internal/third_party/yaml/yaml.go - cue - Git at Google

 // 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 "cuelang.org/go/internal/third_party/yaml"

 import (
 	"errors"
 	"fmt"
 	"io"
 	"reflect"
 	"strconv"
 	"strings"
 	"sync"

 	"cuelang.org/go/cue/ast"
 )

 // MapSlice encodes and decodes as a YAML map.
 // The order of keys is preserved when encoding and decoding.
 type MapSlice []MapItem

 // MapItem is an item in a MapSlice.
 type MapItem struct {
 	Key, Value interface{}
 }

 // The Unmarshaler interface may be implemented by types to customize their
 // behavior when being unmarshaled from a YAML document. The UnmarshalYAML
 // method receives a function that may be called to unmarshal the original
 // YAML value into a field or variable. It is safe to call the unmarshal
 // function parameter more than once if necessary.
 type Unmarshaler interface {
 	UnmarshalYAML(unmarshal func(interface{}) error) error
 }

 // The Marshaler interface may be implemented by types to customize their
 // behavior when being marshaled into a YAML document. The returned value
 // is marshaled in place of the original value implementing Marshaler.
 //
 // If an error is returned by MarshalYAML, the marshaling procedure stops
 // and returns with the provided error.
 type Marshaler interface {
 	MarshalYAML() (interface{}, error)
 }

 // 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 should be compatible with the respective
 // values in out. If one or more values cannot be decoded due to a type
 // mismatches, decoding continues partially until the end of the YAML
 // content, and a *yaml.TypeError is returned with details for all
 // missed values.
 //
 // 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(filename string, in []byte) (expr ast.Expr, err error) {
 	return unmarshal(filename, in)
 }

 // A Decorder reads and decodes YAML values from an input stream.
 type Decoder struct {
 	strict    bool
 	firstDone bool
 	parser    *parser
 }

 // NewDecoder returns a new decoder that reads from r.
 //
 // The decoder introduces its own buffering and may read
 // data from r beyond the YAML values requested.
 func NewDecoder(filename string, src interface{}) (*Decoder, error) {
 	d, err := newParser(filename, src)
 	if err != nil {
 		return nil, err
 	}
 	return &Decoder{parser: d}, nil
 }

 // Decode reads the next YAML-encoded value from its input and stores it in the
 // value pointed to by v. It returns io.EOF if there are no more value in the
 // stream.
 //
 // See the documentation for Unmarshal for details about the conversion of YAML
 // into a Go value.
 func (dec *Decoder) Decode() (expr ast.Expr, err error) {
 	d := newDecoder(dec.parser)
 	defer handleErr(&err)
 	node := dec.parser.parse()
 	if node == nil {
 		if !dec.firstDone {
 			expr = ast.NewNull()
 		}
 		return expr, io.EOF
 	}
 	dec.firstDone = true
 	expr = d.unmarshal(node)
 	if len(d.terrors) > 0 {
 		return nil, &TypeError{d.terrors}
 	}
 	return expr, nil
 }

 func unmarshal(filename string, in []byte) (expr ast.Expr, err error) {
 	defer handleErr(&err)
 	p, err := newParser(filename, in)
 	if err != nil {
 		return nil, err
 	}
 	defer p.destroy()
 	node := p.parse()
 	d := newDecoder(p)
 	if node != nil {
 		expr = d.unmarshal(node)
 	}
 	if len(d.terrors) > 0 {
 		return nil, &TypeError{d.terrors}
 	}
 	return expr, nil
 }

 func handleErr(err *error) {
 	if v := recover(); v != nil {
 		if e, ok := v.(yamlError); ok {
 			*err = e.err
 		} else {
 			panic(v)
 		}
 	}
 }

 type yamlError struct {
 	err error
 }

 func (p *parser) failf(line int, format string, args ...interface{}) {
 	where := p.parser.filename + ":"
 	line++
 	where += strconv.Itoa(line) + ": "
 	panic(yamlError{fmt.Errorf(where+format, args...)})
 }

 // A TypeError is returned by Unmarshal when one or more fields in
 // the YAML document cannot be properly decoded into the requested
 // types. When this error is returned, the value is still
 // unmarshaled partially.
 type TypeError struct {
 	Errors []string
 }

 func (e *TypeError) Error() string {
 	return fmt.Sprintf("yaml: unmarshal errors:\n  %s", strings.Join(e.Errors, "\n  "))
 }

