Github user yjshen commented on a diff in the pull request:
https://github.com/apache/spark/pull/7589#discussion_r35479785
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/DateTimeUtils.scala
---
@@ -573,4 +573,109 @@ object DateTimeUtils {
dayInYear - 334
}
}
+
+ /**
+ * Returns the date value for the first day of the given month.
+ * The month is expressed in months since 1.1.1970, starting from 0.
+ */
+ def getDaysFromMonths(months: Int): Int = {
+ val yearSinceEpoch = if (months < 0) months / 12 - 1 else months / 12
+ val monthInYearFromZero = months - yearSinceEpoch * 12
+ val daysFromYears = getDaysFromYears(yearSinceEpoch)
+ val febDays = if (isLeapYear(1970 + yearSinceEpoch)) 29 else 28
+ val daysForMonths = Seq(31, febDays, 31, 30, 31, 30, 31, 31, 30, 31,
30, 31)
+ daysForMonths.slice(0, monthInYearFromZero).sum + daysFromYears
+ }
+
+ /**
+ * Returns the date value for January 1 of the given year.
+ * The year is expressed in years since 1.1.1970, starting from 0.
+ */
+ def getDaysFromYears(years: Int): Int = {
+ val remainYear = (years % 400 + 400) % 400
+ val cycles = (years - remainYear) / 400
+ val numLeaps = if (remainYear < 130) {
+ remainYear / 4
+ } else if (remainYear < 230) {
+ remainYear / 4 - 1
+ } else if (remainYear < 330) {
+ remainYear / 4 - 2
+ } else {
+ remainYear / 4 - 3
+ }
+ cycles * (365 * 400 + 397) + remainYear * 365 + numLeaps
+ }
+
+ /**
+ * Add date and year-month interval.
+ * Returns a date value, expressed in days since 1.1.1970.
+ */
+ def dateAddYearMonthInterval(days: Int, months: Int): Int = {
+ val currentMonth = (getYear(days) - 1970) * 12 + getMonth(days) - 1 +
months
+ val currentMonthInYear = if (currentMonth < 0) {
+ ((currentMonth % 12) + 12) % 12
+ } else {
+ currentMonth % 12
+ }
+ val currentYear = if (currentMonth < 0) (currentMonth / 12) - 1 else
currentMonth / 12
+ val febDays = if (isLeapYear(1970 + currentYear)) 29 else 28
+ val daysForMonths = Seq(31, febDays, 31, 30, 31, 30, 31, 31, 30, 31,
30, 31)
+ getDaysFromMonths(currentMonth) + math.min(
+ getDayOfMonth(days), daysForMonths(currentMonthInYear)) - 1
+ }
+
+ /**
+ * Add date and full interval.
+ * Returns a timestamp value, expressed in microseconds since 1.1.1970
00:00:00.
+ */
+ def dateAddFullInterval(days: Int, months: Int, microseconds: Long):
Long = {
+ daysToMillis(dateAddYearMonthInterval(days, months)) * 1000L +
microseconds
+ }
+
+ /**
+ * Add timestamp and full interval.
+ * Returns a timestamp value, expressed in microseconds since 1.1.1970
00:00:00.
+ */
+ def timestampAddFullInterval(micros: Long, months: Int, microseconds:
Long): Long = {
+ val days = millisToDays(micros / 1000L)
+ dateAddFullInterval(days, months, microseconds) + micros -
daysToMillis(days) * 1000L
+ }
+
+ /**
+ * Returns the last dayInMonth in the month it belongs to. The date is
expressed
+ * in days since 1.1.1970. the return value starts from 1.
+ */
+ def getLastDayInMonthOfMonth(date: Int): Int = {
+ val month = getMonth(date)
+
+ val febDay = if (isLeapYear(getYear(date))) 29 else 28
+ val days = Seq(31, febDay, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31)
+ days(month - 1)
+ }
+
+ /**
+ * Returns number of months between time1 and time2. time1 and time2 are
expressed in
+ * microseconds since 1.1.1970
+ */
+ def monthsBetween(time1: Long, time2: Long): Double = {
+ val millis1 = time1.asInstanceOf[Long] / 1000L
+ val millis2 = time2.asInstanceOf[Long] / 1000L
+ val date1 = millisToDays(millis1)
+ val date2 = millisToDays(millis2)
+ val dayInMonth1 = getDayOfMonth(date1)
+ val dayInMonth2 = getDayOfMonth(date2)
+ val lastDayMonth1 = getLastDayInMonthOfMonth(date1)
+ val lastDayMonth2 = getLastDayInMonthOfMonth(date2)
+ val months1 = getYear(date1) * 12 + getMonth(date1) - 1
+ val months2 = getYear(date2) * 12 + getMonth(date2) - 1
+ val timeInDay1 = time1 - daysToMillis(date1) * 1000L
+ val timeInDay2 = time2 - daysToMillis(date2) * 1000L
--- End diff --
do we really need to consider timezone here?
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