by Leung Leu » Sat, 02 Dec 1995 04:00:00
Hi all,
I am writing a program which will use Yacc & Lex to get the user's
input. But while waiting for the user's input, I want the program to poll
the message queue at the same time. If there is a message, it will be
displayed on the screen. How to do that ? Seems that I cannot do
anything while waiting for user's input ( yyparse() ) ...
Thanks
Leung
by Wendell G » Sat, 02 Dec 1995 04:00:00
RB>Hi all,
RB> I am writing a program which will use Yacc & Lex to get the user's
RB>input. But while waiting for the user's input, I want the program to poll
RB>the message queue at the same time. If there is a message, it will be
RB>displayed on the screen. How to do that ? Seems that I cannot do
RB>anything while waiting for user's input ( yyparse() ) ...
You can probably use a timer-interrupt to wake your message-poller
every so often...
man alarm
man signal
--r
--
--------------------------------------------------------------------------
| "The density of the information | Rick Bradley |
| presented is near the theoretical | Starving Graduate Student |
| minimum." --FreeBSD manual: comsat(8) | CS Dept. -- SUNY Stony Brook |
--------------------------------------------------------------------------
by Craig P. Forbe » Sat, 02 Dec 1995 04:00:00
If you aren't already you may want to look into flex and bison. I find
them much nicer (and more portable) then the AT&T lex/yacc.
--
Craig P. Forbes McCabe & Associates
5501 Twin Knolls Road, Suite 111
by Leung Leu » Sun, 03 Dec 1995 04:00:00
: RB>Hi all,
: RB> I am writing a program which will use Yacc & Lex to get the user's
: RB>input. But while waiting for the user's input, I want the program to poll
: RB>the message queue at the same time. If there is a message, it will be
: RB>displayed on the screen. How to do that ? Seems that I cannot do
: RB>anything while waiting for user's input ( yyparse() ) ...
: You can probably use a timer-interrupt to wake your message-poller
: every so often...
: man alarm
: man signal
Um ... It is a very good idea.. Thanks ! :)
Any other suggestions are welcom.
by Pete Roumeliot » Mon, 04 Dec 1995 04:00:00
Sound feasibal????
Pete R.
by Mark-Jason Domin » Mon, 04 Dec 1995 04:00:00
I think that `input' is a macro, so the way to do this is to include
#undef input
in the header part of the .l file; then yylex will call your `input'
function instead of using the macro.
--
The night is pleasing to us because, like memory, it erases idle details.
1. Followup YACC & LEX Question
Thanks to all who responded to my recent LEX question.. I managed to take
two of the 4 responses I got and merge them for a solution.. Another question
comes up, now:
I'm still having fun with preprocessors. What I now need to do is to
implement a (YACC) grammar to preprocess hunks of code, disregarding
code that is the actual program body wherever necesary..
For example, Here is a possibility:
? (VAR debug_mode:boolean := TRUE,
unhappy_mode:boolean := TRUE; );?
.
<lots of program body here #1>
.
?IF (debug_mode)
PROCEDURE [XREF] Moo (x:integer);
.
.
<lots of program body here #2>
.
PROCEND Moo;
?ELSE
PROCEDURE [XREF] Moo2 (x:real);
.
.
?IFEND
For clarification of my ambiguous comment above, what I need to do is to
take a YACC grammar that will accept preprocessor directives but that has
no clue about the programming language itself. Thus, I will need to
disregard code that is in "<lots of program body here #1>". I can deal
with program bodies #2 and #3 and their appropriate manipulation, but
can't comprehend how to disregard all that middle code. Anyone have an
idea? Thanks in advance!
-Jeff
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