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io.go
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io.go
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// Copyright © 2020 The Things Network Foundation, The Things Industries B.V.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package io
import (
"bufio"
"bytes"
"encoding/json"
"io"
"go.thethings.network/lorawan-stack/v3/pkg/jsonpb"
)
// Decoder is the interface for the functionality that reads and decodes entities
// from an io.Reader, typically os.Stdin.
type Decoder interface {
Decode(data interface{}) (paths []string, err error)
}
type jsonDecoder struct {
rd *bufio.Reader
dec *json.Decoder
}
// NewJSONDecoder returns a new Decoder on top of r, and that uses the common JSON
// format used in The Things Stack.
func NewJSONDecoder(r io.Reader) Decoder {
rd := bufio.NewReader(r)
return &jsonDecoder{
rd: rd,
dec: json.NewDecoder(rd),
}
}
func (r *jsonDecoder) Decode(data interface{}) (paths []string, err error) {
t, err := r.rd.ReadByte()
if err != nil {
return nil, err
}
if t == '{' {
if err := r.rd.UnreadByte(); err != nil {
return nil, err
}
}
var obj json.RawMessage
if err = r.dec.Decode(&obj); err != nil {
return nil, err
}
var m map[string]interface{}
if err = json.Unmarshal(obj, &m); err != nil {
return nil, err
}
paths = fieldPaths(m, "")
b := bytes.NewBuffer(obj)
if err = jsonpb.TTN().NewDecoder(b).Decode(data); err != nil {
return nil, err
}
r.rd = bufio.NewReader(io.MultiReader(r.dec.Buffered(), r.rd))
r.dec = json.NewDecoder(r.rd)
return paths, nil
}
func fieldPaths(m map[string]interface{}, prefix string) (paths []string) {
for path, sub := range m {
if m, ok := sub.(map[string]interface{}); ok {
paths = append(paths, fieldPaths(m, prefix+path+".")...)
} else {
paths = append(paths, prefix+path)
}
}
return paths
}