vendor/github.com/kelseyhightower/envconfig/envconfig.go - sadis-server - Gitiles

 // Copyright (c) 2013 Kelsey Hightower. All rights reserved.
 // Use of this source code is governed by the MIT License that can be found in
 // the LICENSE file.

 package envconfig

 import (
 	"encoding"
 	"errors"
 	"fmt"
 	"reflect"
 	"regexp"
 	"strconv"
 	"strings"
 	"time"
 )

 // ErrInvalidSpecification indicates that a specification is of the wrong type.
 var ErrInvalidSpecification = errors.New("specification must be a struct pointer")

 // A ParseError occurs when an environment variable cannot be converted to
 // the type required by a struct field during assignment.
 type ParseError struct {
 	KeyName   string
 	FieldName string
 	TypeName  string
 	Value     string
 	Err       error
 }

 // Decoder has the same semantics as Setter, but takes higher precedence.
 // It is provided for historical compatibility.
 type Decoder interface {
 	Decode(value string) error
 }

 // Setter is implemented by types can self-deserialize values.
 // Any type that implements flag.Value also implements Setter.
 type Setter interface {
 	Set(value string) error
 }

 func (e *ParseError) Error() string {
 	return fmt.Sprintf("envconfig.Process: assigning %[1]s to %[2]s: converting '%[3]s' to type %[4]s. details: %[5]s", e.KeyName, e.FieldName, e.Value, e.TypeName, e.Err)
 }

 // varInfo maintains information about the configuration variable
 type varInfo struct {
 	Name  string
 	Alt   string
 	Key   string
 	Field reflect.Value
 	Tags  reflect.StructTag
 }

 // GatherInfo gathers information about the specified struct
 func gatherInfo(prefix string, spec interface{}) ([]varInfo, error) {
 	expr := regexp.MustCompile("([^A-Z]+|[A-Z][^A-Z]+|[A-Z]+)")
 	s := reflect.ValueOf(spec)

 	if s.Kind() != reflect.Ptr {
 		return nil, ErrInvalidSpecification
 	}
 	s = s.Elem()
 	if s.Kind() != reflect.Struct {
 		return nil, ErrInvalidSpecification
 	}
 	typeOfSpec := s.Type()

 	// over allocate an info array, we will extend if needed later
 	infos := make([]varInfo, 0, s.NumField())
 	for i := 0; i < s.NumField(); i++ {
 		f := s.Field(i)
 		ftype := typeOfSpec.Field(i)
 		if !f.CanSet() || ftype.Tag.Get("ignored") == "true" {
 			continue
 		}

 		for f.Kind() == reflect.Ptr {
 			if f.IsNil() {
 				if f.Type().Elem().Kind() != reflect.Struct {
 					// nil pointer to a non-struct: leave it alone
 					break
 				}
 				// nil pointer to struct: create a zero instance
 				f.Set(reflect.New(f.Type().Elem()))
 			}
 			f = f.Elem()
 		}

 		// Capture information about the config variable
 		info := varInfo{
 			Name:  ftype.Name,
 			Field: f,
 			Tags:  ftype.Tag,
 			Alt:   strings.ToUpper(ftype.Tag.Get("envconfig")),
 		}

 		// Default to the field name as the env var name (will be upcased)
 		info.Key = info.Name

 		// Best effort to un-pick camel casing as separate words
 		if ftype.Tag.Get("split_words") == "true" {
 			words := expr.FindAllStringSubmatch(ftype.Name, -1)
 			if len(words) > 0 {
 				var name []string
 				for _, words := range words {
 					name = append(name, words[0])
 				}

 				info.Key = strings.Join(name, "_")
 			}
 		}
 		if info.Alt != "" {
 			info.Key = info.Alt
 		}
 		if prefix != "" {
 			info.Key = fmt.Sprintf("%s_%s", prefix, info.Key)
 		}
 		info.Key = strings.ToUpper(info.Key)
 		infos = append(infos, info)

 		if f.Kind() == reflect.Struct {
 			// honor Decode if present
 			if decoderFrom(f) == nil && setterFrom(f) == nil && textUnmarshaler(f) == nil {
 				innerPrefix := prefix
 				if !ftype.Anonymous {
 					innerPrefix = info.Key
 				}

 				embeddedPtr := f.Addr().Interface()
 				embeddedInfos, err := gatherInfo(innerPrefix, embeddedPtr)
 				if err != nil {
 					return nil, err
 				}
 				infos = append(infos[:len(infos)-1], embeddedInfos...)

