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json.go
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json.go
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// Copyright 2015 go-swagger maintainers
//
// 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 swag
import (
"bytes"
"encoding/json"
"log"
"reflect"
"strings"
"sync"
"github.com/mailru/easyjson/jlexer"
"github.com/mailru/easyjson/jwriter"
)
// nullJSON represents a JSON object with null type
var nullJSON = []byte("null")
// DefaultJSONNameProvider the default cache for types
var DefaultJSONNameProvider = NewNameProvider()
const comma = byte(',')
var closers map[byte]byte
func init() {
closers = map[byte]byte{
'{': '}',
'[': ']',
}
}
type ejMarshaler interface {
MarshalEasyJSON(w *jwriter.Writer)
}
type ejUnmarshaler interface {
UnmarshalEasyJSON(w *jlexer.Lexer)
}
// WriteJSON writes json data, prefers finding an appropriate interface to short-circuit the marshaler
// so it takes the fastest option available.
func WriteJSON(data interface{}) ([]byte, error) {
if d, ok := data.(ejMarshaler); ok {
jw := new(jwriter.Writer)
d.MarshalEasyJSON(jw)
return jw.BuildBytes()
}
if d, ok := data.(json.Marshaler); ok {
return d.MarshalJSON()
}
return json.Marshal(data)
}
// ReadJSON reads json data, prefers finding an appropriate interface to short-circuit the unmarshaler
// so it takes the fastest option available
func ReadJSON(data []byte, value interface{}) error {
trimmedData := bytes.Trim(data, "\x00")
if d, ok := value.(ejUnmarshaler); ok {
jl := &jlexer.Lexer{Data: trimmedData}
d.UnmarshalEasyJSON(jl)
return jl.Error()
}
if d, ok := value.(json.Unmarshaler); ok {
return d.UnmarshalJSON(trimmedData)
}
return json.Unmarshal(trimmedData, value)
}
// DynamicJSONToStruct converts an untyped json structure into a struct
func DynamicJSONToStruct(data interface{}, target interface{}) error {
// TODO: convert straight to a json typed map (mergo + iterate?)
b, err := WriteJSON(data)
if err != nil {
return err
}
return ReadJSON(b, target)
}
// ConcatJSON concatenates multiple json objects efficiently
func ConcatJSON(blobs ...[]byte) []byte {
if len(blobs) == 0 {
return nil
}
last := len(blobs) - 1
for blobs[last] == nil || bytes.Equal(blobs[last], nullJSON) {
// strips trailing null objects
last--
if last < 0 {
// there was nothing but "null"s or nil...
return nil
}
}
if last == 0 {
return blobs[0]
}
var opening, closing byte
var idx, a int
buf := bytes.NewBuffer(nil)
for i, b := range blobs[:last+1] {
if b == nil || bytes.Equal(b, nullJSON) {
// a null object is in the list: skip it
continue
}
if len(b) > 0 && opening == 0 { // is this an array or an object?
opening, closing = b[0], closers[b[0]]
}
if opening != '{' && opening != '[' {
continue // don't know how to concatenate non container objects
}
if len(b) < 3 { // yep empty but also the last one, so closing this thing
if i == last && a > 0 {
if err := buf.WriteByte(closing); err != nil {
log.Println(err)
}
}
continue
}
idx = 0
if a > 0 { // we need to join with a comma for everything beyond the first non-empty item
if err := buf.WriteByte(comma); err != nil {
log.Println(err)
}
idx = 1 // this is not the first or the last so we want to drop the leading bracket
}
if i != last { // not the last one, strip brackets
if _, err := buf.Write(b[idx : len(b)-1]); err != nil {
log.Println(err)
}
} else { // last one, strip only the leading bracket
if _, err := buf.Write(b[idx:]); err != nil {
log.Println(err)
}
}
a++
}
// somehow it ended up being empty, so provide a default value
if buf.Len() == 0 {
if err := buf.WriteByte(opening); err != nil {
log.Println(err)
}
if err := buf.WriteByte(closing); err != nil {
log.Println(err)
}
}
return buf.Bytes()
}
// ToDynamicJSON turns an object into a properly JSON typed structure
func ToDynamicJSON(data interface{}) interface{} {
// TODO: convert straight to a json typed map (mergo + iterate?)
