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Georg.Tenckhoff | 29 Apr 10:19

(no subject)

Hallo everybody,

is there any trick to convince flex to auto-complete options entered e.g. from stdin? Posed the same
question differently: Can I access the flex parse tables as a kind of tree structure indicating which
characters are allowed to follow as branches?

Freundliche Grüße / Kind regards

Georg Tenckhoff
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lookthree | 27 Jan 22:13

Help please

Hi,
I'm a new Flex user.
I'm having the follow problem:

1. I've created one file Example.l:

%option c++
%option yylineno
%option noyywrap
%option caseless

delim [ \t\n]
ws {delim}+
letter [A-Za-z]
digit [0-9]
id {letter}({letter}|{digit})*
number {digit}+(\.{digit}+)?(E[+\-]?{digit}+)?

%%
            int yylval;
{ws}        {;}
if          { return(IF);}
then        { return(THEN);}
else        { return(ELSE);}
{id}        { return(ID);}
{number}    { return(NUMBER);}
"<"         { yylval = LT; return(RELOP);}
"<="        { yylval = LE; return(RELOP);}
"="         { yylval = EQ; return(RELOP);}
"<>"        { yylval = NE; return(RELOP);}
">"         { yylval = GT; return(RELOP);}
">="        {yylval = GE; return(RELOP);}
.           {return(ERROR);}
%%


and i've run >Flex example.l

and it has returned the file lex.yy.cc.

2. Well, i've created also the main program in c++, let's call it main_prog.cpp:



#include <stdio.h>
#include <ctype.h>
enum {LT, LE, NE, GT, GE, EQ, IF, THEN, ELSE, ID, NUMBER, RELOP, ERROR};
#include <FlexLexer.h>
#include "lex.yy.cc"

int main(int argc, char *argv[])
{
    int token;
    FlexLexer* lexer = new yyFlexLexer();
    while ((token=lexer->yylex()) != 0) {
        switch (token) {
        case RELOP: printf("%s","RELOP"); break;
        case NUMBER: printf("%s","NUMBER"); break;
        case ID: printf("%s","ID"); break;
        case IF: printf("%s","IF"); break;
        case THEN: printf("%s","THEN"); break;
        case ELSE: printf("%s","ELSE");break;
        case ERROR: printf("%s", "illegal character"); break;
        default:
                    printf("%s","UNKNOWN");
                    break;
        }
        printf("%s\n", lexer->YYText());
    }
    return 0;
}

The problem becomes when I compile it using

        g++ main_prog.cpp -o main_prog

,infact the system answer me with:

/usr/include/FlexLexer.h:113: error: redefinition of ‘class yyFlexLexer’
/usr/include/FlexLexer.h:113: error: previous definition of ‘class yyFlexLexer’

thank you for helping me,

Simone.










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Eric Fowler | 8 Sep 04:25

Flex empty string

I hear a rumor this is the place for online flex discussion.

I am a relative newbie and I want to match NMEA 0183 strings coming from a GPS.

They look like this:
$GPGGA,123519,4807.038,N,01131.000,E,1,08, 0.9,545.4,M,46.9,M,,*47

except when they look like this:

$GPGGA,123519,4807.038,N,01131.000,E,,,,,,,,,*47

In other words, many fields can be blank, but they are always comma - delimited. When they exist they are nicely structured, e.g. {DIGIT}{4}"."{DIGIT}{3} matches a latitude string.

So how do I distinguish between a field with some specific data and a delimiter, and an empty string followed by the same delimiter?

Thanks.

Eric

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Carlos Smith | 2 Jun 15:47

Building flex-2.5.34 from CVS

Hi,

Just want to confirm i succesfully build
flex 2.5.34 fresh from cvs.

The README.cvs says to use

gettext 0.14.5, but it does not work.
Instead you needs gettext-devl (for autopoint)

Also, is ident 2.8 the correct version.
May be it is 2.2.8 ?

