属性文法举例 例考虑下列简单的整数算术表达式文法 exp -exp term - term term-term* factor factor factor→(exp) I number 文法规则 语义规则 exp1→exp2+term expl. val=expa. val+term. val expl-exp2-term exp, val=exp val-term val exp→term exp. val=term. val term1→term2* factor term, val=termo. val*factor. val term→ factor term. val=factor, val f actor(exp factor. val=exp. val factor→ number factor. val=number. val属性文法举例 例 考虑下列简单的整数算术表达式文法： exp → exp + term | exp - term | term term → term * factor | factor factor →(exp)| number 文法规则 语义规则 exp1→exp2+term exp1.val=exp2.val+term.val exp1→exp2-term exp1.val=exp2.val-term.val exp→term exp.val=term.val term1→term2*factor term1.val=term2.val*factor.val term→factor term.val=factor.val factor→(exp) factor.val=exp.val factor→number factor.val=number.val