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types: Improve Convert function #8

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merged 2 commits into from
Sep 6, 2015
Merged

types: Improve Convert function #8

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d1b3e2d
types: Improve Convert function
shenli Sep 6, 2015
615110e
types: Convert function
shenli Sep 6, 2015
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22 changes: 0 additions & 22 deletions expression/expressions/cast.go
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,6 @@ import (
"github.com/pingcap/tidb/context"
"github.com/pingcap/tidb/expression"
mysql "github.com/pingcap/tidb/mysqldef"
"github.com/pingcap/tidb/util/charset"
"github.com/pingcap/tidb/util/types"
)

Expand Down Expand Up @@ -76,30 +75,9 @@ func (f *FunctionCast) Eval(ctx context.Context, args map[interface{}]interface{
if value == nil {
return nil, nil
}

// TODO: we need a better function convert between any two types according to FieldType.
// Not only check Type, but also consider Flen/Decimal/Charset and so on.
nv, err := types.Convert(value, f.Tp)
if err != nil {
return nil, err
}
if f.Tp.Tp == mysql.TypeString && f.Tp.Charset == charset.CharsetBin {
nv = []byte(nv.(string))
}
if f.Tp.Flen != types.UnspecifiedLength {
switch f.Tp.Tp {
case mysql.TypeString:
v := nv.(string)
if len(v) > int(f.Tp.Flen) {
v = v[:f.Tp.Flen]
}
return v, nil
}
}
if f.Tp.Tp == mysql.TypeLonglong {
if mysql.HasUnsignedFlag(f.Tp.Flag) {
return uint64(nv.(int64)), nil
}
}
return nv, nil
}
11 changes: 11 additions & 0 deletions util/types/convert.go
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@ import (

"github.com/juju/errors"
mysql "github.com/pingcap/tidb/mysqldef"
"github.com/pingcap/tidb/util/charset"
)

// InvConv returns a failed convertion error.
Expand Down Expand Up @@ -71,13 +72,19 @@ func Convert(val interface{}, target *FieldType) (v interface{}, err error) { //
}
// TODO: consider target.Charset/Collate
x = truncateStr(x, target.Flen)
if target.Charset == charset.CharsetBin {
return []byte(x), nil
}
return x, nil
case mysql.TypeBlob:
x, err := ToString(val)
if err != nil {
return InvConv(val, tp)
}
x = truncateStr(x, target.Flen)
if target.Charset == charset.CharsetBin {
return []byte(x), nil
}
return x, nil
case mysql.TypeDuration:
fsp := mysql.DefaultFsp
Expand Down Expand Up @@ -127,6 +134,10 @@ func Convert(val interface{}, target *FieldType) (v interface{}, err error) { //
if err != nil {
return InvConv(val, tp)
}
// TODO: We should first convert to uint64 then check unsigned flag.
if mysql.HasUnsignedFlag(target.Flag) {
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how about negative number?

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Negative number will be converted to a big uint.

mysql> select cast(-5 as unsigned);
+----------------------+
| cast(-5 as unsigned) |
+----------------------+
| 18446744073709551611 |
+----------------------+
1 row in set (0.00 sec)

mysql>

return uint64(x), nil
}
return x, nil
case mysql.TypeNewDecimal:
x, err := ToDecimal(val)
Expand Down
17 changes: 17 additions & 0 deletions util/types/convert_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,12 @@ func (s *testTypeConvertSuite) TestConvertType(c *C) {
v, err := Convert("123456", ft)
c.Assert(err, IsNil)
c.Assert(v, Equals, "1234")
ft = NewFieldType(mysql.TypeString)
ft.Flen = 4
ft.Charset = charset.CharsetBin
v, err = Convert("12345", ft)
c.Assert(err, IsNil)
c.Assert(v, DeepEquals, []byte("1234"))

ft = NewFieldType(mysql.TypeFloat)
ft.Flen = 5
Expand Down Expand Up @@ -111,6 +117,12 @@ func (s *testTypeConvertSuite) TestConvertType(c *C) {
v, err = Convert("12345", ft)
c.Assert(err, IsNil)
c.Assert(v, Equals, "123")
ft = NewFieldType(mysql.TypeString)
ft.Flen = 3
ft.Charset = charset.CharsetBin
v, err = Convert("12345", ft)
c.Assert(err, IsNil)
c.Assert(v, DeepEquals, []byte("123"))

// For TypeDuration
ft = NewFieldType(mysql.TypeDuration)
Expand Down Expand Up @@ -146,6 +158,11 @@ func (s *testTypeConvertSuite) TestConvertType(c *C) {
v, err = Convert("100", ft)
c.Assert(err, IsNil)
c.Assert(v, Equals, int64(100))
ft = NewFieldType(mysql.TypeLonglong)
ft.Flag |= mysql.UnsignedFlag
v, err = Convert("100", ft)
c.Assert(err, IsNil)
c.Assert(v, Equals, uint64(100))

// For TypeNewDecimal
ft = NewFieldType(mysql.TypeNewDecimal)
Expand Down