forked from apache/arrow
-
Notifications
You must be signed in to change notification settings - Fork 0
/
writer.go
116 lines (100 loc) · 2.42 KB
/
writer.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you 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 arrjson // import "github.com/apache/arrow/go/arrow/internal/arrjson"
import (
"encoding/json"
"io"
"github.com/apache/arrow/go/arrow"
"github.com/apache/arrow/go/arrow/array"
"github.com/apache/arrow/go/arrow/arrio"
)
const (
jsonIndent = " "
jsonPrefix = " "
jsonRecPrefix = " "
)
type Writer struct {
w io.Writer
schema *arrow.Schema
nrecs int64
}
func NewWriter(w io.Writer, schema *arrow.Schema) (*Writer, error) {
ww := &Writer{
w: w,
schema: schema,
}
_, err := ww.w.Write([]byte("{\n"))
if err != nil {
return nil, err
}
err = ww.writeSchema()
if err != nil {
return nil, err
}
return ww, nil
}
func (w *Writer) Write(rec array.Record) error {
switch {
case w.nrecs == 0:
_, err := w.w.Write([]byte(",\n" + jsonPrefix + `"batches": [` + "\n" + jsonRecPrefix))
if err != nil {
return err
}
case w.nrecs > 0:
_, err := w.w.Write([]byte(",\n" + jsonRecPrefix))
if err != nil {
return err
}
}
raw, err := json.MarshalIndent(recordToJSON(rec), jsonRecPrefix, jsonIndent)
if err != nil {
return err
}
_, err = w.w.Write(raw)
if err != nil {
return err
}
w.nrecs++
return nil
}
func (w *Writer) writeSchema() error {
_, err := w.w.Write([]byte(` "schema": `))
if err != nil {
return err
}
raw, err := json.MarshalIndent(schemaToJSON(w.schema), jsonPrefix, jsonIndent)
if err != nil {
return err
}
_, err = w.w.Write(raw)
if err != nil {
return err
}
return nil
}
func (w *Writer) Close() error {
if w.w == nil {
return nil
}
_, err := w.w.Write([]byte("\n ]\n}"))
if err == nil {
w.w = nil
}
return err
}
var (
_ arrio.Writer = (*Writer)(nil)
)