200 keymap}. Other keymaps are called @dfn{sparse keymaps}.
201
202 @item @var{string}
203 @cindex keymap prompt string
204 @cindex overall prompt string
205 @cindex prompt string of keymap
206 Aside from elements that specify bindings for keys, a keymap can also
207 have a string as an element. This is called the @dfn{overall prompt
208 string} and makes it possible to use the keymap as a menu.
209 @xref{Defining Menus}.
210
211 @item (keymap @dots{})
212 If an element of a keymap is itself a keymap, it counts as if this inner keymap
213 were inlined in the outer keymap. This is used for multiple-inheritance, such
214 as in @code{make-composed-keymap}.
215 @end table
216
217 When the binding is @code{nil}, it doesn't constitute a definition
218 but it does take precedence over a default binding or a binding in the
219 parent keymap. On the other hand, a binding of @code{nil} does
220 @emph{not} override lower-precedence keymaps; thus, if the local map
221 gives a binding of @code{nil}, Emacs uses the binding from the
222 global map.
223
224 @cindex meta characters lookup
225 Keymaps do not directly record bindings for the meta characters.
226 Instead, meta characters are regarded for purposes of key lookup as
227 sequences of two characters, the first of which is @key{ESC} (or
228 whatever is currently the value of @code{meta-prefix-char}). Thus, the
229 key @kbd{M-a} is internally represented as @kbd{@key{ESC} a}, and its
230 global binding is found at the slot for @kbd{a} in @code{esc-map}
231 (@pxref{Prefix Keys}).
232
233 This conversion applies only to characters, not to function keys or
234 other input events; thus, @kbd{M-@key{end}} has nothing to do with
235 @kbd{@key{ESC} @key{end}}.
236
237 Here as an example is the local keymap for Lisp mode, a sparse
238 keymap. It defines bindings for @key{DEL}, @kbd{C-c C-z},
239 @kbd{C-M-q}, and @kbd{C-M-x} (the actual value also contains a menu
240 binding, which is omitted here for the sake of brevity).
241
242 @example
243 @group
244 lisp-mode-map
245 @result{}
246 @end group
247 @group
248 (keymap
249 (3 keymap
250 ;; @kbd{C-c C-z}
251 (26 . run-lisp))
252 @end group
253 @group
254 (27 keymap
255 ;; @r{@kbd{C-M-x}, treated as @kbd{@key{ESC} C-x}}
256 (24 . lisp-send-defun))
257 @end group
258 @group
259 ;; @r{This part is inherited from @code{lisp-mode-shared-map}.}
260 keymap
261 ;; @key{DEL}
262 (127 . backward-delete-char-untabify)
263 @end group
264 @group
265 (27 keymap
266 ;; @r{@kbd{C-M-q}, treated as @kbd{@key{ESC} C-q}}
267 (17 . indent-sexp)))
268 @end group
269 @end example
270
271 @defun keymapp object
272 This function returns @code{t} if @var{object} is a keymap, @code{nil}
273 otherwise. More precisely, this function tests for a list whose
274 @sc{car} is @code{keymap}, or for a symbol whose function definition
275 satisfies @code{keymapp}.
276
277 @example
278 @group
279 (keymapp '(keymap))
280 @result{} t
281 @end group
282 @group
283 (fset 'foo '(keymap))
284 (keymapp 'foo)
285 @result{} t
286 @end group
287 @group
288 (keymapp (current-global-map))
289 @result{} t
290 @end group
291 @end example
292 @end defun
293
294 @node Creating Keymaps
295 @section Creating Keymaps
296 @cindex creating keymaps
297
298 Here we describe the functions for creating keymaps.
299
300 @defun make-sparse-keymap &optional prompt
301 This function creates and returns a new sparse keymap with no entries.
302 (A sparse keymap is the kind of keymap you usually want.) The new
303 keymap does not contain a char-table, unlike @code{make-keymap}, and
304 does not bind any events.
305
306 @example
307 @group
308 (make-sparse-keymap)
309 @result{} (keymap)
310 @end group
311 @end example
312
313 If you specify @var{prompt}, that becomes the overall prompt string
314 for the keymap. You should specify this only for menu keymaps
315 (@pxref{Defining Menus}). A keymap with an overall prompt string will
316 always present a mouse menu or a keyboard menu if it is active for
317 looking up the next input event. Don't specify an overall prompt string
318 for the main map of a major or minor mode, because that would cause
319 the command loop to present a keyboard menu every time.
320 @end defun
321
322 @defun make-keymap &optional prompt
323 This function creates and returns a new full keymap. That keymap
324 contains a char-table (@pxref{Char-Tables}) with slots for all
325 characters without modifiers. The new keymap initially binds all
326 these characters to @code{nil}, and does not bind any other kind of
327 event. The argument @var{prompt} specifies a
328 prompt string, as in @code{make-sparse-keymap}.
329
330 @c This example seems kind of pointless, but I guess it serves
331 @c to contrast the result with make-sparse-keymap above.
332 @example
333 @group
334 (make-keymap)
335 @result{} (keymap #^[nil nil keymap nil nil nil @dots{}])
336 @end group
337 @end example
338
339 A full keymap is more efficient than a sparse keymap when it holds
340 lots of bindings; for just a few, the sparse keymap is better.
341 @end defun
342
343 @defun copy-keymap keymap
344 This function returns a copy of @var{keymap}. Any keymaps that
345 appear directly as bindings in @var{keymap} are also copied recursively,
346 and so on to any number of levels. However, recursive copying does not
347 take place when the definition of a character is a symbol whose function
348 definition is a keymap; the same symbol appears in the new copy.
349 @c Emacs 19 feature
350
351 @example
352 @group
353 (setq map (copy-keymap (current-local-map)))
354 @result{} (keymap
355 @end group
356 @group
357 ;; @r{(This implements meta characters.)}
358 (27 keymap
359 (83 . center-paragraph)
360 (115 . center-line))
361 (9 . tab-to-tab-stop))
362 @end group
363
364 @group
365 (eq map (current-local-map))
366 @result{} nil
367 @end group
368 @group
369 (equal map (current-local-map))
370 @result{} t
371 @end group
372 @end example
373 @end defun
374
375 @node Inheritance and Keymaps
376 @section Inheritance and Keymaps
377 @cindex keymap inheritance
378 @cindex inheritance, keymap
379
380 A keymap can inherit the bindings of another keymap, which we call the
381 @dfn{parent keymap}. Such a keymap looks like this:
382
383 @example
384 (keymap @var{elements}@dots{} . @var{parent-keymap})
385 @end example
386
387 @noindent
388 The effect is that this keymap inherits all the bindings of
389 @var{parent-keymap}, whatever they may be at the time a key is looked up,
390 but can add to them or override them with @var{elements}.
391
392 If you change the bindings in @var{parent-keymap} using
393 @code{define-key} or other key-binding functions, these changed
394 bindings are visible in the inheriting keymap, unless shadowed by the
395 bindings made by @var{elements}. The converse is not true: if you use
396 @code{define-key} to change bindings in the inheriting keymap, these
397 changes are recorded in @var{elements}, but have no effect on
398 @var{parent-keymap}.
399
400 The proper way to construct a keymap with a parent is to use
401 @code{set-keymap-parent}; if you have code that directly constructs a
402 keymap with a parent, please convert the program to use
403 @code{set-keymap-parent} instead.
404
405 @defun keymap-parent keymap
406 This returns the parent keymap of @var{keymap}. If @var{keymap}
407 has no parent, @code{keymap-parent} returns @code{nil}.
408 @end defun
409
410 @defun set-keymap-parent keymap parent
411 This sets the parent keymap of @var{keymap} to @var{parent}, and returns
412 @var{parent}. If @var{parent} is @code{nil}, this function gives
413 @var{keymap} no parent at all.
414
415 If @var{keymap} has submaps (bindings for prefix keys), they too receive
416 new parent keymaps that reflect what @var{parent} specifies for those
417 prefix keys.
418 @end defun
419
420 Here is an example showing how to make a keymap that inherits
421 from @code{text-mode-map}:
422
423 @example
424 (let ((map (make-sparse-keymap)))
425 (set-keymap-parent map text-mode-map)
426 map)
427 @end example
428
429 A non-sparse keymap can have a parent too, but this is not very
430 useful. A non-sparse keymap always specifies something as the binding
431 for every numeric character code without modifier bits, even if it is
432 @code{nil}, so these character's bindings are never inherited from
433 the parent keymap.
434
435 @cindex keymap inheritance from multiple maps
436 Sometimes you want to make a keymap that inherits from more than one
437 map. You can use the function @code{make-composed-keymap} for this.
438
439 @defun make-composed-keymap maps &optional parent
440 This function returns a new keymap composed of the existing keymap(s)
441 @var{maps}, and optionally inheriting from a parent keymap
442 @var{parent}. @var{maps} can be a single keymap or a list of more
443 than one. When looking up a key in the resulting new map, Emacs
444 searches in each of the @var{maps} in turn, and then in @var{parent},
445 stopping at the first match. A @code{nil} binding in any one of
446 @var{maps} overrides any binding in @var{parent}, but it does not
447 override any non-@code{nil} binding in any other of the @var{maps}.
448 @end defun
449
450 @noindent For example, here is how Emacs sets the parent of
451 @code{help-mode-map}, such that it inherits from both
452 @code{button-buffer-map} and @code{special-mode-map}:
453
454 @example
455 (defvar help-mode-map
456 (let ((map (make-sparse-keymap)))
457 (set-keymap-parent map
458 (make-composed-keymap button-buffer-map special-mode-map))
459 ... map) ... )
460 @end example
461
462
463 @node Prefix Keys
464 @section Prefix Keys
465 @cindex prefix key
466
467 A @dfn{prefix key} is a key sequence whose binding is a keymap. The
468 keymap defines what to do with key sequences that extend the prefix key.
469 For example, @kbd{C-x} is a prefix key, and it uses a keymap that is
470 also stored in the variable @code{ctl-x-map}. This keymap defines
471 bindings for key sequences starting with @kbd{C-x}.
472
473 Some of the standard Emacs prefix keys use keymaps that are
474 also found in Lisp variables:
475
476 @itemize @bullet
477 @item
478 @vindex esc-map
479 @findex ESC-prefix
480 @code{esc-map} is the global keymap for the @key{ESC} prefix key. Thus,
481 the global definitions of all meta characters are actually found here.
482 This map is also the function definition of @code{ESC-prefix}.
483
484 @item
485 @cindex @kbd{C-h}
486 @code{help-map} is the global keymap for the @kbd{C-h} prefix key.
487
488 @item
489 @cindex @kbd{C-c}
490 @vindex mode-specific-map
491 @code{mode-specific-map} is the global keymap for the prefix key
492 @kbd{C-c}. This map is actually global, not mode-specific, but its name
493 provides useful information about @kbd{C-c} in the output of @kbd{C-h b}
494 (@code{display-bindings}), since the main use of this prefix key is for
495 mode-specific bindings.
496
497 @item
498 @cindex @kbd{C-x}
499 @vindex ctl-x-map
500 @findex Control-X-prefix
501 @code{ctl-x-map} is the global keymap used for the @kbd{C-x} prefix key.
502 This map is found via the function cell of the symbol
503 @code{Control-X-prefix}.
504
505 @item
506 @cindex @kbd{C-x @key{RET}}
507 @vindex mule-keymap
508 @code{mule-keymap} is the global keymap used for the @kbd{C-x @key{RET}}
509 prefix key.
510
511 @item
512 @cindex @kbd{C-x 4}
513 @vindex ctl-x-4-map
514 @code{ctl-x-4-map} is the global keymap used for the @kbd{C-x 4} prefix
515 key.
516
517 @item
518 @cindex @kbd{C-x 5}
519 @vindex ctl-x-5-map
520 @code{ctl-x-5-map} is the global keymap used for the @kbd{C-x 5} prefix
521 key.
522
523 @item
524 @cindex @kbd{C-x 6}
525 @vindex 2C-mode-map
526 @code{2C-mode-map} is the global keymap used for the @kbd{C-x 6} prefix
527 key.
528
529 @item
530 @cindex @kbd{C-x v}
531 @vindex vc-prefix-map
532 @code{vc-prefix-map} is the global keymap used for the @kbd{C-x v} prefix
533 key.
534
535 @item
536 @cindex @kbd{M-g}
537 @vindex goto-map
538 @code{goto-map} is the global keymap used for the @kbd{M-g} prefix
539 key.
540
541 @item
542 @cindex @kbd{M-s}
543 @vindex search-map
544 @code{search-map} is the global keymap used for the @kbd{M-s} prefix
545 key.
546
547 @item
548 @cindex @kbd{M-o}
549 @vindex facemenu-keymap
550 @code{facemenu-keymap} is the global keymap used for the @kbd{M-o}
551 prefix key.
552
553 @item
554 The other Emacs prefix keys are @kbd{C-x @@}, @kbd{C-x a i}, @kbd{C-x
555 @key{ESC}} and @kbd{@key{ESC} @key{ESC}}. They use keymaps that have
556 no special names.
557 @end itemize
558
559 The keymap binding of a prefix key is used for looking up the event
560 that follows the prefix key. (It may instead be a symbol whose function
561 definition is a keymap. The effect is the same, but the symbol serves
562 as a name for the prefix key.) Thus, the binding of @kbd{C-x} is the
563 symbol @code{Control-X-prefix}, whose function cell holds the keymap
564 for @kbd{C-x} commands. (The same keymap is also the value of
565 @code{ctl-x-map}.)
566
567 Prefix key definitions can appear in any active keymap. The
568 definitions of @kbd{C-c}, @kbd{C-x}, @kbd{C-h} and @key{ESC} as prefix
569 keys appear in the global map, so these prefix keys are always
570 available. Major and minor modes can redefine a key as a prefix by
571 putting a prefix key definition for it in the local map or the minor
572 mode's map. @xref{Active Keymaps}.
573
574 If a key is defined as a prefix in more than one active map, then its
575 various definitions are in effect merged: the commands defined in the
576 minor mode keymaps come first, followed by those in the local map's
577 prefix definition, and then by those from the global map.
