Add FORMAT clause to convert datetime types to string and vice versa #2388

src/common/TimeZoneUtil.cpp

@@ -80,7 +80,6 @@ namespace
 
 static const TimeZoneDesc* getDesc(USHORT timeZone);
 static inline bool isOffset(USHORT timeZone);
-static USHORT makeFromOffset(int sign, unsigned tzh, unsigned tzm);
 static inline SSHORT offsetZoneToDisplacement(USHORT timeZone);
 static inline USHORT displacementToOffsetZone(SSHORT displacement);
 static int parseNumber(const char*& p, const char* end);
@@ -634,6 +633,20 @@ void TimeZoneUtil::extractOffset(const ISC_TIME_TZ& timeTz, SSHORT* offset)
 	extractOffset(tsTz, offset);
 }
 
+// Makes a time zone id from offsets.
+USHORT TimeZoneUtil::makeFromOffset(int sign, unsigned tzh, unsigned tzm)
+{
+	if (!TimeZoneUtil::isValidOffset(sign, tzh, tzm))
+	{
+		string str;
+		str.printf("%s%02u:%02u", (sign == -1 ? "-" : "+"), tzh, tzm);
+		status_exception::raise(Arg::Gds(isc_invalid_timezone_offset) << str);
+	}
+
+	return (USHORT)displacementToOffsetZone((tzh * 60 + tzm) * sign);
+}
+
+
 // Converts a time from local to UTC.
 void TimeZoneUtil::localTimeToUtc(ISC_TIME& time, ISC_USHORT timeZone)
 {
@@ -1153,19 +1166,6 @@ static inline bool isOffset(USHORT timeZone)
 	return timeZone <= ONE_DAY * 2;
 }
 
-// Makes a time zone id from offsets.
-static USHORT makeFromOffset(int sign, unsigned tzh, unsigned tzm)
-{
-	if (!TimeZoneUtil::isValidOffset(sign, tzh, tzm))
-	{
-		string str;
-		str.printf("%s%02u:%02u", (sign == -1 ? "-" : "+"), tzh, tzm);
-		status_exception::raise(Arg::Gds(isc_invalid_timezone_offset) << str);
-	}
-
-	return (USHORT)displacementToOffsetZone((tzh * 60 + tzm) * sign);
-}
-
 // Gets the displacement from a offset-based time zone id.
 static inline SSHORT offsetZoneToDisplacement(USHORT timeZone)
 {

src/common/TimeZoneUtil.h

@@ -97,6 +97,8 @@ class TimeZoneUtil
 	static void extractOffset(const ISC_TIMESTAMP_TZ& timeStampTz, SSHORT* offset);
 	static void extractOffset(const ISC_TIME_TZ& timeTz, SSHORT* offset);
 
+	static USHORT makeFromOffset(int sign, unsigned tzh, unsigned tzm);
+
 	static void localTimeToUtc(ISC_TIME& time, ISC_USHORT timeZone);
 	static void localTimeToUtc(ISC_TIME_TZ& timeTz);
 

src/common/classes/NoThrowTimeStamp.cpp

@@ -337,6 +337,80 @@ void NoThrowTimeStamp::round_time(ISC_TIME &ntime, const int precision)
 	ntime -= (ntime % period);
 }
 
