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mirror of https://github.com/json-iterator/go.git synced 2024-11-30 08:36:43 +02:00
json-iterator/feature_reflect.go

608 lines
18 KiB
Go

package jsoniter
import (
"encoding"
"encoding/json"
"fmt"
"reflect"
"time"
"unsafe"
)
// ValDecoder is an internal type registered to cache as needed.
// Don't confuse jsoniter.ValDecoder with json.Decoder.
// For json.Decoder's adapter, refer to jsoniter.AdapterDecoder(todo link).
//
// Reflection on type to create decoders, which is then cached
// Reflection on value is avoided as we can, as the reflect.Value itself will allocate, with following exceptions
// 1. create instance of new value, for example *int will need a int to be allocated
// 2. append to slice, if the existing cap is not enough, allocate will be done using Reflect.New
// 3. assignment to map, both key and value will be reflect.Value
// For a simple struct binding, it will be reflect.Value free and allocation free
type ValDecoder interface {
Decode(ptr unsafe.Pointer, iter *Iterator)
}
// ValEncoder is an internal type registered to cache as needed.
// Don't confuse jsoniter.ValEncoder with json.Encoder.
// For json.Encoder's adapter, refer to jsoniter.AdapterEncoder(todo godoc link).
type ValEncoder interface {
IsEmpty(ptr unsafe.Pointer) bool
Encode(ptr unsafe.Pointer, stream *Stream)
EncodeInterface(val interface{}, stream *Stream)
}
type checkIsEmpty interface {
IsEmpty(ptr unsafe.Pointer) bool
}
// WriteToStream the default implementation for TypeEncoder method EncodeInterface
func WriteToStream(val interface{}, stream *Stream, encoder ValEncoder) {
e := (*emptyInterface)(unsafe.Pointer(&val))
if e.word == nil {
stream.WriteNil()
return
}
if reflect.TypeOf(val).Kind() == reflect.Ptr {
encoder.Encode(unsafe.Pointer(&e.word), stream)
} else {
encoder.Encode(e.word, stream)
}
}
var jsonNumberType reflect.Type
var jsoniterNumberType reflect.Type
var jsonRawMessageType reflect.Type
var jsoniterRawMessageType reflect.Type
var anyType reflect.Type
var marshalerType reflect.Type
var unmarshalerType reflect.Type
var textMarshalerType reflect.Type
var textUnmarshalerType reflect.Type
func init() {
jsonNumberType = reflect.TypeOf((*json.Number)(nil)).Elem()
jsoniterNumberType = reflect.TypeOf((*Number)(nil)).Elem()
jsonRawMessageType = reflect.TypeOf((*json.RawMessage)(nil)).Elem()
jsoniterRawMessageType = reflect.TypeOf((*RawMessage)(nil)).Elem()
anyType = reflect.TypeOf((*Any)(nil)).Elem()
marshalerType = reflect.TypeOf((*json.Marshaler)(nil)).Elem()
unmarshalerType = reflect.TypeOf((*json.Unmarshaler)(nil)).Elem()
textMarshalerType = reflect.TypeOf((*encoding.TextMarshaler)(nil)).Elem()
textUnmarshalerType = reflect.TypeOf((*encoding.TextUnmarshaler)(nil)).Elem()
}
// ReadVal copy the underlying JSON into go interface, same as json.Unmarshal
func (iter *Iterator) ReadVal(obj interface{}) {
typ := reflect.TypeOf(obj)
cacheKey := typ.Elem()
decoder := decoderOfType(iter.cfg, "", cacheKey)
e := (*emptyInterface)(unsafe.Pointer(&obj))
if e.word == nil {
iter.ReportError("ReadVal", "can not read into nil pointer")
return
}
decoder.Decode(e.word, iter)
}
// WriteVal copy the go interface into underlying JSON, same as json.Marshal
func (stream *Stream) WriteVal(val interface{}) {
if nil == val {
stream.WriteNil()
return
}
typ := reflect.TypeOf(val)
cacheKey := typ
encoder := encoderOfType(stream.cfg, "", cacheKey)
encoder.EncodeInterface(val, stream)
}
func decoderOfType(cfg *frozenConfig, prefix string, typ reflect.Type) ValDecoder {
cacheKey := typ
decoder := cfg.getDecoderFromCache(cacheKey)
if decoder != nil {
return decoder
}
decoder = getTypeDecoderFromExtension(cfg, typ)
if decoder != nil {
cfg.addDecoderToCache(cacheKey, decoder)
return decoder
}