578
579 In the following example, we make @kbd{C-p} a prefix key in the local
580 keymap, in such a way that @kbd{C-p} is identical to @kbd{C-x}. Then
581 the binding for @kbd{C-p C-f} is the function @code{find-file}, just
582 like @kbd{C-x C-f}. The key sequence @kbd{C-p 6} is not found in any
583 active keymap.
584
585 @example
586 @group
587 (use-local-map (make-sparse-keymap))
588 @result{} nil
589 @end group
590 @group
591 (local-set-key "\C-p" ctl-x-map)
592 @result{} nil
593 @end group
594 @group
595 (key-binding "\C-p\C-f")
596 @result{} find-file
597 @end group
598
599 @group
600 (key-binding "\C-p6")
601 @result{} nil
602 @end group
603 @end example
604
605 @defun define-prefix-command symbol &optional mapvar prompt
606 @cindex prefix command
607 @anchor{Definition of define-prefix-command}
608 This function prepares @var{symbol} for use as a prefix key's binding:
609 it creates a sparse keymap and stores it as @var{symbol}'s function
610 definition. Subsequently binding a key sequence to @var{symbol} will
611 make that key sequence into a prefix key. The return value is @code{symbol}.
612
613 This function also sets @var{symbol} as a variable, with the keymap as
614 its value. But if @var{mapvar} is non-@code{nil}, it sets @var{mapvar}
615 as a variable instead.
616
617 If @var{prompt} is non-@code{nil}, that becomes the overall prompt
618 string for the keymap. The prompt string should be given for menu keymaps
619 (@pxref{Defining Menus}).
620 @end defun
621
622 @node Active Keymaps
623 @section Active Keymaps
624 @cindex active keymap
625 @cindex global keymap
626 @cindex local keymap
627
628 Emacs normally contains many keymaps; at any given time, just a few
629 of them are @dfn{active}, meaning that they participate in the
630 interpretation of user input. All the active keymaps are used
631 together to determine what command to execute when a key is entered.
632
633 Normally the active keymaps are the @code{keymap} property keymap,
634 the keymaps of any enabled minor modes, the current buffer's local
635 keymap, and the global keymap, in that order. Emacs searches for each
636 input key sequence in all these keymaps. @xref{Searching Keymaps},
637 for more details of this procedure.
638
639 When the key sequence starts with a mouse event,
640 the active keymaps are determined based on the
641 position in that event. If the event happened on a string embedded
642 with a @code{display}, @code{before-string}, or @code{after-string}
643 property (@pxref{Special Properties}), the non-@code{nil} map
644 properties of the string override those of the buffer (if the
645 underlying buffer text contains map properties in its text properties
646 or overlays, they are ignored).
647
648 The @dfn{global keymap} holds the bindings of keys that are defined
649 regardless of the current buffer, such as @kbd{C-f}. The variable
650 @code{global-map} holds this keymap, which is always active.
651
652 Each buffer may have another keymap, its @dfn{local keymap}, which
653 may contain new or overriding definitions for keys. The current
654 buffer's local keymap is always active except when
655 @code{overriding-local-map} overrides it. The @code{local-map} text
656 or overlay property can specify an alternative local keymap for certain
657 parts of the buffer; see @ref{Special Properties}.
658
659 Each minor mode can have a keymap; if it does, the keymap is active
660 when the minor mode is enabled. Modes for emulation can specify
661 additional active keymaps through the variable
662 @code{emulation-mode-map-alists}.
663
664 The highest precedence normal keymap comes from the @code{keymap}
665 text or overlay property. If that is non-@code{nil}, it is the first
666 keymap to be processed, in normal circumstances.
667
668 However, there are also special ways for programs to substitute
669 other keymaps for some of those. The variable
670 @code{overriding-local-map}, if non-@code{nil}, specifies a keymap
671 that replaces all the usual active keymaps except the global keymap.
672
673 The very highest precedence keymap comes from
674 @code{overriding-terminal-local-map}; it operates on a per-terminal basis and
675 is normally used for modal/transient keybindings.
676
677 @cindex major mode keymap
678 Since every buffer that uses the same major mode normally uses the
679 same local keymap, you can think of the keymap as local to the mode. A
680 change to the local keymap of a buffer (using @code{local-set-key}, for
681 example) is seen also in the other buffers that share that keymap.
682
683 The local keymaps that are used for Lisp mode and some other major
684 modes exist even if they have not yet been used. These local keymaps are
685 the values of variables such as @code{lisp-mode-map}. For most major
686 modes, which are less frequently used, the local keymap is constructed
687 only when the mode is used for the first time in a session.
688
689 The minibuffer has local keymaps, too; they contain various completion
690 and exit commands. @xref{Intro to Minibuffers}.
691
692 Emacs has other keymaps that are used in a different way---translating
693 events within @code{read-key-sequence}. @xref{Translation Keymaps}.
694
695 @xref{Standard Keymaps}, for a list of some standard keymaps.
696
697 @defun current-active-maps &optional olp position
698 This returns the list of active keymaps that would be used by the
699 command loop in the current circumstances to look up a key sequence.
700 Normally it ignores @code{overriding-local-map} and
701 @code{overriding-terminal-local-map}, but if @var{olp} is non-@code{nil}
702 then it pays attention to them. @var{position} can optionally be either
703 an event position as returned by @code{event-start} or a buffer
704 position, and may change the keymaps as described for
705 @code{key-binding}.
706 @end defun
707
708 @defun key-binding key &optional accept-defaults no-remap position
709 This function returns the binding for @var{key} according to the
710 current active keymaps. The result is @code{nil} if @var{key} is
711 undefined in the keymaps.
712
713 The argument @var{accept-defaults} controls checking for default
714 bindings, as in @code{lookup-key} (@pxref{Functions for Key Lookup}).
715
716 When commands are remapped (@pxref{Remapping Commands}),
717 @code{key-binding} normally processes command remappings so as to
718 return the remapped command that will actually be executed. However,
719 if @var{no-remap} is non-@code{nil}, @code{key-binding} ignores
720 remappings and returns the binding directly specified for @var{key}.
721
722 If @var{key} starts with a mouse event (perhaps following a prefix
723 event), the maps to be consulted are determined based on the event's
724 position. Otherwise, they are determined based on the value of point.
725 However, you can override either of them by specifying @var{position}.
726 If @var{position} is non-@code{nil}, it should be either a buffer
727 position or an event position like the value of @code{event-start}.
728 Then the maps consulted are determined based on @var{position}.
729
730 An error is signaled if @var{key} is not a string or a vector.
731
732 @example
733 @group
734 (key-binding "\C-x\C-f")
735 @result{} find-file
736 @end group
737 @end example
738 @end defun
739
740 @node Searching Keymaps
741 @section Searching the Active Keymaps
742 @cindex searching active keymaps for keys
743
744 After translation of event subsequences (@pxref{Translation
745 Keymaps}) Emacs looks for them in the active keymaps. Here is a
746 pseudo-Lisp description of the order and conditions for searching
747 them:
748
749 @lisp
750 (or (cond
751 (overriding-terminal-local-map
752 (@var{find-in} overriding-terminal-local-map))
753 (overriding-local-map
754 (@var{find-in} overriding-local-map))
755 ((or (@var{find-in} (get-char-property (point) 'keymap))
756 (@var{find-in} @var{temp-map})
757 (@var{find-in-any} emulation-mode-map-alists)
758 (@var{find-in-any} minor-mode-overriding-map-alist)
759 (@var{find-in-any} minor-mode-map-alist)
760 (if (get-text-property (point) 'local-map)
761 (@var{find-in} (get-char-property (point) 'local-map))
762 (@var{find-in} (current-local-map))))))
763 (@var{find-in} (current-global-map)))
764 @end lisp
765
766 @noindent
767 @var{find-in} and @var{find-in-any} are pseudo functions that search
768 in one keymap and in an alist of keymaps, respectively. (Searching a
769 single keymap for a binding is called @dfn{key lookup}; see @ref{Key
770 Lookup}.) If the key sequence starts with a mouse event, that event's position
771 is used instead of point and the current buffer. Mouse events on an
772 embedded string use non-@code{nil} text properties from that string
773 instead of the buffer. @var{temp-map} is a pseudo variable that
774 represents the effect of a @code{set-temporary-overlay-map} call.
775
776 When a match is found (@pxref{Key Lookup}), if the binding in the
777 keymap is a function, the search is over. However if the keymap entry
778 is a symbol with a value or a string, Emacs replaces the input key
779 sequences with the variable's value or the string, and restarts the
780 search of the active keymaps.
781
782 The function finally found might also be remapped. @xref{Remapping
783 Commands}.
784
785 @node Controlling Active Maps
786 @section Controlling the Active Keymaps
787
788 @defvar global-map
789 This variable contains the default global keymap that maps Emacs
790 keyboard input to commands. The global keymap is normally this
791 keymap. The default global keymap is a full keymap that binds
792 @code{self-insert-command} to all of the printing characters.
793
794 It is normal practice to change the bindings in the global keymap, but you
795 should not assign this variable any value other than the keymap it starts
796 out with.
797 @end defvar
798
799 @defun current-global-map
800 This function returns the current global keymap. This is the same as
801 the value of @code{global-map} unless you change one or the other.
802 The return value is a reference, not a copy; if you use
803 @code{define-key} or other functions on it you will alter global
804 bindings.
805
806 @example
807 @group
808 (current-global-map)
809 @result{} (keymap [set-mark-command beginning-of-line @dots{}
810 delete-backward-char])
811 @end group
812 @end example
813 @end defun
814
815 @defun current-local-map
816 This function returns the current buffer's local keymap, or @code{nil}
817 if it has none. In the following example, the keymap for the
818 @file{*scratch*} buffer (using Lisp Interaction mode) is a sparse keymap
819 in which the entry for @key{ESC}, @acronym{ASCII} code 27, is another sparse
820 keymap.
821
822 @example
823 @group
824 (current-local-map)
825 @result{} (keymap
826 (10 . eval-print-last-sexp)
827 (9 . lisp-indent-line)
828 (127 . backward-delete-char-untabify)
829 @end group
830 @group
831 (27 keymap
832 (24 . eval-defun)
833 (17 . indent-sexp)))
834 @end group
835 @end example
836 @end defun
837
838 @code{current-local-map} returns a reference to the local keymap, not
839 a copy of it; if you use @code{define-key} or other functions on it
840 you will alter local bindings.
841
842 @defun current-minor-mode-maps
843 This function returns a list of the keymaps of currently enabled minor modes.
844 @end defun
845
846 @defun use-global-map keymap
847 This function makes @var{keymap} the new current global keymap. It
848 returns @code{nil}.
849
850 It is very unusual to change the global keymap.
851 @end defun
852
853 @defun use-local-map keymap
854 This function makes @var{keymap} the new local keymap of the current
855 buffer. If @var{keymap} is @code{nil}, then the buffer has no local
856 keymap. @code{use-local-map} returns @code{nil}. Most major mode
857 commands use this function.
858 @end defun
859
860 @c Emacs 19 feature
861 @defvar minor-mode-map-alist
862 @anchor{Definition of minor-mode-map-alist}
863 This variable is an alist describing keymaps that may or may not be
864 active according to the values of certain variables. Its elements look
865 like this:
866
867 @example
868 (@var{variable} . @var{keymap})
869 @end example
870
871 The keymap @var{keymap} is active whenever @var{variable} has a
872 non-@code{nil} value. Typically @var{variable} is the variable that
873 enables or disables a minor mode. @xref{Keymaps and Minor Modes}.
874
875 Note that elements of @code{minor-mode-map-alist} do not have the same
876 structure as elements of @code{minor-mode-alist}. The map must be the
877 @sc{cdr} of the element; a list with the map as the second element will
878 not do. The @sc{cdr} can be either a keymap (a list) or a symbol whose
879 function definition is a keymap.
880
881 When more than one minor mode keymap is active, the earlier one in
882 @code{minor-mode-map-alist} takes priority. But you should design
883 minor modes so that they don't interfere with each other. If you do
884 this properly, the order will not matter.
885
886 See @ref{Keymaps and Minor Modes}, for more information about minor
887 modes. See also @code{minor-mode-key-binding} (@pxref{Functions for Key
888 Lookup}).
889 @end defvar
890
891 @defvar minor-mode-overriding-map-alist
892 This variable allows major modes to override the key bindings for
893 particular minor modes. The elements of this alist look like the
894 elements of @code{minor-mode-map-alist}: @code{(@var{variable}
895 . @var{keymap})}.
896
897 If a variable appears as an element of
898 @code{minor-mode-overriding-map-alist}, the map specified by that
899 element totally replaces any map specified for the same variable in
900 @code{minor-mode-map-alist}.
901
902 @code{minor-mode-overriding-map-alist} is automatically buffer-local in
903 all buffers.
904 @end defvar
905
906 @defvar overriding-local-map
907 If non-@code{nil}, this variable holds a keymap to use instead of the
908 buffer's local keymap, any text property or overlay keymaps, and any
909 minor mode keymaps. This keymap, if specified, overrides all other
910 maps that would have been active, except for the current global map.
911 @end defvar
912
913 @defvar overriding-terminal-local-map
914 If non-@code{nil}, this variable holds a keymap to use instead of
915 @code{overriding-local-map}, the buffer's local keymap, text property
916 or overlay keymaps, and all the minor mode keymaps.
917
918 This variable is always local to the current terminal and cannot be
919 buffer-local. @xref{Multiple Terminals}. It is used to implement
920 incremental search mode.
921 @end defvar
922
923 @defvar overriding-local-map-menu-flag
924 If this variable is non-@code{nil}, the value of
925 @code{overriding-local-map} or @code{overriding-terminal-local-map} can
926 affect the display of the menu bar. The default value is @code{nil}, so
927 those map variables have no effect on the menu bar.
928
929 Note that these two map variables do affect the execution of key
930 sequences entered using the menu bar, even if they do not affect the
931 menu bar display. So if a menu bar key sequence comes in, you should
932 clear the variables before looking up and executing that key sequence.
