Add MsgPack Marshal and Unmarshal function（Add Test Case And Change return value to unnamed）

decimal_magpack_test.go

@@ -0,0 +1,55 @@
+package decimal
+
+import (
+	"testing"
+)
+
+func TestMsgPack(t *testing.T) {
+	for _, x := range testTable {
+		s := x.short
+		// limit to 31 digits
+		if len(s) > 31 {
+			s = s[:31]
+			if s[30] == '.' {
+				s = s[:30]
+			}
+		}
+
+		// Prepare Test Decimal Data
+		amount, err := NewFromString(s)
+		if err != nil {
+			t.Error(err)
+		}
+		s = amount.String()
+
+		// MarshalMsg
+		var b []byte
+		out, err := amount.MarshalMsg(b)
+		if err != nil {
+			t.Errorf("error marshalMsg %s: %v", s, err)
+		}
+
+		// check msg type
+		typ := out[0] & 0xe0
+		if typ != 0xa0 {
+			t.Errorf("error marshalMsg, expected type = %b, got %b", 0xa0, typ)
+		}
+
+		// check msg len
+		sz := int(out[0] & 0x1f)
+		if sz != len(s) {
+			t.Errorf("error marshalMsg, expected size = %d, got %d", len(s), sz)
+		}
+
+		// UnmarshalMsg
+		var unmarshalAmount Decimal
+		_, err = unmarshalAmount.UnmarshalMsg(out)
+		if err != nil {
+			t.Errorf("error unmarshalMsg %s: %v", s, err)
+		} else if !unmarshalAmount.Equal(amount) {
+			t.Errorf("expected %s, got %s (%s, %d)",
+				amount.String(), unmarshalAmount.String(),
+				unmarshalAmount.value.String(), unmarshalAmount.exp)
+		}
+	}
+}

decimal_msgpack.go

@@ -0,0 +1,94 @@
+package decimal
+
+import (
+	"errors"
+)
+
+var (
+	errShortBytes = errors.New("msgp: too few bytes left to read object")
+)
+
+// MarshalMsg implements msgp.Marshaler
+//  Note: limit to 31 digits, if d.IntPart size large than 31, will be lose.
+func (d Decimal) MarshalMsg(b []byte) ([]byte, error) {
+	o := require(b, d.Msgsize())
+	str := d.String()
+	sz := len(str)
+	// limit to 31 digits
+	// note, if d.IntPart size large than 3, will be lose.
+	if sz > 31 {
+		sz = 31
+		// if last char is '.' then limit to 30 digits
+		if str[30] == '.' {
+			sz = 30
+		}
+
+		str = str[:sz]
+	}
+
+	o, n := ensure(o, 1+sz)
+	o[n] = byte(0xa0 | sz)
+	n++
+
+	return o[:n+copy(o[n:], str)], nil
+}
+
+// UnmarshalMsg implements msgp.Unmarshaler
+func (d *Decimal) UnmarshalMsg(b []byte) ([]byte, error) {
+	o, err := b, errShortBytes
+
+	l := len(b)
+	if l < 1 {
+		return o, err
+	}
+
+	sz := int(b[0] & 0x1f)
+	if len(b[1:]) < sz {
+		return o, err
+	}
+	if *d, err = NewFromString(string(b[1 : sz+1])); err == nil {
+		o = b[sz:]
+	}
+	return o, err
+}
+
+// Msgsize returns an upper bound estimate of the number of bytes occupied by the serialized message
+func (d Decimal) Msgsize() int {
+	return 32
+}
+
+// Require ensures that cap(old)-len(old) >= extra.
+func require(old []byte, extra int) []byte {
+	l := len(old)
+	c := cap(old)
+	r := l + extra
+	if c >= r {
+		return old
+	} else if l == 0 {
+		return make([]byte, 0, extra)
+	}
+	// the new size is the greater
+	// of double the old capacity
+	// and the sum of the old length
+	// and the number of new bytes
+	// necessary.
+	c <<= 1
+	if c < r {
+		c = r
+	}
+	n := make([]byte, l, c)
+	copy(n, old)
+	return n
+}
+
+// ensure 'sz' extra bytes in 'b' btw len(b) and cap(b)
+func ensure(b []byte, sz int) ([]byte, int) {
+	l := len(b)
+	c := cap(b)
+	if c-l < sz {
+		o := make([]byte, (2*c)+sz) // exponential growth
+		n := copy(o, b)
+		return o[:n+sz], n
+	}
+	return b[:l+sz], l
+}