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copy_stream.go
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/
copy_stream.go
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// Copyright (C) 2019 Satoshi Konno. All rights reserved.
//
// 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 postgresql
import (
"errors"
"io"
"github.com/cybergarage/go-postgresql/postgresql/protocol/message"
)
// CopyStream represents a copy stream.
type CopyStream struct {
*message.MessageReader
}
// NewCopyStreamWithReader returns a new copy stream with the specified reader.
func NewCopyStreamWithReader(reader *message.MessageReader) *CopyStream {
return &CopyStream{
MessageReader: reader,
}
}
// Next returns true if the next message is available.
func (stream *CopyStream) Next() (*message.CopyData, error) {
t, err := stream.MessageReader.PeekType()
if err != nil {
return nil, err
}
skipCopyDone := func(reader *message.MessageReader) error {
_, err := message.NewCopyDoneWithReader(reader)
return err
}
switch t { // nolint:exhaustive
case message.CopyDataMessage:
copyData, copyErr := message.NewCopyDataWithReader(stream.MessageReader)
if copyErr == nil {
return copyData, nil
}
if !errors.Is(copyErr, io.EOF) {
return nil, copyErr
}
ok, peekErr := stream.MessageReader.IsPeekType(message.CopyDoneMessage)
if peekErr != nil {
return nil, peekErr
}
if !ok {
return nil, copyErr
}
if skipErr := skipCopyDone(stream.MessageReader); skipErr != nil {
return nil, skipErr
}
return nil, copyErr
case message.CopyDoneMessage:
err := skipCopyDone(stream.MessageReader)
if err != nil {
return nil, err
}
return nil, io.EOF
}
return nil, io.EOF
}