%% expression : IDENTIFIER { $$ = parse_expression_identifier($1); } | expression PLUS expression { $$ = parse_expression_addition($1, $3); } | expression ASSIGN expression { $$ = parse_expression_assignment($1, $3); } | etc etc ;	%{ translator *context; %} %% expression : IDENTIFIER { $$ = context->expression_identifier($1); } | expression PLUS expression { $$ = context->expression_addition($1, $3); } | expression ASSIGN expression { $$ = context->expression_assignment($1, $3); } | etc etc ;

Aha! What if the methods were virtual?