 				continue
 			}
 		}
 	}
 	return infos, nil
 }

 // Process populates the specified struct based on environment variables
 func Process(prefix string, spec interface{}) error {
 	infos, err := gatherInfo(prefix, spec)

 	for _, info := range infos {

 		// `os.Getenv` cannot differentiate between an explicitly set empty value
 		// and an unset value. `os.LookupEnv` is preferred to `syscall.Getenv`,
 		// but it is only available in go1.5 or newer. We're using Go build tags
 		// here to use os.LookupEnv for >=go1.5
 		value, ok := lookupEnv(info.Key)
 		if !ok && info.Alt != "" {
 			value, ok = lookupEnv(info.Alt)
 		}

 		def := info.Tags.Get("default")
 		if def != "" && !ok {
 			value = def
 		}

 		req := info.Tags.Get("required")
 		if !ok && def == "" {
 			if req == "true" {
 				return fmt.Errorf("required key %s missing value", info.Key)
 			}
 			continue
 		}

 		err := processField(value, info.Field)
 		if err != nil {
 			return &ParseError{
 				KeyName:   info.Key,
 				FieldName: info.Name,
 				TypeName:  info.Field.Type().String(),
 				Value:     value,
 				Err:       err,
 			}
 		}
 	}

 	return err
 }

 // MustProcess is the same as Process but panics if an error occurs
 func MustProcess(prefix string, spec interface{}) {
 	if err := Process(prefix, spec); err != nil {
 		panic(err)
 	}
 }

 func processField(value string, field reflect.Value) error {
 	typ := field.Type()

 	decoder := decoderFrom(field)
 	if decoder != nil {
 		return decoder.Decode(value)
 	}
 	// look for Set method if Decode not defined
 	setter := setterFrom(field)
 	if setter != nil {
 		return setter.Set(value)
 	}

 	if t := textUnmarshaler(field); t != nil {
 		return t.UnmarshalText([]byte(value))
 	}

 	if typ.Kind() == reflect.Ptr {
 		typ = typ.Elem()
 		if field.IsNil() {
 			field.Set(reflect.New(typ))
 		}
 		field = field.Elem()
 	}

 	switch typ.Kind() {
 	case reflect.String:
 		field.SetString(value)
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
 		var (
 			val int64
 			err error
 		)
 		if field.Kind() == reflect.Int64 && typ.PkgPath() == "time" && typ.Name() == "Duration" {
 			var d time.Duration
 			d, err = time.ParseDuration(value)
 			val = int64(d)
 		} else {
 			val, err = strconv.ParseInt(value, 0, typ.Bits())
 		}
 		if err != nil {
 			return err
 		}

 		field.SetInt(val)
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
 		val, err := strconv.ParseUint(value, 0, typ.Bits())
 		if err != nil {
 			return err
 		}
 		field.SetUint(val)
 	case reflect.Bool:
 		val, err := strconv.ParseBool(value)
 		if err != nil {
 			return err
 		}
 		field.SetBool(val)
 	case reflect.Float32, reflect.Float64:
 		val, err := strconv.ParseFloat(value, typ.Bits())
 		if err != nil {
 			return err
 		}
 		field.SetFloat(val)
 	case reflect.Slice:
 		vals := strings.Split(value, ",")
 		sl := reflect.MakeSlice(typ, len(vals), len(vals))
 		for i, val := range vals {
 			err := processField(val, sl.Index(i))
 			if err != nil {
 				return err
 			}
 		}
 		field.Set(sl)
 	case reflect.Map:
 		pairs := strings.Split(value, ",")
 		mp := reflect.MakeMap(typ)
 		for _, pair := range pairs {
 			kvpair := strings.Split(pair, ":")
 			if len(kvpair) != 2 {
 				return fmt.Errorf("invalid map item: %q", pair)
 			}
 			k := reflect.New(typ.Key()).Elem()
 			err := processField(kvpair[0], k)
 			if err != nil {
 				return err
 			}
 			v := reflect.New(typ.Elem()).Elem()
 			err = processField(kvpair[1], v)
 			if err != nil {
 				return err
 			}
 			mp.SetMapIndex(k, v)
 		}
 		field.Set(mp)
 	}

 	return nil
 }

 func interfaceFrom(field reflect.Value, fn func(interface{}, *bool)) {
 	// it may be impossible for a struct field to fail this check
 	if !field.CanInterface() {
 		return
 	}
 	var ok bool
 	fn(field.Interface(), &ok)
 	if !ok && field.CanAddr() {
 		fn(field.Addr().Interface(), &ok)
 	}
 }

 func decoderFrom(field reflect.Value) (d Decoder) {
 	interfaceFrom(field, func(v interface{}, ok *bool) { d, *ok = v.(Decoder) })
 	return d
 }

 func setterFrom(field reflect.Value) (s Setter) {
 	interfaceFrom(field, func(v interface{}, ok *bool) { s, *ok = v.(Setter) })
 	return s
 }

 func textUnmarshaler(field reflect.Value) (t encoding.TextUnmarshaler) {
 	interfaceFrom(field, func(v interface{}, ok *bool) { t, *ok = v.(encoding.TextUnmarshaler) })
 	return t
 }
	// Copyright (c) 2013 Kelsey Hightower. All rights reserved.
	// Use of this source code is governed by the MIT License that can be found in
	// the LICENSE file.