933 Modes that use the variables would typically do this anyway; normally
934 they respond to events that they do not handle by ``unreading'' them and
935 exiting.
936 @end defvar
937
938 @defvar special-event-map
939 This variable holds a keymap for special events. If an event type has a
940 binding in this keymap, then it is special, and the binding for the
941 event is run directly by @code{read-event}. @xref{Special Events}.
942 @end defvar
943
944 @defvar emulation-mode-map-alists
945 This variable holds a list of keymap alists to use for emulations
946 modes. It is intended for modes or packages using multiple minor-mode
947 keymaps. Each element is a keymap alist which has the same format and
948 meaning as @code{minor-mode-map-alist}, or a symbol with a variable
949 binding which is such an alist. The ``active'' keymaps in each alist
950 are used before @code{minor-mode-map-alist} and
951 @code{minor-mode-overriding-map-alist}.
952 @end defvar
953
954 @defun set-temporary-overlay-map keymap &optional keep
955 This function adds @var{keymap} as a temporary keymap that takes
956 precedence over most other keymaps. It does not take precedence over
957 the ``overriding'' maps (see above); and unlike them, if no match for
958 a key is found in @var{keymap}, the search continues.
959
960 Normally, @var{keymap} is used only once. If the optional argument
961 @var{pred} is @code{t}, the map stays active if a key from @var{keymap}
962 is used. @var{pred} can also be a function of no arguments: if it returns
963 non-@code{nil} then @var{keymap} stays active.
964
965 For a pseudo-Lisp description of exactly how and when this keymap applies,
966 @pxref{Searching Keymaps}.
967 @end defun
968
969 @node Key Lookup
970 @section Key Lookup
971 @cindex key lookup
972 @cindex keymap entry
973
974 @dfn{Key lookup} is the process of finding the binding of a key
975 sequence from a given keymap. The execution or use of the binding is
976 not part of key lookup.
977
978 Key lookup uses just the event type of each event in the key sequence;
979 the rest of the event is ignored. In fact, a key sequence used for key
980 lookup may designate a mouse event with just its types (a symbol)
981 instead of the entire event (a list). @xref{Input Events}. Such
982 a ``key sequence'' is insufficient for @code{command-execute} to run,
983 but it is sufficient for looking up or rebinding a key.
984
985 When the key sequence consists of multiple events, key lookup
986 processes the events sequentially: the binding of the first event is
987 found, and must be a keymap; then the second event's binding is found in
988 that keymap, and so on until all the events in the key sequence are used
989 up. (The binding thus found for the last event may or may not be a
990 keymap.) Thus, the process of key lookup is defined in terms of a
991 simpler process for looking up a single event in a keymap. How that is
992 done depends on the type of object associated with the event in that
993 keymap.
994
995 Let's use the term @dfn{keymap entry} to describe the value found by
996 looking up an event type in a keymap. (This doesn't include the item
997 string and other extra elements in a keymap element for a menu item, because
998 @code{lookup-key} and other key lookup functions don't include them in
999 the returned value.) While any Lisp object may be stored in a keymap
1000 as a keymap entry, not all make sense for key lookup. Here is a table
1001 of the meaningful types of keymap entries:
1002
1003 @table @asis
1004 @item @code{nil}
1005 @cindex @code{nil} in keymap
1006 @code{nil} means that the events used so far in the lookup form an
1007 undefined key. When a keymap fails to mention an event type at all, and
1008 has no default binding, that is equivalent to a binding of @code{nil}
1009 for that event type.
1010
1011 @item @var{command}
1012 @cindex command in keymap
1013 The events used so far in the lookup form a complete key,
1014 and @var{command} is its binding. @xref{What Is a Function}.
1015
1016 @item @var{array}
1017 @cindex string in keymap
1018 The array (either a string or a vector) is a keyboard macro. The events
1019 used so far in the lookup form a complete key, and the array is its
1020 binding. See @ref{Keyboard Macros}, for more information.
1021
1022 @item @var{keymap}
1023 @cindex keymap in keymap
1024 The events used so far in the lookup form a prefix key. The next
1025 event of the key sequence is looked up in @var{keymap}.
1026
1027 @item @var{list}
1028 @cindex list in keymap
1029 The meaning of a list depends on what it contains:
1030
1031 @itemize @bullet
1032 @item
1033 If the @sc{car} of @var{list} is the symbol @code{keymap}, then the list
1034 is a keymap, and is treated as a keymap (see above).
1035
1036 @item
1037 @cindex @code{lambda} in keymap
1038 If the @sc{car} of @var{list} is @code{lambda}, then the list is a
1039 lambda expression. This is presumed to be a function, and is treated
1040 as such (see above). In order to execute properly as a key binding,
1041 this function must be a command---it must have an @code{interactive}
1042 specification. @xref{Defining Commands}.
1043
1044 @item
1045 If the @sc{car} of @var{list} is a keymap and the @sc{cdr} is an event
1046 type, then this is an @dfn{indirect entry}:
1047
1048 @example
1049 (@var{othermap} . @var{othertype})
1050 @end example
1051
1052 When key lookup encounters an indirect entry, it looks up instead the
1053 binding of @var{othertype} in @var{othermap} and uses that.
1054
1055 This feature permits you to define one key as an alias for another key.
1056 For example, an entry whose @sc{car} is the keymap called @code{esc-map}
1057 and whose @sc{cdr} is 32 (the code for @key{SPC}) means, ``Use the global
1058 binding of @kbd{Meta-@key{SPC}}, whatever that may be''.
1059 @end itemize
1060
1061 @item @var{symbol}
1062 @cindex symbol in keymap
1063 The function definition of @var{symbol} is used in place of
1064 @var{symbol}. If that too is a symbol, then this process is repeated,
1065 any number of times. Ultimately this should lead to an object that is
1066 a keymap, a command, or a keyboard macro. A list is allowed if it is a
1067 keymap or a command, but indirect entries are not understood when found
1068 via symbols.
1069
1070 Note that keymaps and keyboard macros (strings and vectors) are not
1071 valid functions, so a symbol with a keymap, string, or vector as its
1072 function definition is invalid as a function. It is, however, valid as
1073 a key binding. If the definition is a keyboard macro, then the symbol
1074 is also valid as an argument to @code{command-execute}
1075 (@pxref{Interactive Call}).
1076
1077 @cindex @code{undefined} in keymap
1078 The symbol @code{undefined} is worth special mention: it means to treat
1079 the key as undefined. Strictly speaking, the key is defined, and its
1080 binding is the command @code{undefined}; but that command does the same
1081 thing that is done automatically for an undefined key: it rings the bell
1082 (by calling @code{ding}) but does not signal an error.
1083
1084 @cindex preventing prefix key
1085 @code{undefined} is used in local keymaps to override a global key
1086 binding and make the key ``undefined'' locally. A local binding of
1087 @code{nil} would fail to do this because it would not override the
1088 global binding.
1089
1090 @item @var{anything else}
1091 If any other type of object is found, the events used so far in the
1092 lookup form a complete key, and the object is its binding, but the
1093 binding is not executable as a command.
1094 @end table
1095
1096 In short, a keymap entry may be a keymap, a command, a keyboard
1097 macro, a symbol that leads to one of them, or an indirection or
1098 @code{nil}.
1099
1100 @node Functions for Key Lookup
1101 @section Functions for Key Lookup
1102
1103 Here are the functions and variables pertaining to key lookup.
1104
1105 @defun lookup-key keymap key &optional accept-defaults
1106 This function returns the definition of @var{key} in @var{keymap}. All
1107 the other functions described in this chapter that look up keys use
1108 @code{lookup-key}. Here are examples:
1109
1110 @example
1111 @group
1112 (lookup-key (current-global-map) "\C-x\C-f")
1113 @result{} find-file
1114 @end group
1115 @group
1116 (lookup-key (current-global-map) (kbd "C-x C-f"))
1117 @result{} find-file
1118 @end group
1119 @group
1120 (lookup-key (current-global-map) "\C-x\C-f12345")
1121 @result{} 2
1122 @end group
1123 @end example
1124
1125 If the string or vector @var{key} is not a valid key sequence according
1126 to the prefix keys specified in @var{keymap}, it must be ``too long''
1127 and have extra events at the end that do not fit into a single key
1128 sequence. Then the value is a number, the number of events at the front
1129 of @var{key} that compose a complete key.
1130
1131 @c Emacs 19 feature
1132 If @var{accept-defaults} is non-@code{nil}, then @code{lookup-key}
1133 considers default bindings as well as bindings for the specific events
1134 in @var{key}. Otherwise, @code{lookup-key} reports only bindings for
1135 the specific sequence @var{key}, ignoring default bindings except when
1136 you explicitly ask about them. (To do this, supply @code{t} as an
1137 element of @var{key}; see @ref{Format of Keymaps}.)
1138
1139 If @var{key} contains a meta character (not a function key), that
1140 character is implicitly replaced by a two-character sequence: the value
1141 of @code{meta-prefix-char}, followed by the corresponding non-meta
1142 character. Thus, the first example below is handled by conversion into
1143 the second example.
1144
1145 @example
1146 @group
1147 (lookup-key (current-global-map) "\M-f")
1148 @result{} forward-word
1149 @end group
1150 @group
1151 (lookup-key (current-global-map) "\ef")
1152 @result{} forward-word
1153 @end group
1154 @end example
1155
1156 Unlike @code{read-key-sequence}, this function does not modify the
1157 specified events in ways that discard information (@pxref{Key Sequence
1158 Input}). In particular, it does not convert letters to lower case and
1159 it does not change drag events to clicks.
1160 @end defun
1161
1162 @deffn Command undefined
1163 Used in keymaps to undefine keys. It calls @code{ding}, but does
1164 not cause an error.
1165 @end deffn
1166
1167 @defun local-key-binding key &optional accept-defaults
1168 This function returns the binding for @var{key} in the current
1169 local keymap, or @code{nil} if it is undefined there.
1170
1171 @c Emacs 19 feature
1172 The argument @var{accept-defaults} controls checking for default bindings,
1173 as in @code{lookup-key} (above).
1174 @end defun
1175
1176 @defun global-key-binding key &optional accept-defaults
1177 This function returns the binding for command @var{key} in the
1178 current global keymap, or @code{nil} if it is undefined there.
1179
1180 @c Emacs 19 feature
1181 The argument @var{accept-defaults} controls checking for default bindings,
1182 as in @code{lookup-key} (above).
1183 @end defun
1184
1185 @c Emacs 19 feature
1186 @defun minor-mode-key-binding key &optional accept-defaults
1187 This function returns a list of all the active minor mode bindings of
1188 @var{key}. More precisely, it returns an alist of pairs
1189 @code{(@var{modename} . @var{binding})}, where @var{modename} is the
1190 variable that enables the minor mode, and @var{binding} is @var{key}'s
1191 binding in that mode. If @var{key} has no minor-mode bindings, the
1192 value is @code{nil}.
1193
1194 If the first binding found is not a prefix definition (a keymap or a
1195 symbol defined as a keymap), all subsequent bindings from other minor
1196 modes are omitted, since they would be completely shadowed. Similarly,
1197 the list omits non-prefix bindings that follow prefix bindings.
1198
1199 The argument @var{accept-defaults} controls checking for default
1200 bindings, as in @code{lookup-key} (above).
1201 @end defun
1202
1203 @defopt meta-prefix-char
1204 @cindex @key{ESC}
1205 This variable is the meta-prefix character code. It is used for
1206 translating a meta character to a two-character sequence so it can be
1207 looked up in a keymap. For useful results, the value should be a
1208 prefix event (@pxref{Prefix Keys}). The default value is 27, which is
1209 the @acronym{ASCII} code for @key{ESC}.
1210
1211 As long as the value of @code{meta-prefix-char} remains 27, key lookup
1212 translates @kbd{M-b} into @kbd{@key{ESC} b}, which is normally defined
1213 as the @code{backward-word} command. However, if you were to set
1214 @code{meta-prefix-char} to 24, the code for @kbd{C-x}, then Emacs will
1215 translate @kbd{M-b} into @kbd{C-x b}, whose standard binding is the
1216 @code{switch-to-buffer} command. (Don't actually do this!) Here is an
1217 illustration of what would happen:
1218
1219 @smallexample
1220 @group
1221 meta-prefix-char ; @r{The default value.}
1222 @result{} 27
1223 @end group
1224 @group
1225 (key-binding "\M-b")
1226 @result{} backward-word
1227 @end group
1228 @group
1229 ?\C-x ; @r{The print representation}
1230 @result{} 24 ; @r{of a character.}
1231 @end group
1232 @group
1233 (setq meta-prefix-char 24)
1234 @result{} 24
1235 @end group
1236 @group
1237 (key-binding "\M-b")
1238 @result{} switch-to-buffer ; @r{Now, typing @kbd{M-b} is}
1239 ; @r{like typing @kbd{C-x b}.}
1240
1241 (setq meta-prefix-char 27) ; @r{Avoid confusion!}
1242 @result{} 27 ; @r{Restore the default value!}
1243 @end group
1244 @end smallexample
1245
1246 This translation of one event into two happens only for characters, not
1247 for other kinds of input events. Thus, @kbd{M-@key{F1}}, a function
1248 key, is not converted into @kbd{@key{ESC} @key{F1}}.
1249 @end defopt
1250
1251 @node Changing Key Bindings
1252 @section Changing Key Bindings
1253 @cindex changing key bindings
1254 @cindex rebinding
1255
1256 The way to rebind a key is to change its entry in a keymap. If you
1257 change a binding in the global keymap, the change is effective in all
1258 buffers (though it has no direct effect in buffers that shadow the
1259 global binding with a local one). If you change the current buffer's
1260 local map, that usually affects all buffers using the same major mode.
1261 The @code{global-set-key} and @code{local-set-key} functions are
1262 convenient interfaces for these operations (@pxref{Key Binding
1263 Commands}). You can also use @code{define-key}, a more general
1264 function; then you must explicitly specify the map to change.
