gopkg.in/yaml.v3/README.md

# 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
```

1	# YAML support for the Go language
2
3	Introduction
4	------------
5
6	The yaml package enables Go programs to comfortably encode and decode YAML
7	values. It was developed within [Canonical](https://www.canonical.com) as
8	part of the [juju](https://juju.ubuntu.com) project, and is based on a
9	pure Go port of the well-known [libyaml](http://pyyaml.org/wiki/LibYAML)
10	C library to parse and generate YAML data quickly and reliably.
11
12	Compatibility
13	-------------
14
15	The yaml package supports most of YAML 1.2, but preserves some behavior
16	from 1.1 for backwards compatibility.
17
18	Specifically, as of v3 of the yaml package:
19
20	- YAML 1.1 bools (_yes/no, on/off_) are supported as long as they are being
21	decoded into a typed bool value. Otherwise they behave as a string. Booleans
22	in YAML 1.2 are _true/false_ only.
23	- Octals encode and decode as _0777_ per YAML 1.1, rather than _0o777_
24	as specified in YAML 1.2, because most parsers still use the old format.
25	Octals in the _0o777_ format are supported though, so new files work.
26	- Does not support base-60 floats. These are gone from YAML 1.2, and were
27	actually never supported by this package as it's clearly a poor choice.
28
29	and offers backwards
30	compatibility with YAML 1.1 in some cases.
31	1.2, including support for
32	anchors, tags, map merging, etc. Multi-document unmarshalling is not yet
33	implemented, and base-60 floats from YAML 1.1 are purposefully not
34	supported since they're a poor design and are gone in YAML 1.2.
35
36	Installation and usage
37	----------------------
38
39	The import path for the package is gopkg.in/yaml.v3.
40
41	To install it, run:
42
43	go get gopkg.in/yaml.v3
44
45	API documentation
46	-----------------
47
48	If opened in a browser, the import path itself leads to the API documentation:
49
50	- [https://gopkg.in/yaml.v3](https://gopkg.in/yaml.v3)
51
52	API stability
53	-------------
54
55	The package API for yaml v3 will remain stable as described in [gopkg.in](https://gopkg.in).
56
57
58	License
59	-------
60
61	The yaml package is licensed under the MIT and Apache License 2.0 licenses.
62	Please see the LICENSE file for details.
63
64
65	Example
66	-------
67
68	```Go
69	package main
70
71	import (
72	"fmt"
73	"log"
74
75	"gopkg.in/yaml.v3"
76	)
77
78	var data = `
79	a: Easy!
80	b:
81	c: 2
82	d: [3, 4]
83	`
84
85	// Note: struct fields must be public in order for unmarshal to
86	// correctly populate the data.
87	type T struct {
88	A string
89	B struct {
90	RenamedC int `yaml:"c"`
91	D []int `yaml:",flow"`
92	}
93	}
94
95	func main() {
96	t := T{}
97
98	err := yaml.Unmarshal([]byte(data), &t)
99	if err != nil {
100	log.Fatalf("error: %v", err)
101	}
102	fmt.Printf("--- t:\n%v\n\n", t)
103
104	d, err := yaml.Marshal(&t)
105	if err != nil {
106	log.Fatalf("error: %v", err)
107	}
108	fmt.Printf("--- t dump:\n%s\n\n", string(d))
109
110	m := make(map[interface{}]interface{})
111
112	err = yaml.Unmarshal([]byte(data), &m)
113	if err != nil {
114	log.Fatalf("error: %v", err)
115	}
116	fmt.Printf("--- m:\n%v\n\n", m)
117
118	d, err = yaml.Marshal(&m)
119	if err != nil {
120	log.Fatalf("error: %v", err)
121	}
122	fmt.Printf("--- m dump:\n%s\n\n", string(d))
123	}
124	```
125
126	This example will generate the following output:
127
128	```
129	--- t:
130	{Easy! {2 [3 4]}}
131
132	--- t dump:
133	a: Easy!
134	b:
135	c: 2
136	d: [3, 4]
137
138
139	--- m:
140	map[a:Easy! b:map[c:2 d:[3 4]]]
141
142	--- m dump:
143	a: Easy!
144	b:
145	c: 2
146	d:
147	- 3
148	- 4
149	```
150
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