Centralize json and jsonb handling of datetime types

The creates a single function JsonEncodeDateTime which will format these
data types in an efficient and consistent manner. This will be all the
more important when we come to jsonpath so we don't have to implement yet
more code doing the same thing in two more places.

This also extends the code to handle time and timetz types which were
not previously handled specially. This requires exposing the time2tm and
timetz2tm functions.

Patch from Nikita Glukhov

src/backend/utils/adt/date.c

@@ -41,8 +41,6 @@
 #endif
 
 
-static int	time2tm(TimeADT time, struct pg_tm *tm, fsec_t *fsec);
-static int	timetz2tm(TimeTzADT *time, struct pg_tm *tm, fsec_t *fsec, int *tzp);
 static int	tm2time(struct pg_tm *tm, fsec_t fsec, TimeADT *result);
 static int	tm2timetz(struct pg_tm *tm, fsec_t fsec, int tz, TimeTzADT *result);
 static void AdjustTimeForTypmod(TimeADT *time, int32 typmod);
@@ -1249,7 +1247,7 @@ tm2time(struct pg_tm *tm, fsec_t fsec, TimeADT *result)
  * If out of this range, leave as UTC (in practice that could only happen
  * if pg_time_t is just 32 bits) - thomas 97/05/27
  */
-static int
+int
 time2tm(TimeADT time, struct pg_tm *tm, fsec_t *fsec)
 {
 	tm->tm_hour = time / USECS_PER_HOUR;
@@ -2073,7 +2071,7 @@ timetztypmodout(PG_FUNCTION_ARGS)
 /* timetz2tm()
  * Convert TIME WITH TIME ZONE data type to POSIX time structure.
  */
-static int
+int
 timetz2tm(TimeTzADT *time, struct pg_tm *tm, fsec_t *fsec, int *tzp)
 {
 	TimeOffset	trem = time->time;

src/backend/utils/adt/json.c

@@ -1504,62 +1504,25 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 			break;
 		case JSONTYPE_DATE:
 			{
-				DateADT		date;
-				struct pg_tm tm;
 				char		buf[MAXDATELEN + 1];
 
-				date = DatumGetDateADT(val);
+				JsonEncodeDateTime(buf, val, DATEOID);
-				/* Same as date_out(), but forcing DateStyle */
-				if (DATE_NOT_FINITE(date))
-					EncodeSpecialDate(date, buf);
-				else
-				{
-					j2date(date + POSTGRES_EPOCH_JDATE,
-						   &(tm.tm_year), &(tm.tm_mon), &(tm.tm_mday));
-					EncodeDateOnly(&tm, USE_XSD_DATES, buf);
-				}
 				appendStringInfo(result, "\"%s\"", buf);
 			}
 			break;
 		case JSONTYPE_TIMESTAMP:
 			{
-				Timestamp	timestamp;
-				struct pg_tm tm;
-				fsec_t		fsec;
 				char		buf[MAXDATELEN + 1];
 
-				timestamp = DatumGetTimestamp(val);
+				JsonEncodeDateTime(buf, val, TIMESTAMPOID);
-				/* Same as timestamp_out(), but forcing DateStyle */
-				if (TIMESTAMP_NOT_FINITE(timestamp))
-					EncodeSpecialTimestamp(timestamp, buf);
-				else if (timestamp2tm(timestamp, NULL, &tm, &fsec, NULL, NULL) == 0)
-					EncodeDateTime(&tm, fsec, false, 0, NULL, USE_XSD_DATES, buf);
-				else
-					ereport(ERROR,
-							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
-							 errmsg("timestamp out of range")));
 				appendStringInfo(result, "\"%s\"", buf);
 			}
 			break;
 		case JSONTYPE_TIMESTAMPTZ:
 			{
-				TimestampTz timestamp;
-				struct pg_tm tm;
-				int			tz;
-				fsec_t		fsec;
-				const char *tzn = NULL;
 				char		buf[MAXDATELEN + 1];
 
-				timestamp = DatumGetTimestampTz(val);
+				JsonEncodeDateTime(buf, val, TIMESTAMPTZOID);
-				/* Same as timestamptz_out(), but forcing DateStyle */
-				if (TIMESTAMP_NOT_FINITE(timestamp))
-					EncodeSpecialTimestamp(timestamp, buf);
-				else if (timestamp2tm(timestamp, &tz, &tm, &fsec, &tzn, NULL) == 0)
-					EncodeDateTime(&tm, fsec, true, tz, tzn, USE_XSD_DATES, buf);
-				else
-					ereport(ERROR,
-							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
-							 errmsg("timestamp out of range")));
 				appendStringInfo(result, "\"%s\"", buf);
 			}
 			break;
@@ -1585,6 +1548,107 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 	}
 }
 
