Add helper function to return the number of days since epoch for a week-of-month date

velox/type/TimestampConversion.cpp

@@ -144,6 +144,26 @@ bool isValidWeekDate(int32_t weekYear, int32_t weekOfYear, int32_t dayOfWeek) {
   return true;
 }
 
+bool isValidWeekOfMonthDate(
+    int32_t year,
+    int32_t month,
+    int32_t weekOfMonth,
+    int32_t dayOfWeek) {
+  if (dayOfWeek < 1 || dayOfWeek > 7) {
+    return false;
+  }
+  if (weekOfMonth < 1 || weekOfMonth > 5) {
+    return false;
+  }
+  if (month < 1 || month > 12) {
+    return false;
+  }
+  if (year < kMinYear || year > kMaxYear) {
+    return false;
+  }
+  return true;
+}
+
 inline bool validDate(int64_t daysSinceEpoch) {
   return daysSinceEpoch >= std::numeric_limits<int32_t>::min() &&
       daysSinceEpoch <= std::numeric_limits<int32_t>::max();
@@ -593,6 +613,26 @@ Status daysSinceEpochFromWeekDate(
   return Status::OK();
 }
 
+Status daysSinceEpochFromWeekOfMonthDate(
+    int32_t year,
+    int32_t month,
+    int32_t weekOfMonth,
+    int32_t dayOfWeek,
+    int64_t& out) {
+  if (!isValidWeekOfMonthDate(year, month, weekOfMonth, dayOfWeek)) {
+    return Status::UserError(
+        "Date out of range: {}-{}-{}-{}", year, month, weekOfMonth, dayOfWeek);
+  }
+  int64_t daysSinceEpochOfFirstDayOfMonth;
+  VELOX_RETURN_NOT_OK(
+      daysSinceEpochFromDate(year, month, 1, daysSinceEpochOfFirstDayOfMonth));
+  int32_t firstDayOfWeek =
+      extractISODayOfTheWeek(daysSinceEpochOfFirstDayOfMonth);
+  out = daysSinceEpochOfFirstDayOfMonth - (firstDayOfWeek - 1) +
+      7 * (weekOfMonth - 1) + dayOfWeek - 1;
+  return Status::OK();
+}
+
 Status
 daysSinceEpochFromDayOfYear(int32_t year, int32_t dayOfYear, int64_t& out) {
   if (!isValidDayOfYear(year, dayOfYear)) {

velox/type/TimestampConversion.h

@@ -107,6 +107,15 @@ Status daysSinceEpochFromWeekDate(
     int32_t dayOfWeek,
     int64_t& out);
 
+/// Computes the (signed) number of days since unix epoch (1970-01-01).
+/// Returns UserError status if the date is invalid.
+Status daysSinceEpochFromWeekOfMonthDate(
+    int32_t year,
+    int32_t month,
+    int32_t weekOfMonth,
+    int32_t dayOfWeek,
+    int64_t& out);
+
 /// Computes the (signed) number of days since unix epoch (1970-01-01).
 /// Returns UserError status if the date is invalid.
 Status

velox/type/tests/TimestampConversionTest.cpp

@@ -104,6 +104,35 @@ TEST(DateTimeUtilTest, fromDateInvalid) {
       1970, 6, 31, "Date out of range: 1970-6-31"));
 }
 
+TEST(DateTimeUtilTest, fromWeekOfMonthDate) {
+  auto testDaysSinceEpochFromWeekOfMonthDate =
+      [](int32_t year, int32_t month, int32_t weekOfMonth, int32_t dayOfWeek) {
+        int64_t daysSinceEpoch;
+        auto status = util::daysSinceEpochFromWeekOfMonthDate(
+            year, month, weekOfMonth, dayOfWeek, daysSinceEpoch);
+        EXPECT_TRUE(status.ok());
+        return daysSinceEpoch;
+      };
+  EXPECT_EQ(4, testDaysSinceEpochFromWeekOfMonthDate(1970, 1, 2, 1));
+  EXPECT_EQ(361, testDaysSinceEpochFromWeekOfMonthDate(1971, 1, 1, 1));
+  EXPECT_EQ(396, testDaysSinceEpochFromWeekOfMonthDate(1971, 2, 1, 1));
+
+  EXPECT_EQ(10952, testDaysSinceEpochFromWeekOfMonthDate(2000, 1, 1, 1));
+  EXPECT_EQ(19905, testDaysSinceEpochFromWeekOfMonthDate(2024, 7, 1, 1));
+
+  // Before unix epoch.
+  EXPECT_EQ(-3, testDaysSinceEpochFromWeekOfMonthDate(1970, 1, 1, 1));
+  EXPECT_EQ(-2, testDaysSinceEpochFromWeekOfMonthDate(1970, 1, 1, 2));
+  EXPECT_EQ(-31, testDaysSinceEpochFromWeekOfMonthDate(1969, 12, 1, 1));
+  EXPECT_EQ(-367, testDaysSinceEpochFromWeekOfMonthDate(1969, 1, 1, 1));
+  EXPECT_EQ(-724, testDaysSinceEpochFromWeekOfMonthDate(1968, 1, 2, 1));
+  EXPECT_EQ(-719533, testDaysSinceEpochFromWeekOfMonthDate(0, 1, 1, 1));
+
+  // Negative year - BC.
+  EXPECT_EQ(-719561, testDaysSinceEpochFromWeekOfMonthDate(-1, 12, 1, 1));
+  EXPECT_EQ(-719897, testDaysSinceEpochFromWeekOfMonthDate(-1, 1, 1, 1));
+}
+
 TEST(DateTimeUtilTest, fromDateString) {
   for (ParseMode mode : {ParseMode::kPrestoCast, ParseMode::kSparkCast}) {
     EXPECT_EQ(0, parseDate("1970-01-01", mode));