Add a package for transaction serialization

encoding/transaction can be used to serialize Steem transactions.

Author: tchap

encoding/transaction/encoder.go

@@ -0,0 +1,100 @@
+package transaction
+
+import (
+	// Stdlib
+	"encoding/binary"
+	"io"
+	"strings"
+
+	// Vendor
+	"github.com/pkg/errors"
+)
+
+type Encoder struct {
+	w io.Writer
+}
+
+func NewEncoder(w io.Writer) *Encoder {
+	return &Encoder{w}
+}
+
+func (encoder *Encoder) EncodeVarint(i int64) error {
+	if i >= 0 {
+		return encoder.EncodeUVarint(uint64(i))
+	}
+
+	b := make([]byte, binary.MaxVarintLen64)
+	n := binary.PutVarint(b, i)
+	return encoder.writeBytes(b[:n])
+}
+
+func (encoder *Encoder) EncodeUVarint(i uint64) error {
+	b := make([]byte, binary.MaxVarintLen64)
+	n := binary.PutUvarint(b, i)
+	return encoder.writeBytes(b[:n])
+}
+
+func (encoder *Encoder) EncodeNumber(v interface{}) error {
+	if err := binary.Write(encoder.w, binary.LittleEndian, v); err != nil {
+		return errors.Wrapf(err, "encoder: failed to write number: %v", v)
+	}
+	return nil
+}
+
+func (encoder *Encoder) Encode(v interface{}) error {
+	if marshaller, ok := v.(TransactionMarshaller); ok {
+		return marshaller.MarshalTransaction(encoder)
+	}
+
+	switch v := v.(type) {
+	case int:
+		return encoder.EncodeNumber(v)
+	case int8:
+		return encoder.EncodeNumber(v)
+	case int16:
+		return encoder.EncodeNumber(v)
+	case int32:
+		return encoder.EncodeNumber(v)
+	case int64:
+		return encoder.EncodeNumber(v)
+
+	case uint:
+		return encoder.EncodeNumber(v)
+	case uint8:
+		return encoder.EncodeNumber(v)
+	case uint16:
+		return encoder.EncodeNumber(v)
+	case uint32:
+		return encoder.EncodeNumber(v)
+	case uint64:
+		return encoder.EncodeNumber(v)
+
+	case string:
+		return encoder.encodeString(v)
+
+	default:
+		return errors.Errorf("encoder: unsupported type encountered")
+	}
+}
+
+func (encoder *Encoder) encodeString(v string) error {
+	if err := encoder.EncodeUVarint(uint64(len(v))); err != nil {
+		return errors.Wrapf(err, "encoder: failed to write string: %v", v)
+	}
+
+	return encoder.writeString(v)
+}
+
+func (encoder *Encoder) writeBytes(bs []byte) error {
+	if _, err := encoder.w.Write(bs); err != nil {
+		return errors.Wrapf(err, "encoder: failed to write bytes: %v", bs)
+	}
+	return nil
+}
+
+func (encoder *Encoder) writeString(s string) error {
+	if _, err := io.Copy(encoder.w, strings.NewReader(s)); err != nil {
+		return errors.Wrapf(err, "encoder: failed to write string: %v", s)
+	}
+	return nil
+}

encoding/transaction/encoder_rolling.go

@@ -0,0 +1,38 @@
+package transaction
+
+type RollingEncoder struct {
+	next *Encoder
+	err  error
+}
+
+func NewRollingEncoder(next *Encoder) *RollingEncoder {
+	return &RollingEncoder{next, nil}
+}
+
+func (encoder *RollingEncoder) EncodeVarint(i int64) {
+	if encoder.err == nil {
+		encoder.err = encoder.next.EncodeVarint(i)
+	}
+}
+
+func (encoder *RollingEncoder) EncodeUVarint(i uint64) {
+	if encoder.err == nil {
+		encoder.err = encoder.next.EncodeUVarint(i)
+	}
+}
+
+func (encoder *RollingEncoder) EncodeNumber(v interface{}) {
+	if encoder.err == nil {
+		encoder.err = encoder.next.EncodeNumber(v)
+	}
+}
+
+func (encoder *RollingEncoder) Encode(v interface{}) {
+	if encoder.err == nil {
+		encoder.err = encoder.next.Encode(v)
+	}
+}
+
+func (encoder *RollingEncoder) Err() error {
+	return encoder.err
+}

encoding/transaction/encoding.go

@@ -0,0 +1,5 @@
+package transaction
+
+type TransactionMarshaller interface {
+	MarshalTransaction(*Encoder) error
+}