Re: [Iverilog-devel] Is there any way to avoid this shift/reduce conflict?

[Martin W. <mai...@ma...>]

Stephen Williams wrote:
> This problem has been solved in the parser for module ports.

OK, that's basically what I had in mind when I said I could solve this by 
building my own mini state machine and parser within the modport_ports_list 
rule (and what Niels suggested as well). It's a bit more complicated than the 
module ports case, because you have modport expressions, task/function 
import/export, and clocking declarations thrown into the mix. It's ugly, but 
it works.

For anyone interested, the solution looks like this:

modport_ports_list
   : modport_port_declaration
   | modport_ports_list ',' modport_port_declaration
   | modport_ports_list ',' modport_simple_port
       { if (last_modport_port != MODPORT_SIMPLE)
               yyerror(@3, "syntax error");
       }
   | modport_ports_list ',' modport_tf_port
       { if (last_modport_port != MODPORT_TF)
               yyerror(@3, "syntax error");
       }
   | modport_ports_list ',' IDENTIFIER
       { if (last_modport_port == MODPORT_CLOCKING)
               yyerror(@3, "syntax error");
       }
   | modport_ports_list ','
       { yyerror(@2, "error: NULL port declarations are not allowed"); }
   ;

modport_port_declaration
   : attribute_list_opt port_direction IDENTIFIER
       { last_modport_port = MODPORT_SIMPLE;
       }
   | attribute_list_opt port_direction modport_simple_port
       { last_modport_port = MODPORT_SIMPLE;
       }
   | attribute_list_opt import_export IDENTIFIER
       { last_modport_port = MODPORT_TF;
       }
   | attribute_list_opt import_export modport_tf_port
       { last_modport_port = MODPORT_TF;
       }
   | attribute_list_opt K_clocking IDENTIFIER
       { last_modport_port = MODPORT_CLOCKING;
       }
   ;

modport_simple_port
   : '.' IDENTIFIER '(' expression ')'
   ;

modport_tf_port
   : K_task IDENTIFIER
   | K_task IDENTIFIER '(' tf_port_list_opt ')'
   | K_function data_type_or_implicit_or_void IDENTIFIER
   | K_function data_type_or_implicit_or_void IDENTIFIER '(' tf_port_list_opt ')'
   ;

(and yes, I'll be putting in better error messages).