整数/分数四则运算表达式分析并给出详细运算过程，四则运算表达式,为我女儿练习分数四则运算

整数/分数四则运算表达式分析并给出详细运算过程，四则运算表达式,为我女儿练习分数四则运算

为我女儿练习分数四则运算而编写，可以输入任意长度四则运算表达式（整数/分数），稍微改一下也可以应用于小数和负数

import reimport fractionsimport mathimport syslevel = 0line = 1class node:    def __init__(self, category=0):        self.operator = ''## category=1 : leaf node## category=0 : intermediate node                 self.category = category        self.leftChild = None        self.rightChild = None        self.parent = None        self.bracelet = False        self.value = ''        self.result = ''def popStack(subOpStack, subNumStack):    if len(subOpStack) == 0:        temp = subNumStack.pop()        return temp    else:        temp = node(0)        temp.value = subOpStack.pop()        tmp = subNumStack.pop()        temp.rightChild = tmp        temp.rightChild.parent = temp        temp.leftChild = popStack(subOpStack, subNumStack)        temp.leftChild.parent = temp        return tempdef depthTree(temp):    if temp.leftChild == None or temp.rightChild == None:        return 0    leftLen = depthTree(temp.leftChild) + 1    rightLen = depthTree(temp.rightChild) + 1    return max(leftLen, rightLen)def parseTree(opStack, numStack, subOpStack, subNumStack):    global level    if len(opStack) == 0:        if (len(numStack) > 0):            nn = numStack.pop()            subNumStack.insert(0, nn)        localNode = popStack(subOpStack, subNumStack)        return localNode    op = opStack.pop()    if (op in "+-"):        localNode = node()        localNode.value = op        nn = numStack.pop()        subNumStack.insert(0, nn)        localNode.rightChild = popStack(subOpStack, subNumStack)        localNode.leftChild = parseTree(opStack, numStack, subOpStack, subNumStack)        localNode.rightChild.parent = localNode        localNode.leftChild.parent = localNode        return localNode    elif (op in "*/"):            nn = numStack.pop()        subNumStack.insert(0, nn)        subOpStack.insert(0, op)        res = parseTree(opStack, numStack, subOpStack, subNumStack)        return res    elif (op == ")"):        numStack1 = []        opStack1 = []        subOpStack1 = []        subNumStack1 = []        flag = True        while flag:            op = opStack.pop()            if op == ")":                level = level + 1                opStack1.insert(0, op)            elif op == "(":                if level == 0:                    nn = numStack.pop()                    numStack1.insert(0, nn)                    flag = False                    break;                else:                    level = level - 1                    opStack1.insert(0, op)                else:                opStack1.insert(0, op)                nn = numStack.pop()                numStack1.insert(0, nn)        res = parseTree(opStack1, numStack1, subOpStack1, subNumStack1)        res.bracelet = True        numStack.append(res)        res = parseTree(opStack, numStack, subOpStack, subNumStack)        return resdef calculateExpress(expr, subExpr):    if subExpr==None:        return    calculateExpress(expr, subExpr.leftChild)    calculateExpress(expr, subExpr.rightChild)                   if (not subExpr.leftChild==None and not subExpr.leftChild==None and subExpr.leftChild.category == 1 and subExpr.rightChild.category == 1):        left = fractions.Fraction(subExpr.leftChild.value)        right = fractions.Fraction(subExpr.rightChild.value)        op = subExpr.value        if op=="+":            result = left + right        elif op=="-":            result = left - right        elif op=="*":            result = left * right        elif op=="/":            result = left / right        subExpr.category = 1        subExpr.value = str(result)        subExpr.bracelet = False        subExpr.leftChild = None        subExpr.rightChild = None        outputExpress(expr)    returndef outputExpress(expr):    global line    print str(line)+":\\t",    printExpress(expr)    print    line = line + 1    returndef printExpress(expr):    if expr == None:        return    if expr.bracelet:        print "(",    printExpress(expr.leftChild)    print expr.value,    printExpress(expr.rightChild)        if expr.bracelet:        print ")",    returnif __name__ == '__main__':    str1 = '(1/9+1/8*(1/7+1/6)+1/9)/(1/2+(1/4+1/3)*1/2/(1/4+1/5))+1/2'    pattern = '[\\(\\)\\+\\-\\*\\/]|\\d+/\\d+'    result = re.findall(pattern, str1)    operators = '()+-*/'    opStack = []    numStack = []    subNumStack = []    subOpStack = []    for item in result:        if item in operators:            opStack.append(item)        else:            tmp = node(1)            tmp.value = item            numStack.append(tmp)    oo = parseTree(opStack, numStack, subOpStack, subNumStack)    calculateExpress(oo,oo)#该片段来自于http://byrx.net