expression, executor: rewrite built-in func length using new expression evaluation architecture

executor/executor_test.go

@@ -784,11 +784,18 @@ func (s *testSuite) TestStringBuiltin(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
 
+	// for length
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t(a int, b double, c datetime, d time, e char(20), f bit(10))")
+	tk.MustExec(`insert into t values(1, 1.1, "2017-01-01 12:01:01", "12:01:01", "abcdef", 0b10101)`)
+	result := tk.MustQuery("select length(a), length(b), length(c), length(d), length(e), length(f), length(null) from t")
+	result.Check(testkit.Rows("1 3 19 8 6 2 <nil>"))
+
 	// for concat
 	tk.MustExec("drop table if exists t")
 	tk.MustExec("create table t(a int, b double, c datetime, d time, e char(20))")
 	tk.MustExec(`insert into t values(1, 1.1, "2017-01-01 12:01:01", "12:01:01", "abcdef")`)
-	result := tk.MustQuery("select concat(a, b, c, d, e) from t")
+	result = tk.MustQuery("select concat(a, b, c, d, e) from t")
 	result.Check(testkit.Rows("11.12017-01-01 12:01:0112:01:01abcdef"))
 	result = tk.MustQuery("select concat(null)")
 	result.Check(testkit.Rows("<nil>"))

expression/builtin_string.go

@@ -132,32 +132,29 @@ type lengthFunctionClass struct {
 }
 
 func (c *lengthFunctionClass) getFunction(args []Expression, ctx context.Context) (builtinFunc, error) {
-	sig := &builtinLengthSig{newBaseBuiltinFunc(args, ctx)}
+	tp := types.NewFieldType(mysql.TypeLonglong)
+	types.SetBinChsClnFlag(tp)
+	sig := &builtinLengthSig{baseIntBuiltinFunc{newBaseBuiltinFuncWithTp(args, tp, ctx)}}
 	return sig.setSelf(sig), errors.Trace(c.verifyArgs(args))
 }
 
 type builtinLengthSig struct {
-	baseBuiltinFunc
+	baseIntBuiltinFunc
 }
 
 // eval evals a builtinLengthSig.
 // See https://dev.mysql.com/doc/refman/5.7/en/string-functions.html
-func (b *builtinLengthSig) eval(row []types.Datum) (d types.Datum, err error) {
-	args, err := b.evalArgs(row)
+func (b *builtinLengthSig) evalInt(row []types.Datum) (int64, bool, error) {
+	ctx, sc := b.ctx, b.ctx.GetSessionVars().StmtCtx
+	arg0, err := WrapWithCastAsString(b.args[0], ctx)
 	if err != nil {
-		return types.Datum{}, errors.Trace(err)
+		return 0, false, errors.Trace(err)
 	}
-	switch args[0].Kind() {
-	case types.KindNull:
-		return d, nil
-	default:
-		s, err := args[0].ToString()
-		if err != nil {
-			return d, errors.Trace(err)
-		}
-		d.SetInt64(int64(len(s)))
-		return d, nil
+	val, isNull, err := arg0.EvalString(row, sc)
+	if isNull || err != nil {
+		return 0, isNull, errors.Trace(err)
 	}
+	return int64(len([]byte(val))), false, nil
 }
 