+/*
+ * Encode 'value' of datetime type 'typid' into JSON string in ISO format using
+ * optionally preallocated buffer 'buf'.
+ */
+char *
+JsonEncodeDateTime(char *buf, Datum value, Oid typid)
+{
+	if (!buf)
+		buf = palloc(MAXDATELEN + 1);
+
+	switch (typid)
+	{
+		case DATEOID:
+			{
+				DateADT		date;
+				struct pg_tm tm;
+
+				date = DatumGetDateADT(value);
+
+				/* Same as date_out(), but forcing DateStyle */
+				if (DATE_NOT_FINITE(date))
+					EncodeSpecialDate(date, buf);
+				else
+				{
+					j2date(date + POSTGRES_EPOCH_JDATE,
+						   &(tm.tm_year), &(tm.tm_mon), &(tm.tm_mday));
+					EncodeDateOnly(&tm, USE_XSD_DATES, buf);
+				}
+			}
+			break;
+		case TIMEOID:
+			{
+				TimeADT		time = DatumGetTimeADT(value);
+				struct pg_tm tt,
+						   *tm = &tt;
+				fsec_t		fsec;
+
+				/* Same as time_out(), but forcing DateStyle */
+				time2tm(time, tm, &fsec);
+				EncodeTimeOnly(tm, fsec, false, 0, USE_XSD_DATES, buf);
+			}
+			break;
+		case TIMETZOID:
+			{
+				TimeTzADT  *time = DatumGetTimeTzADTP(value);
+				struct pg_tm tt,
+						   *tm = &tt;
+				fsec_t		fsec;
+				int			tz;
+
+				/* Same as timetz_out(), but forcing DateStyle */
+				timetz2tm(time, tm, &fsec, &tz);
+				EncodeTimeOnly(tm, fsec, true, tz, USE_XSD_DATES, buf);
+			}
+			break;
+		case TIMESTAMPOID:
+			{
+				Timestamp	timestamp;
+				struct pg_tm tm;
+				fsec_t		fsec;
+
+				timestamp = DatumGetTimestamp(value);
+				/* Same as timestamp_out(), but forcing DateStyle */
+				if (TIMESTAMP_NOT_FINITE(timestamp))
+					EncodeSpecialTimestamp(timestamp, buf);
+				else if (timestamp2tm(timestamp, NULL, &tm, &fsec, NULL, NULL) == 0)
+					EncodeDateTime(&tm, fsec, false, 0, NULL, USE_XSD_DATES, buf);
+				else
+					ereport(ERROR,
+							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+							 errmsg("timestamp out of range")));
+			}
+			break;
+		case TIMESTAMPTZOID:
+			{
+				TimestampTz timestamp;
+				struct pg_tm tm;
+				int			tz;
+				fsec_t		fsec;
+				const char *tzn = NULL;
+
+				timestamp = DatumGetTimestampTz(value);
+				/* Same as timestamptz_out(), but forcing DateStyle */
+				if (TIMESTAMP_NOT_FINITE(timestamp))
+					EncodeSpecialTimestamp(timestamp, buf);
+				else if (timestamp2tm(timestamp, &tz, &tm, &fsec, &tzn, NULL) == 0)
+					EncodeDateTime(&tm, fsec, true, tz, tzn, USE_XSD_DATES, buf);
+				else
+					ereport(ERROR,
+							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+							 errmsg("timestamp out of range")));
+			}
+			break;
+		default:
+			elog(ERROR, "unknown jsonb value datetime type oid %d", typid);
+			return NULL;
+	}
+
+	return buf;
+}
+
 /*
  * Process a single dimension of an array.
  * If it's the innermost dimension, output the values, otherwise call

