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message.go
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message.go
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// Copyright 2013 The Zenio Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package zenio
import (
"bytes"
"io"
"github.com/op/zenio/protocol"
)
type BytesMessage struct {
buf [][]byte
idx int
}
func NewBytesMessage(frames [][]byte) *BytesMessage {
return &BytesMessage{frames, 0}
}
func (b *BytesMessage) Reset() {
b.idx = 0
}
func (b *BytesMessage) More() bool {
return b.idx < len(b.buf)
}
func (b *BytesMessage) Next() (protocol.Frame, error) {
if b.idx >= len(b.buf) {
// TODO error
panic("zenio: out of range")
}
defer func() { b.idx++ }()
return bytes.NewReader(b.buf[b.idx]), nil
}
// frameTeeReader is just like a io.TeeReader except it also
// adds the Len() method expected by the protocol.Frame interface.
type frameTeeReader struct {
tee io.Reader
f protocol.Frame
}
func newFrameTeeReader(f protocol.Frame, w io.Writer) *frameTeeReader {
return &frameTeeReader{io.TeeReader(f, w), f}
}
func (f *frameTeeReader) Read(p []byte) (int, error) {
return f.tee.Read(p)
}
func (f *frameTeeReader) Len() int {
return f.f.Len()
}
// BufferMessage adds buffering to a message. It makes it possible to read the
// whole message into memory and rewind it again.
type BufferMessage struct {
M protocol.Message
idx int
buf []*bytes.Buffer
}
func NewBufferMessage(m protocol.Message) *BufferMessage {
return &BufferMessage{M: m}
}
func (b *BufferMessage) Reset() {
b.idx = 0
}
func (b *BufferMessage) More() bool {
if b.idx < len(b.buf) {
return true
}
return b.M.More()
}
func (b *BufferMessage) Next() (protocol.Frame, error) {
defer func() { b.idx++ }()
if b.idx < len(b.buf) {
return bytes.NewReader(b.buf[b.idx].Bytes()), nil
}
f, err := b.M.Next()
if err != nil {
return nil, err
}
buf := &bytes.Buffer{}
b.buf = append(b.buf, buf)
return newFrameTeeReader(f, buf), nil
}