 // --------------------------------------------------------------------------
 // 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
 	// Id holds the unique field identifier, so we can cheaply
 	// check for field duplicates without maintaining an extra map.
 	Id int

 	// 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

 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 != "" && !field.Anonymous {
 			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:
 					return nil, errors.New(fmt.Sprintf("Unsupported flag %q in tag %q of type %s", flag, tag, st))
 				}
 			}
 			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...)
 					}
 					finfo.Id = len(fieldsList)
 					fieldsMap[finfo.Key] = finfo
 					fieldsList = append(fieldsList, finfo)
 				}
 			default:
 				//return nil, errors.New("Option ,inline needs a struct value or map field")
 				return nil, errors.New("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)
 		}

 		info.Id = len(fieldsList)
 		fieldsList = append(fieldsList, info)
 		fieldsMap[info.Key] = info
 	}

 	sinfo = &structInfo{
 		FieldsMap:  fieldsMap,
 		FieldsList: fieldsList,
 		InlineMap:  inlineMap,
 	}

 	fieldMapMutex.Lock()
 	structMap[st] = sinfo
 	fieldMapMutex.Unlock()
 	return sinfo, nil
 }

 // IsZeroer is used to check whether an object is zero to
 // determine whether it should be omitted when marshaling
 // with the omitempty flag. One notable implementation
 // is time.Time.
 type IsZeroer interface {
 	IsZero() bool
 }

 func isZero(v reflect.Value) bool {
 	kind := v.Kind()
 	if z, ok := v.Interface().(IsZeroer); ok {
 		if (kind == reflect.Ptr || kind == reflect.Interface) && v.IsNil() {
 			return true
 		}
 		return z.IsZero()
 	}
 	switch 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.Float32, reflect.Float64:
 		return v.Float() == 0
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
 		return v.Uint() == 0
 	case reflect.Bool:
 		return !v.Bool()
 	case reflect.Struct:
 		vt := v.Type()
 		for i := v.NumField() - 1; i >= 0; i-- {
 			if vt.Field(i).PkgPath != "" {
 				continue // Private field
 			}
 			if !isZero(v.Field(i)) {
 				return false
 			}
 		}
 		return true
 	}
 	return false
 }
	// 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 "cuelang.org/go/internal/third_party/yaml"

	import (
	"errors"
	"fmt"
	"io"
	"reflect"
	"strconv"
	"strings"
	"sync"

	"cuelang.org/go/cue/ast"
	)

	// MapSlice encodes and decodes as a YAML map.
	// The order of keys is preserved when encoding and decoding.
	type MapSlice []MapItem

	// MapItem is an item in a MapSlice.
	type MapItem struct {
	Key, Value interface{}
	}

	// The Unmarshaler interface may be implemented by types to customize their
	// behavior when being unmarshaled from a YAML document. The UnmarshalYAML
	// method receives a function that may be called to unmarshal the original
	// YAML value into a field or variable. It is safe to call the unmarshal
	// function parameter more than once if necessary.
	type Unmarshaler interface {
	UnmarshalYAML(unmarshal func(interface{}) error) error
	}

	// The Marshaler interface may be implemented by types to customize their
	// behavior when being marshaled into a YAML document. The returned value
	// is marshaled in place of the original value implementing Marshaler.
	//
	// If an error is returned by MarshalYAML, the marshaling procedure stops
	// and returns with the provided error.
	type Marshaler interface {
	MarshalYAML() (interface{}, error)
	}

	// 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 should be compatible with the respective
	// values in out. If one or more values cannot be decoded due to a type
	// mismatches, decoding continues partially until the end of the YAML
	// content, and a *yaml.TypeError is returned with details for all
	// missed values.
	//
	// 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(filename string, in []byte) (expr ast.Expr, err error) {
	return unmarshal(filename, in)
	}

	// A Decorder reads and decodes YAML values from an input stream.
	type Decoder struct {
	strict bool
	firstDone bool
	parser *parser
	}

	// NewDecoder returns a new decoder that reads from r.
	//
	// The decoder introduces its own buffering and may read
	// data from r beyond the YAML values requested.
	func NewDecoder(filename string, src interface{}) (*Decoder, error) {
	d, err := newParser(filename, src)
	if err != nil {
	return nil, err
	}
	return &Decoder{parser: d}, nil
	}

