Re: Passing string literals in function calls in an interpreter

On 26 Dec 2002 23:37:53 -0500, jimmyp@hal.csd.auth.gr (Dimitris)
wrote:


> I'm using bison for the parser so freeing malloced buffers can be a
> problem so if anyone has any ideas on where to find temporary space
> that is freed automagically (like space on the stack frame) I'd be
> very interested.


I use the following code:


      #define SCRA_SZ (4096)
      char *scratch;
      int scratchndx;
....
      scratch=(char *)malloc(SCRA_SZ);
      scratchndx=0;
....


      char *maketmp(char *s)
      {
            int i;
            char *p;
            i=strlen(s)+1;
            if( (scratch+scratchndx+i) >(scratch+SCRA_SZ-1) ) {
                  scratchndx=0;
            }


            strcpy(scratch+scratchndx,s);
            p=scratch+scratchndx;
          scratchndx+=i;
            return p;
      }


It's essentially a ring-buffer. I reset the buffer index to zero if I
run out of room and hope that I'm not destroying any active strings.
The buffer just keeps filling until we approach the end, then it
starts over.


While I don't use this for literals, I use it for temporary copies of
strings, such as those that result from a concatenation operation or
something.


Jim Lawless * jimbo@radiks.net * http://www.radiks.net/~jimbo
http://www.mailsend-online.com * Command-line e-mail tools,
tiny scheduler, DUN hangup, batch script language
[Ugh. I'd rather something deterministic, like chaining all the allocated
space together and releasing it all at once when you know you're not
using it any more. -John]

Return to the comp.compilers page.
Search the comp.compilers archives again.