arena: add NewNumberBytes to Arena.

arena.go

@@ -110,6 +110,18 @@ func (a *Arena) NewNumberString(s string) *Value {
 	return v
 }
 
+// NewNumberBytes returns new number value containing s.
+//
+// The returned number is valid until Reset is called on a.
+func (a *Arena) NewNumberBytes(b []byte) *Value {
+	v := a.c.getValue()
+	v.t = TypeNumber
+	bLen := len(a.b)
+	a.b = append(a.b, b...)
+	v.s = b2s(a.b[bLen:])
+	return v
+}
+
 // NewNull returns null value.
 func (a *Arena) NewNull() *Value {
 	return valueNull

arena_test.go

@@ -56,6 +56,7 @@ func testArena(a *Arena) error {
 	o.Set("ni", ni)
 	o.Set("nf", a.NewNumberFloat64(1.23))
 	o.Set("ns", a.NewNumberString("34.43"))
+	o.Set("nb", a.NewNumberBytes([]byte("12.12")))
 	s := a.NewString("foo")
 	o.Set("str1", s)
 	o.Set("str2", a.NewStringBytes([]byte("xx")))
@@ -69,7 +70,7 @@ func testArena(a *Arena) error {
 	o.Set("obj", obj)
 
 	str := o.String()
-	strExpected := `{"nil1":null,"nil2":null,"false":false,"true":true,"ni":123,"nf":1.23,"ns":34.43,"str1":"foo","str2":"xx","a":["foo",123],"obj":{"s":"foo"}}`
+	strExpected := `{"nil1":null,"nil2":null,"false":false,"true":true,"ni":123,"nf":1.23,"ns":34.43,"nb":12.12,"str1":"foo","str2":"xx","a":["foo",123],"obj":{"s":"foo"}}`
 	if str != strExpected {
 		return fmt.Errorf("unexpected json\ngot\n%s\nwant\n%s", str, strExpected)
 	}