[antlr-interest] C++ target and excpetions

[Gokulakannan Somasundaram]

Hmm.. I am confused. Don't catch the exception in displayRecognitionError.
throw it from inside. In the my_rule, setup some instance variable of the
parser to the kind of exception, you want to throw. Inside
displayRecognitionError, access the instance variable and throw either
different kinds of exception / same exception with its instance variable
set to different values. So it should be like this.

@parser::context {
    enum RuleType {
                 MY_RULE1
                 , MY_RULE2
                 ......
    };
    RuleType m_rule_type;

     void displayRecognitionError(.... )
     {
            switch( m_rule_type ){
                 case MY_RULE1:
                         throw ipaddress_error("invalid ipaddress at line "
+ get_line( ex) );
                          .....
            }
     }
}

my_rule1
@init{
    m_rule_type = MY_RULE1;
}
   : ID '=' IPADDRESS { ... }
   ;

Better catch these exceptions at the level, where you call the parser.

Usually It is a bad idea in C++ to setup a lot of try..catch blocks. But i
also want to provide the decision making power to the library user. So i
have created and uploaded the latest jar file which supports rulecatch
directive correctly.

Adding the group, as it might be useful for everyone.

Thanks,
Gokul.

On Thu, Feb 23, 2012 at 12:54 AM, Oliver Kowalke <oliver.kowalke at gmx.de>wrote:

> Hi Gokul,
>
> I've another requirement related to exceptions. As you already told me you
> consider not to implement @rulecatch directive.
> Could you provide a rule-specific catch directive?
>
> my_rule
>    : ID '=' IPADDRESS { ... }
>    ;
>    catch[RecognitionError const& e]
>    { throw ipaddress_error("invalid ipaddress at line " + get_line( ex) );
> }
>
> Only rules with the catch-directive would get a try-catch block. If I
> catch this implementation in displayRecognitionError() I don't know if it
> was an illformed ipaddres or an invalid interface etc.
>
> regards,
> Oliver
>