RE: Flex help anyone ?

[Marco Draijer]

Mike,

\"([^"]|\"\")*\"
should do the trick, I guess.

However, I usually define exclusive start states for this:

%x SQSTRING DQSTRING
%%
\'  {BEGIN(SQSTRING); strBuf="";}
\"  {BEGIN(DQSTRING); strBuf="";}
<SQSTRING>\'\'  {strBuf+="'";}
<DQSTRING>\"\"  {strBuf+="\"";}
<SQSTRING>\'    {BEGIN(INITIAL); return(STRING);}
<DQSTRING>\"    {BEGIN(INITIAL); return(STRING);}
<SQSTRING,DQSTRING>. {strBuf+=yytext;}

Perhaps you don't need single and double quotes split in two flows, but usually it comes in handy. strBuf is a variable that can be retrieved from yacc when it receives a STRING token.

Note that you should know how to process a newline token: Is it part of the string?
But I know that exclusive start states have their drawbacks, although I have forgotten which ones exactly.

>>> "Ning Cao" <address@hidden> 01/15/04 07:28 AM >>>
Hi,

"Hello " will be matched by the first rule
"World" will be matched by the first rule
and " would be ok" will be also matched by the first rule.

this the reason why you got three strings.

-----Original Message-----
From: address@hidden [mailto:address@hidden]On Behalf Of Mike Aubury (by way of Hans Aberg)

Sent: Thursday, January 15, 2004 1:54 AM
To: Flex Help
Subject: Flex help anyone ?

Yes - I know this is a bison list - but someone might know...

I've got to detect strings so I have matches for :

\"[^\"]+\"    {  return CHAR_VALUE;}
\"\" { return CHAR_VALUE;}

in my flex definition file (or similar at least)
(The first for a string, the second for an empty string)

In the language I'm trying to parse - its permissible to embed quotes within a
string if you double up..

so :

        "Hello ""World"" would be ok"

Obviously - I'm getting this back as three strings ("Hello " , "World"  &
"would be ok") which is messing up the parser...

Any ideas ?

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