功能：給定開始日期和結束日期，返回匹配該段日期區間的正則表達式。生成的正則表達式假定了每個月都有39天，即01-39，所以不要使用該模塊來判斷日期的合法性。該模塊生成的正則表達式的使用場景是從一組合法日期中提取給定區間內的日期。源碼如下，使用scala實現。

def genRegexp(start:String,end:String): String = {
        //s:開始e：結束y：年m：月d：日o：個位t：十位
        //sy:開始年em：結束月，其他變量命名規則相同
        val sy = start.substring(0, 4)
        val sm 
 
= start.substring(4, 6)
        val sd = start.substring(6, 8)
        val ey = end.substring(0, 4)
        val em = end.substring(4, 6)
        val ed = end.substring(6, 8)
        val sdo = sd.substring(1, 2)
        val sdt = sd.substring(0, 1)
        val smo = sm.substring(1, 2)
        val smt = sm.substring(0, 1)
        val syo 
 
= sy.substring(3, 4)
        val syt = sy.substring(2, 3)
        val edo = ed.substring(1, 2)
        val edt = ed.substring(0, 1)
        val emo = em.substring(1, 2)
        val emt = em.substring(0, 1)
        val eyo = ey.substring(3, 4)
        val eyt = ey.substring(2, 3)
        var PAL = ""
        var PAR 
 
= ""
        var PA = ""
        var PB = ""
        var PC = ""
        var PCL = ""
        var PCR = ""
        var pattern = ""
        var PL = ""
        var PR = ""
        var PRT = ""
        if (sy == ey) {
            if (sm == em) {
                if (sdt == edt) {
                    pattern = "(^%s%s%s[%s-%s]$)".format(sy, sm, sdt, sdo, edo)
                }
                else {
                    if (sdt.toInt + 1 == edt.toInt) {
                        pattern = "(^%s%s((%s[%s-9])|(%s[0-%s]))$)".format(sy, sm, sdt, sdo, edt, edo)
                    }
                    else {
                        pattern = "(^%s%s((%s[%s-9])|(%s[0-%s])|([%d-%d]\\d))$)".format(sy, sm, sdt, sdo,
                            edt, edo, sdt.toInt + 1, edt.toInt - 1)
                    }
                }
            }
            else {
                if (sdt == "3") {
                    PL = "(%s3[%s-9])".format(sm, sdo)
                }
                else {
                    PL = "(%s((%s[%s-9])|([%d-3]\\d)))".format(sm, sdt, sdo, sdt.toInt + 1)
                }
                if (edt == "0") {
                    PR = "(%s0[0-%s])".format(em, edo)
                }
                else {
                    PR = "(%s(([0-%d]\\d)|(%s[0-%s])))".format(em, edt.toInt - 1, edt, edo)
                }
                PRT = "(pass)"
                if (sm.toInt + 1 != em.toInt) {
                    val sma = sm.toInt + 1
                    val emr = em.toInt - 1
                    if (sma < 10) {
                        if (emr < 10) {
                            PRT = "(0[%d-%d]\\d{2})".format(sma, emr)
                        }
                        else {
                            PRT = "(((0[%d-9])|(1[0-%d]))\\d{2})".format(smo.toInt + 1, emo.toInt - 1)
                        }
                    }
                    else {
                        PRT = "((1[%s-%s])\\d{2})".format((sma.toString).substring(1,2),
                            (emr.toString).substring(1,2))
                    }
                }
                pattern = "(^%s(%s|%s|%s)$)".format(sy, PL, PR, PRT)
            }
        }
        else {
            //構造PA
            if (sdt == "3") {
                PAL = "%s(%s[%s-9])".format(sm, sdt, sdo)
            }
            else {
                PAL = "(%s((%s[%s-9])|([%d-3]\\d)))".format(sm, sdt, sdo, sdt.toInt + 1)
            }
            if (sm.toInt == 12) {
                PAR = "(pass)"
            }
            else if (sm.toInt >= 9) {
                var sm2 = (sm.toInt + 1).toString
                var smo2 = sm2.substring(1,2)
                PAR = "(1[%s-2]\\d\\d)".format(smo2)
            }
            else {
                PAR = "(((0[%d-9])|(1[0-2]))\\d{2})".format(smo.toInt + 1)
            }
            PA = "(^%s(%s|%s)$)".format(sy, PAL, PAR)
            //構造PB,已知問題，結束年不可為2000
            if (sy.toInt + 1 != ey.toInt) {
                var sy2 = (sy.toInt + 1).toString
                var syt2 = sy2.substring(2,3)
                var syo2 = sy2.substring(3,4)
                var ey2 = (ey.toInt - 1).toString
                var eyt2 = ey2.substring(2,3)
                var eyo2 = ey2.substring(3,4)
                if (syt2 == eyt2) {
                    PB = "(^20%s[%s-%s]\\d{4}$)".format(syt2, syo2, eyo2)
                }
                else {
                    if (syt2.toInt + 1 != eyt2.toInt) {
                        PB = "(^20((%s[%d-9])|([%d-%d]\\d)|(%s[0-%s]))\\d{4}$)".format(syt2, syo2.toInt,
                            syt2.toInt + 1, eyt2.toInt - 1, eyt2, eyo2)
                    }
                    else {
                        PB = "(^20((%s[%d-9])|(%s[0-%s]))\\d{4}$)".format(syt2, syo2.toInt,
                            eyt2, eyo2)
                    }
                }
            }
            else {
                PB = "(pass)"
            }
            //構造PC
            if (edt == "0") {
                PCR = "(%s%s[0-%s])".format(em, edt, edo)
            }
            else {
                PCR = "(%s(([0-%d]\\d)|(%s[0-%s])))".format(em, edt.toInt - 1, edt, edo)
            }
            if (em.toInt >= 11) {
                PCL = "(((0[1-9])|(1[0-%d]))\\d{2})".format( emo.toInt - 1)
            }
            else if (em.toInt == 10) {
                PCL = "(0[1-9]\\d{2})"
            }
            else {
                PCL = "(0[0-%d]\\d{2})".format(emo.toInt - 1)
            }
            PC = "(^%s(%s|%s)$)".format(ey, PCL, PCR)
            pattern = "%s|%s|%s".format(PA, PB, PC)
        }
        pattern
    }

日期區間正則表達式生成模塊