-
Notifications
You must be signed in to change notification settings - Fork 384
/
output.go
164 lines (140 loc) · 3.56 KB
/
output.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
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
/*
Copyright 2018 The Doctl Authors 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 displayers
import (
"bytes"
"encoding/json"
"fmt"
"io"
"reflect"
"strings"
"text/tabwriter"
)
// Displayable is a displable entity. These are used for printing results.
type Displayable interface {
Cols() []string
ColMap() map[string]string
KV() []map[string]interface{}
JSON(io.Writer) error
}
// Displayer has the display options, the item to display, and where to display to
type Displayer struct {
OutputType string
ColumnList string
NoHeaders bool
Item Displayable
Out io.Writer
}
// Display ends up rendering the content in one of two formats (text|json)
func (d *Displayer) Display() error {
switch d.OutputType {
case "json":
if containsOnlyNilSlice(d.Item) {
_, err := d.Out.Write([]byte("[]"))
return err
}
return d.Item.JSON(d.Out)
case "text":
var cols []string
for _, c := range strings.Split(strings.Join(strings.Fields(d.ColumnList), ""), ",") {
if c != "" {
cols = append(cols, c)
}
}
return DisplayText(d.Item, d.Out, d.NoHeaders, cols)
default:
return fmt.Errorf("unknown output type")
}
}
// DisplayText writes tabbed content to the passed in io.Writer
// while potentially adding or removing headers.
func DisplayText(item Displayable, out io.Writer, noHeaders bool, includeCols []string) error {
w := new(tabwriter.Writer)
w.Init(out, 0, 0, 4, ' ', 0)
cols := item.Cols()
if len(includeCols) > 0 && includeCols[0] != "" {
cols = includeCols
}
if !noHeaders {
headers := []string{}
for _, k := range cols {
col := item.ColMap()[k]
if col == "" {
return fmt.Errorf("unknown column %q", k)
}
headers = append(headers, col)
}
fmt.Fprintln(w, strings.Join(headers, "\t"))
}
for _, r := range item.KV() {
values := []interface{}{}
formats := []string{}
for _, col := range cols {
v := r[col]
values = append(values, v)
switch v.(type) {
case string:
formats = append(formats, "%s")
case int:
formats = append(formats, "%d")
case float64:
formats = append(formats, "%f")
case bool:
formats = append(formats, "%v")
default:
formats = append(formats, "%v")
}
}
format := strings.Join(formats, "\t")
fmt.Fprintf(w, format+"\n", values...)
}
return w.Flush()
}
func writeJSON(item interface{}, w io.Writer) error {
b, err := json.Marshal(item)
if err != nil {
return err
}
var out bytes.Buffer
err = json.Indent(&out, b, "", " ")
if err != nil {
return err
}
_, err = out.WriteTo(w)
return err
}
// containsOnlyNiSlice returns true if the given interface's concrete type is
// a pointer to a struct that contains a single nil slice field.
func containsOnlyNilSlice(i interface{}) bool {
if reflect.TypeOf(i).Kind() != reflect.Ptr {
return false
}
element := reflect.ValueOf(i).Elem()
if element.NumField() != 1 {
return false
}
slice := element.Field(0)
if slice.Kind() != reflect.Slice {
return false
}
if slice.Cap() != 0 {
return false
}
if slice.Len() != 0 {
return false
}
if slice.Pointer() != 0 {
return false
}
return true
}