Implement PacketBuilder. close #46

net/packet/builder.go

@@ -0,0 +1,17 @@
+package packet
+
+import "bytes"
+
+type Builder struct {
+	buf bytes.Buffer
+}
+
+func (p *Builder) WriteField(fields ...FieldEncoder) {
+	for _, f := range fields {
+		p.buf.Write(f.Encode())
+	}
+}
+
+func (p *Builder) Packet(id int32) Packet {
+	return Packet{ID: id, Data: p.buf.Bytes()}
+}