[antlr-interest] Fortran lexer problem

[Jim Idle]

You need gated predicate. Read the getting stared articles in the wiki.

Jim

On Jan 15, 2010, at 10:56, Юрушкин Михаил  
<yurushkin at rambler.ru> wrote:

> I have the following term
>
> LINE_COMMENT
>    : ({blabla}? ('c' | 'C' | '*') | '!' )  ~('\n')*
>        {
>            $channel = HIDDEN;
>        }
>    ;
>
> but it only pasts the following code at the end:
>
>
>           switch (alt31)
>            {
>            case 1:
>                {
>                    if ( !((blabla)) )
>                    {
>                            CONSTRUCTEX();
>                            EXCEPTION->type         =  
> ANTLR3_FAILED_PREDICATE_EXCEPTION;
>                            EXCEPTION->message      = (void *)"blabla";
>                            EXCEPTION->ruleName     = (void  
> *)"LINE_COMMENT";
>                    }
>
>
> if "blabla" is false, an error is occured... but it's not right.
>
> Юрушкин Михаил <yurushkin at rambler.ru> писал(а) в  
> своём письме Fri, 15 Jan 2010 21:27:22 +0300:
>
>> Excuse me, but how can I specify this condition (is it a first  
>> symbol and
>> symbol='c')?
>> Could you send me a piece of lexer grammar?
>>
>>
>> Jim Idle <jimi at temporal-wave.com> писал(а) в своём  
>> письме Fri, 15 Jan 2010
>> 21:20:46 +0300:
>>
>>> I think Fortran comments that start with C have to have the C in
>>> character position 0 (or 1 in Fortran I guess ;-). So your comment  
>>> rule
>>> can be predicated by checking for line position 0 in ANTLR terms.
>>>
>>> Jim
>>>
>>>> -----Original Message-----
>>>> From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-
>>>> bounces at antlr.org] On Behalf Of Þðóøêèí Ìèõàèë
>>>> Sent: Friday, January 15, 2010 9:51 AM
>>>> To: antlr-interest at antlr.org
>>>> Subject: [antlr-interest] Fortran lexer problem
>>>>
>>>> Good day,
>>>>
>>>> I want to add comments of Fortran 77:
>>>>
>>>> "c xxxxx";
>>>> First symbol in column is 'c' - it means that the following line  
>>>> is a
>>>> line
>>>> of comment.
>>>>
>>>> but I also have NAME token, that will conflict with such COMMENT  
>>>> rule.
>>>> ('c' can be a name).
>>>>
>>>> Is it possible to select rule by my own predicate? Are there any  
>>>> other
>>>> more clear solvings of
>>>> this problem?
>>>>
>>>>
>>>> --
>>>> Best regards,
>>>> Michael
>>>>
>>>> List: http://www.antlr.org/mailman/listinfo/antlr-interest
>>>> Unsubscribe: http://www.antlr.org/mailman/options/antlr-interest/your-
>>>> email-address
>>>
>>>
>>>
>>>
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>>
>>
>
>
> -- 
> Best regards,
> Michael