Perl Regex Engine

Bonus

regcomp.c:2253

     {
         char *p;
         static char parens[] = "=!<,>";

         if (paren && (p = strchr(parens, paren))) {
             int node = ((p - parens) % 2) ? UNLESSM : IFMATCH;
             int flag = (p - parens) > 1;

             if (paren == '>')
                 node = SUSPEND, flag = 0;
             reginsert(pRExC_state, node,ret);
             ret->flags = flag;
             regtail(pRExC_state, ret, reg_node(pRExC_state, TAIL));
         }
     }