We can implement syntax-directed translation in either a top-down or a bottom-up parser Access to attributes in yacc The syntax $1, $2 is used to access the attribute of the nth token on the right side of the production The global variable yylval is set by the scanner and that value is saved with the token when placed on the parse stack. When a rule is reduced, a new state is placed on the stack, the default behavior is to just copy the attribute of $1 for that new state, this can be controlled by assigning to $S in the action for the ruleWe can implement syntax-directed translation in either a top-down or a bottom-up parser. Access to attributes in yacc . The syntax $1, $2 is used to access the attribute of the nth token on the right side of the production. The global variable yylval is set by the scanner and that value is saved with the token when placed on the parse stack. When a rule is reduced, a new state is placed on the stack, the default behavior is to just copy the attribute of $1 for that new state, this can be controlled by assigning to $$ in the action for the rule