-- carlos
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harsh | 31 May 08:11

warning

Hi,

 

I get a warning dealing with "yy_flex_realloc" saying that:'void* yy_flex_realloc(void*, yy_size_t)' defined but not used,

I would like to know how it's posssible to avoid it.

 

Best regards,

Harsh

 

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post2li | 29 May 13:09

Flex/Bison Segment Fault?

I am trying to test the code in the book "Lex & Yacc, 2nd", however,
it didn't work as described. Pls.

# uname -a
Linux redhat9 2.4.20-8 #1 Thu Mar 13 17:54:28 EST 2003 i686 i686 i386
GNU/Linux

# flex -V
flex version 2.5.4

# bison -V
bison (GNU Bison) 1.35

# flex -olexa.yy.c ch1-05.l
# bison -obisa.tab.c ch1-05.y
# gcc -o ex bisa.tab.c lexa.yy.c -ll

# ./ex
Segmentation fault
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kkc | 25 May 18:34

lex & yacc, Second Edition example compile code problem


I try compile all code using "make" command in linux, but it come back with
compile error, please help.

thank you!

/* output
[work]$ make
flex ch1-01.l
mv lex.yy.c ch1-01.c
gcc -g -o ch1-01.pgm ch1-01.c -ly -ll
/usr/bin/ld: cannot find -ly
collect2: ld returned 1 exit status
make: *** [ch1-01.pgm] Error 1
[work]$

*/
--

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View this message in context: http://www.nabble.com/lex---yacc%2C-Second-Edition-example-compile-code-problem-tf3817146.html#a10806368
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arun kv | 30 Apr 12:54

memory errors ....

  
Hi All, 

I have implemented a parser using lex and yacc ,  my lex and yacc files are named parser.y and scanner.l 
(these files are compiled with flex++ and bison++  to make my parser compatible with C++) 
My parser is working fine but .... 
The issue is when I run my parser with purify (a memory detection tool ) .It gives out memory errors in the flex
and bison generated  source codes (parser.cpp , parser.h and scanner.h )

The purify errors for the parser are : 
IPR :Invalid pointer read , IPW :Invalid pointer write , BSR: Beyond stack read error 
Shown by these variables in parser.cpp 
yystate
yyn    
yyssp  
yyvsp  
yyerrstatus    
yycharl

For detailed purify log please see the attached file. 
What I want to know is that, Is there any way in which I can control these variables form my lex and yacc files. 
Or how else I can fix these memory errors shown by purify. 
Best Regards 
Arun
Attachment (parser.log): application/octet-stream, 41 KiB
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Sachin Puttur | 6 Apr 10:12

hi

hi
There is problem with the file lang_scan.c  which is a lexical scanner 
developed by flex. The error is that it could not find file "y.tab.h". 
can you please able to send this to me ?

Thank you

--

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With Regards
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Altair's Grid Technologies
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+91-80- 6629 4500 ext-4794 (O)
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henrik.sorensen | 2 Apr 16:41

Getting YY_CURRENT_BUFFER when using reentrant scanner

Hi List,

Just wondering how you are using YY_CURRENT_BUFFER in a reentrant scanner.

When using the %option reentrant, I have to do the following hack to use the 
YY_CURRENT_BUFFER in a function that only takes the yyscan_t yyscanner as 
parameter.

struct yyguts_t * yyg = (struct yyguts_t*)yyscanner; /* <== HACK HACK */

yy_flush_buffer((YY_CURRENT_BUFFER),yyscanner);

Is there anyother way, that doesnt require the yyg variable ?

thanks for your help
Henrik
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Kamel SEGHAIER | 31 Jan 10:31

Segmentation Fault on Flex 2.5.33


> Hi all ,
>
> I have a segmentation fault in file.lex on linux 64 bits in this line of file_lex.c : 
> 
> yy_hold_char = *++yy_c_buf_p
>
> I have no more indication for the debuger.
> When I turn on linux32 I have no segmentation but an error in another file.

> I'm using flex 2.5.33
>
> Is this a Flex bug!!!!!!!!
> Best regards
>
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