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+/**!
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+ *
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+ * Copyright(c) boyce and other contributors.
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+ * MIT Licensed
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+ *
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+ * Authors:
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+ * boyce <boyce.ywr@gmail.com> (http://www.jianshu.com/users/9b5b907d9bce)
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+ */
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+
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+'use strict'
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+
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+const STATE = {
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+ INIT: 0, //初始状态
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+ RESULT: 1, //结果状态
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+ FIRST_UNDOT: 2, //记录第一个操作数，且该操作数没有小数点
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+ FIRST_DOT: 3, //记录第一个操作数，且该操作数有小数点
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+ SECOND_UNDOT: 4, //记录第二个操作数，且该操作数没有小数点
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+ SECOND_DOT: 5 //记录第二个操作数，且该操作数有小数点
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+}
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+
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+let curState = STATE.INIT //状态机所在状态
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+let curResult = 0 //计算结果
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+let opNum1 = '0' //操作数1
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+let opNum2 = '' //操作数2
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+let op = '' //操作符
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+
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+let displayNum = opNum1 //界面上应当显示的数值
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+let displayOp = "" //界面上应当显示的操作符
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+
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+/**
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+ * 重置程序状态
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+ */
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+function reset() {
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+ curState = STATE.INIT
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+ curResult = 0
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+ opNum1 = '0'
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+ opNum2 = ''
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+ op = ''
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+}
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+
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+/**
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+ * 是否为零
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+ */
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+function isZero(code) {
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+ return code == '0'
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+}
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+
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+/**
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+ * 是否数字
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+ */
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+function isNumber(code) {
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+ return code >= '0' && code <= '9'
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+}
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+
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+/**
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+ * 是否操作符
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+ */
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+function isOperator(code) {
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+ return code == '+' || code == '-'
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+ || code == 'x' || code == '/' || code == '%'
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+}
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+
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+/**
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+ * 是否小数点
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+ */
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+function isDot(code) {
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+ return code == '.'
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+}
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+
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+/**
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+ * 是否是等号
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+ */
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+function isEquel(code) {
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+ return code == '='
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+}
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+
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+/**
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+ * 是否清楚
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+ */
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+function isClear(code) {
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+ return code == 'c'
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+}
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+
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+/**
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+ * 是否删除
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+ */
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+function isDelete(code) {
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+ return code == 'd'
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+}
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+
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+/**
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+ * 转换为可现实的操作符
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+ */
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+function op2Show(code) {
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+ return code == '/' ? '÷' : (code == 'x' ? '×' : code)
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+}
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+
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+/**
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+ *
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+ */
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+function tryAppend(num, code) {
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+ if (num.length < 15) {
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+ num += code
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+ }
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+ return num
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+}
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+
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+function tryTrunc(num) {
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+ let str = '' + num
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+ if (str.length > 15) {
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+ str = str.substr(0, 15)
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+ }
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+ return str
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+}
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+
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+/**
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+ *
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+ */
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+function tryDelete() {
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+ if (curState == STATE.SECOND_DOT
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+ || curState == STATE.SECOND_UNDOT) {
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+ if (opNum2.length > 0) {
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+ opNum2 = opNum2.substr(0, opNum2.length - 1)
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+ }
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+ if (opNum2 == '') {
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+ opNum2 = '0'
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+ }
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+ return
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+ } else {
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+ if (opNum1.length > 0 && opNum1 != '0') {
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+ opNum1 = opNum1.substr(0, opNum1.length - 1)
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+ }
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+ if (opNum1 == '') {
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+ opNum1 = '0'
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+ }
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+ return
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+ }
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+}
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+
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+function tryCalc() {
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+ let n1 = parseFloat(opNum1)
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+ let n2 = parseFloat(opNum2)
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+ switch (op) {
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+ case '+':
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+ curResult = n1 + n2
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+ break
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+ case '-':
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+ curResult = n1 - n2
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+ break
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+ case 'x':
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+ curResult = n1 * n2
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+ break
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+ case '/':
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+ if (n2 == 0) {
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+ reset()
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+ curResult = 'NaN'
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+ displayOp = ''
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+ } else {
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+ curResult = n1 / n2
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+ }
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+ break
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+ case '%':
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+ if (n2 == 0) {
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+ reset()
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+ curResult = 'NaN'
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+ displayOp = ''
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+ } else {
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+ curResult = n1 % n2
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+ }
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+ break
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+ }
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+ curResult = tryTrunc(curResult)
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+}
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+
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+function addOp(code) {
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+ switch (curState) {
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+ case STATE.RESULT:
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+ case STATE.INIT:
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+ if (isNumber(code) && !isZero(code)) {
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+ curState = STATE.FIRST_UNDOT
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+ opNum1 = code
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+ } else if (isDot(code)) {
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+ curState = STATE.FIRST_DOT
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+ opNum1 = '0.'
