上下文无关文法的例子 简单算术表达式的文法: 终结诗号:id+-*/() 非终结符号: expression,term, factor 开始符号: expression 生式集合 expression expression term expression expression -term expression term tem→term* factor term→term/ factor tem→ factor factor >(expression) factor→id上下文无关文法的例子 • 简单算术表达式的文法： – 终结符号：id + - * / ( ) – 非终结符号：expression, term, factor – 开始符号：expression – 产生式集合： expression → expression + term expression → expression – term expression → term term → term * factor term → term / factor term → factor factor → (expression) factor → id