b, err := json.Marshal(data)
if err != nil {
log.Println(err)
}
var res interface{}
if err := json.Unmarshal(b, &res); err != nil {
log.Println(err)
}
return res
}
// FromDynamicJSON turns an object into a properly JSON typed structure
func FromDynamicJSON(data, target interface{}) error {
b, err := json.Marshal(data)
if err != nil {
log.Println(err)
}
return json.Unmarshal(b, target)
}
// NameProvider represents an object capable of translating from go property names
// to json property names
// This type is thread-safe.
type NameProvider struct {
lock *sync.Mutex
index map[reflect.Type]nameIndex
}
type nameIndex struct {
jsonNames map[string]string
goNames map[string]string
}
// NewNameProvider creates a new name provider
func NewNameProvider() *NameProvider {
return &NameProvider{
lock: &sync.Mutex{},
index: make(map[reflect.Type]nameIndex),
}
}
func buildnameIndex(tpe reflect.Type, idx, reverseIdx map[string]string) {
for i := 0; i < tpe.NumField(); i++ {
targetDes := tpe.Field(i)
if targetDes.PkgPath != "" { // unexported
continue
}
if targetDes.Anonymous { // walk embedded structures tree down first
buildnameIndex(targetDes.Type, idx, reverseIdx)
continue
}
if tag := targetDes.Tag.Get("json"); tag != "" {
parts := strings.Split(tag, ",")
if len(parts) == 0 {
continue
}
nm := parts[0]
if nm == "-" {
continue
}
if nm == "" { // empty string means we want to use the Go name
nm = targetDes.Name
}
idx[nm] = targetDes.Name
reverseIdx[targetDes.Name] = nm
}
}
}
func newNameIndex(tpe reflect.Type) nameIndex {
var idx = make(map[string]string, tpe.NumField())
var reverseIdx = make(map[string]string, tpe.NumField())
buildnameIndex(tpe, idx, reverseIdx)
return nameIndex{jsonNames: idx, goNames: reverseIdx}
}
// GetJSONNames gets all the json property names for a type
func (n *NameProvider) GetJSONNames(subject interface{}) []string {
n.lock.Lock()
defer n.lock.Unlock()
tpe := reflect.Indirect(reflect.ValueOf(subject)).Type()
names, ok := n.index[tpe]
if !ok {
names = n.makeNameIndex(tpe)
}
res := make([]string, 0, len(names.jsonNames))
for k := range names.jsonNames {
res = append(res, k)
}
return res
}
// GetJSONName gets the json name for a go property name
func (n *NameProvider) GetJSONName(subject interface{}, name string) (string, bool) {
tpe := reflect.Indirect(reflect.ValueOf(subject)).Type()
return n.GetJSONNameForType(tpe, name)
}
// GetJSONNameForType gets the json name for a go property name on a given type
func (n *NameProvider) GetJSONNameForType(tpe reflect.Type, name string) (string, bool) {
n.lock.Lock()
defer n.lock.Unlock()
names, ok := n.index[tpe]
if !ok {
names = n.makeNameIndex(tpe)
}
nme, ok := names.goNames[name]
return nme, ok
}
func (n *NameProvider) makeNameIndex(tpe reflect.Type) nameIndex {
names := newNameIndex(tpe)
n.index[tpe] = names
return names
}
// GetGoName gets the go name for a json property name
func (n *NameProvider) GetGoName(subject interface{}, name string) (string, bool) {
tpe := reflect.Indirect(reflect.ValueOf(subject)).Type()
return n.GetGoNameForType(tpe, name)
}
// GetGoNameForType gets the go name for a given type for a json property name
func (n *NameProvider) GetGoNameForType(tpe reflect.Type, name string) (string, bool) {
n.lock.Lock()
defer n.lock.Unlock()
names, ok := n.index[tpe]
if !ok {
names = n.makeNameIndex(tpe)
}
nme, ok := names.jsonNames[name]
return nme, ok
}