	// Decode reads the next YAML-encoded value from its input and stores it in the
	// value pointed to by v. It returns io.EOF if there are no more value in the
	// stream.
	//
	// See the documentation for Unmarshal for details about the conversion of YAML
	// into a Go value.
	func (dec *Decoder) Decode() (expr ast.Expr, err error) {
	d := newDecoder(dec.parser)
	defer handleErr(&err)
	node := dec.parser.parse()
	if node == nil {
	if !dec.firstDone {
	expr = ast.NewNull()
	}
	return expr, io.EOF
	}
	dec.firstDone = true
	expr = d.unmarshal(node)
	if len(d.terrors) > 0 {
	return nil, &TypeError{d.terrors}
	}
	return expr, nil
	}

	func unmarshal(filename string, in []byte) (expr ast.Expr, err error) {
	defer handleErr(&err)
	p, err := newParser(filename, in)
	if err != nil {
	return nil, err
	}
	defer p.destroy()
	node := p.parse()
	d := newDecoder(p)
	if node != nil {
	expr = d.unmarshal(node)
	}
	if len(d.terrors) > 0 {
	return nil, &TypeError{d.terrors}
	}
	return expr, nil
	}

	func handleErr(err *error) {
	if v := recover(); v != nil {
	if e, ok := v.(yamlError); ok {
	*err = e.err
	} else {
	panic(v)
	}
	}
	}

	type yamlError struct {
	err error
	}

	func (p *parser) failf(line int, format string, args ...interface{}) {
	where := p.parser.filename + ":"
	line++
	where += strconv.Itoa(line) + ": "
	panic(yamlError{fmt.Errorf(where+format, args...)})
	}

	// A TypeError is returned by Unmarshal when one or more fields in
	// the YAML document cannot be properly decoded into the requested
	// types. When this error is returned, the value is still
	// unmarshaled partially.
	type TypeError struct {
	Errors []string
	}

	func (e *TypeError) Error() string {
	return fmt.Sprintf("yaml: unmarshal errors:\n %s", strings.Join(e.Errors, "\n "))
	}

	// --------------------------------------------------------------------------
	// 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
	// Id holds the unique field identifier, so we can cheaply
	// check for field duplicates without maintaining an extra map.
	Id int

	// 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

	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 != "" && !field.Anonymous {
	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:
	return nil, errors.New(fmt.Sprintf("Unsupported flag %q in tag %q of type %s", flag, tag, st))
	}
	}
	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...)
	}
	finfo.Id = len(fieldsList)
	fieldsMap[finfo.Key] = finfo
	fieldsList = append(fieldsList, finfo)
	}
	default:
	//return nil, errors.New("Option ,inline needs a struct value or map field")
	return nil, errors.New("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)
	}

	info.Id = len(fieldsList)
	fieldsList = append(fieldsList, info)
	fieldsMap[info.Key] = info
	}

	sinfo = &structInfo{
	FieldsMap: fieldsMap,
	FieldsList: fieldsList,
	InlineMap: inlineMap,
	}

	fieldMapMutex.Lock()
	structMap[st] = sinfo
	fieldMapMutex.Unlock()
	return sinfo, nil
	}

	// IsZeroer is used to check whether an object is zero to
	// determine whether it should be omitted when marshaling
	// with the omitempty flag. One notable implementation
	// is time.Time.
	type IsZeroer interface {
	IsZero() bool
	}

	func isZero(v reflect.Value) bool {
	kind := v.Kind()
	if z, ok := v.Interface().(IsZeroer); ok {
	if (kind == reflect.Ptr \|\| kind == reflect.Interface) && v.IsNil() {
	return true
	}
	return z.IsZero()
	}
	switch 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.Float32, reflect.Float64:
	return v.Float() == 0
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
	return v.Uint() == 0
	case reflect.Bool:
	return !v.Bool()
	case reflect.Struct:
	vt := v.Type()
	for i := v.NumField() - 1; i >= 0; i-- {
	if vt.Field(i).PkgPath != "" {
	continue // Private field
	}
	if !isZero(v.Field(i)) {
	return false
	}
	}
	return true
	}
	return false
	}