	package envconfig

	import (
	"encoding"
	"errors"
	"fmt"
	"reflect"
	"regexp"
	"strconv"
	"strings"
	"time"
	)

	// ErrInvalidSpecification indicates that a specification is of the wrong type.
	var ErrInvalidSpecification = errors.New("specification must be a struct pointer")

	// A ParseError occurs when an environment variable cannot be converted to
	// the type required by a struct field during assignment.
	type ParseError struct {
	KeyName string
	FieldName string
	TypeName string
	Value string
	Err error
	}

	// Decoder has the same semantics as Setter, but takes higher precedence.
	// It is provided for historical compatibility.
	type Decoder interface {
	Decode(value string) error
	}

	// Setter is implemented by types can self-deserialize values.
	// Any type that implements flag.Value also implements Setter.
	type Setter interface {
	Set(value string) error
	}

	func (e *ParseError) Error() string {
	return fmt.Sprintf("envconfig.Process: assigning %[1]s to %[2]s: converting '%[3]s' to type %[4]s. details: %[5]s", e.KeyName, e.FieldName, e.Value, e.TypeName, e.Err)
	}

	// varInfo maintains information about the configuration variable
	type varInfo struct {
	Name string
	Alt string
	Key string
	Field reflect.Value
	Tags reflect.StructTag
	}

	// GatherInfo gathers information about the specified struct
	func gatherInfo(prefix string, spec interface{}) ([]varInfo, error) {
	expr := regexp.MustCompile("([^A-Z]+\|[A-Z][^A-Z]+\|[A-Z]+)")
	s := reflect.ValueOf(spec)

	if s.Kind() != reflect.Ptr {
	return nil, ErrInvalidSpecification
	}
	s = s.Elem()
	if s.Kind() != reflect.Struct {
	return nil, ErrInvalidSpecification
	}
	typeOfSpec := s.Type()

	// over allocate an info array, we will extend if needed later
	infos := make([]varInfo, 0, s.NumField())
	for i := 0; i < s.NumField(); i++ {
	f := s.Field(i)
	ftype := typeOfSpec.Field(i)
	if !f.CanSet() \|\| ftype.Tag.Get("ignored") == "true" {
	continue
	}

	for f.Kind() == reflect.Ptr {
	if f.IsNil() {
	if f.Type().Elem().Kind() != reflect.Struct {
	// nil pointer to a non-struct: leave it alone
	break
	}
	// nil pointer to struct: create a zero instance
	f.Set(reflect.New(f.Type().Elem()))
	}
	f = f.Elem()
	}

	// Capture information about the config variable
	info := varInfo{
	Name: ftype.Name,
	Field: f,
	Tags: ftype.Tag,
	Alt: strings.ToUpper(ftype.Tag.Get("envconfig")),
	}

	// Default to the field name as the env var name (will be upcased)
	info.Key = info.Name

	// Best effort to un-pick camel casing as separate words
	if ftype.Tag.Get("split_words") == "true" {
	words := expr.FindAllStringSubmatch(ftype.Name, -1)
	if len(words) > 0 {
	var name []string
	for _, words := range words {
	name = append(name, words[0])
	}

	info.Key = strings.Join(name, "_")
	}
	}
	if info.Alt != "" {
	info.Key = info.Alt
	}
	if prefix != "" {
	info.Key = fmt.Sprintf("%s_%s", prefix, info.Key)
	}
	info.Key = strings.ToUpper(info.Key)
	infos = append(infos, info)

	if f.Kind() == reflect.Struct {
	// honor Decode if present
	if decoderFrom(f) == nil && setterFrom(f) == nil && textUnmarshaler(f) == nil {
	innerPrefix := prefix
	if !ftype.Anonymous {
	innerPrefix = info.Key
	}

	embeddedPtr := f.Addr().Interface()
	embeddedInfos, err := gatherInfo(innerPrefix, embeddedPtr)
	if err != nil {
	return nil, err
	}
	infos = append(infos[:len(infos)-1], embeddedInfos...)