decoder = &placeholderDecoder{cfg: cfg, cacheKey: cacheKey}
cfg.addDecoderToCache(cacheKey, decoder)
decoder = createDecoderOfType(cfg, prefix, typ)
for _, extension := range extensions {
decoder = extension.DecorateDecoder(typ, decoder)
}
for _, extension := range cfg.extensions {
decoder = extension.DecorateDecoder(typ, decoder)
}
cfg.addDecoderToCache(cacheKey, decoder)
return decoder
}
func createDecoderOfType(cfg *frozenConfig, prefix string, typ reflect.Type) ValDecoder {
typeName := typ.String()
if typ == jsonRawMessageType {
return &jsonRawMessageCodec{}
}
if typ == jsoniterRawMessageType {
return &jsoniterRawMessageCodec{}
}
if typ.AssignableTo(jsonNumberType) {
return &jsonNumberCodec{}
}
if typ.AssignableTo(jsoniterNumberType) {
return &jsoniterNumberCodec{}
}
if typ.Implements(unmarshalerType) {
templateInterface := reflect.New(typ).Elem().Interface()
var decoder ValDecoder = &unmarshalerDecoder{extractInterface(templateInterface)}
if typ.Kind() == reflect.Ptr {
decoder = &OptionalDecoder{typ.Elem(), decoder}
}
return decoder
}
if reflect.PtrTo(typ).Implements(unmarshalerType) {
templateInterface := reflect.New(typ).Interface()
var decoder ValDecoder = &unmarshalerDecoder{extractInterface(templateInterface)}
return decoder
}
if typ.Implements(textUnmarshalerType) {
templateInterface := reflect.New(typ).Elem().Interface()
var decoder ValDecoder = &textUnmarshalerDecoder{extractInterface(templateInterface)}
if typ.Kind() == reflect.Ptr {
decoder = &OptionalDecoder{typ.Elem(), decoder}
}
return decoder
}
if reflect.PtrTo(typ).Implements(textUnmarshalerType) {
templateInterface := reflect.New(typ).Interface()
var decoder ValDecoder = &textUnmarshalerDecoder{extractInterface(templateInterface)}
return decoder
}
if typ.Kind() == reflect.Slice && typ.Elem().Kind() == reflect.Uint8 {
sliceDecoder := decoderOfSlice(cfg, prefix, typ)
return &base64Codec{sliceDecoder: sliceDecoder}
}
if typ.Implements(anyType) {
return &anyCodec{}
}
switch typ.Kind() {
case reflect.String:
if typeName != "string" {
return decoderOfType(cfg, prefix, reflect.TypeOf((*string)(nil)).Elem())
}
return &stringCodec{}
case reflect.Int:
if typeName != "int" {
return decoderOfType(cfg, prefix, reflect.TypeOf((*int)(nil)).Elem())
}
return &intCodec{}
case reflect.Int8:
if typeName != "int8" {
return decoderOfType(cfg, prefix, reflect.TypeOf((*int8)(nil)).Elem())
}
return &int8Codec{}
case reflect.Int16:
if typeName != "int16" {
return decoderOfType(cfg, prefix, reflect.TypeOf((*int16)(nil)).Elem())
}
return &int16Codec{}
case reflect.Int32:
if typeName != "int32" {
return decoderOfType(cfg, prefix, reflect.TypeOf((*int32)(nil)).Elem())
}
return &int32Codec{}
case reflect.Int64:
if typeName != "int64" {
return decoderOfType(cfg, prefix, reflect.TypeOf((*int64)(nil)).Elem())
}
return &int64Codec{}
case reflect.Uint:
if typeName != "uint" {
return decoderOfType(cfg, prefix, reflect.TypeOf((*uint)(nil)).Elem())
}
return &uintCodec{}
case reflect.Uint8:
if typeName != "uint8" {
return decoderOfType(cfg, prefix, reflect.TypeOf((*uint8)(nil)).Elem())
}
return &uint8Codec{}
case reflect.Uint16:
if typeName != "uint16" {
return decoderOfType(cfg, prefix, reflect.TypeOf((*uint16)(nil)).Elem())
}
return &uint16Codec{}
case reflect.Uint32:
if typeName != "uint32" {
return decoderOfType(cfg, prefix, reflect.TypeOf((*uint32)(nil)).Elem())
}
return &uint32Codec{}
case reflect.Uintptr:
if typeName != "uintptr" {
return decoderOfType(cfg, prefix, reflect.TypeOf((*uintptr)(nil)).Elem())
}
return &uintptrCodec{}
case reflect.Uint64:
if typeName != "uint64" {
return decoderOfType(cfg, prefix, reflect.TypeOf((*uint64)(nil)).Elem())
}
return &uint64Codec{}
case reflect.Float32:
if typeName != "float32" {
return decoderOfType(cfg, prefix, reflect.TypeOf((*float32)(nil)).Elem())
}
