Re: [Flex-help] Unsuccessfully trying to use {NAME}

[Chris v. <che...@gm...>]

I think this is a superset of your later question about comments messing up
named patterns, yes?

-Chris



On Sun, Oct 27, 2013 at 4:43 PM, Arthur Schwarz <asc...@at...>wrote:

> Sorry to be a pest (well, not really). I'm trying to use a neat feature
> that you have in flex, the ability to define a named regular expression in
> the definitions section and use it in the rules. Alas, all is lost. I've
> tried to follow the direction in Section 5.1 of the flex manual to no
> success. The code below shows an example of what I'm trying to do. It seems
> dead simple and I'm doing something dead wrong.
>
> >From Section 5.1 the expansion of {WHITESPACE} is "[ \a\b\f\r\t\v]" and
> {TRUE} is "([tT][rR][uU][eE])". Using the named expressions don't work.
> Substituting the regular expression is as a pattern the code works (except
> for executing the statements associated with '\n').
>
>
> Could you explain what is wrong with the code so that I can use named
> regular expressions?
>
> art
>
> %option main
>
> %{
> #include <stdio.h>
> %}
>
> WHITESPACE  [ \a\b\f\r\t\v]                        /* white space   */
> TRUE        [tT][rR][uU][eE]                       /* true          */
>
> %%
>   /*
>    * rule 1: flex complains "unrecognized rule"
>    * rule 2: flex complains "unrecognized rule"
>    * rule 3: No complaint and pattern is not recognized on input
>    * rule '[ \a\b\f\r\t\v]+' works
>    * rule '[tT][rR][uU][eE]' works
>    * rule '\n'               no output but seems to work
>    * rule '.'                works
>    */
>
>  /* rule 1  {WHITESPACE}+                    { printf("%35s %s\n",
> "{WHITESPACE}+", yytext); } */
>  /* rule 2  {TRUE}                           { printf("%35s %s\n",
> "{TRUE}", yytext); } */
>  /* rule 3  [{TRUE}]                         { printf("%35s %s\n",
> "{TRUE}", yytext); } */
> ([ \a\b\f\r\t\v]+)               { printf("%35s %s\n", "[
> \\a\\b\\f\\r\\t\\v]+", yytext); }
> ([tT][rR][uU][eE])               { printf("%35s %s\n", "[tT][rR][uU][eE]",
> yytext); }
> <<EOF>>                          { printf("%35s %s", "\n", "<<EOF>>" );
> return 1; }
> \n                               { printf("%35s %s", "\n", "" ); }
> .                                { printf("%35s %s\n", ".", yytext); }
>
>
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