1265
1266 When choosing the key sequences for Lisp programs to rebind, please
1267 follow the Emacs conventions for use of various keys (@pxref{Key
1268 Binding Conventions}).
1269
1270 @cindex meta character key constants
1271 @cindex control character key constants
1272 In writing the key sequence to rebind, it is good to use the special
1273 escape sequences for control and meta characters (@pxref{String Type}).
1274 The syntax @samp{\C-} means that the following character is a control
1275 character and @samp{\M-} means that the following character is a meta
1276 character. Thus, the string @code{"\M-x"} is read as containing a
1277 single @kbd{M-x}, @code{"\C-f"} is read as containing a single
1278 @kbd{C-f}, and @code{"\M-\C-x"} and @code{"\C-\M-x"} are both read as
1279 containing a single @kbd{C-M-x}. You can also use this escape syntax in
1280 vectors, as well as others that aren't allowed in strings; one example
1281 is @samp{[?\C-\H-x home]}. @xref{Character Type}.
1282
1283 The key definition and lookup functions accept an alternate syntax for
1284 event types in a key sequence that is a vector: you can use a list
1285 containing modifier names plus one base event (a character or function
1286 key name). For example, @code{(control ?a)} is equivalent to
1287 @code{?\C-a} and @code{(hyper control left)} is equivalent to
1288 @code{C-H-left}. One advantage of such lists is that the precise
1289 numeric codes for the modifier bits don't appear in compiled files.
1290
1291 The functions below signal an error if @var{keymap} is not a keymap,
1292 or if @var{key} is not a string or vector representing a key sequence.
1293 You can use event types (symbols) as shorthand for events that are
1294 lists. The @code{kbd} function (@pxref{Key Sequences}) is a
1295 convenient way to specify the key sequence.
1296
1297 @defun define-key keymap key binding
1298 This function sets the binding for @var{key} in @var{keymap}. (If
1299 @var{key} is more than one event long, the change is actually made
1300 in another keymap reached from @var{keymap}.) The argument
1301 @var{binding} can be any Lisp object, but only certain types are
1302 meaningful. (For a list of meaningful types, see @ref{Key Lookup}.)
1303 The value returned by @code{define-key} is @var{binding}.
1304
1305 If @var{key} is @code{[t]}, this sets the default binding in
1306 @var{keymap}. When an event has no binding of its own, the Emacs
1307 command loop uses the keymap's default binding, if there is one.
1308
1309 @cindex invalid prefix key error
1310 @cindex key sequence error
1311 Every prefix of @var{key} must be a prefix key (i.e., bound to a keymap)
1312 or undefined; otherwise an error is signaled. If some prefix of
1313 @var{key} is undefined, then @code{define-key} defines it as a prefix
1314 key so that the rest of @var{key} can be defined as specified.
1315
1316 If there was previously no binding for @var{key} in @var{keymap}, the
1317 new binding is added at the beginning of @var{keymap}. The order of
1318 bindings in a keymap makes no difference for keyboard input, but it
1319 does matter for menu keymaps (@pxref{Menu Keymaps}).
1320 @end defun
1321
1322 This example creates a sparse keymap and makes a number of
1323 bindings in it:
1324
1325 @smallexample
1326 @group
1327 (setq map (make-sparse-keymap))
1328 @result{} (keymap)
1329 @end group
1330 @group
1331 (define-key map "\C-f" 'forward-char)
1332 @result{} forward-char
1333 @end group
1334 @group
1335 map
1336 @result{} (keymap (6 . forward-char))
1337 @end group
1338
1339 @group
1340 ;; @r{Build sparse submap for @kbd{C-x} and bind @kbd{f} in that.}
1341 (define-key map (kbd "C-x f") 'forward-word)
1342 @result{} forward-word
1343 @end group
1344 @group
1345 map
1346 @result{} (keymap
1347 (24 keymap ; @kbd{C-x}
1348 (102 . forward-word)) ; @kbd{f}
1349 (6 . forward-char)) ; @kbd{C-f}
1350 @end group
1351
1352 @group
1353 ;; @r{Bind @kbd{C-p} to the @code{ctl-x-map}.}
1354 (define-key map (kbd "C-p") ctl-x-map)
1355 ;; @code{ctl-x-map}
1356 @result{} [nil @dots{} find-file @dots{} backward-kill-sentence]
1357 @end group
1358
1359 @group
1360 ;; @r{Bind @kbd{C-f} to @code{foo} in the @code{ctl-x-map}.}
1361 (define-key map (kbd "C-p C-f") 'foo)
1362 @result{} 'foo
1363 @end group
1364 @group
1365 map
1366 @result{} (keymap ; @r{Note @code{foo} in @code{ctl-x-map}.}
1367 (16 keymap [nil @dots{} foo @dots{} backward-kill-sentence])
1368 (24 keymap
1369 (102 . forward-word))
1370 (6 . forward-char))
1371 @end group
1372 @end smallexample
1373
1374 @noindent
1375 Note that storing a new binding for @kbd{C-p C-f} actually works by
1376 changing an entry in @code{ctl-x-map}, and this has the effect of
1377 changing the bindings of both @kbd{C-p C-f} and @kbd{C-x C-f} in the
1378 default global map.
1379
1380 The function @code{substitute-key-definition} scans a keymap for
1381 keys that have a certain binding and rebinds them with a different
1382 binding. Another feature which is cleaner and can often produce the
1383 same results to remap one command into another (@pxref{Remapping
1384 Commands}).
1385
1386 @defun substitute-key-definition olddef newdef keymap &optional oldmap
1387 @cindex replace bindings
1388 This function replaces @var{olddef} with @var{newdef} for any keys in
1389 @var{keymap} that were bound to @var{olddef}. In other words,
1390 @var{olddef} is replaced with @var{newdef} wherever it appears. The
1391 function returns @code{nil}.
1392
1393 For example, this redefines @kbd{C-x C-f}, if you do it in an Emacs with
1394 standard bindings:
1395
1396 @smallexample
1397 @group
1398 (substitute-key-definition
1399 'find-file 'find-file-read-only (current-global-map))
1400 @end group
1401 @end smallexample
1402
1403 @c Emacs 19 feature
1404 If @var{oldmap} is non-@code{nil}, that changes the behavior of
1405 @code{substitute-key-definition}: the bindings in @var{oldmap} determine
1406 which keys to rebind. The rebindings still happen in @var{keymap}, not
1407 in @var{oldmap}. Thus, you can change one map under the control of the
1408 bindings in another. For example,
1409
1410 @smallexample
1411 (substitute-key-definition
1412 'delete-backward-char 'my-funny-delete
1413 my-map global-map)
1414 @end smallexample
1415
1416 @noindent
1417 puts the special deletion command in @code{my-map} for whichever keys
1418 are globally bound to the standard deletion command.
1419
1420 Here is an example showing a keymap before and after substitution:
1421
1422 @smallexample
1423 @group
1424 (setq map '(keymap
1425 (?1 . olddef-1)
1426 (?2 . olddef-2)
1427 (?3 . olddef-1)))
1428 @result{} (keymap (49 . olddef-1) (50 . olddef-2) (51 . olddef-1))
1429 @end group
1430
1431 @group
1432 (substitute-key-definition 'olddef-1 'newdef map)
1433 @result{} nil
1434 @end group
1435 @group
1436 map
1437 @result{} (keymap (49 . newdef) (50 . olddef-2) (51 . newdef))
1438 @end group
1439 @end smallexample
1440 @end defun
1441
1442 @defun suppress-keymap keymap &optional nodigits
1443 @cindex @code{self-insert-command} override
1444 This function changes the contents of the full keymap @var{keymap} by
1445 remapping @code{self-insert-command} to the command @code{undefined}
1446 (@pxref{Remapping Commands}). This has the effect of undefining all
1447 printing characters, thus making ordinary insertion of text impossible.
1448 @code{suppress-keymap} returns @code{nil}.
1449
1450 If @var{nodigits} is @code{nil}, then @code{suppress-keymap} defines
1451 digits to run @code{digit-argument}, and @kbd{-} to run
1452 @code{negative-argument}. Otherwise it makes them undefined like the
1453 rest of the printing characters.
1454
1455 @cindex yank suppression
1456 @cindex @code{quoted-insert} suppression
1457 The @code{suppress-keymap} function does not make it impossible to
1458 modify a buffer, as it does not suppress commands such as @code{yank}
1459 and @code{quoted-insert}. To prevent any modification of a buffer, make
1460 it read-only (@pxref{Read Only Buffers}).
1461
1462 Since this function modifies @var{keymap}, you would normally use it
1463 on a newly created keymap. Operating on an existing keymap
1464 that is used for some other purpose is likely to cause trouble; for
1465 example, suppressing @code{global-map} would make it impossible to use
1466 most of Emacs.
1467
1468 This function can be used to initialize the local keymap of a major
1469 mode for which insertion of text is not desirable. But usually such a
1470 mode should be derived from @code{special-mode} (@pxref{Basic Major
1471 Modes}); then its keymap will automatically inherit from
1472 @code{special-mode-map}, which is already suppressed. Here is how
1473 @code{special-mode-map} is defined:
1474
1475 @smallexample
1476 @group
1477 (defvar special-mode-map
1478 (let ((map (make-sparse-keymap)))
1479 (suppress-keymap map)
1480 (define-key map "q" 'quit-window)
1481 @dots{}
1482 map))
1483 @end group
1484 @end smallexample
1485 @end defun
1486
1487 @node Remapping Commands
1488 @section Remapping Commands
1489 @cindex remapping commands
1490
1491 A special kind of key binding can be used to @dfn{remap} one command
1492 to another, without having to refer to the key sequence(s) bound to
1493 the original command. To use this feature, make a key binding for a
1494 key sequence that starts with the dummy event @code{remap}, followed
1495 by the command name you want to remap; for the binding, specify the
1496 new definition (usually a command name, but possibly any other valid
1497 definition for a key binding).
1498
1499 For example, suppose My mode provides a special command
1500 @code{my-kill-line}, which should be invoked instead of
1501 @code{kill-line}. To establish this, its mode keymap should contain
1502 the following remapping:
1503
1504 @smallexample
1505 (define-key my-mode-map [remap kill-line] 'my-kill-line)
1506 @end smallexample
1507
1508 @noindent
1509 Then, whenever @code{my-mode-map} is active, if the user types
1510 @kbd{C-k} (the default global key sequence for @code{kill-line}) Emacs
1511 will instead run @code{my-kill-line}.
1512
1513 Note that remapping only takes place through active keymaps; for
1514 example, putting a remapping in a prefix keymap like @code{ctl-x-map}
1515 typically has no effect, as such keymaps are not themselves active.
1516 In addition, remapping only works through a single level; in the
1517 following example,
1518
1519 @smallexample
1520 (define-key my-mode-map [remap kill-line] 'my-kill-line)
1521 (define-key my-mode-map [remap my-kill-line] 'my-other-kill-line)
1522 @end smallexample
1523
1524 @noindent
1525 @code{kill-line} is @emph{not} remapped to @code{my-other-kill-line}.
1526 Instead, if an ordinary key binding specifies @code{kill-line}, it is
1527 remapped to @code{my-kill-line}; if an ordinary binding specifies
1528 @code{my-kill-line}, it is remapped to @code{my-other-kill-line}.
1529
1530 To undo the remapping of a command, remap it to @code{nil}; e.g.,
1531
1532 @smallexample
1533 (define-key my-mode-map [remap kill-line] nil)
1534 @end smallexample
1535
1536 @defun command-remapping command &optional position keymaps
1537 This function returns the remapping for @var{command} (a symbol),
1538 given the current active keymaps. If @var{command} is not remapped
1539 (which is the usual situation), or not a symbol, the function returns
1540 @code{nil}. @code{position} can optionally specify a buffer position
1541 or an event position to determine the keymaps to use, as in
1542 @code{key-binding}.
1543
1544 If the optional argument @code{keymaps} is non-@code{nil}, it
1545 specifies a list of keymaps to search in. This argument is ignored if
1546 @code{position} is non-@code{nil}.
1547 @end defun
1548
1549 @node Translation Keymaps
1550 @section Keymaps for Translating Sequences of Events
1551 @cindex keymaps for translating events
1552
1553 This section describes keymaps that are used during reading a key
1554 sequence, to translate certain event sequences into others.
1555 @code{read-key-sequence} checks every subsequence of the key sequence
1556 being read, as it is read, against @code{input-decode-map}, then
1557 @code{local-function-key-map}, and then against @code{key-translation-map}.
1558
1559 These keymaps have the same structure as other keymaps, but they are used
1560 differently: they specify translations to make while reading key sequences,
1561 rather than bindings for key sequences.
1562
1563 If one of these keymaps ``binds'' a key sequence @var{k} to a vector
1564 @var{v}, then when @var{k} appears as a subsequence @emph{anywhere} in a
1565 key sequence, it is replaced with the events in @var{v}.
1566
1567 For example, VT100 terminals send @kbd{@key{ESC} O P} when the
1568 keypad @key{PF1} key is pressed. Therefore, we want Emacs to translate
1569 that sequence of events into the single event @code{pf1}. We accomplish
1570 this by ``binding'' @kbd{@key{ESC} O P} to @code{[pf1]} in
1571 @code{input-decode-map}, when using a VT100.
1572
1573 Thus, typing @kbd{C-c @key{PF1}} sends the character sequence @kbd{C-c
1574 @key{ESC} O P}; later the function @code{read-key-sequence} translates
1575 this back into @kbd{C-c @key{PF1}}, which it returns as the vector
1576 @code{[?\C-c pf1]}.
1577
1578 @defvar input-decode-map
1579 This variable holds a keymap that describes the character sequences sent
1580 by function keys on an ordinary character terminal.
1581
1582 The value of @code{input-decode-map} is usually set up automatically
1583 according to the terminal's Terminfo or Termcap entry, but sometimes
1584 those need help from terminal-specific Lisp files. Emacs comes with
1585 terminal-specific files for many common terminals; their main purpose is
1586 to make entries in @code{input-decode-map} beyond those that can be
1587 deduced from Termcap and Terminfo. @xref{Terminal-Specific}.
