@anchor{Definition of this-command-keys}
This function returns a string or vector containing the key sequence
that invoked the present command, plus any previous commands that
-generated the prefix argument for this command. However, if the
-command has called @code{read-key-sequence}, it returns the last read
-key sequence. @xref{Key Sequence Input}. The value is a string if
-all events in the sequence were characters that fit in a string.
-@xref{Input Events}.
+generated the prefix argument for this command. Any events read by the
+command using @code{read-event} without a timeout get tacked on to the end.
+
+However, if the command has called @code{read-key-sequence}, it
+returns the last read key sequence. @xref{Key Sequence Input}. The
+value is a string if all events in the sequence were characters that
+fit in a string. @xref{Input Events}.
@example
@group
latter as the symbol @code{tab}.
Most of the time, it's not useful to distinguish the two. So normally
-@code{function-key-map} (@pxref{Translating Input}) is set up to map
+@code{function-key-map} (@pxref{Translation Keymaps}) is set up to map
@code{tab} into 9. Thus, a key binding for character code 9 (the
character @kbd{C-i}) also applies to @code{tab}. Likewise for the other
symbols in this group. The function @code{read-char} likewise converts
See also @code{momentary-string-display} in @ref{Temporary Displays},
and @code{sit-for} in @ref{Waiting}. @xref{Terminal Input}, for
functions and variables for controlling terminal input modes and
-debugging terminal input. @xref{Translating Input}, for features you
-can use for translating or modifying input events while reading them.
+debugging terminal input.
For higher-level input facilities, see @ref{Minibuffers}.
@menu
* Key Sequence Input:: How to read one key sequence.
* Reading One Event:: How to read just one event.
+* Event Mod:: How Emacs modifies events as they are read.
* Invoking the Input Method:: How reading an event uses the input method.
* Quoted Character Input:: Asking the user to specify a character.
* Event Input Misc:: How to reread or throw away input events.
vector are the events in the key sequence.
Reading a key sequence includes translating the events in various
-ways. @xref{Translating Input}.
+ways. @xref{Translation Keymaps}.
The argument @var{prompt} is either a string to be displayed in the
echo area as a prompt, or @code{nil}, meaning not to display a prompt.
button and modifier keys. The information about the window part is kept
elsewhere in the event---in the coordinates. But
@code{read-key-sequence} translates this information into imaginary
-``prefix keys'', all of which are symbols: @code{header-line},
+``prefix keys,'' all of which are symbols: @code{header-line},
@code{horizontal-scroll-bar}, @code{menu-bar}, @code{mode-line},
@code{vertical-line}, and @code{vertical-scroll-bar}. You can define
meanings for mouse clicks in special window parts by defining key
None of the three functions below suppresses quitting.
-@defun read-event &optional prompt inherit-input-method
+@defun read-event &optional prompt inherit-input-method seconds
This function reads and returns the next event of command input, waiting
if necessary until an event is available. Events can come directly from
the user or from a keyboard macro.
moves the cursor temporarily to the echo area, to the end of any message
displayed there. Otherwise @code{read-event} does not move the cursor.
+If @var{seconds} is non-@code{nil}, it should be a number specifying
+the maximum time to wait for input, in seconds. If no input arrives
+within that time, @code{read-event} stops waiting and returns
+@code{nil}. A floating-point value for @var{seconds} means to wait
+for a fractional number of seconds. Some systems support only a whole
+number of seconds; on these systems, @var{seconds} is rounded down.
+If @var{seconds} is @code{nil}, @code{read-event} waits as long as
+necessary for input to arrive.
+
+If @var{seconds} is @code{nil}, Emacs is considered idle while waiting
+for user input to arrive. Idle timers---those created with
+@code{run-with-idle-timer} (@pxref{Idle Timers})---can run during this
+period. However, if @var{seconds} is non-@code{nil}, the state of
+idleness remains unchanged. If Emacs is non-idle when
+@code{read-event} is called, it remains non-idle throughout the
+operation of @code{read-event}; if Emacs is idle (which can happen if
+the call happens inside an idle timer), it remains idle.
+
If @code{read-event} gets an event that is defined as a help character,
then in some cases @code{read-event} processes the event directly without
returning. @xref{Help Functions}. Certain other events, called
@end example
@end defun
-@defun read-char &optional prompt inherit-input-method
+@defun read-char &optional prompt inherit-input-method seconds
This function reads and returns a character of command input. If the
user generates an event which is not a character (i.e. a mouse click or
function key event), @code{read-char} signals an error. The arguments
@end example
@end defun
-@defun read-char-exclusive &optional prompt inherit-input-method
+@defun read-char-exclusive &optional prompt inherit-input-method seconds
This function reads and returns a character of command input. If the
user generates an event which is not a character,
@code{read-char-exclusive} ignores it and reads another event, until it
from the terminal---not counting those generated by keyboard macros.
@end defvar
+@node Event Mod
+@subsection Modifying and Translating Input Events
+
+ Emacs modifies every event it reads according to
+@code{extra-keyboard-modifiers}, then translates it through
+@code{keyboard-translate-table} (if applicable), before returning it
+from @code{read-event}.