 type asciiFunctionClass struct {

expression/builtin_string_test.go

@@ -30,34 +30,45 @@ import (
 
 func (s *testEvaluatorSuite) TestLength(c *C) {
 	defer testleak.AfterTest(c)()
-	fc := funcs[ast.Length]
-	f, err := fc.getFunction(datumsToConstants(types.MakeDatums(nil)), s.ctx)
-	c.Assert(err, IsNil)
-	d, err := f.eval(nil)
-	c.Assert(err, IsNil)
-	c.Assert(d.Kind(), Equals, types.KindNull)
-
-	tbl := []struct {
-		Input    interface{}
-		Expected int64
+	cases := []struct {
+		args     interface{}
+		expected int64
+		isNil    bool
+		getErr   bool
 	}{
-		{"abc", 3},
-		{1, 1},
-		{3.14, 4},
-		{types.Time{Time: types.FromGoTime(time.Now()), Fsp: 6, Type: mysql.TypeDatetime}, 26},
-		{types.Bit{Value: 1, Width: 8}, 1},
-		{types.Hex{Value: 1}, 1},
-		{types.Set{Value: 1, Name: "abc"}, 3},
+		{"abc", 3, false, false},
+		{"你好", 6, false, false},
+		{1, 1, false, false},
+		{3.14, 4, false, false},
+		{types.NewDecFromFloatForTest(123.123), 7, false, false},
+		{types.Time{Time: types.FromGoTime(time.Now()), Fsp: 6, Type: mysql.TypeDatetime}, 26, false, false},
+		{types.Bit{Value: 1, Width: 8}, 1, false, false},
+		{types.Hex{Value: 1}, 1, false, false},
+		{types.Set{Value: 1, Name: "abc"}, 3, false, false},
+		{types.Duration{Duration: time.Duration(12*time.Hour + 1*time.Minute + 1*time.Second), Fsp: types.DefaultFsp}, 8, false, false},
+		{nil, 0, true, false},
+		{errors.New("must error"), 0, false, true},
 	}
 
-	dtbl := tblToDtbl(tbl)
-
-	for _, t := range dtbl {
-		f, err := fc.getFunction(datumsToConstants(t["Input"]), s.ctx)
-		c.Assert(err, IsNil)
-		d, err = f.eval(nil)
-		c.Assert(err, IsNil)
-		c.Assert(d, testutil.DatumEquals, t["Expected"][0])
+	for _, t := range cases {
+		f, err := newFunctionForTest(s.ctx, ast.Length, primitiveValsToConstants([]interface{}{t.args})...)
+		c.Assert(err, IsNil)
+		tp := f.GetType()
+		c.Assert(tp.Tp, Equals, mysql.TypeLonglong)
+		c.Assert(tp.Charset, Equals, charset.CharsetBin)
+		c.Assert(tp.Collate, Equals, charset.CollationBin)
+		c.Assert(tp.Flag, Equals, uint(mysql.BinaryFlag))
+		d, err := f.Eval(nil)
+		if t.getErr {
+			c.Assert(err, NotNil)
+		} else {
+			c.Assert(err, IsNil)
+			if t.isNil {
+				c.Assert(d.Kind(), Equals, types.KindNull)
+			} else {
+				c.Assert(d.GetInt64(), Equals, t.expected)
+			}
+		}
 	}
 }
 

expression/expression.go

@@ -185,7 +185,7 @@ func evalExprToString(expr Expression, row []types.Datum, _ *variable.StatementC
 	if val.IsNull() || err != nil {
 		return res, val.IsNull(), errors.Trace(err)
 	}
-	if expr.GetTypeClass() == types.ClassString {
+	if expr.GetTypeClass() == types.ClassString || IsHybridType(expr) {
 		// We cannot use val.GetString() directly.
 		// For example, `Bit` is regarded as ClassString,
 		// while we can not use val.GetString() to get the value of a Bit variable,

expression/util.go

@@ -91,9 +91,9 @@ var kindToMysqlType = map[byte]byte{
 	types.KindFloat64:       mysql.TypeDouble,
 	types.KindString:        mysql.TypeVarString,
 	types.KindBytes:         mysql.TypeVarString,
-	types.KindMysqlBit:      mysql.TypeVarString,
-	types.KindMysqlEnum:     mysql.TypeVarString,
-	types.KindMysqlSet:      mysql.TypeVarString,
+	types.KindMysqlBit:      mysql.TypeBit,
+	types.KindMysqlEnum:     mysql.TypeEnum,
+	types.KindMysqlSet:      mysql.TypeSet,
 	types.KindRow:           mysql.TypeVarString,
 	types.KindInterface:     mysql.TypeVarString,
 	types.KindMysqlDecimal:  mysql.TypeNewDecimal,