1588 @end defvar
1589
1590 @defvar local-function-key-map
1591 This variable holds a keymap similar to @code{input-decode-map} except
1592 that it describes key sequences which should be translated to
1593 alternative interpretations that are usually preferred. It applies
1594 after @code{input-decode-map} and before @code{key-translation-map}.
1595
1596 Entries in @code{local-function-key-map} are ignored if they conflict
1597 with bindings made in the minor mode, local, or global keymaps. I.e.,
1598 the remapping only applies if the original key sequence would
1599 otherwise not have any binding.
1600
1601 @code{local-function-key-map} inherits from @code{function-key-map},
1602 but the latter should not be used directly.
1603 @end defvar
1604
1605 @defvar key-translation-map
1606 This variable is another keymap used just like @code{input-decode-map}
1607 to translate input events into other events. It differs from
1608 @code{input-decode-map} in that it goes to work after
1609 @code{local-function-key-map} is finished rather than before; it
1610 receives the results of translation by @code{local-function-key-map}.
1611
1612 Just like @code{input-decode-map}, but unlike
1613 @code{local-function-key-map}, this keymap is applied regardless of
1614 whether the input key-sequence has a normal binding. Note however
1615 that actual key bindings can have an effect on
1616 @code{key-translation-map}, even though they are overridden by it.
1617 Indeed, actual key bindings override @code{local-function-key-map} and
1618 thus may alter the key sequence that @code{key-translation-map}
1619 receives. Clearly, it is better to avoid this type of situation.
1620
1621 The intent of @code{key-translation-map} is for users to map one
1622 character set to another, including ordinary characters normally bound
1623 to @code{self-insert-command}.
1624 @end defvar
1625
1626 @cindex key translation function
1627 You can use @code{input-decode-map}, @code{local-function-key-map},
1628 and @code{key-translation-map} for more than simple aliases, by using
1629 a function, instead of a key sequence, as the ``translation'' of a
1630 key. Then this function is called to compute the translation of that
1631 key.
1632
1633 The key translation function receives one argument, which is the prompt
1634 that was specified in @code{read-key-sequence}---or @code{nil} if the
1635 key sequence is being read by the editor command loop. In most cases
1636 you can ignore the prompt value.
1637
1638 If the function reads input itself, it can have the effect of altering
1639 the event that follows. For example, here's how to define @kbd{C-c h}
1640 to turn the character that follows into a Hyper character:
1641
1642 @example
1643 @group
1644 (defun hyperify (prompt)
1645 (let ((e (read-event)))
1646 (vector (if (numberp e)
1647 (logior (lsh 1 24) e)
1648 (if (memq 'hyper (event-modifiers e))
1649 e
1650 (add-event-modifier "H-" e))))))
1651
1652 (defun add-event-modifier (string e)
1653 (let ((symbol (if (symbolp e) e (car e))))
1654 (setq symbol (intern (concat string
1655 (symbol-name symbol))))
1656 (if (symbolp e)
1657 symbol
1658 (cons symbol (cdr e)))))
1659
1660 (define-key local-function-key-map "\C-ch" 'hyperify)
1661 @end group
1662 @end example
1663
1664 If you have enabled keyboard character set decoding using
1665 @code{set-keyboard-coding-system}, decoding is done before the
1666 translations listed above. @xref{Terminal I/O Encoding}.
1667
1668 @subsection Interaction with normal keymaps
1669
1670 The end of a key sequence is detected when that key sequence either is bound
1671 to a command, or when Emacs determines that no additional event can lead
1672 to a sequence that is bound to a command.
1673
1674 This means that, while @code{input-decode-map} and @code{key-translation-map}
1675 apply regardless of whether the original key sequence would have a binding, the
1676 presence of such a binding can still prevent translation from taking place.
1677 For example, let us return to our VT100 example above and add a binding for
1678 @kbd{C-c @key{ESC}} to the global map; now when the user hits @kbd{C-c
1679 @key{PF1}} Emacs will fail to decode @kbd{C-c @key{ESC} O P} into @kbd{C-c
1680 @key{PF1}} because it will stop reading keys right after @kbd{C-x @key{ESC}},
1681 leaving @kbd{O P} for later. This is in case the user really hit @kbd{C-c
1682 @key{ESC}}, in which case Emacs should not sit there waiting for the next key
1683 to decide whether the user really pressed @kbd{@key{ESC}} or @kbd{@key{PF1}}.
1684
1685 For that reason, it is better to avoid binding commands to key sequences where
1686 the end of the key sequence is a prefix of a key translation. The main such
1687 problematic suffixes/prefixes are @kbd{@key{ESC}}, @kbd{M-O} (which is really
1688 @kbd{@key{ESC} O}) and @kbd{M-[} (which is really @kbd{@key{ESC} [}).
1689
1690 @node Key Binding Commands
1691 @section Commands for Binding Keys
1692
1693 This section describes some convenient interactive interfaces for
1694 changing key bindings. They work by calling @code{define-key}.
1695
1696 People often use @code{global-set-key} in their init files
1697 (@pxref{Init File}) for simple customization. For example,
1698
1699 @smallexample
1700 (global-set-key (kbd "C-x C-\\") 'next-line)
1701 @end smallexample
1702
1703 @noindent
1704 or
1705
1706 @smallexample
1707 (global-set-key [?\C-x ?\C-\\] 'next-line)
1708 @end smallexample
1709
1710 @noindent
1711 or
1712
1713 @smallexample
1714 (global-set-key [(control ?x) (control ?\\)] 'next-line)
1715 @end smallexample
1716
1717 @noindent
1718 redefines @kbd{C-x C-\} to move down a line.
1719
1720 @smallexample
1721 (global-set-key [M-mouse-1] 'mouse-set-point)
1722 @end smallexample
1723
1724 @noindent
1725 redefines the first (leftmost) mouse button, entered with the Meta key, to
1726 set point where you click.
1727
1728 @cindex non-@acronym{ASCII} text in keybindings
1729 Be careful when using non-@acronym{ASCII} text characters in Lisp
1730 specifications of keys to bind. If these are read as multibyte text, as
1731 they usually will be in a Lisp file (@pxref{Loading Non-ASCII}), you
1732 must type the keys as multibyte too. For instance, if you use this:
1733
1734 @smallexample
1735 (global-set-key "@"o" 'my-function) ; bind o-umlaut
1736 @end smallexample
1737
1738 @noindent
1739 or
1740
1741 @smallexample
1742 (global-set-key ?@"o 'my-function) ; bind o-umlaut
1743 @end smallexample
1744
1745 @noindent
1746 and your language environment is multibyte Latin-1, these commands
1747 actually bind the multibyte character with code 246, not the byte
1748 code 246 (@kbd{M-v}) sent by a Latin-1 terminal. In order to use this
1749 binding, you need to teach Emacs how to decode the keyboard by using an
1750 appropriate input method (@pxref{Input Methods, , Input Methods, emacs, The GNU
1751 Emacs Manual}).
1752
1753 @deffn Command global-set-key key binding
1754 This function sets the binding of @var{key} in the current global map
1755 to @var{binding}.
1756
1757 @smallexample
1758 @group
1759 (global-set-key @var{key} @var{binding})
1760 @equiv{}
1761 (define-key (current-global-map) @var{key} @var{binding})
1762 @end group
1763 @end smallexample
1764 @end deffn
1765
1766 @deffn Command global-unset-key key
1767 @cindex unbinding keys
1768 This function removes the binding of @var{key} from the current
1769 global map.
1770
1771 One use of this function is in preparation for defining a longer key
1772 that uses @var{key} as a prefix---which would not be allowed if
1773 @var{key} has a non-prefix binding. For example:
1774
1775 @smallexample
1776 @group
1777 (global-unset-key "\C-l")
1778 @result{} nil
1779 @end group
1780 @group
1781 (global-set-key "\C-l\C-l" 'redraw-display)
1782 @result{} nil
1783 @end group
1784 @end smallexample
1785
1786 This function is equivalent to using @code{define-key} as follows:
1787
1788 @smallexample
1789 @group
1790 (global-unset-key @var{key})
1791 @equiv{}
1792 (define-key (current-global-map) @var{key} nil)
1793 @end group
1794 @end smallexample
1795 @end deffn
1796
1797 @deffn Command local-set-key key binding
1798 This function sets the binding of @var{key} in the current local
1799 keymap to @var{binding}.
1800
1801 @smallexample
1802 @group
1803 (local-set-key @var{key} @var{binding})
1804 @equiv{}
1805 (define-key (current-local-map) @var{key} @var{binding})
1806 @end group
1807 @end smallexample
1808 @end deffn
1809
1810 @deffn Command local-unset-key key
1811 This function removes the binding of @var{key} from the current
1812 local map.
1813
1814 @smallexample
1815 @group
1816 (local-unset-key @var{key})
1817 @equiv{}
1818 (define-key (current-local-map) @var{key} nil)
1819 @end group
1820 @end smallexample
1821 @end deffn
1822
1823 @node Scanning Keymaps
1824 @section Scanning Keymaps
1825
1826 This section describes functions used to scan all the current keymaps
1827 for the sake of printing help information.
1828
1829 @defun accessible-keymaps keymap &optional prefix
1830 This function returns a list of all the keymaps that can be reached (via
1831 zero or more prefix keys) from @var{keymap}. The value is an
1832 association list with elements of the form @code{(@var{key} .@:
1833 @var{map})}, where @var{key} is a prefix key whose definition in
1834 @var{keymap} is @var{map}.
1835
1836 The elements of the alist are ordered so that the @var{key} increases
1837 in length. The first element is always @code{([] .@: @var{keymap})},
1838 because the specified keymap is accessible from itself with a prefix of
1839 no events.
1840
1841 If @var{prefix} is given, it should be a prefix key sequence; then
1842 @code{accessible-keymaps} includes only the submaps whose prefixes start
1843 with @var{prefix}. These elements look just as they do in the value of
1844 @code{(accessible-keymaps)}; the only difference is that some elements
1845 are omitted.
1846
1847 In the example below, the returned alist indicates that the key
1848 @key{ESC}, which is displayed as @samp{^[}, is a prefix key whose
1849 definition is the sparse keymap @code{(keymap (83 .@: center-paragraph)
1850 (115 .@: foo))}.
1851
1852 @smallexample
1853 @group
1854 (accessible-keymaps (current-local-map))
1855 @result{}(([] keymap
1856 (27 keymap ; @r{Note this keymap for @key{ESC} is repeated below.}
1857 (83 . center-paragraph)
1858 (115 . center-line))
1859 (9 . tab-to-tab-stop))
1860 @end group
1861
1862 @group
1863 ("^[" keymap
1864 (83 . center-paragraph)
1865 (115 . foo)))
1866 @end group
1867 @end smallexample
1868
1869 In the following example, @kbd{C-h} is a prefix key that uses a sparse
1870 keymap starting with @code{(keymap (118 . describe-variable)@dots{})}.
1871 Another prefix, @kbd{C-x 4}, uses a keymap which is also the value of
1872 the variable @code{ctl-x-4-map}. The event @code{mode-line} is one of
1873 several dummy events used as prefixes for mouse actions in special parts
1874 of a window.
1875
1876 @smallexample
1877 @group
1878 (accessible-keymaps (current-global-map))
1879 @result{} (([] keymap [set-mark-command beginning-of-line @dots{}
1880 delete-backward-char])
1881 @end group
1882 @group
1883 ("^H" keymap (118 . describe-variable) @dots{}
1884 (8 . help-for-help))
1885 @end group
1886 @group
1887 ("^X" keymap [x-flush-mouse-queue @dots{}
1888 backward-kill-sentence])
1889 @end group
1890 @group
1891 ("^[" keymap [mark-sexp backward-sexp @dots{}
1892 backward-kill-word])
1893 @end group
1894 ("^X4" keymap (15 . display-buffer) @dots{})
1895 @group
1896 ([mode-line] keymap
1897 (S-mouse-2 . mouse-split-window-horizontally) @dots{}))
1898 @end group
1899 @end smallexample
1900
1901 @noindent
1902 These are not all the keymaps you would see in actuality.
1903 @end defun
1904
1905 @defun map-keymap function keymap
1906 The function @code{map-keymap} calls @var{function} once
1907 for each binding in @var{keymap}. It passes two arguments,
1908 the event type and the value of the binding. If @var{keymap}
1909 has a parent, the parent's bindings are included as well.
1910 This works recursively: if the parent has itself a parent, then the
1911 grandparent's bindings are also included and so on.
1912
1913 This function is the cleanest way to examine all the bindings
1914 in a keymap.
1915 @end defun
1916
1917 @defun where-is-internal command &optional keymap firstonly noindirect no-remap
1918 This function is a subroutine used by the @code{where-is} command
1919 (@pxref{Help, , Help, emacs,The GNU Emacs Manual}). It returns a list
1920 of all key sequences (of any length) that are bound to @var{command} in a
1921 set of keymaps.
1922
1923 The argument @var{command} can be any object; it is compared with all
1924 keymap entries using @code{eq}.
1925
1926 If @var{keymap} is @code{nil}, then the maps used are the current active
1927 keymaps, disregarding @code{overriding-local-map} (that is, pretending
1928 its value is @code{nil}). If @var{keymap} is a keymap, then the
1929 maps searched are @var{keymap} and the global keymap. If @var{keymap}
1930 is a list of keymaps, only those keymaps are searched.
1931
1932 Usually it's best to use @code{overriding-local-map} as the expression
1933 for @var{keymap}. Then @code{where-is-internal} searches precisely
1934 the keymaps that are active. To search only the global map, pass the
1935 value @code{(keymap)} (an empty keymap) as @var{keymap}.
1936
1937 If @var{firstonly} is @code{non-ascii}, then the value is a single
1938 vector representing the first key sequence found, rather than a list of
1939 all possible key sequences. If @var{firstonly} is @code{t}, then the
1940 value is the first key sequence, except that key sequences consisting
1941 entirely of @acronym{ASCII} characters (or meta variants of @acronym{ASCII}
1942 characters) are preferred to all other key sequences and that the
1943 return value can never be a menu binding.
