Path: csiph.com!newsfeed.hal-mli.net!feeder3.hal-mli.net!newsfeed.hal-mli.net!feeder1.hal-mli.net!news.misty.com!news.iecc.com!.POSTED!nerds-end
From: Hans Aberg <haberg-news@telia.com>
Newsgroups: comp.compilers
Subject: Re: parsing function name and arguments
Date: Fri, 10 May 2013 22:24:30 +0200
Organization: A noiseless patient Spider
Lines: 31
Sender: johnl@iecc.com
Approved: comp.compilers@iecc.com
Message-ID: <13-05-007@comp.compilers>
References: <13-05-005@comp.compilers>
NNTP-Posting-Host: news.iecc.com
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
X-Trace: leila.iecc.com 1368249582 80555 64.57.183.58 (11 May 2013 05:19:42 GMT)
X-Complaints-To: abuse@iecc.com
NNTP-Posting-Date: Sat, 11 May 2013 05:19:42 +0000 (UTC)
Keywords: lex, debug
Posted-Date: 11 May 2013 01:19:42 EDT
X-submission-address: compilers@iecc.com
X-moderator-address: compilers-request@iecc.com
X-FAQ-and-archives: http://compilers.iecc.com
Xref: csiph.com comp.compilers:893

On 2013/05/09 13:05, Lee wrote:
> I have the flex file defined as:
...
> SYMBOL_ID       [a-zA-Z]+[a-zA-Z0-9_]*
...
> %%
...

> {SYMBOL_ID}       { printf("2.yylval =  %s\n", yytext);
>                      yylval.all_str = yytext;
>                      return (SYMBOLID);
>                      }
...
> %%

You have forgotten to copy the string pointed at by yytext...

> and the grammar as:
...
>      %%
>      program
>                  : FUNCTION SYMBOLID '(' SYMBOLID ')'
>                      { printf("FUNCTION SYMBOL = %s\n", $2);
>                        printf("func name and args: '%s' '%s'\n", $2, $4);
>                      }

...so here, the action will only be executed after all grammar
components have been pointed at, and then yytext of the first SYMBOLID
points at something else. If you are using C, then you must also clean
up allocated strings no longer in use. In C++, this can be done using
the std::string class.