	continue
	}
	}
	}
	return infos, nil
	}

	// Process populates the specified struct based on environment variables
	func Process(prefix string, spec interface{}) error {
	infos, err := gatherInfo(prefix, spec)

	for _, info := range infos {

	// `os.Getenv` cannot differentiate between an explicitly set empty value
	// and an unset value. `os.LookupEnv` is preferred to `syscall.Getenv`,
	// but it is only available in go1.5 or newer. We're using Go build tags
	// here to use os.LookupEnv for >=go1.5
	value, ok := lookupEnv(info.Key)
	if !ok && info.Alt != "" {
	value, ok = lookupEnv(info.Alt)
	}

	def := info.Tags.Get("default")
	if def != "" && !ok {
	value = def
	}

	req := info.Tags.Get("required")
	if !ok && def == "" {
	if req == "true" {
	return fmt.Errorf("required key %s missing value", info.Key)
	}
	continue
	}

	err := processField(value, info.Field)
	if err != nil {
	return &ParseError{
	KeyName: info.Key,
	FieldName: info.Name,
	TypeName: info.Field.Type().String(),
	Value: value,
	Err: err,
	}
	}
	}

	return err
	}

	// MustProcess is the same as Process but panics if an error occurs
	func MustProcess(prefix string, spec interface{}) {
	if err := Process(prefix, spec); err != nil {
	panic(err)
	}
	}

	func processField(value string, field reflect.Value) error {
	typ := field.Type()

	decoder := decoderFrom(field)
	if decoder != nil {
	return decoder.Decode(value)
	}
	// look for Set method if Decode not defined
	setter := setterFrom(field)
	if setter != nil {
	return setter.Set(value)
	}

	if t := textUnmarshaler(field); t != nil {
	return t.UnmarshalText([]byte(value))
	}

	if typ.Kind() == reflect.Ptr {
	typ = typ.Elem()
	if field.IsNil() {
	field.Set(reflect.New(typ))
	}
	field = field.Elem()
	}

	switch typ.Kind() {
	case reflect.String:
	field.SetString(value)
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
	var (
	val int64
	err error
	)
	if field.Kind() == reflect.Int64 && typ.PkgPath() == "time" && typ.Name() == "Duration" {
	var d time.Duration
	d, err = time.ParseDuration(value)
	val = int64(d)
	} else {
	val, err = strconv.ParseInt(value, 0, typ.Bits())
	}
	if err != nil {
	return err
	}

	field.SetInt(val)
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
	val, err := strconv.ParseUint(value, 0, typ.Bits())
	if err != nil {
	return err
	}
	field.SetUint(val)
	case reflect.Bool:
	val, err := strconv.ParseBool(value)
	if err != nil {
	return err
	}
	field.SetBool(val)
	case reflect.Float32, reflect.Float64:
	val, err := strconv.ParseFloat(value, typ.Bits())
	if err != nil {
	return err
	}
	field.SetFloat(val)
	case reflect.Slice:
	vals := strings.Split(value, ",")
	sl := reflect.MakeSlice(typ, len(vals), len(vals))
	for i, val := range vals {
	err := processField(val, sl.Index(i))
	if err != nil {
	return err
	}
	}
	field.Set(sl)
	case reflect.Map:
	pairs := strings.Split(value, ",")
	mp := reflect.MakeMap(typ)
	for _, pair := range pairs {
	kvpair := strings.Split(pair, ":")
	if len(kvpair) != 2 {
	return fmt.Errorf("invalid map item: %q", pair)
	}
	k := reflect.New(typ.Key()).Elem()
	err := processField(kvpair[0], k)
	if err != nil {
	return err
	}
	v := reflect.New(typ.Elem()).Elem()
	err = processField(kvpair[1], v)
	if err != nil {
	return err
	}
	mp.SetMapIndex(k, v)
	}
	field.Set(mp)
	}

	return nil
	}

	func interfaceFrom(field reflect.Value, fn func(interface{}, *bool)) {
	// it may be impossible for a struct field to fail this check
	if !field.CanInterface() {
	return
	}
	var ok bool
	fn(field.Interface(), &ok)
	if !ok && field.CanAddr() {
	fn(field.Addr().Interface(), &ok)
	}
	}

	func decoderFrom(field reflect.Value) (d Decoder) {
	interfaceFrom(field, func(v interface{}, ok bool) { d, ok = v.(Decoder) })
	return d
	}

	func setterFrom(field reflect.Value) (s Setter) {
	interfaceFrom(field, func(v interface{}, ok bool) { s, ok = v.(Setter) })
	return s
	}

	func textUnmarshaler(field reflect.Value) (t encoding.TextUnmarshaler) {
	interfaceFrom(field, func(v interface{}, ok bool) { t, ok = v.(encoding.TextUnmarshaler) })
	return t
	}