1944
1945 If @var{noindirect} is non-@code{nil}, @code{where-is-internal} doesn't
1946 follow indirect keymap bindings. This makes it possible to search for
1947 an indirect definition itself.
1948
1949 The fifth argument, @var{no-remap}, determines how this function
1950 treats command remappings (@pxref{Remapping Commands}). There are two
1951 cases of interest:
1952
1953 @table @asis
1954 @item If a command @var{other-command} is remapped to @var{command}:
1955 If @var{no-remap} is @code{nil}, find the bindings for
1956 @var{other-command} and treat them as though they are also bindings
1957 for @var{command}. If @var{no-remap} is non-@code{nil}, include the
1958 vector @code{[remap @var{other-command}]} in the list of possible key
1959 sequences, instead of finding those bindings.
1960
1961 @item If @var{command} is remapped to @var{other-command}:
1962 If @var{no-remap} is @code{nil}, return the bindings for
1963 @var{other-command} rather than @var{command}. If @var{no-remap} is
1964 non-@code{nil}, return the bindings for @var{command}, ignoring the
1965 fact that it is remapped.
1966 @end table
1967 @end defun
1968
1969 @deffn Command describe-bindings &optional prefix buffer-or-name
1970 This function creates a listing of all current key bindings, and
1971 displays it in a buffer named @file{*Help*}. The text is grouped by
1972 modes---minor modes first, then the major mode, then global bindings.
1973
1974 If @var{prefix} is non-@code{nil}, it should be a prefix key; then the
1975 listing includes only keys that start with @var{prefix}.
1976
1977 When several characters with consecutive @acronym{ASCII} codes have the
1978 same definition, they are shown together, as
1979 @samp{@var{firstchar}..@var{lastchar}}. In this instance, you need to
1980 know the @acronym{ASCII} codes to understand which characters this means.
1981 For example, in the default global map, the characters @samp{@key{SPC}
1982 ..@: ~} are described by a single line. @key{SPC} is @acronym{ASCII} 32,
1983 @kbd{~} is @acronym{ASCII} 126, and the characters between them include all
1984 the normal printing characters, (e.g., letters, digits, punctuation,
1985 etc.@:); all these characters are bound to @code{self-insert-command}.
1986
1987 If @var{buffer-or-name} is non-@code{nil}, it should be a buffer or a
1988 buffer name. Then @code{describe-bindings} lists that buffer's bindings,
1989 instead of the current buffer's.
1990 @end deffn
1991
1992 @node Menu Keymaps
1993 @section Menu Keymaps
1994 @cindex menu keymaps
1995
1996 A keymap can operate as a menu as well as defining bindings for
1997 keyboard keys and mouse buttons. Menus are usually actuated with the
1998 mouse, but they can function with the keyboard also. If a menu keymap
1999 is active for the next input event, that activates the keyboard menu
2000 feature.
2001
2002 @menu
2003 * Defining Menus:: How to make a keymap that defines a menu.
2004 * Mouse Menus:: How users actuate the menu with the mouse.
2005 * Keyboard Menus:: How users actuate the menu with the keyboard.
2006 * Menu Example:: Making a simple menu.
2007 * Menu Bar:: How to customize the menu bar.
2008 * Tool Bar:: A tool bar is a row of images.
2009 * Modifying Menus:: How to add new items to a menu.
2010 * Easy Menu:: A convenience macro for making menus.
2011 @end menu
2012
2013 @node Defining Menus
2014 @subsection Defining Menus
2015 @cindex defining menus
2016 @cindex menu prompt string
2017 @cindex prompt string (of menu)
2018 @cindex menu item
2019
2020 A keymap acts as a menu if it has an @dfn{overall prompt string},
2021 which is a string that appears as an element of the keymap.
2022 (@xref{Format of Keymaps}.) The string should describe the purpose of
2023 the menu's commands. Emacs displays the overall prompt string as the
2024 menu title in some cases, depending on the toolkit (if any) used for
2025 displaying menus.@footnote{It is required for menus which do not use a
2026 toolkit, e.g., under MS-DOS.} Keyboard menus also display the
2027 overall prompt string.
2028
2029 The easiest way to construct a keymap with a prompt string is to
2030 specify the string as an argument when you call @code{make-keymap},
2031 @code{make-sparse-keymap} (@pxref{Creating Keymaps}), or
2032 @code{define-prefix-command} (@pxref{Definition of
2033 define-prefix-command}). If you do not want the keymap to operate as
2034 a menu, don't specify a prompt string for it.
2035
2036 @defun keymap-prompt keymap
2037 This function returns the overall prompt string of @var{keymap},
2038 or @code{nil} if it has none.
2039 @end defun
2040
2041 The menu's items are the bindings in the keymap. Each binding
2042 associates an event type to a definition, but the event types have no
2043 significance for the menu appearance. (Usually we use pseudo-events,
2044 symbols that the keyboard cannot generate, as the event types for menu
2045 item bindings.) The menu is generated entirely from the bindings that
2046 correspond in the keymap to these events.
2047
2048 The order of items in the menu is the same as the order of bindings in
2049 the keymap. Since @code{define-key} puts new bindings at the front, you
2050 should define the menu items starting at the bottom of the menu and
2051 moving to the top, if you care about the order. When you add an item to
2052 an existing menu, you can specify its position in the menu using
2053 @code{define-key-after} (@pxref{Modifying Menus}).
2054
2055 @menu
2056 * Simple Menu Items:: A simple kind of menu key binding.
2057 * Extended Menu Items:: More complex menu item definitions.
2058 * Menu Separators:: Drawing a horizontal line through a menu.
2059 * Alias Menu Items:: Using command aliases in menu items.
2060 @end menu
2061
2062 @node Simple Menu Items
2063 @subsubsection Simple Menu Items
2064
2065 The simpler (and original) way to define a menu item is to bind some
2066 event type (it doesn't matter what event type) to a binding like this:
2067
2068 @example
2069 (@var{item-string} . @var{real-binding})
2070 @end example
2071
2072 @noindent
2073 The @sc{car}, @var{item-string}, is the string to be displayed in the
2074 menu. It should be short---preferably one to three words. It should
2075 describe the action of the command it corresponds to. Note that not
2076 all graphical toolkits can display non-@acronym{ASCII} text in menus
2077 (it will work for keyboard menus and will work to a large extent with
2078 the GTK+ toolkit).
2079
2080 You can also supply a second string, called the help string, as follows:
2081
2082 @example
2083 (@var{item-string} @var{help} . @var{real-binding})
2084 @end example
2085
2086 @noindent
2087 @var{help} specifies a ``help-echo'' string to display while the mouse
2088 is on that item in the same way as @code{help-echo} text properties
2089 (@pxref{Help display}).
2090
2091 As far as @code{define-key} is concerned, @var{item-string} and
2092 @var{help-string} are part of the event's binding. However,
2093 @code{lookup-key} returns just @var{real-binding}, and only
2094 @var{real-binding} is used for executing the key.
2095
2096 If @var{real-binding} is @code{nil}, then @var{item-string} appears in
2097 the menu but cannot be selected.
2098
2099 If @var{real-binding} is a symbol and has a non-@code{nil}
2100 @code{menu-enable} property, that property is an expression that
2101 controls whether the menu item is enabled. Every time the keymap is
2102 used to display a menu, Emacs evaluates the expression, and it enables
2103 the menu item only if the expression's value is non-@code{nil}. When a
2104 menu item is disabled, it is displayed in a ``fuzzy'' fashion, and
2105 cannot be selected.
2106
2107 The menu bar does not recalculate which items are enabled every time you
2108 look at a menu. This is because the X toolkit requires the whole tree
2109 of menus in advance. To force recalculation of the menu bar, call
2110 @code{force-mode-line-update} (@pxref{Mode Line Format}).
2111
2112 @node Extended Menu Items
2113 @subsubsection Extended Menu Items
2114 @kindex menu-item
2115 @cindex extended menu item
2116
2117 An extended-format menu item is a more flexible and also cleaner
2118 alternative to the simple format. You define an event type with a
2119 binding that's a list starting with the symbol @code{menu-item}.
2120 For a non-selectable string, the binding looks like this:
2121
2122 @example
2123 (menu-item @var{item-name})
2124 @end example
2125
2126 @noindent
2127 A string starting with two or more dashes specifies a separator line;
2128 see @ref{Menu Separators}.
2129
2130 To define a real menu item which can be selected, the extended format
2131 binding looks like this:
2132
2133 @example
2134 (menu-item @var{item-name} @var{real-binding}
2135 . @var{item-property-list})
2136 @end example
2137
2138 @noindent
2139 Here, @var{item-name} is an expression which evaluates to the menu item
2140 string. Thus, the string need not be a constant. The third element,
2141 @var{real-binding}, is the command to execute. The tail of the list,
2142 @var{item-property-list}, has the form of a property list which contains
2143 other information.
2144
2145 Here is a table of the properties that are supported:
2146
2147 @table @code
2148 @item :enable @var{form}
2149 The result of evaluating @var{form} determines whether the item is
2150 enabled (non-@code{nil} means yes). If the item is not enabled,
2151 you can't really click on it.
2152
2153 @item :visible @var{form}
2154 The result of evaluating @var{form} determines whether the item should
2155 actually appear in the menu (non-@code{nil} means yes). If the item
2156 does not appear, then the menu is displayed as if this item were
2157 not defined at all.
2158
2159 @item :help @var{help}
2160 The value of this property, @var{help}, specifies a ``help-echo'' string
2161 to display while the mouse is on that item. This is displayed in the
2162 same way as @code{help-echo} text properties (@pxref{Help display}).
2163 Note that this must be a constant string, unlike the @code{help-echo}
2164 property for text and overlays.
2165
2166 @item :button (@var{type} . @var{selected})
2167 This property provides a way to define radio buttons and toggle buttons.
2168 The @sc{car}, @var{type}, says which: it should be @code{:toggle} or
2169 @code{:radio}. The @sc{cdr}, @var{selected}, should be a form; the
2170 result of evaluating it says whether this button is currently selected.
2171
2172 A @dfn{toggle} is a menu item which is labeled as either ``on'' or ``off''
2173 according to the value of @var{selected}. The command itself should
2174 toggle @var{selected}, setting it to @code{t} if it is @code{nil},
2175 and to @code{nil} if it is @code{t}. Here is how the menu item
2176 to toggle the @code{debug-on-error} flag is defined:
2177
2178 @example
2179 (menu-item "Debug on Error" toggle-debug-on-error
2180 :button (:toggle
2181 . (and (boundp 'debug-on-error)
2182 debug-on-error)))
2183 @end example
2184
2185 @noindent
2186 This works because @code{toggle-debug-on-error} is defined as a command
2187 which toggles the variable @code{debug-on-error}.
2188
2189 @dfn{Radio buttons} are a group of menu items, in which at any time one
2190 and only one is ``selected''. There should be a variable whose value
2191 says which one is selected at any time. The @var{selected} form for
2192 each radio button in the group should check whether the variable has the
2193 right value for selecting that button. Clicking on the button should
2194 set the variable so that the button you clicked on becomes selected.
2195
2196 @item :key-sequence @var{key-sequence}
2197 This property specifies which key sequence is likely to be bound to the
2198 same command invoked by this menu item. If you specify the right key
2199 sequence, that makes preparing the menu for display run much faster.
2200
2201 If you specify the wrong key sequence, it has no effect; before Emacs
2202 displays @var{key-sequence} in the menu, it verifies that
2203 @var{key-sequence} is really equivalent to this menu item.
2204
2205 @item :key-sequence nil
2206 This property indicates that there is normally no key binding which is
2207 equivalent to this menu item. Using this property saves time in
2208 preparing the menu for display, because Emacs does not need to search
2209 the keymaps for a keyboard equivalent for this menu item.
2210
2211 However, if the user has rebound this item's definition to a key
2212 sequence, Emacs ignores the @code{:keys} property and finds the keyboard
2213 equivalent anyway.
2214
2215 @item :keys @var{string}
2216 This property specifies that @var{string} is the string to display
2217 as the keyboard equivalent for this menu item. You can use
2218 the @samp{\\[...]} documentation construct in @var{string}.
2219
2220 @item :filter @var{filter-fn}
2221 This property provides a way to compute the menu item dynamically.
2222 The property value @var{filter-fn} should be a function of one argument;
2223 when it is called, its argument will be @var{real-binding}. The
2224 function should return the binding to use instead.
2225
2226 Emacs can call this function at any time that it does redisplay or
2227 operates on menu data structures, so you should write it so it can
2228 safely be called at any time.
2229 @end table
2230
2231 @node Menu Separators
2232 @subsubsection Menu Separators
2233 @cindex menu separators
2234
2235 A menu separator is a kind of menu item that doesn't display any
2236 text---instead, it divides the menu into subparts with a horizontal line.
2237 A separator looks like this in the menu keymap:
2238
2239 @example
2240 (menu-item @var{separator-type})
2241 @end example
2242
2243 @noindent
2244 where @var{separator-type} is a string starting with two or more dashes.
2245
2246 In the simplest case, @var{separator-type} consists of only dashes.
2247 That specifies the default kind of separator. (For compatibility,
2248 @code{""} and @code{-} also count as separators.)
2249
2250 Certain other values of @var{separator-type} specify a different
2251 style of separator. Here is a table of them:
2252
2253 @table @code
2254 @item "--no-line"
2255 @itemx "--space"
2256 An extra vertical space, with no actual line.
2257
2258 @item "--single-line"
2259 A single line in the menu's foreground color.
2260
2261 @item "--double-line"
2262 A double line in the menu's foreground color.
2263
2264 @item "--single-dashed-line"
2265 A single dashed line in the menu's foreground color.
2266
2267 @item "--double-dashed-line"
2268 A double dashed line in the menu's foreground color.
2269
2270 @item "--shadow-etched-in"
2271 A single line with a 3D sunken appearance. This is the default,
2272 used separators consisting of dashes only.
