Generic functions for character input
(GRAY:STREAM-READ-CHAR
stream
)
If a character was pushed back using GRAY:STREAM-UNREAD-CHAR
,
returns and consumes it. Otherwise returns and consumes the next
character from the stream. Returns :EOF
if the end-of-stream
is reached.
You must define a method for this function.
(GRAY:STREAM-UNREAD-CHAR
stream
char
)
Pushes char
, which must be the last character
read from the stream
, back onto the front of the stream
.
You must define a method for this function.
(GRAY:STREAM-READ-CHAR-NO-HANG
stream
)
Returns a character or :EOF
, like GRAY:STREAM-READ-CHAR
, if
that would return immediately. If GRAY:STREAM-READ-CHAR
's value is not available
immediately, returns NIL
instead of waiting.
The default method simply calls GRAY:STREAM-READ-CHAR
; this is sufficient for streams
whose GRAY:STREAM-READ-CHAR
method never blocks.
(GRAY:STREAM-PEEK-CHAR stream
)
If a character was pushed back using GRAY:STREAM-UNREAD-CHAR
,
returns it. Otherwise returns the next character from the stream,
avoiding any side effects GRAY:STREAM-READ-CHAR
would do. Returns :EOF
if the
end-of-stream
is reached.
The default method calls GRAY:STREAM-READ-CHAR
and GRAY:STREAM-UNREAD-CHAR
; this is
sufficient for streams whose GRAY:STREAM-READ-CHAR
method has no
side-effects.
(GRAY:STREAM-LISTEN stream
)
If a character was pushed back using GRAY:STREAM-UNREAD-CHAR
,
returns it. Otherwise returns the next character from the stream, if
already available. If no character is available immediately, or if
end-of-stream
is reached, returns NIL
.
The default method calls GRAY:STREAM-READ-CHAR-NO-HANG
and GRAY:STREAM-UNREAD-CHAR
; this is
sufficient for streams whose GRAY:STREAM-READ-CHAR
method has no
side-effects.
(GRAY:STREAM-READ-CHAR-WILL-HANG-P
stream
)
Returns NIL
if GRAY:STREAM-READ-CHAR
will return immediately.
Otherwise it returns true.
The default method calls GRAY:STREAM-READ-CHAR-NO-HANG
and GRAY:STREAM-UNREAD-CHAR
; this is
sufficient for streams whose GRAY:STREAM-READ-CHAR
method has no side-effects.
This function is a CLISP extension (see EXT:READ-CHAR-WILL-HANG-P
).
(GRAY:STREAM-READ-CHAR-SEQUENCE
stream
sequence
&OPTIONAL
[start
[end
]])
Fills the subsequence of sequence
specified by
:START
and :END
with characters consecutively read from stream
.
Returns the index of the first element of sequence
that was not
updated (=
end
, or <
end
if the stream reached its end).
sequence
is an ARRAY
of CHARACTER
s, i.e. a STRING
.
start
is a nonnegative INTEGER
and defaults to 0
.
end
is a nonnegative INTEGER
or NIL
and defaults to NIL
,
which stands for (
.
LENGTH
sequence
)
The default method repeatedly calls GRAY:STREAM-READ-CHAR
; this
is always sufficient if speed does not matter.
This function is a CLISP extension (see
EXT:READ-CHAR-SEQUENCE
).
(GRAY:STREAM-READ-LINE stream
)
Reads a line of characters, and return two values:
the line (a STRING
, without the terminating #\Newline character),
and a BOOLEAN
value which is true if the line was terminated by
end-of-stream
instead of #\Newline.
The default method repeatedly calls GRAY:STREAM-READ-CHAR
; this
is always sufficient.
(GRAY:STREAM-CLEAR-INPUT stream
)
Clears all pending interactive input from the
stream
, and returns true if some pending input was removed.
The default method does nothing and returns NIL
; this is
sufficient for non-interactive streams.
These notes document CLISP version 2.49 | Last modified: 2010-07-07 |