On Tue, Mar 2, 2010 at 7:00 PM, Bart Kiers <[email protected]> wrote:
>
>
> On Tue, Mar 2, 2010 at 5:25 PM, Philippe Frankson <
> [email protected]> wrote:
>
>> ...
>>
>> @int('444') is a function converting a string into integer.
>> If I don't have parentheses, then it is not a function, it is only a
>> column name. Ex.: @test, @integer, @in, ....
>>
>> Here is a part of lexer rules:
>>
>> fragment DIGIT : ('0'..'9');
>> fragment ALPHA : ('a'..'z'|'A'..'Z'|'_');
>>
>> OB : '(';
>> INTTOKEN : ('@int' OB)=> '@int'; // so I check if there is an open
>> parenthesis to return INTTOKEN.
>> AT : '@';
>> NAME : ALPHA (ALPHA | DIGIT)*; ...
>>
>
> Why not just include the OB in your lexer rule?
> Something like this:
>
> INT_METHOD : AT 'int' OB; // or: AT 'int' OB STRING CB;
> COLUMN : AT NAME;
>
> OB : '(';
>
> AT : '@';
> NAME : ALPHA (ALPHA | DIGIT)*;
>
> fragment DIGIT : ('0'..'9');
> fragment ALPHA : ('a'..'z'|'A'..'Z'|'_');
>
> and because lexer rules are matched from top to bottom, '@int' will be
> matched as 'AT NAME'.
>
> Regards,
>
> Bart.
>
But, maybe better, move the "responsibility" to the parser instead of the
lexer:
parse : method | column;
method : AT NAME OB STRING CB;
column : AT NAME;
STRING : '"' ~('"')* '"';
OB : '(';
CB : ')';
AT : '@';
NAME : ALPHA (ALPHA | DIGIT)*;
fragment DIGIT : ('0'..'9');
fragment ALPHA : ('a'..'z'|'A'..'Z'|'_');
Regards,
Bart.
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