// Package yaml implements YAML support for the Go language.
//
// Source code and other details for the project are available at GitHub:
//
// https://github.com/go-yaml/yaml
//
package yaml
import (
"errors"
"fmt"
"reflect"
"runtime"
"strings"
"sync"
)
func handleErr(err *error) {
if r := recover(); r != nil {
if _, ok := r.(runtime.Error); ok {
panic(r)
} else if _, ok := r.(*reflect.ValueError); ok {
panic(r)
} else if _, ok := r.(externalPanic); ok {
panic(r)
} else if s, ok := r.(string); ok {
*err = errors.New("YAML error: " + s)
} else if e, ok := r.(error); ok {
*err = e
} else {
panic(r)
}
}
}
// The Setter interface may be implemented by types to do their own custom
// unmarshalling of YAML values, rather than being implicitly assigned by
// the yaml package machinery. If setting the value works, the method should
// return true. If it returns false, the value is considered unsupported
// and is omitted from maps and slices.
type Setter interface {
SetYAML(tag string, value interface{}) bool
}
// The Getter interface is implemented by types to do their own custom
// marshalling into a YAML tag and value.
type Getter interface {
GetYAML() (tag string, value interface{})
}
// Unmarshal decodes the first document found within the in byte slice
// and assigns decoded values into the out value.
//
// Maps and pointers (to a struct, string, int, etc) are accepted as out
// values. If an internal pointer within a struct is not initialized,
// the yaml package will initialize it if necessary for unmarshalling
// the provided data. The out parameter must not be nil.
//
// The type of the decoded values and the type of out will be considered,
// and Unmarshal will do the best possible job to unmarshal values
// appropriately. It is NOT considered an error, though, to skip values
// because they are not available in the decoded YAML, or if they are not
// compatible with the out value. To ensure something was properly
// unmarshaled use a map or compare against the previous value for the
// field (usually the zero value).
//
// Struct fields are only unmarshalled if they are exported (have an
// upper case first letter), and are unmarshalled using the field name
// lowercased as the default key. Custom keys may be defined via the
// "yaml" name in the field tag: the content preceding the first comma
// is used as the key, and the following comma-separated options are
// used to tweak the marshalling process (see Marshal).
// Conflicting names result in a runtime error.
//
// For example:
//
// type T struct {
// F int `yaml:"a,omitempty"`
// B int
// }
// var T t
// yaml.Unmarshal([]byte("a: 1\nb: 2"), &t)
//
// See the documentation of Marshal for the format of tags and a list of
// supported tag options.
//
func Unmarshal(in []byte, out interface{}) (err error) {
defer handleErr(&err)
d := newDecoder()
p := newParser(in)
defer p.destroy()
node := p.parse()
if node != nil {
d.unmarshal(node, reflect.ValueOf(out))
}
return nil
}
// Marshal serializes the value provided into a YAML document. The structure
// of the generated document will reflect the structure of the value itself.
// Maps and pointers (to struct, string, int, etc) are accepted as the in value.
//
// Struct fields are only unmarshalled if they are exported (have an upper case
// first letter), and are unmarshalled using the field name lowercased as the
// default key. Custom keys may be defined via the "yaml" name in the field
// tag: the content preceding the first comma is used as the key, and the
// following comma-separated options are used to tweak the marshalling process.
// Conflicting names result in a runtime error.
//
// The field tag format accepted is:
//
// `(...) yaml:"[<key>][,<flag1>[,<flag2>]]" (...)`
//
// The following flags are currently supported:
//
// omitempty Only include the field if it's not set to the zero
// value for the type or to empty slices or maps.
// Does not apply to zero valued structs.
//
// flow Marshal using a flow style (useful for structs,
// sequences and maps.
//
// inline Inline the struct it's applied to, so its fields
// are processed as if they were part of the outer
// struct.
//
// In addition, if the key is "-", the field is ignored.
