// DecodeDecimal decodes bytes to decimal.
func DecodeDecimal(b []byte) ([]byte, types.Datum, error) {
var d types.Datum
if len(b) < 3 {
return b, d, errors.New("insufficient bytes to decode value")
}
precision := int(b[0])
frac := int(b[1])
b = b[2:]
dec := new(mysql.MyDecimal)
binSize, err := dec.FromBin(b, precision, frac)
b = b[binSize:]
if err != nil {
return b, d, errors.Trace(err)
}
d.SetLength(precision)
d.SetFrac(frac)
d.SetMysqlDecimal(dec)
return b, d, nil
}
func (s *testCodecSuite) TestDecimal(c *C) {
defer testleak.AfterTest(c)()
tbl := []string{
"1234.00",
"1234",
"12.34",
"12.340",
"0.1234",
"0.0",
"0",
"-0.0",
"-0.0000",
"-1234.00",
"-1234",
"-12.34",
"-12.340",
"-0.1234",
}
for _, t := range tbl {
dec := new(mysql.MyDecimal)
err := dec.FromString([]byte(t))
c.Assert(err, IsNil)
b, err := EncodeKey(nil, types.NewDatum(dec))
c.Assert(err, IsNil)
v, err := Decode(b)
c.Assert(err, IsNil)
c.Assert(v, HasLen, 1)
vv := v[0].GetMysqlDecimal()
c.Assert(vv.Compare(dec), Equals, 0)
}
tblCmp := []struct {
Arg1 interface{}
Arg2 interface{}
Ret int
}{
// Test for float type decimal.
{"1234", "123400", -1},
{"12340", "123400", -1},
{"1234", "1234.5", -1},
{"1234", "1234.0000", 0},
{"1234", "12.34", 1},
{"12.34", "12.35", -1},
{"0.12", "0.1234", -1},
{"0.1234", "12.3400", -1},
{"0.1234", "0.1235", -1},
{"0.123400", "12.34", -1},
{"12.34000", "12.34", 0},
{"0.01234", "0.01235", -1},
{"0.1234", "0", 1},
{"0.0000", "0", 0},
{"0.0001", "0", 1},
{"0.0001", "0.0000", 1},
{"0", "-0.0000", 0},
{"-0.0001", "0", -1},
{"-0.1234", "0", -1},
{"-0.1234", "-0.12", -1},
{"-0.12", "-0.1234", 1},
{"-0.12", "-0.1200", 0},
{"-0.1234", "0.1234", -1},
{"-1.234", "-12.34", 1},
{"-0.1234", "-12.34", 1},
{"-12.34", "1234", -1},
{"-12.34", "-12.35", 1},
{"-0.01234", "-0.01235", 1},
{"-1234", "-123400", 1},
{"-12340", "-123400", 1},
// Test for int type decimal.
{int64(-1), int64(1), -1},
{int64(math.MaxInt64), int64(math.MinInt64), 1},
{int64(math.MaxInt64), int64(math.MaxInt32), 1},
{int64(math.MinInt32), int64(math.MaxInt16), -1},
{int64(math.MinInt64), int64(math.MaxInt8), -1},
{int64(0), int64(math.MaxInt8), -1},
{int64(math.MinInt8), int64(0), -1},
{int64(math.MinInt16), int64(math.MaxInt16), -1},
{int64(1), int64(-1), 1},
{int64(1), int64(0), 1},
{int64(-1), int64(0), -1},
{int64(0), int64(0), 0},
{int64(math.MaxInt16), int64(math.MaxInt16), 0},
// Test for uint type decimal.
{uint64(0), uint64(0), 0},
{uint64(1), uint64(0), 1},
{uint64(0), uint64(1), -1},
{uint64(math.MaxInt8), uint64(math.MaxInt16), -1},
{uint64(math.MaxUint32), uint64(math.MaxInt32), 1},
{uint64(math.MaxUint8), uint64(math.MaxInt8), 1},
{uint64(math.MaxUint16), uint64(math.MaxInt32), -1},
{uint64(math.MaxUint64), uint64(math.MaxInt64), 1},
{uint64(math.MaxInt64), uint64(math.MaxUint32), 1},
{uint64(math.MaxUint64), uint64(0), 1},
{uint64(0), uint64(math.MaxUint64), -1},
}
for _, t := range tblCmp {
d1 := types.NewDatum(t.Arg1)
dec1, err := d1.ToDecimal()
c.Assert(err, IsNil)
d1.SetMysqlDecimal(dec1)
d2 := types.NewDatum(t.Arg2)
dec2, err := d2.ToDecimal()
c.Assert(err, IsNil)
d2.SetMysqlDecimal(dec2)
d1.SetLength(30)
d1.SetFrac(6)
d2.SetLength(30)
d2.SetFrac(6)
b1, err := EncodeKey(nil, d1)
c.Assert(err, IsNil)
b2, err := EncodeKey(nil, d2)
c.Assert(err, IsNil)
ret := bytes.Compare(b1, b2)
c.Assert(ret, Equals, t.Ret, Commentf("%v %x %x", t, b1, b2))
}
floats := []float64{-123.45, -123.40, -23.45, -1.43, -0.93, -0.4333, -0.068,
-0.0099, 0, 0.001, 0.0012, 0.12, 1.2, 1.23, 123.3, 2424.242424}
var decs [][]byte
for i := range floats {
dec := mysql.NewDecFromFloatForTest(floats[i])
var d types.Datum
d.SetLength(20)
d.SetFrac(6)
d.SetMysqlDecimal(dec)
decs = append(decs, EncodeDecimal(nil, d))
}
for i := 0; i < len(decs)-1; i++ {
cmp := bytes.Compare(decs[i], decs[i+1])
c.Assert(cmp, LessEqual, 0)
}
}