+int NoThrowTimeStamp::convertGregorianDateToWeekDate(const struct tm& times)
+{
+	// Algorithm for Converting Gregorian Dates to ISO 8601 Week Date by Rick McCarty, 1999
+	// http://personal.ecu.edu/mccartyr/ISOwdALG.txt
+
+	const int y = times.tm_year + 1900;
+	const int dayOfYearNumber = times.tm_yday + 1;
+
+	// Find the jan1Weekday for y (Monday=1, Sunday=7)
+	const int yy = (y - 1) % 100;
+	const int c = (y - 1) - yy;
+	const int g = yy + yy / 4;
+	const int jan1Weekday = 1 + (((((c / 100) % 4) * 5) + g) % 7);
+
+	// Find the weekday for y m d
+	const int h = dayOfYearNumber + (jan1Weekday - 1);
+	const int weekday = 1 + ((h - 1) % 7);
+
+	// Find if y m d falls in yearNumber y-1, weekNumber 52 or 53
+	int yearNumber, weekNumber;
+
+	if ((dayOfYearNumber <= (8 - jan1Weekday)) && (jan1Weekday > 4))
+	{
+		yearNumber = y - 1;
+		weekNumber = ((jan1Weekday == 5) || ((jan1Weekday == 6) &&
+			isLeapYear(yearNumber))) ? 53 : 52;
+	}
+	else
+	{
+		yearNumber = y;
+
+		// Find if y m d falls in yearNumber y+1, weekNumber 1
+		int i = isLeapYear(y) ? 366 : 365;
+
+		if ((i - dayOfYearNumber) < (4 - weekday))
+		{
+			yearNumber = y + 1;
+			weekNumber = 1;
+		}
+	}
+
+	// Find if y m d falls in yearNumber y, weekNumber 1 through 53
+	if (yearNumber == y)
+	{
+		int j = dayOfYearNumber + (7 - weekday) + (jan1Weekday - 1);
+		weekNumber = j / 7;
+		if (jan1Weekday > 4)
+			weekNumber--;
+	}
+
+	return weekNumber;
+}
+
+int NoThrowTimeStamp::convertGregorianDateToJulianDate(int year, int month, int day)
+{
+	int jdn = (1461 * (year + 4800 + (month - 14)/12))/4 + (367 * (month - 2 - 12 * ((month - 14)/12)))
+		/ 12 - (3 * ((year + 4900 + (month - 14)/12)/100))/4 + day - 32075;
+	return jdn;
+}
+
+void NoThrowTimeStamp::convertJulianDateToGregorianDate(int jdn, int& outYear, int& outMonth, int& outDay)
+{
+	int a = jdn + 32044;
+	int b = (4 * a +3 ) / 146097;
+	int c = a - (146097 * b) / 4;
+	int d = (4 * c + 3) / 1461;
+	int e = c - (1461 * d) / 4;
+	int m = (5 * e + 2) / 153;
+
+	outDay = e - (153 * m + 2) / 5 + 1;
+	outMonth  = m + 3 - 12 * (m / 10);
+	outYear = 100 * b + d - 4800 + (m / 10);
+}
+
 // Encode timestamp from UNIX datetime structure
 void NoThrowTimeStamp::encode(const struct tm* times, int fractions)
 {

src/common/classes/NoThrowTimeStamp.h

@@ -168,6 +168,10 @@ class NoThrowTimeStamp
 	static void add10msec(ISC_TIMESTAMP* v, SINT64 msec, SINT64 multiplier);
 	static void round_time(ISC_TIME& ntime, const int precision);
 
+	static int convertGregorianDateToWeekDate(const struct tm& times);
+	static int convertGregorianDateToJulianDate(int year, int month, int day);
+	static void convertJulianDateToGregorianDate(int jdn, int& outYear, int& outMonth, int& outDay);
+
 	static inline bool isLeapYear(const int year) throw()
 	{
 		return (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0);

src/common/common.h

@@ -993,6 +993,32 @@ static const TEXT* const FB_LONG_MONTHS_UPPER[] =
 	0
 };
 
+// Starts with SUNDAY cuz tm.tm_wday starts with it
+static const TEXT FB_SHORT_DAYS[][4] =
+{
+	"Sun",
+	"Mon",
+	"Tue",
+	"Wed",
+	"Thu",
+	"Fri",
+	"Sat",
+	"\0"
+};
+
+// Starts with SUNDAY cuz tm.tm_wday starts with it
+static const TEXT* const FB_LONG_DAYS_UPPER[] =
+{
+	"SUNDAY",
+	"MONDAY",
+	"TUESDAY",
+	"WEDNESDAY",
+	"THURSDAY",
+	"FRIDAY",
+	"SATURDAY",
+	"\0"
+};
+
 const FB_SIZE_T FB_MAX_SIZEOF = ~FB_SIZE_T(0); // Assume FB_SIZE_T is unsigned
 
 inline FB_SIZE_T fb_strlen(const char* str)