//
// For example:
//
// type T struct {
// F int "a,omitempty"
// B int
// }
// yaml.Marshal(&T{B: 2}) // Returns "b: 2\n"
// yaml.Marshal(&T{F: 1}} // Returns "a: 1\nb: 0\n"
//
func Marshal(in interface{}) (out []byte, err error) {
defer handleErr(&err)
e := newEncoder()
defer e.destroy()
e.marshal("", reflect.ValueOf(in))
e.finish()
out = e.out
return
}
// --------------------------------------------------------------------------
// Maintain a mapping of keys to structure field indexes
// The code in this section was copied from mgo/bson.
// structInfo holds details for the serialization of fields of
// a given struct.
type structInfo struct {
FieldsMap map[string]fieldInfo
FieldsList []fieldInfo
// InlineMap is the number of the field in the struct that
// contains an ,inline map, or -1 if there's none.
InlineMap int
}
type fieldInfo struct {
Key string
Num int
OmitEmpty bool
Flow bool
// Inline holds the field index if the field is part of an inlined struct.
Inline []int
}
var structMap = make(map[reflect.Type]*structInfo)
var fieldMapMutex sync.RWMutex
type externalPanic string
func (e externalPanic) String() string {
return string(e)
}
func getStructInfo(st reflect.Type) (*structInfo, error) {
fieldMapMutex.RLock()
sinfo, found := structMap[st]
fieldMapMutex.RUnlock()
if found {
return sinfo, nil
}
n := st.NumField()
fieldsMap := make(map[string]fieldInfo)
fieldsList := make([]fieldInfo, 0, n)
inlineMap := -1
for i := 0; i != n; i++ {
field := st.Field(i)
if field.PkgPath != "" {
continue // Private field
}
info := fieldInfo{Num: i}
tag := field.Tag.Get("yaml")
if tag == "" && strings.Index(string(field.Tag), ":") < 0 {
tag = string(field.Tag)
}
if tag == "-" {
continue
}
inline := false
fields := strings.Split(tag, ",")
if len(fields) > 1 {
for _, flag := range fields[1:] {
switch flag {
case "omitempty":
info.OmitEmpty = true
case "flow":
info.Flow = true
case "inline":
inline = true
default:
msg := fmt.Sprintf("Unsupported flag %q in tag %q of type %s", flag, tag, st)
panic(externalPanic(msg))
}
}
tag = fields[0]
}
if inline {
switch field.Type.Kind() {
//case reflect.Map:
// if inlineMap >= 0 {
// return nil, errors.New("Multiple ,inline maps in struct " + st.String())
// }
// if field.Type.Key() != reflect.TypeOf("") {
// return nil, errors.New("Option ,inline needs a map with string keys in struct " + st.String())
// }
// inlineMap = info.Num
case reflect.Struct:
sinfo, err := getStructInfo(field.Type)
if err != nil {
return nil, err
}
for _, finfo := range sinfo.FieldsList {
if _, found := fieldsMap[finfo.Key]; found {
msg := "Duplicated key '" + finfo.Key + "' in struct " + st.String()
return nil, errors.New(msg)
}
if finfo.Inline == nil {
finfo.Inline = []int{i, finfo.Num}
} else {
finfo.Inline = append([]int{i}, finfo.Inline...)
}
fieldsMap[finfo.Key] = finfo
fieldsList = append(fieldsList, finfo)
}
default:
//panic("Option ,inline needs a struct value or map field")
panic("Option ,inline needs a struct value field")
}
continue
}
if tag != "" {
info.Key = tag
} else {
info.Key = strings.ToLower(field.Name)
}
if _, found = fieldsMap[info.Key]; found {
msg := "Duplicated key '" + info.Key + "' in struct " + st.String()
return nil, errors.New(msg)
}
fieldsList = append(fieldsList, info)
fieldsMap[info.Key] = info
}
sinfo = &structInfo{fieldsMap, fieldsList, inlineMap}
fieldMapMutex.Lock()
structMap[st] = sinfo
fieldMapMutex.Unlock()
return sinfo, nil
}
func isZero(v reflect.Value) bool {
switch v.Kind() {
case reflect.String:
return len(v.String()) == 0
case reflect.Interface, reflect.Ptr:
return v.IsNil()
case reflect.Slice:
return v.Len() == 0
case reflect.Map:
return v.Len() == 0
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
return v.Int() == 0
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
return v.Uint() == 0
case reflect.Bool:
return !v.Bool()
}
return false
}