forked from goadesign/goa
/
encoding.go
102 lines (85 loc) · 2.19 KB
/
encoding.go
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package gogoprotobuf
import (
"bytes"
"errors"
"io"
"github.com/goadesign/goa"
"github.com/gogo/protobuf/proto"
)
// Enforce that codec.Decoder satisfies goa.ResettableDecoder at compile time
var (
_ goa.ResettableDecoder = (*ProtoDecoder)(nil)
_ goa.ResettableEncoder = (*ProtoEncoder)(nil)
)
type (
// ProtoDecoder stores state between Reset and Decode
ProtoDecoder struct {
pBuf *proto.Buffer
bBuf *bytes.Buffer
r io.Reader
}
// ProtoEncoder stores state between Reset and Encode
ProtoEncoder struct {
pBuf *proto.Buffer
w io.Writer
}
)
// NewDecoder returns a new proto.Decoder that satisfies goa.Decoder
func NewDecoder(r io.Reader) goa.Decoder {
return &ProtoDecoder{
pBuf: proto.NewBuffer(nil),
bBuf: &bytes.Buffer{},
r: r,
}
}
// Decode unmarshals an io.Reader into proto.Message v
func (dec *ProtoDecoder) Decode(v interface{}) error {
msg, ok := v.(proto.Message)
if !ok {
return errors.New("Cannot decode into struct that doesn't implement proto.Message")
}
var err error
// derekperkins TODO: pipe reader directly to proto.Buffer
if _, err = dec.bBuf.ReadFrom(dec.r); err != nil {
return err
}
dec.pBuf.SetBuf(dec.bBuf.Bytes())
if err = dec.pBuf.Unmarshal(msg); err != nil {
return err
}
return nil
}
// Reset stores the new reader and resets its bytes.Buffer and proto.Buffer
func (dec *ProtoDecoder) Reset(r io.Reader) {
dec.pBuf.Reset()
dec.bBuf.Reset()
dec.r = r
}
// NewEncoder returns a new proto.Encoder that satisfies goa.Encoder
func NewEncoder(w io.Writer) goa.Encoder {
return &ProtoEncoder{
pBuf: proto.NewBuffer(nil),
w: w,
}
}
// Encode marshals a proto.Message and writes it to an io.Writer
func (enc *ProtoEncoder) Encode(v interface{}) error {
msg, ok := v.(proto.Message)
if !ok {
return errors.New("Cannot encode struct that doesn't implement proto.Message")
}
var err error
// derekperkins TODO: pipe marshal directly to writer
if err = enc.pBuf.Marshal(msg); err != nil {
return err
}
if _, err = enc.w.Write(enc.pBuf.Bytes()); err != nil {
return err
}
return nil
}
// Reset stores the new writer and resets its proto.Buffer
func (enc *ProtoEncoder) Reset(w io.Writer) {
enc.pBuf.Reset()
enc.w = w
}