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char-ready? for soft ports
From: |
Neil Jerram |
Subject: |
char-ready? for soft ports |
Date: |
03 Oct 2002 23:33:05 +0100 |
User-agent: |
Gnus/5.0808 (Gnus v5.8.8) Emacs/20.7 |
Currently, char-ready? always returns #t for a soft port.
The patch below extends make-soft-port so that its vector argument can have 6
as well as 5 elements. If present and not #f, the 6th element is used
as the input-waiting thunk for the soft port - i.e. it should return
the number of characters available for reading without blocking. The
patch to (ice-9 buffered-input) gives an example of how to define such
a thunk.
Thoughts? Is there a reason I've missed why soft ports should not
support char-ready? completely? Should I commit this? (Is the use of
SCM_INUM in sf_input_waiting safe?)
Regards,
Neil
Index: libguile/vports.c
===================================================================
RCS file: /cvsroot/guile/guile/guile-core/libguile/vports.c,v
retrieving revision 1.57
diff -u -r1.57 vports.c
--- libguile/vports.c 15 Aug 2002 21:17:21 -0000 1.57
+++ libguile/vports.c 3 Oct 2002 22:27:21 -0000
@@ -139,6 +139,22 @@
}
+static int
+sf_input_waiting (SCM port)
+{
+ SCM p = SCM_PACK (SCM_STREAM (port));
+ if (SCM_VECTOR_LENGTH (p) >= 6)
+ {
+ SCM f = SCM_VELTS (p)[5];
+ if (SCM_NFALSEP (f))
+ return SCM_INUM (scm_call_0 (f));
+ }
+ /* Default is such that char-ready? for soft ports returns #t, as it
+ did before this extension was implemented. */
+ return 1;
+}
+
+
SCM_DEFINE (scm_make_soft_port, "make-soft-port", 2, 0, 0,
(SCM pv, SCM modes),
@@ -185,9 +201,13 @@
"@end lisp")
#define FUNC_NAME s_scm_make_soft_port
{
+ int vlen;
scm_t_port *pt;
SCM z;
- SCM_VALIDATE_VECTOR_LEN (1, pv,5);
+
+ SCM_VALIDATE_VECTOR (1, pv);
+ vlen = SCM_VECTOR_LENGTH (pv);
+ SCM_ASSERT ((vlen == 5) || (vlen == 6), pv, 1, FUNC_NAME);
SCM_VALIDATE_STRING (2, modes);
SCM_DEFER_INTS;
@@ -211,6 +231,7 @@
scm_set_port_mark (tc, scm_markstream);
scm_set_port_flush (tc, sf_flush);
scm_set_port_close (tc, sf_close);
+ scm_set_port_input_waiting (tc, sf_input_waiting);
return tc;
}
Index: ice-9/buffered-input.scm
===================================================================
RCS file: /cvsroot/guile/guile/guile-core/ice-9/buffered-input.scm,v
retrieving revision 1.4
diff -u -r1.4 buffered-input.scm
--- ice-9/buffered-input.scm 3 Jun 2001 23:29:45 -0000 1.4
+++ ice-9/buffered-input.scm 3 Oct 2002 22:27:10 -0000
@@ -105,8 +105,15 @@
(if (not (char-whitespace? res))
(set! (buffered-input-continuation? port) #t))
res)))))
+ (input-waiting
+ (lambda ()
+ ;(write read-string)
+ ;(newline)
+ (if (eof-object? read-string)
+ 1
+ (- (string-length read-string) string-index))))
(port #f))
- (set! port (make-soft-port (vector #f #f #f get-character #f) "r"))
+ (set! port (make-soft-port (vector #f #f #f get-character #f
input-waiting) "r"))
(set! (buffered-input-continuation? port) #f)
port)))
- char-ready? for soft ports,
Neil Jerram <=