$ ./caculator 
Please input express:
1+2*1-12+2-(1+2*3)
[1 + 2 * 1 - 12 + 2 - ( 1 + 2 * 3 )]      //中缀表达式
[1 2 1 * + 12 - 2 + 1 2 3 * + -]			//后缀表达式
-14										//结果

func pre2stuf(exps []string) (exps2 []string) {
	list1 := list.New()
	list2 := list.New()

	for _, exp := range exps {
		if isOperate(exp) {
			if op, ok := isPop(list1, exp); ok {
				for _, s := range op {
					list2.PushBack(s)
				}
			}
			if exp == ")" {
				continue
			}
			list1.PushBack(exp)
		} else {
			list2.PushBack(exp)
		}
	}

	for cur := list1.Back(); cur != nil; cur = cur.Prev() {
		list2.PushBack(cur.Value)
	}

	for cur := list2.Front(); cur != nil; cur = cur.Next() {
		if curValue, ok := cur.Value.(string); ok {
			exps2 = append(exps2, curValue)
		}
	}
	return
}

git clone git@github.com:khalily/caculate.git