2273
2274 @item "--shadow-etched-out"
2275 A single line with a 3D raised appearance.
2276
2277 @item "--shadow-etched-in-dash"
2278 A single dashed line with a 3D sunken appearance.
2279
2280 @item "--shadow-etched-out-dash"
2281 A single dashed line with a 3D raised appearance.
2282
2283 @item "--shadow-double-etched-in"
2284 Two lines with a 3D sunken appearance.
2285
2286 @item "--shadow-double-etched-out"
2287 Two lines with a 3D raised appearance.
2288
2289 @item "--shadow-double-etched-in-dash"
2290 Two dashed lines with a 3D sunken appearance.
2291
2292 @item "--shadow-double-etched-out-dash"
2293 Two dashed lines with a 3D raised appearance.
2294 @end table
2295
2296 You can also give these names in another style, adding a colon after
2297 the double-dash and replacing each single dash with capitalization of
2298 the following word. Thus, @code{"--:singleLine"}, is equivalent to
2299 @code{"--single-line"}.
2300
2301 You can use a longer form to specify keywords such as @code{:enable}
2302 and @code{:visible} for a menu separator:
2303
2304 @code{(menu-item @var{separator-type} nil . @var{item-property-list})}
2305
2306 For example:
2307
2308 @example
2309 (menu-item "--" nil :visible (boundp 'foo))
2310 @end example
2311
2312 Some systems and display toolkits don't really handle all of these
2313 separator types. If you use a type that isn't supported, the menu
2314 displays a similar kind of separator that is supported.
2315
2316 @node Alias Menu Items
2317 @subsubsection Alias Menu Items
2318
2319 Sometimes it is useful to make menu items that use the ``same''
2320 command but with different enable conditions. The best way to do this
2321 in Emacs now is with extended menu items; before that feature existed,
2322 it could be done by defining alias commands and using them in menu
2323 items. Here's an example that makes two aliases for
2324 @code{read-only-mode} and gives them different enable conditions:
2325
2326 @example
2327 (defalias 'make-read-only 'read-only-mode)
2328 (put 'make-read-only 'menu-enable '(not buffer-read-only))
2329 (defalias 'make-writable 'read-only-mode)
2330 (put 'make-writable 'menu-enable 'buffer-read-only)
2331 @end example
2332
2333 When using aliases in menus, often it is useful to display the
2334 equivalent key bindings for the ``real'' command name, not the aliases
2335 (which typically don't have any key bindings except for the menu
2336 itself). To request this, give the alias symbol a non-@code{nil}
2337 @code{menu-alias} property. Thus,
2338
2339 @example
2340 (put 'make-read-only 'menu-alias t)
2341 (put 'make-writable 'menu-alias t)
2342 @end example
2343
2344 @noindent
2345 causes menu items for @code{make-read-only} and @code{make-writable} to
2346 show the keyboard bindings for @code{read-only-mode}.
2347
2348 @node Mouse Menus
2349 @subsection Menus and the Mouse
2350
2351 The usual way to make a menu keymap produce a menu is to make it the
2352 definition of a prefix key. (A Lisp program can explicitly pop up a
2353 menu and receive the user's choice---see @ref{Pop-Up Menus}.)
2354
2355 If the prefix key ends with a mouse event, Emacs handles the menu keymap
2356 by popping up a visible menu, so that the user can select a choice with
2357 the mouse. When the user clicks on a menu item, the event generated is
2358 whatever character or symbol has the binding that brought about that
2359 menu item. (A menu item may generate a series of events if the menu has
2360 multiple levels or comes from the menu bar.)
2361
2362 It's often best to use a button-down event to trigger the menu. Then
2363 the user can select a menu item by releasing the button.
2364
2365 @cindex submenu
2366 If the menu keymap contains a binding to a nested keymap, the nested
2367 keymap specifies a @dfn{submenu}. There will be a menu item, labeled
2368 by the nested keymap's item string, and clicking on this item
2369 automatically pops up the specified submenu. As a special exception,
2370 if the menu keymap contains a single nested keymap and no other menu
2371 items, the menu shows the contents of the nested keymap directly, not
2372 as a submenu.
2373
2374 However, if Emacs is compiled without X toolkit support, submenus
2375 are not supported. Each nested keymap is shown as a menu item, but
2376 clicking on it does not automatically pop up the submenu. If you wish
2377 to imitate the effect of submenus, you can do that by giving a nested
2378 keymap an item string which starts with @samp{@@}. This causes Emacs
2379 to display the nested keymap using a separate @dfn{menu pane}; the
2380 rest of the item string after the @samp{@@} is the pane label. If
2381 Emacs is compiled without X toolkit support, menu panes are not used;
2382 in that case, a @samp{@@} at the beginning of an item string is
2383 omitted when the menu label is displayed, and has no other effect.
2384
2385 @node Keyboard Menus
2386 @subsection Menus and the Keyboard
2387
2388 When a prefix key ending with a keyboard event (a character or
2389 function key) has a definition that is a menu keymap, the keymap
2390 operates as a keyboard menu; the user specifies the next event by
2391 choosing a menu item with the keyboard.
2392
2393 Emacs displays the keyboard menu with the map's overall prompt
2394 string, followed by the alternatives (the item strings of the map's
2395 bindings), in the echo area. If the bindings don't all fit at once,
2396 the user can type @key{SPC} to see the next line of alternatives.
2397 Successive uses of @key{SPC} eventually get to the end of the menu and
2398 then cycle around to the beginning. (The variable
2399 @code{menu-prompt-more-char} specifies which character is used for
2400 this; @key{SPC} is the default.)
2401
2402 When the user has found the desired alternative from the menu, he or
2403 she should type the corresponding character---the one whose binding is
2404 that alternative.
2405
2406 @defvar menu-prompt-more-char
2407 This variable specifies the character to use to ask to see
2408 the next line of a menu. Its initial value is 32, the code
2409 for @key{SPC}.
2410 @end defvar
2411
2412 @node Menu Example
2413 @subsection Menu Example
2414 @cindex menu definition example
2415
2416 Here is a complete example of defining a menu keymap. It is the
2417 definition of the @samp{Replace} submenu in the @samp{Edit} menu in
2418 the menu bar, and it uses the extended menu item format
2419 (@pxref{Extended Menu Items}). First we create the keymap, and give
2420 it a name:
2421
2422 @smallexample
2423 (defvar menu-bar-replace-menu (make-sparse-keymap "Replace"))
2424 @end smallexample
2425
2426 @noindent
2427 Next we define the menu items:
2428
2429 @smallexample
2430 (define-key menu-bar-replace-menu [tags-repl-continue]
2431 '(menu-item "Continue Replace" tags-loop-continue
2432 :help "Continue last tags replace operation"))
2433 (define-key menu-bar-replace-menu [tags-repl]
2434 '(menu-item "Replace in tagged files" tags-query-replace
2435 :help "Interactively replace a regexp in all tagged files"))
2436 (define-key menu-bar-replace-menu [separator-replace-tags]
2437 '(menu-item "--"))
2438 ;; @r{@dots{}}
2439 @end smallexample
2440
2441 @noindent
2442 Note the symbols which the bindings are ``made for''; these appear
2443 inside square brackets, in the key sequence being defined. In some
2444 cases, this symbol is the same as the command name; sometimes it is
2445 different. These symbols are treated as ``function keys'', but they are
2446 not real function keys on the keyboard. They do not affect the
2447 functioning of the menu itself, but they are ``echoed'' in the echo area
2448 when the user selects from the menu, and they appear in the output of
2449 @code{where-is} and @code{apropos}.
2450
2451 The menu in this example is intended for use with the mouse. If a
2452 menu is intended for use with the keyboard, that is, if it is bound to
2453 a key sequence ending with a keyboard event, then the menu items
2454 should be bound to characters or ``real'' function keys, that can be
2455 typed with the keyboard.
2456
2457 The binding whose definition is @code{("--")} is a separator line.
2458 Like a real menu item, the separator has a key symbol, in this case
2459 @code{separator-replace-tags}. If one menu has two separators, they
2460 must have two different key symbols.
2461
2462 Here is how we make this menu appear as an item in the parent menu:
2463
2464 @example
2465 (define-key menu-bar-edit-menu [replace]
2466 (list 'menu-item "Replace" menu-bar-replace-menu))
2467 @end example
2468
2469 @noindent
2470 Note that this incorporates the submenu keymap, which is the value of
2471 the variable @code{menu-bar-replace-menu}, rather than the symbol
2472 @code{menu-bar-replace-menu} itself. Using that symbol in the parent
2473 menu item would be meaningless because @code{menu-bar-replace-menu} is
2474 not a command.
2475
2476 If you wanted to attach the same replace menu to a mouse click, you
2477 can do it this way:
2478
2479 @example
2480 (define-key global-map [C-S-down-mouse-1]
2481 menu-bar-replace-menu)
2482 @end example
2483
2484 @node Menu Bar
2485 @subsection The Menu Bar
2486 @cindex menu bar
2487
2488 On graphical displays, there is usually a @dfn{menu bar} at the top
2489 of each frame. @xref{Menu Bars,,,emacs, The GNU Emacs Manual}. Menu
2490 bar items are subcommands of the fake ``function key''
2491 @code{menu-bar}, as defined in the active keymaps.
2492
2493 To add an item to the menu bar, invent a fake ``function key'' of your
2494 own (let's call it @var{key}), and make a binding for the key sequence
2495 @code{[menu-bar @var{key}]}. Most often, the binding is a menu keymap,
2496 so that pressing a button on the menu bar item leads to another menu.
2497
2498 When more than one active keymap defines the same ``function key''
2499 for the menu bar, the item appears just once. If the user clicks on
2500 that menu bar item, it brings up a single, combined menu containing
2501 all the subcommands of that item---the global subcommands, the local
2502 subcommands, and the minor mode subcommands.
2503
2504 The variable @code{overriding-local-map} is normally ignored when
2505 determining the menu bar contents. That is, the menu bar is computed
2506 from the keymaps that would be active if @code{overriding-local-map}
2507 were @code{nil}. @xref{Active Keymaps}.
2508
2509 Here's an example of setting up a menu bar item:
2510
2511 @example
2512 @group
2513 ;; @r{Make a menu keymap (with a prompt string)}
2514 ;; @r{and make it the menu bar item's definition.}
2515 (define-key global-map [menu-bar words]
2516 (cons "Words" (make-sparse-keymap "Words")))
2517 @end group
2518
2519 @group
2520 ;; @r{Define specific subcommands in this menu.}
2521 (define-key global-map
2522 [menu-bar words forward]
2523 '("Forward word" . forward-word))
2524 @end group
2525 @group
2526 (define-key global-map
2527 [menu-bar words backward]
2528 '("Backward word" . backward-word))
2529 @end group
2530 @end example
2531
2532 A local keymap can cancel a menu bar item made by the global keymap by
2533 rebinding the same fake function key with @code{undefined} as the
2534 binding. For example, this is how Dired suppresses the @samp{Edit} menu
2535 bar item:
2536
2537 @example
2538 (define-key dired-mode-map [menu-bar edit] 'undefined)
2539 @end example
2540
2541 @noindent
2542 Here, @code{edit} is the fake function key used by the global map for
2543 the @samp{Edit} menu bar item. The main reason to suppress a global
2544 menu bar item is to regain space for mode-specific items.
2545
2546 @defvar menu-bar-final-items
2547 Normally the menu bar shows global items followed by items defined by the
2548 local maps.
2549
2550 This variable holds a list of fake function keys for items to display at
2551 the end of the menu bar rather than in normal sequence. The default
2552 value is @code{(help-menu)}; thus, the @samp{Help} menu item normally appears
2553 at the end of the menu bar, following local menu items.
2554 @end defvar
2555
2556 @defvar menu-bar-update-hook
2557 This normal hook is run by redisplay to update the menu bar contents,
2558 before redisplaying the menu bar. You can use it to update submenus
2559 whose contents should vary. Since this hook is run frequently, we
2560 advise you to ensure that the functions it calls do not take much time
2561 in the usual case.
2562 @end defvar
2563
2564 Next to every menu bar item, Emacs displays a key binding that runs
2565 the same command (if such a key binding exists). This serves as a
2566 convenient hint for users who do not know the key binding. If a
2567 command has multiple bindings, Emacs normally displays the first one
2568 it finds. You can specify one particular key binding by assigning an
2569 @code{:advertised-binding} symbol property to the command. @xref{Keys
2570 in Documentation}.
2571
2572 @node Tool Bar
2573 @subsection Tool bars
2574 @cindex tool bar
2575
2576 A @dfn{tool bar} is a row of clickable icons at the top of a frame,
2577 just below the menu bar. @xref{Tool Bars,,,emacs, The GNU Emacs
2578 Manual}.
2579
2580 On each frame, the frame parameter @code{tool-bar-lines} controls
2581 how many lines' worth of height to reserve for the tool bar. A zero
2582 value suppresses the tool bar. If the value is nonzero, and
2583 @code{auto-resize-tool-bars} is non-@code{nil}, the tool bar expands
2584 and contracts automatically as needed to hold the specified contents.
2585 If the value is @code{grow-only}, the tool bar expands automatically,
2586 but does not contract automatically.
2587
2588 The tool bar contents are controlled by a menu keymap attached to a
2589 fake ``function key'' called @code{tool-bar} (much like the way the menu
2590 bar is controlled). So you define a tool bar item using
2591 @code{define-key}, like this:
2592
2593 @example
2594 (define-key global-map [tool-bar @var{key}] @var{item})
2595 @end example
2596
2597 @noindent
2598 where @var{key} is a fake ``function key'' to distinguish this item from
2599 other items, and @var{item} is a menu item key binding (@pxref{Extended
2600 Menu Items}), which says how to display this item and how it behaves.
2601
2602 The usual menu keymap item properties, @code{:visible},
2603 @code{:enable}, @code{:button}, and @code{:filter}, are useful in
2604 tool bar bindings and have their normal meanings. The @var{real-binding}
2605 in the item must be a command, not a keymap; in other words, it does not
2606 work to define a tool bar icon as a prefix key.
