expression, plan: rewrite builtin func get_format (#4422)

expression/builtin_time.go

@@ -1199,63 +1199,73 @@ func (c *getFormatFunctionClass) getFunction(ctx context.Context, args []Express
 	if err := c.verifyArgs(args); err != nil {
 		return nil, errors.Trace(err)
 	}
-	sig := &builtinGetFormatSig{newBaseBuiltinFunc(args, ctx)}
+	bf := newBaseBuiltinFuncWithTp(args, ctx, tpString, tpString, tpString)
+	bf.tp.Flen = 17
+	sig := &builtinGetFormatSig{baseStringBuiltinFunc{bf}}
 	return sig.setSelf(sig), nil
 }
 
 type builtinGetFormatSig struct {
-	baseBuiltinFunc
+	baseStringBuiltinFunc
 }
 
-// eval evals a builtinGetFormatSig.
+// evalString evals a builtinGetFormatSig.
 // See https://dev.mysql.com/doc/refman/5.7/en/date-and-time-functions.html#function_get-format
-func (b *builtinGetFormatSig) eval(row []types.Datum) (d types.Datum, err error) {
-	args, err := b.evalArgs(row)
-	t := args[0].GetString()
-	l := args[1].GetString()
+func (b *builtinGetFormatSig) evalString(row []types.Datum) (string, bool, error) {
+	sc := b.ctx.GetSessionVars().StmtCtx
+	t, isNull, err := b.args[0].EvalString(row, sc)
+	if isNull || err != nil {
+		return "", isNull, errors.Trace(err)
+	}
+	l, isNull, err := b.args[1].EvalString(row, sc)
+	if isNull || err != nil {
+		return "", isNull, errors.Trace(err)
+	}
+
+	var res string
 	switch t {
 	case dateFormat:
 		switch l {
 		case usaLocation:
-			d.SetString("%m.%d.%Y")
+			res = "%m.%d.%Y"
 		case jisLocation:
-			d.SetString("%Y-%m-%d")
+			res = "%Y-%m-%d"
 		case isoLocation:
-			d.SetString("%Y-%m-%d")
+			res = "%Y-%m-%d"
 		case eurLocation:
-			d.SetString("%d.%m.%Y")
+			res = "%d.%m.%Y"
 		case internalLocation:
-			d.SetString("%Y%m%d")
+			res = "%Y%m%d"
 		}
 	case datetimeFormat, timestampFormat:
 		switch l {
 		case usaLocation:
-			d.SetString("%Y-%m-%d %H.%i.%s")
+			res = "%Y-%m-%d %H.%i.%s"
 		case jisLocation:
-			d.SetString("%Y-%m-%d %H:%i:%s")
+			res = "%Y-%m-%d %H:%i:%s"
 		case isoLocation:
-			d.SetString("%Y-%m-%d %H:%i:%s")
+			res = "%Y-%m-%d %H:%i:%s"
 		case eurLocation:
-			d.SetString("%Y-%m-%d %H.%i.%s")
+			res = "%Y-%m-%d %H.%i.%s"
 		case internalLocation:
-			d.SetString("%Y%m%d%H%i%s")
+			res = "%Y%m%d%H%i%s"
 		}
 	case timeFormat:
 		switch l {
 		case usaLocation:
-			d.SetString("%h:%i:%s %p")
+			res = "%h:%i:%s %p"
 		case jisLocation:
-			d.SetString("%H:%i:%s")
+			res = "%H:%i:%s"
 		case isoLocation:
-			d.SetString("%H:%i:%s")
+			res = "%H:%i:%s"
 		case eurLocation:
-			d.SetString("%H.%i.%s")
+			res = "%H.%i.%s"
 		case internalLocation:
-			d.SetString("%H%i%s")
+			res = "%H%i%s"
 		}
 	}
 
-	return
+	return res, false, nil
 }
 
 type strToDateFunctionClass struct {

expression/builtin_time_test.go

@@ -1737,6 +1737,7 @@ func (s *testEvaluatorSuite) TestGetFormat(c *C) {
 		t := []types.Datum{types.NewStringDatum(test.unit), types.NewStringDatum(test.location)}
 		f, err := fc.getFunction(s.ctx, datumsToConstants(t))
 		c.Assert(err, IsNil)
+		c.Assert(f.canBeFolded(), IsTrue)
 		d, err := f.eval(nil)
 		c.Assert(err, IsNil)
 		result, _ := d.ToString()

expression/integration_test.go

@@ -1432,6 +1432,13 @@ func (s *testIntegrationSuite) TestTimeBuiltin(c *C) {
 	// TODO: MySQL returns "<nil> <nil>".
 	result.Check(testkit.Rows("0000-00-01 <nil>"))
 	tk.MustQuery("show warnings").Check(testutil.RowsWithSep("|", "Warning|1105|invalid time format"))
+
+	// for get_format
+	result = tk.MustQuery(`select GET_FORMAT(DATE,'USA'), GET_FORMAT(DATE,'JIS'), GET_FORMAT(DATE,'ISO'), GET_FORMAT(DATE,'EUR'),
+	GET_FORMAT(DATE,'INTERNAL'), GET_FORMAT(DATETIME,'USA') , GET_FORMAT(DATETIME,'JIS'), GET_FORMAT(DATETIME,'ISO'),
+	GET_FORMAT(DATETIME,'EUR') , GET_FORMAT(DATETIME,'INTERNAL'), GET_FORMAT(TIME,'USA') , GET_FORMAT(TIME,'JIS'),
+	GET_FORMAT(TIME,'ISO'), GET_FORMAT(TIME,'EUR'), GET_FORMAT(TIME,'INTERNAL')`)
+	result.Check(testkit.Rows("%m.%d.%Y %Y-%m-%d %Y-%m-%d %d.%m.%Y %Y%m%d %Y-%m-%d %H.%i.%s %Y-%m-%d %H:%i:%s %Y-%m-%d %H:%i:%s %Y-%m-%d %H.%i.%s %Y%m%d%H%i%s %h:%i:%s %p %H:%i:%s %H:%i:%s %H.%i.%s %H%i%s"))
 }
 
 func (s *testIntegrationSuite) TestOpBuiltin(c *C) {

plan/typeinfer_test.go

@@ -1676,6 +1676,8 @@ func (s *testPlanSuite) createTestCase4TimeFuncs() []typeInferTestCase {
 		{"period_diff(c_blob_d     , c_int_d)", mysql.TypeLonglong, charset.CharsetBin, mysql.BinaryFlag, 6, 0},
 		{"period_diff(c_set        , c_int_d)", mysql.TypeLonglong, charset.CharsetBin, mysql.BinaryFlag, 6, 0},
 		{"period_diff(c_enum       , c_int_d)", mysql.TypeLonglong, charset.CharsetBin, mysql.BinaryFlag, 6, 0},
+
+		{"get_format(DATE, 'USA')", mysql.TypeVarString, charset.CharsetUTF8, 0, 17, types.UnspecifiedLength},
 	}
 }