src/backend/utils/adt/jsonb.c

@@ -786,71 +786,19 @@ datum_to_jsonb(Datum val, bool is_null, JsonbInState *result,
 				}
 				break;
 			case JSONBTYPE_DATE:
-				{
-					DateADT		date;
-					struct pg_tm tm;
-					char		buf[MAXDATELEN + 1];
-
-					date = DatumGetDateADT(val);
-					/* Same as date_out(), but forcing DateStyle */
-					if (DATE_NOT_FINITE(date))
-						EncodeSpecialDate(date, buf);
-					else
-					{
-						j2date(date + POSTGRES_EPOCH_JDATE,
-							   &(tm.tm_year), &(tm.tm_mon), &(tm.tm_mday));
-						EncodeDateOnly(&tm, USE_XSD_DATES, buf);
-					}
 				jb.type = jbvString;
-					jb.val.string.len = strlen(buf);
+				jb.val.string.val = JsonEncodeDateTime(NULL, val, DATEOID);
-					jb.val.string.val = pstrdup(buf);
+				jb.val.string.len = strlen(jb.val.string.val);
-				}
 				break;
 			case JSONBTYPE_TIMESTAMP:
-				{
-					Timestamp	timestamp;
-					struct pg_tm tm;
-					fsec_t		fsec;
-					char		buf[MAXDATELEN + 1];
-
-					timestamp = DatumGetTimestamp(val);
-					/* Same as timestamp_out(), but forcing DateStyle */
-					if (TIMESTAMP_NOT_FINITE(timestamp))
-						EncodeSpecialTimestamp(timestamp, buf);
-					else if (timestamp2tm(timestamp, NULL, &tm, &fsec, NULL, NULL) == 0)
-						EncodeDateTime(&tm, fsec, false, 0, NULL, USE_XSD_DATES, buf);
-					else
-						ereport(ERROR,
-								(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
-								 errmsg("timestamp out of range")));
 				jb.type = jbvString;
-					jb.val.string.len = strlen(buf);
+				jb.val.string.val = JsonEncodeDateTime(NULL, val, TIMESTAMPOID);
-					jb.val.string.val = pstrdup(buf);
+				jb.val.string.len = strlen(jb.val.string.val);
-				}
 				break;
 			case JSONBTYPE_TIMESTAMPTZ:
-				{
-					TimestampTz timestamp;
-					struct pg_tm tm;
-					int			tz;
-					fsec_t		fsec;
-					const char *tzn = NULL;
-					char		buf[MAXDATELEN + 1];
-
-					timestamp = DatumGetTimestampTz(val);
-					/* Same as timestamptz_out(), but forcing DateStyle */
-					if (TIMESTAMP_NOT_FINITE(timestamp))
-						EncodeSpecialTimestamp(timestamp, buf);
-					else if (timestamp2tm(timestamp, &tz, &tm, &fsec, &tzn, NULL) == 0)
-						EncodeDateTime(&tm, fsec, true, tz, tzn, USE_XSD_DATES, buf);
-					else
-						ereport(ERROR,
-								(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
-								 errmsg("timestamp out of range")));
 				jb.type = jbvString;
-					jb.val.string.len = strlen(buf);
+				jb.val.string.val = JsonEncodeDateTime(NULL, val, TIMESTAMPTZOID);
-					jb.val.string.val = pstrdup(buf);
+				jb.val.string.len = strlen(jb.val.string.val);
-				}
 				break;
 			case JSONBTYPE_JSONCAST:
 			case JSONBTYPE_JSON:

src/include/utils/date.h

@@ -17,7 +17,7 @@
 #include <math.h>
 
 #include "fmgr.h"
-
+#include "datatype/timestamp.h"
 
 typedef int32 DateADT;
 
@@ -73,5 +73,7 @@ extern void EncodeSpecialDate(DateADT dt, char *str);
 extern DateADT GetSQLCurrentDate(void);
 extern TimeTzADT *GetSQLCurrentTime(int32 typmod);
 extern TimeADT GetSQLLocalTime(int32 typmod);
+extern int	time2tm(TimeADT time, struct pg_tm *tm, fsec_t *fsec);
+extern int	timetz2tm(TimeTzADT *time, struct pg_tm *tm, fsec_t *fsec, int *tzp);
 
 #endif							/* DATE_H */

src/include/utils/jsonapi.h

@@ -147,4 +147,6 @@ extern Jsonb *transform_jsonb_string_values(Jsonb *jsonb, void *action_state,
 extern text *transform_json_string_values(text *json, void *action_state,
 							 JsonTransformStringValuesAction transform_action);
 
+extern char *JsonEncodeDateTime(char *buf, Datum value, Oid typid);
+
 #endif							/* JSONAPI_H */