%{
// parser for Boolean equations
//
void yyerror( const char *msg); /* called for parser syntax error */
int yylex( void);               /* declare to avoid gcc warnings */
%}

%token AND OR ID

%%
list:   /* nothing, matches before start of input */

        | list eqn ';'

        | list error ';' { yyerrok; }
        ;

primary:  ID
        | '(' or ')'
        ;
        
and:      primary
        | and AND primary
        ;

or:       and
        | or OR and
        ;

eqn:      ID '=' or
        ;
%%

int main( void)
{
  return yyparse();
}