evalengine: Implement TO_DAYS (#15065)

Signed-off-by: Noble Mittal <[email protected]>

go/mysql/datetime/datetime.go

@@ -610,7 +610,7 @@ func (dt *DateTime) addInterval(itv *Interval) bool {
 		dt.Time.minute = uint8((dur % time.Hour) / time.Minute)
 		dt.Time.hour = uint16(dur / time.Hour)
 
-		daynum := mysqlDayNumber(dt.Date.Year(), dt.Date.Month(), 1) + int(days)
+		daynum := MysqlDayNumber(dt.Date.Year(), dt.Date.Month(), 1) + int(days)
 		if daynum < 0 || daynum > maxDay {
 			return false
 		}
@@ -619,7 +619,7 @@ func (dt *DateTime) addInterval(itv *Interval) bool {
 		return true
 
 	case itv.unit.HasDayParts():
-		daynum := mysqlDayNumber(dt.Date.Year(), dt.Date.Month(), dt.Date.Day())
+		daynum := MysqlDayNumber(dt.Date.Year(), dt.Date.Month(), dt.Date.Day())
 		daynum += itv.day
 		dt.Date.year, dt.Date.month, dt.Date.day = mysqlDateFromDayNumber(daynum)
 		return true

go/mysql/datetime/mydate.go

@@ -16,7 +16,7 @@ limitations under the License.
 
 package datetime
 
-// mysqlDayNumber converts a date into an absolute day number.
+// MysqlDayNumber converts a date into an absolute day number.
 // This is an algorithm that has been reverse engineered from MySQL;
 // the tables used as a reference can be found in `testdata/year_to_daynr.json`.
 // It is worth noting that this absolute day number does not match the
@@ -29,7 +29,7 @@ package datetime
 // This API should only be used when performing datetime calculations (addition
 // and subtraction), so that the results match MySQL's. All other date handling
 // operations must use our helpers based on Go's standard library.
-func mysqlDayNumber(year, month, day int) int {
+func MysqlDayNumber(year, month, day int) int {
 	if year == 0 && month == 0 {
 		return 0
 	}
@@ -49,8 +49,8 @@ func mysqlDayNumber(year, month, day int) int {
 // mysqlDateFromDayNumber converts an absolute day number into a date (a year, month, day triplet).
 // This is an algorithm that has been reverse engineered from MySQL;
 // the tables used as a reference can be found in `testdata/daynr_to_date.json`.
-// See the warning from mysqlDayNumber: the day number used as an argument to
-// this function must come from mysqlDayNumber or the results won't be correct.
+// See the warning from MysqlDayNumber: the day number used as an argument to
+// this function must come from MysqlDayNumber or the results won't be correct.
 // This API should only be used when performing datetime calculations (addition
 // and subtraction), so that the results match MySQL's. All other date handling
 // operations must use our helpers based on Go's standard library.

go/mysql/datetime/mydate_test.go

@@ -35,7 +35,7 @@ func TestDayNumber(t *testing.T) {
 	require.NoError(t, err)
 
 	for year, daynr := range expected {
-		assert.Equal(t, daynr, mysqlDayNumber(year, 1, 1))
+		assert.Equal(t, daynr, MysqlDayNumber(year, 1, 1))
 	}
 }
 
@@ -54,6 +54,6 @@ func TestDayNumberFields(t *testing.T) {
 		assert.Equal(t, tc[2], int(m))
 		assert.Equal(t, tc[3], int(d))
 
-		assert.Equalf(t, tc[0], mysqlDayNumber(tc[1], tc[2], tc[3]), "date %d-%d-%d", tc[1], tc[2], tc[3])
+		assert.Equalf(t, tc[0], MysqlDayNumber(tc[1], tc[2], tc[3]), "date %d-%d-%d", tc[1], tc[2], tc[3])
 	}
 }

go/vt/vtgate/evalengine/compiler_asm.go

@@ -3795,6 +3795,22 @@ func (asm *assembler) Fn_LAST_DAY() {
 	}, "FN LAST_DAY DATETIME(SP-1)")
 }
 
+func (asm *assembler) Fn_TO_DAYS() {
+	asm.emit(func(env *ExpressionEnv) int {
+		if env.vm.stack[env.vm.sp-1] == nil {
+			return 1
+		}
+		arg := env.vm.stack[env.vm.sp-1].(*evalTemporal)
+		if arg.dt.Date.IsZero() {
+			env.vm.stack[env.vm.sp-1] = nil
+		} else {
+			numDays := datetime.MysqlDayNumber(arg.dt.Date.Year(), arg.dt.Date.Month(), arg.dt.Date.Day())
+			env.vm.stack[env.vm.sp-1] = env.vm.arena.newEvalInt64(int64(numDays))
+		}
+		return 1
+	}, "FN TO_DAYS DATE(SP-1)")
+}
+
 func (asm *assembler) Fn_FROM_DAYS() {
 	asm.emit(func(env *ExpressionEnv) int {
 		arg := env.vm.stack[env.vm.sp-1].(*evalInt64)

