mirror of
https://github.com/ceph/ceph-csi.git
synced 2024-11-27 00:30:18 +00:00
151 lines
3.4 KiB
Markdown
151 lines
3.4 KiB
Markdown
# YAML support for the Go language
|
|
|
|
Introduction
|
|
------------
|
|
|
|
The yaml package enables Go programs to comfortably encode and decode YAML
|
|
values. It was developed within [Canonical](https://www.canonical.com) as
|
|
part of the [juju](https://juju.ubuntu.com) project, and is based on a
|
|
pure Go port of the well-known [libyaml](http://pyyaml.org/wiki/LibYAML)
|
|
C library to parse and generate YAML data quickly and reliably.
|
|
|
|
Compatibility
|
|
-------------
|
|
|
|
The yaml package supports most of YAML 1.2, but preserves some behavior
|
|
from 1.1 for backwards compatibility.
|
|
|
|
Specifically, as of v3 of the yaml package:
|
|
|
|
- YAML 1.1 bools (_yes/no, on/off_) are supported as long as they are being
|
|
decoded into a typed bool value. Otherwise they behave as a string. Booleans
|
|
in YAML 1.2 are _true/false_ only.
|
|
- Octals encode and decode as _0777_ per YAML 1.1, rather than _0o777_
|
|
as specified in YAML 1.2, because most parsers still use the old format.
|
|
Octals in the _0o777_ format are supported though, so new files work.
|
|
- Does not support base-60 floats. These are gone from YAML 1.2, and were
|
|
actually never supported by this package as it's clearly a poor choice.
|
|
|
|
and offers backwards
|
|
compatibility with YAML 1.1 in some cases.
|
|
1.2, including support for
|
|
anchors, tags, map merging, etc. Multi-document unmarshalling is not yet
|
|
implemented, and base-60 floats from YAML 1.1 are purposefully not
|
|
supported since they're a poor design and are gone in YAML 1.2.
|
|
|
|
Installation and usage
|
|
----------------------
|
|
|
|
The import path for the package is *gopkg.in/yaml.v3*.
|
|
|
|
To install it, run:
|
|
|
|
go get gopkg.in/yaml.v3
|
|
|
|
API documentation
|
|
-----------------
|
|
|
|
If opened in a browser, the import path itself leads to the API documentation:
|
|
|
|
- [https://gopkg.in/yaml.v3](https://gopkg.in/yaml.v3)
|
|
|
|
API stability
|
|
-------------
|
|
|
|
The package API for yaml v3 will remain stable as described in [gopkg.in](https://gopkg.in).
|
|
|
|
|
|
License
|
|
-------
|
|
|
|
The yaml package is licensed under the MIT and Apache License 2.0 licenses.
|
|
Please see the LICENSE file for details.
|
|
|
|
|
|
Example
|
|
-------
|
|
|
|
```Go
|
|
package main
|
|
|
|
import (
|
|
"fmt"
|
|
"log"
|
|
|
|
"gopkg.in/yaml.v3"
|
|
)
|
|
|
|
var data = `
|
|
a: Easy!
|
|
b:
|
|
c: 2
|
|
d: [3, 4]
|
|
`
|
|
|
|
// Note: struct fields must be public in order for unmarshal to
|
|
// correctly populate the data.
|
|
type T struct {
|
|
A string
|
|
B struct {
|
|
RenamedC int `yaml:"c"`
|
|
D []int `yaml:",flow"`
|
|
}
|
|
}
|
|
|
|
func main() {
|
|
t := T{}
|
|
|
|
err := yaml.Unmarshal([]byte(data), &t)
|
|
if err != nil {
|
|
log.Fatalf("error: %v", err)
|
|
}
|
|
fmt.Printf("--- t:\n%v\n\n", t)
|
|
|
|
d, err := yaml.Marshal(&t)
|
|
if err != nil {
|
|
log.Fatalf("error: %v", err)
|
|
}
|
|
fmt.Printf("--- t dump:\n%s\n\n", string(d))
|
|
|
|
m := make(map[interface{}]interface{})
|
|
|
|
err = yaml.Unmarshal([]byte(data), &m)
|
|
if err != nil {
|
|
log.Fatalf("error: %v", err)
|
|
}
|
|
fmt.Printf("--- m:\n%v\n\n", m)
|
|
|
|
d, err = yaml.Marshal(&m)
|
|
if err != nil {
|
|
log.Fatalf("error: %v", err)
|
|
}
|
|
fmt.Printf("--- m dump:\n%s\n\n", string(d))
|
|
}
|
|
```
|
|
|
|
This example will generate the following output:
|
|
|
|
```
|
|
--- t:
|
|
{Easy! {2 [3 4]}}
|
|
|
|
--- t dump:
|
|
a: Easy!
|
|
b:
|
|
c: 2
|
|
d: [3, 4]
|
|
|
|
|
|
--- m:
|
|
map[a:Easy! b:map[c:2 d:[3 4]]]
|
|
|
|
--- m dump:
|
|
a: Easy!
|
|
b:
|
|
c: 2
|
|
d:
|
|
- 3
|
|
- 4
|
|
```
|
|
|