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stop yyparse() at <<EOF>>

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  stop yyparse() at <<EOF>> Jens Kallup <jkallup@web.de> - 2015-12-22 16:29 +0100
    Re: stop yyparse() at <<EOF>> Kaz Kylheku <kaz@kylheku.com> - 2015-12-27 10:59 -0500

#1654 — stop yyparse() at <<EOF>>

Hello,

I work on multiple parser's in a GUI.  When I start 1st, the code
generation is fine.  But, when I start 2nd start, the code generator
produce some junk.  I have used "yyterminate();" but this seems to not
help.

The source:
? "Ploppers" + "ppp" + "huhu"

The pre-processed text file:
#output asm, cli
? "Ploppers" + "ppp" + "huhu"

The first pass (flex):
1: "Ploppers"
  plus
  2: "ppp"
  plus
  2: "huhu"

The second pass:
#output asm, cli? 2: "Ploppers"
  plus
  2: "ppp"
  plus
  2: "huhu"
Segmentation fault


\#"output cpp"      { outype = 0; return _CPP_PARSER_; }
\#"output asm"      { outype = 1; return _ASM_PARSER_; }
\#"output asm, cli" { outype = 1; return _ASM_PARSER_; }

(\"([a-zA-Z0-9_])*\")* {
   printf("1: %s\n",yytext); strcpy(yytext,"");
   BEGIN(STRINGER);
   strcpy(yytext,"");
}
<STRINGER>{
(\"([a-zA-Z0-9_])*\")* { printf("2: %s\n",yytext);
   strcpy(yytext,""); BEGIN(STRINGER); strcpy(yytext,"");
}
\+        { printf("plus\n"); BEGIN(STRINGER); }
\n
}


I would like use it in gnu "bison" so:

string_expr
     : _STRING_ { printf("---> %s\n",yylval.text); }
     ;


Is that a Bug, or my mistakes?

TIA
Jens

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#1655

On 2015-12-22, Jens Kallup <jkallup@web.de> wrote:
> (\"([a-zA-Z0-9_])*\")* {
>    printf("1: %s\n",yytext); strcpy(yytext,"");
>    BEGIN(STRINGER);
>    strcpy(yytext,"");

[ snip ]
>
> Is that a Bug, or my mistakes?

Not saying this is the crash, but do not modify yytext; it is (or may
be) a pointer directly into the lexical analyzer's buffer, and not a
copy.

You might be confusing the flex scanner somehow by putting a null in
there.

> string_expr
>      : _STRING_ { printf("---> %s\n",yylval.text); }
>      ;


You haven't shown any lexer code which sets up yylval.text and returns
the _STRING_ token.

The lex rules you have surrounding your STRINGER state don't return
anything.

[Good points.  In recent versoins of flex, yytext points into the
input buffer and chaning what it points to is asking for trouble.
If you need to change it, make a copy.
Also, there's no BEGIN(INITIAL) to reset the start states. -John]

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