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+ } else if (isOperator(code)) {
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+ curState = STATE.SECOND_UNDOT
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+ opNum1 = '0'
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+ opNum2 = ''
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+ op = code
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+ }
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+ displayNum = opNum1
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+ displayOp = ''
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+ break
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+ case STATE.FIRST_UNDOT:
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+ displayOp = ''
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+ if (isNumber(code)) {
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+ if (!isZero(opNum1)) {
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+ opNum1 = tryAppend(opNum1, code)
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+ } else {
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+ opNum1 = code
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+ }
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+ } else if (isDot(code)) {
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+ curState = STATE.FIRST_DOT
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+ opNum1 = opNum1 == '' ? '0' : tryAppend(opNum1, '.')
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+ } else if (isDelete(code)) {
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+ tryDelete()
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+ } else if (isOperator(code)) {
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+ curState = STATE.SECOND_UNDOT
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+ op = code
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+ opNum2 = ''
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+ displayOp = op
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+ }
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+ displayNum = opNum1
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+ break
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+ case STATE.FIRST_DOT:
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+ displayOp = ''
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+ if (isNumber(code)) {
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+ opNum1 = tryAppend(opNum1, code)
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+ } else if (isDelete(code)) {
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+ tryDelete()
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+ if (opNum1.indexOf('.') < 0)
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+ curState = STATE.FIRST_UNDOT
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+ } else if (isOperator(code)) {
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+ curState = STATE.SECOND_UNDOT
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+ op = code
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+ opNum2 = ''
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+ displayOp = op
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+ }
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+ displayNum = opNum1
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+ break
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+ case STATE.SECOND_UNDOT:
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+ if (isNumber(code)) {
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+ if (!isZero(opNum2)) {
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+ opNum2 = tryAppend(opNum2, code)
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+ } else {
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+ opNum2 = code
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+ }
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+ displayNum = opNum2
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+ } else if (isDot(code)) {
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+ curState = STATE.SECOND_DOT
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+ opNum2 = opNum2 == '' ? '0' : tryAppend(opNum2, '.')
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+ displayNum = opNum2
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+ } else if (isDelete(code)) {
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+ tryDelete()
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+ displayNum = opNum2
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+ } else if (isOperator(code)) {
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+ if (opNum2 != '') {
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+ //直接计算
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+ tryCalc()
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+ curState = STATE.SECOND_UNDOT
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+ opNum1 = curResult
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+ opNum2 = ''
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+ displayNum = curResult
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+ }
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+ op = code
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+ displayOp = op
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+ } else if (isEquel(code)) {
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+ if (opNum2 != '') {
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+ tryCalc()
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+ curState = STATE.RESULT
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+ opNum1 = '0'
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+ opNum2 = ''
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+ displayNum = curResult
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+ }
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+ op = code
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+ displayOp = op
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+ }
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+ break
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+ case STATE.SECOND_DOT:
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+ if (isNumber(code)) {
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+ opNum2 = tryAppend(opNum2, code)
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+ displayNum = opNum2
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+ } else if (isDelete(code)) {
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+ tryDelete()
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+ if (opNum2.indexOf('.') < 0)
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+ curState = STATE.SECOND_UNDOT
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+ displayNum = opNum2
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+ } else if (isOperator(code)) {
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+ if (opNum2 != '') {
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+ //直接计算
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+ tryCalc()
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+ curState = STATE.SECOND_UNDOT
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+ opNum1 = curResult
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+ opNum2 = ''
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+ displayNum = curResult
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+ }
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+ op = code
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+ displayOp = op
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+ } else if (isEquel(code)) {
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+ if (opNum2 != '') {
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+ tryCalc()
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+ curState = STATE.RESULT
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+ opNum1 = '0'
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+ opNum2 = ''
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+ displayNum = curResult
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+ }
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+ op = code
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+ displayOp = op
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+ }
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+ break
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+ }
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+ if (isClear(code)) {
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+ reset()
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+ displayNum = opNum1
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+ displayOp = ''
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+ }
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+ displayOp = op2Show(displayOp)
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+}
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+
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+reset()
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+
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+module.exports = {
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+ reset, addOp, getVars(){
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+ return {curState, curResult, opNum1, opNum2, op, displayNum, displayOp}
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+ }
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+}
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MiniStar
1 year ago