woodward@uicbert.eecs.uic.edu (07/27/90)
i have been trying to parse a straightforward stream of bytes using the
c-preprocessors lex & yacc. being a new user of these utilities, i have
a couple of problems for which i'd like to solicit your suggestions:
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1.) how does one redefine the i/o in a yacc/lex piece of code? i.e.
the code which is generated defaults to stdin and stdout for input and
output, respectively. i'd like to redefine these defaults w/o having
to hack on the intermediate c-code, since this is a live production
project; i'd like to be able to update and modify the program simply by
saying "make".
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2.) how can one get the automagically-defined #defines, which can
normally be created from yacc with the -d flag, to come out when you
use a makefile? i.e. suppose i have lex.l and yacc.y lex and yacc
source files, respectively, and i have object files defined in my makefile
called lex.o and yacc.o such that "make" follows default rules to create
these from the aforementioned source files.
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3.) if i have a yacc construct such as:
line3 : A B C
{ yacc action sequence }
which indicates that the construct line3 is composed of the 3 tokens
A B and C, in that order ...
how can i now assign the values of A, B, and C into local vars of my
choice? the problem lies in the fact that each of A B and C represent
three calls to lex, and if i pass back a pointer to yytext[] from lex,
i only retain the value of the last token in the sequence, in this case C,
when i get to the action sequence in my yacc code. what if i want to
be able to select the EXACT ascii tokens for each of A B and C above in
my yacc code. how do i do that?
any comments or suggestions would be most heartily appreciated.
jp woodward
univ of ill at chicago
312-996-0939