Re: reentrant parser - how?

[Hans Aberg]

At 23:26 +0200 2005/05/04, Carsten Krueger wrote:
> can anybody tell me how this lexer-parser-combination would look if it
> is a reentrant parser?

I recall Paul Eggert said that the Bison generated parser, which he 
wrote, now is fully pure. If you have some data to be passed to the 
parser, that should be done via the arguments to yyparse, and there 
are some macros for doing that; see the Bison manual. If yyparse 
needs some local data, then there might not be support for doing that 
right now. Then you need to figure out how to make the Flex generated 
lexer to become pure; for that, check in the Help-Flex list 
<address@hidden>.

> ---------------lexer.l-------------------------------
> %option yylineno
> %option case-insensitive
>
> %{
>   #include "parser.tab.h"
>   /* hier C-includes*/
> %}
>
> %%
> .        { return LINE;
>          }
> %%
>
> int yywrap(){ return 1; /* 1: beendet lex */ }
>
> ---------------lexer.l-------------------------------
>
> ---------------parser.y------------------------------
> %{
>   /* hier C-includes*/
> %}
>
> %token LINE
>
> %%
>
> PROGRAM : LINE { /* meine C-Anweisung */ }
>
> %%
>
> int yyerror (char const *s)
> {
>   exit(1);
>   return 0;
> }
>
> ---------------parser.y------------------------------
>
> ---------------main.c--------------------------------
> extern int yyparse();
>
> int main()
> {
>   /* YYIN = file_descriptor_1; */
>   yyparse();
>   /* reset_parser - ?????????????? */
>
>   /* YYIN = file_descriptor_2; */
>   /* yyparse();  */
>   return 0;
> }
> ---------------main.c--------------------------------
>
> --------------make.sh--------------------------------
> #!/bin/bash
> bison -d parser.y
> flex lexer.l
>
> gcc -c parser.tab.c
> gcc -c lex.yy.c
> gcc -c main.c
>
> gcc -o main parser.tab.o lex.yy.o main.o
> --------------make.sh--------------------------------