frostfs-s3-gw/pkg/s3select/csv/recordtransform.go

93 lines
1.9 KiB
Go

/*
* MinIO Cloud Storage, (C) 2019 MinIO, Inc.
*
* 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 csv
import (
"bytes"
"io"
)
// recordTransform will convert records to always have newline records.
type recordTransform struct {
reader io.Reader
// recordDelimiter can be up to 2 characters.
recordDelimiter []byte
oneByte []byte
useOneByte bool
}
func (rr *recordTransform) Read(p []byte) (n int, err error) {
if rr.useOneByte {
p[0] = rr.oneByte[0]
rr.useOneByte = false
n, err = rr.reader.Read(p[1:])
n++
} else {
n, err = rr.reader.Read(p)
}
if err != nil {
return n, err
}
// Do nothing if record-delimiter is already newline.
if string(rr.recordDelimiter) == "\n" {
return n, nil
}
// Change record delimiters to newline.
if len(rr.recordDelimiter) == 1 {
for idx := 0; idx < len(p); {
i := bytes.Index(p[idx:], rr.recordDelimiter)
if i < 0 {
break
}
idx += i
p[idx] = '\n'
}
return n, nil
}
// 2 characters...
for idx := 0; idx < len(p); {
i := bytes.Index(p[idx:], rr.recordDelimiter)
if i < 0 {
break
}
idx += i
p[idx] = '\n'
p = append(p[:idx+1], p[idx+2:]...)
n--
}
if p[n-1] != rr.recordDelimiter[0] {
return n, nil
}
if _, err = rr.reader.Read(rr.oneByte); err != nil {
return n, err
}
if rr.oneByte[0] == rr.recordDelimiter[1] {
p[n-1] = '\n'
return n, nil
}
rr.useOneByte = true
return n, nil
}