go/vt/vtgate/evalengine/fn_time.go

@@ -111,6 +111,10 @@ type (
 		CallExpr
 	}
 
+	builtinToDays struct {
+		CallExpr
+	}
+
 	builtinFromDays struct {
 		CallExpr
 	}
@@ -177,6 +181,7 @@ var _ IR = (*builtinMinute)(nil)
 var _ IR = (*builtinMonth)(nil)
 var _ IR = (*builtinMonthName)(nil)
 var _ IR = (*builtinLastDay)(nil)
+var _ IR = (*builtinToDays)(nil)
 var _ IR = (*builtinFromDays)(nil)
 var _ IR = (*builtinQuarter)(nil)
 var _ IR = (*builtinSecond)(nil)
@@ -1254,6 +1259,41 @@ func (call *builtinLastDay) compile(c *compiler) (ctype, error) {
 	return ctype{Type: sqltypes.Date, Flag: arg.Flag | flagNullable}, nil
 }
 
+func (b *builtinToDays) eval(env *ExpressionEnv) (eval, error) {
+	date, err := b.arg1(env)
+	if err != nil {
+		return nil, err
+	}
+	if date == nil {
+		return nil, nil
+	}
+	dt := evalToDate(date, env.now, env.sqlmode.AllowZeroDate())
+	if dt == nil || dt.isZero() {
+		return nil, nil
+	}
+
+	numDays := datetime.MysqlDayNumber(dt.dt.Date.Year(), dt.dt.Date.Month(), dt.dt.Date.Day())
+	return newEvalInt64(int64(numDays)), nil
+}
+
+func (call *builtinToDays) compile(c *compiler) (ctype, error) {
+	arg, err := call.Arguments[0].compile(c)
+	if err != nil {
+		return ctype{}, err
+	}
+
+	skip := c.compileNullCheck1(arg)
+
+	switch arg.Type {
+	case sqltypes.Date, sqltypes.Datetime:
+	default:
+		c.asm.Convert_xD(1, true)
+	}
+	c.asm.Fn_TO_DAYS()
+	c.asm.jumpDestination(skip)
+	return ctype{Type: sqltypes.Int64, Col: collationNumeric, Flag: arg.Flag | flagNullable}, nil
+}
+
 func (b *builtinFromDays) eval(env *ExpressionEnv) (eval, error) {
 	arg, err := b.arg1(env)
 	if arg == nil {
@@ -1279,6 +1319,7 @@ func (call *builtinFromDays) compile(c *compiler) (ctype, error) {
 	}
 
 	skip := c.compileNullCheck1(arg)
+
 	switch arg.Type {
 	case sqltypes.Int64:
 	default:

go/vt/vtgate/evalengine/testcases/cases.go

@@ -131,6 +131,7 @@ var Cases = []TestCase{
 	{Run: FnMonth},
 	{Run: FnMonthName},
 	{Run: FnLastDay},
+	{Run: FnToDays},
 	{Run: FnFromDays},
 	{Run: FnQuarter},
 	{Run: FnSecond},
@@ -1769,6 +1770,30 @@ func FnLastDay(yield Query) {
 	}
 }
 
+func FnToDays(yield Query) {
+	for _, d := range inputConversions {
+		yield(fmt.Sprintf("TO_DAYS(%s)", d), nil)
+	}
+
+	dates := []string{
+		`DATE'0000-00-00'`,
+		`0`,
+		`'0000-00-00'`,
+		`DATE'2023-09-03 00:00:00'`,
+		`DATE'2023-09-03 07:00:00'`,
+		`DATE'0000-00-00 00:00:00'`,
+		`950501`,
+		`'2007-10-07'`,
+		`'2008-10-07'`,
+		`'08-10-07'`,
+		`'0000-01-01'`,
+	}
+
+	for _, d := range dates {
+		yield(fmt.Sprintf("TO_DAYS(%s)", d), nil)
+	}
+}
+
 func FnFromDays(yield Query) {
 	for _, d := range inputConversions {
 		yield(fmt.Sprintf("FROM_DAYS(%s)", d), nil)

go/vt/vtgate/evalengine/translate_builtin.go

@@ -419,6 +419,11 @@ func (ast *astCompiler) translateFuncExpr(fn *sqlparser.FuncExpr) (IR, error) {
 			return nil, argError(method)
 		}
 		return &builtinLastDay{CallExpr: call}, nil
+	case "to_days":
+		if len(args) != 1 {
+			return nil, argError(method)
+		}
+		return &builtinToDays{CallExpr: call}, nil
 	case "from_days":
 		if len(args) != 1 {
 			return nil, argError(method)