2607
2608 The @code{:help} property specifies a ``help-echo'' string to display
2609 while the mouse is on that item. This is displayed in the same way as
2610 @code{help-echo} text properties (@pxref{Help display}).
2611
2612 In addition, you should use the @code{:image} property;
2613 this is how you specify the image to display in the tool bar:
2614
2615 @table @code
2616 @item :image @var{image}
2617 @var{images} is either a single image specification or a vector of four
2618 image specifications. If you use a vector of four,
2619 one of them is used, depending on circumstances:
2620
2621 @table @asis
2622 @item item 0
2623 Used when the item is enabled and selected.
2624 @item item 1
2625 Used when the item is enabled and deselected.
2626 @item item 2
2627 Used when the item is disabled and selected.
2628 @item item 3
2629 Used when the item is disabled and deselected.
2630 @end table
2631 @end table
2632
2633 If @var{image} is a single image specification, Emacs draws the tool bar
2634 button in disabled state by applying an edge-detection algorithm to the
2635 image.
2636
2637 The @code{:rtl} property specifies an alternative image to use for
2638 right-to-left languages. Only the GTK+ version of Emacs supports this
2639 at present.
2640
2641 Like the menu bar, the tool bar can display separators (@pxref{Menu
2642 Separators}). Tool bar separators are vertical rather than
2643 horizontal, though, and only a single style is supported. They are
2644 represented in the tool bar keymap by @code{(menu-item "--")} entries;
2645 properties like @code{:visible} are not supported for tool bar
2646 separators. Separators are rendered natively in GTK+ and Nextstep
2647 tool bars; in the other cases, they are rendered using an image of a
2648 vertical line.
2649
2650 The default tool bar is defined so that items specific to editing do not
2651 appear for major modes whose command symbol has a @code{mode-class}
2652 property of @code{special} (@pxref{Major Mode Conventions}). Major
2653 modes may add items to the global bar by binding @code{[tool-bar
2654 @var{foo}]} in their local map. It makes sense for some major modes to
2655 replace the default tool bar items completely, since not many can be
2656 accommodated conveniently, and the default bindings make this easy by
2657 using an indirection through @code{tool-bar-map}.
2658
2659 @defvar tool-bar-map
2660 By default, the global map binds @code{[tool-bar]} as follows:
2661
2662 @example
2663 (global-set-key [tool-bar]
2664 `(menu-item ,(purecopy "tool bar") ignore
2665 :filter tool-bar-make-keymap))
2666 @end example
2667
2668 @noindent
2669 The function @code{tool-bar-make-keymap}, in turn, derives the actual
2670 tool bar map dynamically from the value of the variable
2671 @code{tool-bar-map}. Hence, you should normally adjust the default
2672 (global) tool bar by changing that map. Some major modes, such as
2673 Info mode, completely replace the global tool bar by making
2674 @code{tool-bar-map} buffer-local and setting it to a different keymap.
2675 @end defvar
2676
2677 There are two convenience functions for defining tool bar items, as
2678 follows.
2679
2680 @defun tool-bar-add-item icon def key &rest props
2681 This function adds an item to the tool bar by modifying
2682 @code{tool-bar-map}. The image to use is defined by @var{icon}, which
2683 is the base name of an XPM, XBM or PBM image file to be located by
2684 @code{find-image}. Given a value @samp{"exit"}, say, @file{exit.xpm},
2685 @file{exit.pbm} and @file{exit.xbm} would be searched for in that order
2686 on a color display. On a monochrome display, the search order is
2687 @samp{.pbm}, @samp{.xbm} and @samp{.xpm}. The binding to use is the
2688 command @var{def}, and @var{key} is the fake function key symbol in the
2689 prefix keymap. The remaining arguments @var{props} are additional
2690 property list elements to add to the menu item specification.
2691
2692 To define items in some local map, bind @code{tool-bar-map} with
2693 @code{let} around calls of this function:
2694 @example
2695 (defvar foo-tool-bar-map
2696 (let ((tool-bar-map (make-sparse-keymap)))
2697 (tool-bar-add-item @dots{})
2698 @dots{}
2699 tool-bar-map))
2700 @end example
2701 @end defun
2702
2703 @defun tool-bar-add-item-from-menu command icon &optional map &rest props
2704 This function is a convenience for defining tool bar items which are
2705 consistent with existing menu bar bindings. The binding of
2706 @var{command} is looked up in the menu bar in @var{map} (default
2707 @code{global-map}) and modified to add an image specification for
2708 @var{icon}, which is found in the same way as by
2709 @code{tool-bar-add-item}. The resulting binding is then placed in
2710 @code{tool-bar-map}, so use this function only for global tool bar
2711 items.
2712
2713 @var{map} must contain an appropriate keymap bound to
2714 @code{[menu-bar]}. The remaining arguments @var{props} are additional
2715 property list elements to add to the menu item specification.
2716 @end defun
2717
2718 @defun tool-bar-local-item-from-menu command icon in-map &optional from-map &rest props
2719 This function is used for making non-global tool bar items. Use it
2720 like @code{tool-bar-add-item-from-menu} except that @var{in-map}
2721 specifies the local map to make the definition in. The argument
2722 @var{from-map} is like the @var{map} argument of
2723 @code{tool-bar-add-item-from-menu}.
2724 @end defun
2725
2726 @defvar auto-resize-tool-bars
2727 If this variable is non-@code{nil}, the tool bar automatically resizes to
2728 show all defined tool bar items---but not larger than a quarter of the
2729 frame's height.
2730
2731 If the value is @code{grow-only}, the tool bar expands automatically,
2732 but does not contract automatically. To contract the tool bar, the
2733 user has to redraw the frame by entering @kbd{C-l}.
2734
2735 If Emacs is built with GTK or Nextstep, the tool bar can only show one
2736 line, so this variable has no effect.
2737 @end defvar
2738
2739 @defvar auto-raise-tool-bar-buttons
2740 If this variable is non-@code{nil}, tool bar items display
2741 in raised form when the mouse moves over them.
2742 @end defvar
2743
2744 @defvar tool-bar-button-margin
2745 This variable specifies an extra margin to add around tool bar items.
2746 The value is an integer, a number of pixels. The default is 4.
2747 @end defvar
2748
2749 @defvar tool-bar-button-relief
2750 This variable specifies the shadow width for tool bar items.
2751 The value is an integer, a number of pixels. The default is 1.
2752 @end defvar
2753
2754 @defvar tool-bar-border
2755 This variable specifies the height of the border drawn below the tool
2756 bar area. An integer value specifies height as a number of pixels.
2757 If the value is one of @code{internal-border-width} (the default) or
2758 @code{border-width}, the tool bar border height corresponds to the
2759 corresponding frame parameter.
2760 @end defvar
2761
2762 You can define a special meaning for clicking on a tool bar item with
2763 the shift, control, meta, etc., modifiers. You do this by setting up
2764 additional items that relate to the original item through the fake
2765 function keys. Specifically, the additional items should use the
2766 modified versions of the same fake function key used to name the
2767 original item.
2768
2769 Thus, if the original item was defined this way,
2770
2771 @example
2772 (define-key global-map [tool-bar shell]
2773 '(menu-item "Shell" shell
2774 :image (image :type xpm :file "shell.xpm")))
2775 @end example
2776
2777 @noindent
2778 then here is how you can define clicking on the same tool bar image with
2779 the shift modifier:
2780
2781 @example
2782 (define-key global-map [tool-bar S-shell] 'some-command)
2783 @end example
2784
2785 @xref{Function Keys}, for more information about how to add modifiers to
2786 function keys.
2787
2788 @node Modifying Menus
2789 @subsection Modifying Menus
2790
2791 When you insert a new item in an existing menu, you probably want to
2792 put it in a particular place among the menu's existing items. If you
2793 use @code{define-key} to add the item, it normally goes at the front of
2794 the menu. To put it elsewhere in the menu, use @code{define-key-after}:
2795
2796 @defun define-key-after map key binding &optional after
2797 Define a binding in @var{map} for @var{key}, with value @var{binding},
2798 just like @code{define-key}, but position the binding in @var{map} after
2799 the binding for the event @var{after}. The argument @var{key} should be
2800 of length one---a vector or string with just one element. But
2801 @var{after} should be a single event type---a symbol or a character, not
2802 a sequence. The new binding goes after the binding for @var{after}. If
2803 @var{after} is @code{t} or is omitted, then the new binding goes last, at
2804 the end of the keymap. However, new bindings are added before any
2805 inherited keymap.
2806
2807 Here is an example:
2808
2809 @example
2810 (define-key-after my-menu [drink]
2811 '("Drink" . drink-command) 'eat)
2812 @end example
2813
2814 @noindent
2815 makes a binding for the fake function key @key{DRINK} and puts it
2816 right after the binding for @key{EAT}.
2817
2818 Here is how to insert an item called @samp{Work} in the @samp{Signals}
2819 menu of Shell mode, after the item @code{break}:
2820
2821 @example
2822 (define-key-after
2823 (lookup-key shell-mode-map [menu-bar signals])
2824 [work] '("Work" . work-command) 'break)
2825 @end example
2826 @end defun
2827
2828 @node Easy Menu
2829 @subsection Easy Menu
2830
2831 The following macro provides a convenient way to define pop-up menus
2832 and/or menu bar menus.
2833
2834 @defmac easy-menu-define symbol maps doc menu
2835 This macro defines a pop-up menu and/or menu bar submenu, whose
2836 contents are given by @var{menu}.
2837
2838 If @var{symbol} is non-@code{nil}, it should be a symbol; then this
2839 macro defines @var{symbol} as a function for popping up the menu
2840 (@pxref{Pop-Up Menus}), with @var{doc} as its documentation string.
2841 @var{symbol} should not be quoted.
2842
2843 Regardless of the value of @var{symbol}, if @var{maps} is a keymap,
2844 the menu is added to that keymap, as a top-level menu for the menu bar
2845 (@pxref{Menu Bar}). It can also be a list of keymaps, in which case
2846 the menu is added separately to each of those keymaps.
2847
2848 The first element of @var{menu} must be a string, which serves as the
2849 menu label. It may be followed by any number of the following
2850 keyword-argument pairs:
2851
2852 @table @code
2853 @item :filter @var{function}
2854 @var{function} must be a function which, if called with one
2855 argument---the list of the other menu items---returns the actual items
2856 to be displayed in the menu.
2857
2858 @item :visible @var{include}
2859 @var{include} is an expression; if it evaluates to @code{nil}, the
2860 menu is made invisible. @code{:included} is an alias for
2861 @code{:visible}.
2862
2863 @item :active @var{enable}
2864 @var{enable} is an expression; if it evaluates to @code{nil}, the menu
2865 is not selectable. @code{:enable} is an alias for @code{:active}.
2866 @end table
2867
2868 The remaining elements in @var{menu} are menu items.
2869
2870 A menu item can be a vector of three elements, @code{[@var{name}
2871 @var{callback} @var{enable}]}. @var{name} is the menu item name (a
2872 string). @var{callback} is a command to run, or an expression to
2873 evaluate, when the item is chosen. @var{enable} is an expression; if
2874 it evaluates to @code{nil}, the item is disabled for selection.
2875
2876 Alternatively, a menu item may have the form:
2877
2878 @smallexample
2879 [ @var{name} @var{callback} [ @var{keyword} @var{arg} ]... ]
2880 @end smallexample
2881
2882 @noindent
2883 where @var{name} and @var{callback} have the same meanings as above,
2884 and each optional @var{keyword} and @var{arg} pair should be one of
2885 the following:
2886
2887 @table @code
2888 @item :keys @var{keys}
2889 @var{keys} is a keyboard equivalent to the menu item (a string). This
2890 is normally not needed, as keyboard equivalents are computed
2891 automatically. @var{keys} is expanded with
2892 @code{substitute-command-keys} before it is displayed (@pxref{Keys in
2893 Documentation}).
2894
2895 @item :key-sequence @var{keys}
2896 @var{keys} is a hint for speeding up Emacs's first display of the
2897 menu. It should be nil if you know that the menu item has no keyboard
2898 equivalent; otherwise it should be a string or vector specifying a
2899 keyboard equivalent for the menu item.
2900
2901 @item :active @var{enable}
2902 @var{enable} is an expression; if it evaluates to @code{nil}, the item
2903 is make unselectable.. @code{:enable} is an alias for @code{:active}.
2904
2905 @item :visible @var{include}
2906 @var{include} is an expression; if it evaluates to @code{nil}, the
2907 item is made invisible. @code{:included} is an alias for
2908 @code{:visible}.
2909
2910 @item :label @var{form}
2911 @var{form} is an expression that is evaluated to obtain a value which
2912 serves as the menu item's label (the default is @var{name}).
2913
2914 @item :suffix @var{form}
2915 @var{form} is an expression that is dynamically evaluated and whose
2916 value is concatenated with the menu entry's label.
2917
2918 @item :style @var{style}
2919 @var{style} is a symbol describing the type of menu item; it should be
2920 @code{toggle} (a checkbox), or @code{radio} (a radio button), or
2921 anything else (meaning an ordinary menu item).
2922
2923 @item :selected @var{selected}
2924 @var{selected} is an expression; the checkbox or radio button is
2925 selected whenever the expression's value is non-nil.
2926
2927 @item :help @var{help}
2928 @var{help} is a string describing the menu item.
2929 @end table
2930
2931 Alternatively, a menu item can be a string. Then that string appears
2932 in the menu as unselectable text. A string consisting of dashes is
2933 displayed as a separator (@pxref{Menu Separators}).
2934
2935 Alternatively, a menu item can be a list with the same format as
2936 @var{menu}. This is a submenu.
2937 @end defmac
2938
2939 Here is an example of using @code{easy-menu-define} to define a menu
2940 similar to the one defined in the example in @ref{Menu Bar}:
2941
2942 @example
2943 (easy-menu-define words-menu global-map
2944 "Menu for word navigation commands."
2945 '("Words"
2946 ["Forward word" forward-word]
2947 ["Backward word" backward-word]))
2948 @end example