[antlr-interest] C++ target and excpetions

[Oliver Kowalke]

Hello Gokul,

it's a missunderstanding - I was asking for specializing the catch clauses per rule, not globaly as I provide with @rulecatch.
I'm referring to the book 'The Definitive ANTLR Reference', T. Parr, chap. 10.5, p. 243.

regards,
Oliver

> 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
> >

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