shift/reduce elimination technique?

Stephen Torri <storri@xxxxxxxxx> · Wed, 14 Jun 2006 11:32:27 -0500

I understand that I am having a shift/reduce conflict on a Tk_left_paren
'(' character with the Declarator production. Is my interpretation of
the first line right?

shift/reduce conflict in state [stack: PDirectDeclarator *] on TTkLeftParen in {
	[ PDeclarator = PDirectDeclarator * ] followed by TTkLeftParen (reduce),
	[ PDirectDeclarator = PDirectDeclarator * TTkLeftParen PParameterDeclarationClause TTkRightParen PCvQualifierSeq PExceptionSpecification ] (shift),
	[ PDirectDeclarator = PDirectDeclarator * TTkLeftParen PParameterDeclarationClause TTkRightParen PCvQualifierSeq ] (shift),
	[ PDirectDeclarator = PDirectDeclarator * TTkLeftParen PParameterDeclarationClause TTkRightParen PExceptionSpecification ] (shift),
	[ PDirectDeclarator = PDirectDeclarator * TTkLeftParen PParameterDeclarationClause TTkRightParen ] (shift)
}

The rules below are from a C++ grammar. I read the rules from the ANSI
standard I found on the web, ofcourse this does not mean what Iread is
right (see http://www.csci.csusb.edu/dick/c++std/cd2/gram.html ).

  declarator =
        {dd} direct_declarator |
        {ptr} ptr_operator declarator;

  declarator_id =
        {first} tk_double_colon
            id_expression |
        {nested} tk_double_colon
            nested_name_specifier
            type_name;

  direct_declarator =
        {di} declarator_id |
        {dd} direct_declarator
            tk_left_paren
            parameter_declaration_clause
            tk_right_paren
            cv_qualifier_seq?
            exception_specification? |
        {dd_array} direct_declarator
            tk_left_bracket
            constant_expression?
            tk_right_bracket|
        {paren} tk_left_paren
            declarator
            tk_right_paren;

I believe that the published ANSI grammar did not have a shift-reduce
conflict in it. So my guess is I am messing up somewhere. I could alter
the grammar so that the left paren has the same level of precedence but
I feel that is going too far. The whole grammar is attached (tar.gz).

What is a good technique for eliminating shift-reduce conflicts in a
grammar?

Stephen