Re: Resolving shift/reduce conflict in Bison grammar

[Panayiotis Karabassis]

Hi!

Use the -v (verbose) flag on bison to generate the xxx.output file that 
contains more information about the parser automaton (including where 
the conflicts appear). Then please post it here.

You may also want to read the debugging section from:

info bison

Regards,
    Panayiotis

On 07/31/2010 04:54 PM, anandvn wrote:
> Hi,
>
> Could any one please help me in resolving the shift/reduce in the following
> grammar?
>
> %{
> #include<stdio.h>
> extern char yytext[];
> extern int column;
> void yyerror(char const *s);
> %}
>
> %union
> {
>         unsigned int tokVal;
>         unsigned char *tokValStr;
> }
>
> /* C operators */
> %token<tokVal>  STATIC CONST VOLATILE EXTERN INT UNSIGNED VARNAME EQUAL
> COLON OP_BRACE CL_BRACE IDENTIFIER
>
> %type<tokVal>  declaration translation_unit declaration_specifiers
> storage_class_specifier type_specifier type_qualifier init_declarator_list
>
> /* Parsing starts with this transalation unit */
> %start translation_unit
>
> %%
>
> translation_unit
>         : external_declaration
>         | translation_unit external_declaration
>         ;
>
> external_declaration
>         : function_definition
>         | declaration
>         ;
>
> function_definition
>         : declaration_specifiers declarator compound_statement
>         ;
>
> declarator
>         : IDENTIFIER
>         ;
>
> compound_statement
>         : OP_BRACE CL_BRACE
>         ;
>         
> declaration
>         : init_dec declaration_specifiers COLON
>         | init_dec declaration_specifiers init_declarator_list COLON
>         ;       
>
> init_dec
>         : {printf("*** Process for Initialization ***\n\n");}
>         
> init_declarator_list
>         :       EQUAL VARNAME
>         ;
>         
> declaration_specifiers
>         : storage_class_specifier
>         | storage_class_specifier declaration_specifiers
>         | type_specifier
>         | type_specifier declaration_specifiers
>         | type_qualifier
>         | type_qualifier declaration_specifiers
>         ;
>         
> storage_class_specifier
>         : EXTERN
>         | STATIC
>         ;
>
> type_specifier
>         : INT
>         | UNSIGNED
>         ;       
>         
> type_qualifier
>         : CONST
>         | VOLATILE
>         ;
>         
> %%
>
> void yyerror(char const *s)
> {
>         fflush(stdout);
>         printf("\n%*s\n%*s\n", column, "^", column, s);
> }
>
> In the rule "declaration", I want to perform initalization activities using
> the empty rule "init_dec" (original code here
> http://old.nabble.com/file/p29313133/Test.zip Test.zip ). But i'm getting
> shift/reduce conflict. Since I'm new to this bison, i need help from you to
> resolve this conflict. I tried by i felt very difficult.
>
> Thanks
> Anand V
>