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|
package objects
import (
"fmt"
"io"
"strconv"
"strings"
)
type ObjectId interface {
fmt.Stringer
}
type ObjectType string
const (
OTBlob ObjectType = "blob"
OTFile ObjectType = "file"
OTTree ObjectType = "tree"
OTSnapshot ObjectType = "snapshot"
)
type Object struct {
Type ObjectType
Payload []byte
}
func (o Object) Serialize(w io.Writer) error {
if _, err := fmt.Fprintf(w, "%s %d\n", o.Type, len(o.Payload)); err != nil {
return err
}
_, err := w.Write(o.Payload)
return err
}
type UnserializeError struct {
Reason error
}
func (err UnserializeError) Error() string {
if err.Reason == nil {
return "Invalid object"
} else {
return fmt.Sprintf("Invalid object: %s", err.Reason)
}
}
type bytewiseReader struct {
r io.Reader
buf []byte
}
func newBytewiseReader(r io.Reader) io.ByteReader {
return &bytewiseReader{
r: r,
buf: make([]byte, 1),
}
}
func (br *bytewiseReader) ReadByte() (b byte, err error) {
_, err = br.r.Read(br.buf)
b = br.buf[0]
return
}
func UnserializeObject(r io.Reader) (Object, error) {
br := newBytewiseReader(r)
line := []byte{}
for {
b, err := br.ReadByte()
if err != nil {
return Object{}, UnserializeError{err}
}
if b == '\n' {
break
}
line = append(line, b)
}
parts := strings.SplitN(string(line), " ", 2)
if len(parts) != 2 {
return Object{}, UnserializeError{}
}
size, err := strconv.ParseUint(parts[1], 10, 64)
if err != nil {
return Object{}, UnserializeError{err}
}
o := Object{
Type: ObjectType(parts[0]),
Payload: make([]byte, size),
}
if _, err := io.ReadFull(r, o.Payload); err != nil {
return Object{}, UnserializeError{err}
}
return o, nil
}
|
