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|
package mapstructure
import (
"errors"
"reflect"
"strconv"
"strings"
"time"
)
// typedDecodeHook takes a raw DecodeHookFunc (an interface{}) and turns
// it into the proper DecodeHookFunc type, such as DecodeHookFuncType.
func typedDecodeHook(h DecodeHookFunc) DecodeHookFunc {
// Create variables here so we can reference them with the reflect pkg
var f1 DecodeHookFuncType
var f2 DecodeHookFuncKind
// Fill in the variables into this interface and the rest is done
// automatically using the reflect package.
potential := []interface{}{f1, f2}
v := reflect.ValueOf(h)
vt := v.Type()
for _, raw := range potential {
pt := reflect.ValueOf(raw).Type()
if vt.ConvertibleTo(pt) {
return v.Convert(pt).Interface()
}
}
return nil
}
// DecodeHookExec executes the given decode hook. This should be used
// since it'll naturally degrade to the older backwards compatible DecodeHookFunc
// that took reflect.Kind instead of reflect.Type.
func DecodeHookExec(
raw DecodeHookFunc,
from reflect.Type, to reflect.Type,
data interface{}) (interface{}, error) {
switch f := typedDecodeHook(raw).(type) {
case DecodeHookFuncType:
return f(from, to, data)
case DecodeHookFuncKind:
return f(from.Kind(), to.Kind(), data)
default:
return nil, errors.New("invalid decode hook signature")
}
}
// ComposeDecodeHookFunc creates a single DecodeHookFunc that
// automatically composes multiple DecodeHookFuncs.
//
// The composed funcs are called in order, with the result of the
// previous transformation.
func ComposeDecodeHookFunc(fs ...DecodeHookFunc) DecodeHookFunc {
return func(
f reflect.Type,
t reflect.Type,
data interface{}) (interface{}, error) {
var err error
for _, f1 := range fs {
data, err = DecodeHookExec(f1, f, t, data)
if err != nil {
return nil, err
}
// Modify the from kind to be correct with the new data
f = nil
if val := reflect.ValueOf(data); val.IsValid() {
f = val.Type()
}
}
return data, nil
}
}
// StringToSliceHookFunc returns a DecodeHookFunc that converts
// string to []string by splitting on the given sep.
func StringToSliceHookFunc(sep string) DecodeHookFunc {
return func(
f reflect.Kind,
t reflect.Kind,
data interface{}) (interface{}, error) {
if f != reflect.String || t != reflect.Slice {
return data, nil
}
raw := data.(string)
if raw == "" {
return []string{}, nil
}
return strings.Split(raw, sep), nil
}
}
// StringToTimeDurationHookFunc returns a DecodeHookFunc that converts
// strings to time.Duration.
func StringToTimeDurationHookFunc() DecodeHookFunc {
return func(
f reflect.Type,
t reflect.Type,
data interface{}) (interface{}, error) {
if f.Kind() != reflect.String {
return data, nil
}
if t != reflect.TypeOf(time.Duration(5)) {
return data, nil
}
// Convert it by parsing
return time.ParseDuration(data.(string))
}
}
// StringToTimeHookFunc returns a DecodeHookFunc that converts
// strings to time.Time.
func StringToTimeHookFunc(layout string) DecodeHookFunc {
return func(
f reflect.Type,
t reflect.Type,
data interface{}) (interface{}, error) {
if f.Kind() != reflect.String {
return data, nil
}
if t != reflect.TypeOf(time.Time{}) {
return data, nil
}
// Convert it by parsing
return time.Parse(layout, data.(string))
}
}
// WeaklyTypedHook is a DecodeHookFunc which adds support for weak typing to
// the decoder.
//
// Note that this is significantly different from the WeaklyTypedInput option
// of the DecoderConfig.
func WeaklyTypedHook(
f reflect.Kind,
t reflect.Kind,
data interface{}) (interface{}, error) {
dataVal := reflect.ValueOf(data)
switch t {
case reflect.String:
switch f {
case reflect.Bool:
if dataVal.Bool() {
return "1", nil
}
return "0", nil
case reflect.Float32:
return strconv.FormatFloat(dataVal.Float(), 'f', -1, 64), nil
case reflect.Int:
return strconv.FormatInt(dataVal.Int(), 10), nil
case reflect.Slice:
dataType := dataVal.Type()
elemKind := dataType.Elem().Kind()
if elemKind == reflect.Uint8 {
return string(dataVal.Interface().([]uint8)), nil
}
case reflect.Uint:
return strconv.FormatUint(dataVal.Uint(), 10), nil
}
}
return data, nil
}
|
