227 lines
4.8 KiB
Go
227 lines
4.8 KiB
Go
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package jsonutil
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import (
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"encoding/base64"
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"encoding/json"
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"fmt"
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"io"
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"io/ioutil"
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"reflect"
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"time"
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"github.com/aws/aws-sdk-go/aws"
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"github.com/aws/aws-sdk-go/private/protocol"
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)
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// UnmarshalJSON reads a stream and unmarshals the results in object v.
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func UnmarshalJSON(v interface{}, stream io.Reader) error {
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var out interface{}
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b, err := ioutil.ReadAll(stream)
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if err != nil {
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return err
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}
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if len(b) == 0 {
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return nil
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}
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if err := json.Unmarshal(b, &out); err != nil {
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return err
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}
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return unmarshalAny(reflect.ValueOf(v), out, "")
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}
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func unmarshalAny(value reflect.Value, data interface{}, tag reflect.StructTag) error {
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vtype := value.Type()
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if vtype.Kind() == reflect.Ptr {
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vtype = vtype.Elem() // check kind of actual element type
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}
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t := tag.Get("type")
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if t == "" {
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switch vtype.Kind() {
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case reflect.Struct:
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// also it can't be a time object
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if _, ok := value.Interface().(*time.Time); !ok {
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t = "structure"
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}
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case reflect.Slice:
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// also it can't be a byte slice
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if _, ok := value.Interface().([]byte); !ok {
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t = "list"
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}
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case reflect.Map:
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// cannot be a JSONValue map
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if _, ok := value.Interface().(aws.JSONValue); !ok {
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t = "map"
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}
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}
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}
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switch t {
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case "structure":
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if field, ok := vtype.FieldByName("_"); ok {
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tag = field.Tag
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}
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return unmarshalStruct(value, data, tag)
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case "list":
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return unmarshalList(value, data, tag)
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case "map":
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return unmarshalMap(value, data, tag)
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default:
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return unmarshalScalar(value, data, tag)
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}
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}
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func unmarshalStruct(value reflect.Value, data interface{}, tag reflect.StructTag) error {
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if data == nil {
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return nil
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}
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mapData, ok := data.(map[string]interface{})
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if !ok {
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return fmt.Errorf("JSON value is not a structure (%#v)", data)
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}
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t := value.Type()
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if value.Kind() == reflect.Ptr {
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if value.IsNil() { // create the structure if it's nil
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s := reflect.New(value.Type().Elem())
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value.Set(s)
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value = s
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}
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value = value.Elem()
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t = t.Elem()
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}
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// unwrap any payloads
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if payload := tag.Get("payload"); payload != "" {
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field, _ := t.FieldByName(payload)
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return unmarshalAny(value.FieldByName(payload), data, field.Tag)
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}
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for i := 0; i < t.NumField(); i++ {
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field := t.Field(i)
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if field.PkgPath != "" {
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continue // ignore unexported fields
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}
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// figure out what this field is called
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name := field.Name
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if locName := field.Tag.Get("locationName"); locName != "" {
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name = locName
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}
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member := value.FieldByIndex(field.Index)
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err := unmarshalAny(member, mapData[name], field.Tag)
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if err != nil {
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return err
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}
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}
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return nil
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}
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func unmarshalList(value reflect.Value, data interface{}, tag reflect.StructTag) error {
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if data == nil {
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return nil
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}
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listData, ok := data.([]interface{})
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if !ok {
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return fmt.Errorf("JSON value is not a list (%#v)", data)
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}
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if value.IsNil() {
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l := len(listData)
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value.Set(reflect.MakeSlice(value.Type(), l, l))
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}
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for i, c := range listData {
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err := unmarshalAny(value.Index(i), c, "")
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if err != nil {
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return err
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}
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}
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return nil
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}
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func unmarshalMap(value reflect.Value, data interface{}, tag reflect.StructTag) error {
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if data == nil {
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return nil
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}
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mapData, ok := data.(map[string]interface{})
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if !ok {
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return fmt.Errorf("JSON value is not a map (%#v)", data)
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}
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if value.IsNil() {
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value.Set(reflect.MakeMap(value.Type()))
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}
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for k, v := range mapData {
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kvalue := reflect.ValueOf(k)
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vvalue := reflect.New(value.Type().Elem()).Elem()
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unmarshalAny(vvalue, v, "")
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value.SetMapIndex(kvalue, vvalue)
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}
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return nil
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}
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func unmarshalScalar(value reflect.Value, data interface{}, tag reflect.StructTag) error {
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errf := func() error {
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return fmt.Errorf("unsupported value: %v (%s)", value.Interface(), value.Type())
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}
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switch d := data.(type) {
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case nil:
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return nil // nothing to do here
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case string:
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switch value.Interface().(type) {
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case *string:
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value.Set(reflect.ValueOf(&d))
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case []byte:
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b, err := base64.StdEncoding.DecodeString(d)
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if err != nil {
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return err
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}
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value.Set(reflect.ValueOf(b))
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case aws.JSONValue:
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// No need to use escaping as the value is a non-quoted string.
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v, err := protocol.DecodeJSONValue(d, protocol.NoEscape)
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if err != nil {
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return err
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}
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value.Set(reflect.ValueOf(v))
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default:
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return errf()
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}
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case float64:
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switch value.Interface().(type) {
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case *int64:
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di := int64(d)
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value.Set(reflect.ValueOf(&di))
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case *float64:
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value.Set(reflect.ValueOf(&d))
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case *time.Time:
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t := time.Unix(int64(d), 0).UTC()
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value.Set(reflect.ValueOf(&t))
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default:
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return errf()
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}
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case bool:
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switch value.Interface().(type) {
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case *bool:
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value.Set(reflect.ValueOf(&d))
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default:
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return errf()
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}
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default:
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return fmt.Errorf("unsupported JSON value (%v)", data)
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}
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return nil
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}
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