+
+@c Emacs 19 feature
+@defvar extra-keyboard-modifiers
+This variable lets Lisp programs ``press'' the modifier keys on the
+keyboard. The value is a character. Only the modifiers of the
+character matter. Each time the user types a keyboard key, it is
+altered as if those modifier keys were held down. For instance, if
+you bind @code{extra-keyboard-modifiers} to @code{?\C-\M-a}, then all
+keyboard input characters typed during the scope of the binding will
+have the control and meta modifiers applied to them. The character
+@code{?\C-@@}, equivalent to the integer 0, does not count as a control
+character for this purpose, but as a character with no modifiers.
+Thus, setting @code{extra-keyboard-modifiers} to zero cancels any
+modification.
+
+When using a window system, the program can ``press'' any of the
+modifier keys in this way. Otherwise, only the @key{CTL} and @key{META}
+keys can be virtually pressed.
+
+Note that this variable applies only to events that really come from
+the keyboard, and has no effect on mouse events or any other events.
+@end defvar
+
+@defvar keyboard-translate-table
+This variable is the translate table for keyboard characters. It lets
+you reshuffle the keys on the keyboard without changing any command
+bindings. Its value is normally a char-table, or else @code{nil}.
+(It can also be a string or vector, but this is considered obsolete.)
+
+If @code{keyboard-translate-table} is a char-table
+(@pxref{Char-Tables}), then each character read from the keyboard is
+looked up in this char-table. If the value found there is
+non-@code{nil}, then it is used instead of the actual input character.
+
+Note that this translation is the first thing that happens to a
+character after it is read from the terminal. Record-keeping features
+such as @code{recent-keys} and dribble files record the characters after
+translation.
+
+Note also that this translation is done before the characters are
+supplied to input methods (@pxref{Input Methods}). Use
+@code{translation-table-for-input} (@pxref{Translation of Characters}),
+if you want to translate characters after input methods operate.
+@end defvar
+
+@defun keyboard-translate from to
+This function modifies @code{keyboard-translate-table} to translate
+character code @var{from} into character code @var{to}. It creates
+the keyboard translate table if necessary.
+@end defun
+
+ Here's an example of using the @code{keyboard-translate-table} to
+make @kbd{C-x}, @kbd{C-c} and @kbd{C-v} perform the cut, copy and paste
+operations:
+
+@example
+(keyboard-translate ?\C-x 'control-x)
+(keyboard-translate ?\C-c 'control-c)
+(keyboard-translate ?\C-v 'control-v)
+(global-set-key [control-x] 'kill-region)
+(global-set-key [control-c] 'kill-ring-save)
+(global-set-key [control-v] 'yank)
+@end example
+
+@noindent
+On a graphical terminal that supports extended @acronym{ASCII} input,
+you can still get the standard Emacs meanings of one of those
+characters by typing it with the shift key. That makes it a different
+character as far as keyboard translation is concerned, but it has the
+same usual meaning.
+
+ @xref{Translation Keymaps}, for mechanisms that translate event sequences
+at the level of @code{read-key-sequence}.
+
@node Invoking the Input Method
@subsection Invoking the Input Method
@defvar unread-command-char
This variable holds a character to be read as command input.
-A value of -1 means ``empty''.
+A value of -1 means ``empty.''
This variable is mostly obsolete now that you can use
@code{unread-command-events} instead; it exists only to support programs
@defun sit-for seconds &optional nodisp
This function performs redisplay (provided there is no pending input
from the user), then waits @var{seconds} seconds, or until input is
-available. The value is @code{t} if @code{sit-for} waited the full
-time with no input arriving (see @code{input-pending-p} in @ref{Event
-Input Misc}). Otherwise, the value is @code{nil}.
+available. The usual purpose of @code{sit-for} is to give the user
+time to read text that you display. The value is @code{t} if
+@code{sit-for} waited the full time with no input arriving
+(@pxref{Event Input Misc}). Otherwise, the value is @code{nil}.
The argument @var{seconds} need not be an integer. If it is a floating
point number, @code{sit-for} waits for a fractional number of seconds.
Some systems support only a whole number of seconds; on these systems,
@var{seconds} is rounded down.
-If @var{seconds} is negative, force a redisplay even if there is
-pending input. So use @code{(sit-for -1)} to force a redisplay.
-
-The expression @code{(sit-for 0)} is a convenient way to request a
-redisplay, without any delay, if there is no pending input. @xref{Forcing Redisplay}.
+The expression @code{(sit-for 0)} is equivalent to @code{(redisplay)},
+i.e. it requests a redisplay, without any delay, if there is no pending input.
+@xref{Forcing Redisplay}.
If @var{nodisp} is non-@code{nil}, then @code{sit-for} does not
redisplay, but it still returns as soon as input is available (or when
the timeout elapses).
-Iconifying or deiconifying a frame makes @code{sit-for} return, because
-that generates an event. @xref{Misc Events}.
-
-The usual purpose of @code{sit-for} is to give the user time to read
-text that you display.
+In batch mode (@pxref{Batch Mode}), @code{sit-for} cannot be
+interrupted, even by input from the standard input descriptor. It is
+thus equivalent to @code{sleep-for}, which is described below.
It is also possible to call @code{sit-for} with three arguments,
as @code{(sit-for @var{seconds} @var{millisec} @var{nodisp})},
change the major mode of the current buffer temporarily to a special
major mode, which should have a command to go back to the previous mode.
(The @kbd{e} command in Rmail uses this technique.) Or, if you wish to
-give the user different text to edit ``recursively'', create and select
+give the user different text to edit ``recursively,'' create and select
a new buffer in a special mode. In this mode, define a command to
complete the processing and go back to the previous buffer. (The
@kbd{m} command in Rmail does this.)