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From: john@basho.uucp (John Lacey)
Newsgroups: comp.lang.c,comp.unix.questions
Subject: Using Lex (and Yacc) on a string.
Message-ID: <1990Aug10.012927.5558@basho.uucp>
Date: 10 Aug 90 01:29:27 GMT
Organization: Sportsware
Lines: 41

Normally, of course, one wants a scanner (and a parser) to work from 
a file, perhaps stdin.  Sigh.  Well, I want one that works from a string.

I am using Flex 2.3, and Bison 1.11.  I tried the following few #define's:

#undef  YY_INPUT
#define YY_INPUT(buf,result,max_size) \
{ \
for ( result = 0;  *ch_this && result < max_size; result ++ ) \
   buf[result] = *ch_this++; \
}

#define YY_USER_INIT \
   if ( scan_init ) { \
      if ( yy_flex_debug ) \
         printf ( "-- initializing for scan %d\n", scan_init ); \
      ch_this = inbuffer; \
      scan_init = 0; }

with the following couple of definitions and declarations in the scanner:

static char * ch_this;
extern char * inbuffer;
extern int scan_init;

and with inbuffer and scan_init defined in the code that calls yyparse().
This didn't work.  Well, actually, it works the first time yyparse() is 
called, but not again.  Now, YY_USER_INIT is used inside an if statement
that checks yy_init, so I moved it out of there in the scanner skeleton
so that YY_USER_INIT is seen every time the scanner is called.  Still 
no go.

Has anyone done this, or see a way to do it, or know a way to do it, or ....

Thanks.

-- 
John Lacey, 
   E-mail:  ...!osu-cis!n8emr!uncle!basho!john  (coming soon: john@basho.uucp)
   V-mail:  (614) 436--3773, or 487--8570
"What was the name of the dog on Rin-tin-tin?"  --Mickey Rivers, ex-Yankee CF