return &float32Codec{}
case reflect.Float64:
if typeName != "float64" {
return decoderOfType(cfg, prefix, reflect.TypeOf((*float64)(nil)).Elem())
}
return &float64Codec{}
case reflect.Bool:
if typeName != "bool" {
return decoderOfType(cfg, prefix, reflect.TypeOf((*bool)(nil)).Elem())
}
return &boolCodec{}
case reflect.Interface:
if typ.NumMethod() == 0 {
return &emptyInterfaceCodec{}
}
return &nonEmptyInterfaceCodec{}
case reflect.Struct:
return decoderOfStruct(cfg, prefix, typ)
case reflect.Array:
return decoderOfArray(cfg, prefix, typ)
case reflect.Slice:
return decoderOfSlice(cfg, prefix, typ)
case reflect.Map:
return decoderOfMap(cfg, prefix, typ)
case reflect.Ptr:
return decoderOfOptional(cfg, prefix, typ)
default:
return &lazyErrorDecoder{err: fmt.Errorf("%s%s is unsupported type", prefix, typ.String())}
}
}
func encoderOfType(cfg *frozenConfig, prefix string, typ reflect.Type) ValEncoder {
cacheKey := typ
encoder := cfg.getEncoderFromCache(cacheKey)
if encoder != nil {
return encoder
}
encoder = getTypeEncoderFromExtension(cfg, typ)
if encoder != nil {
cfg.addEncoderToCache(cacheKey, encoder)
return encoder
}
encoder = &placeholderEncoder{cfg: cfg, cacheKey: cacheKey}
cfg.addEncoderToCache(cacheKey, encoder)
encoder = createEncoderOfType(cfg, prefix, typ)
for _, extension := range extensions {
encoder = extension.DecorateEncoder(typ, encoder)
}
for _, extension := range cfg.extensions {
encoder = extension.DecorateEncoder(typ, encoder)
}
cfg.addEncoderToCache(cacheKey, encoder)
return encoder
}
func createEncoderOfType(cfg *frozenConfig, prefix string, typ reflect.Type) ValEncoder {
if typ == jsonRawMessageType {
return &jsonRawMessageCodec{}
}
if typ == jsoniterRawMessageType {
return &jsoniterRawMessageCodec{}
}
if typ.AssignableTo(jsonNumberType) {
return &jsonNumberCodec{}
}
if typ.AssignableTo(jsoniterNumberType) {
return &jsoniterNumberCodec{}
}
if typ.Implements(marshalerType) {
checkIsEmpty := createCheckIsEmpty(cfg, typ)
templateInterface := reflect.New(typ).Elem().Interface()
var encoder ValEncoder = &marshalerEncoder{
templateInterface: extractInterface(templateInterface),
checkIsEmpty: checkIsEmpty,
}
if typ.Kind() == reflect.Ptr {
encoder = &OptionalEncoder{encoder}
}
return encoder
}
if reflect.PtrTo(typ).Implements(marshalerType) {
checkIsEmpty := createCheckIsEmpty(cfg, reflect.PtrTo(typ))
templateInterface := reflect.New(typ).Interface()
var encoder ValEncoder = &marshalerEncoder{
templateInterface: extractInterface(templateInterface),
checkIsEmpty: checkIsEmpty,
}
return encoder
}
if typ.Implements(textMarshalerType) {
checkIsEmpty := createCheckIsEmpty(cfg, typ)
templateInterface := reflect.New(typ).Elem().Interface()
var encoder ValEncoder = &textMarshalerEncoder{
templateInterface: extractInterface(templateInterface),
checkIsEmpty: checkIsEmpty,
}
if typ.Kind() == reflect.Ptr {
encoder = &OptionalEncoder{encoder}
}
return encoder
}
if typ.Kind() == reflect.Slice && typ.Elem().Kind() == reflect.Uint8 {
return &base64Codec{}
}
if typ.Implements(anyType) {
return &anyCodec{}
}
return createEncoderOfSimpleType(cfg, prefix, typ)
}
func createCheckIsEmpty(cfg *frozenConfig, typ reflect.Type) checkIsEmpty {
kind := typ.Kind()
switch kind {
case reflect.String:
return &stringCodec{}
case reflect.Int:
return &intCodec{}
case reflect.Int8:
return &int8Codec{}
case reflect.Int16:
return &int16Codec{}
case reflect.Int32:
return &int32Codec{}
case reflect.Int64:
return &int64Codec{}
case reflect.Uint:
return &uintCodec{}
case reflect.Uint8:
return &uint8Codec{}
case reflect.Uint16:
return &uint16Codec{}
case reflect.Uint32:
return &uint32Codec{}
case reflect.Uintptr:
return &uintptrCodec{}
case reflect.Uint64:
return &uint64Codec{}
case reflect.Float32:
return &float32Codec{}
case reflect.Float64:
return &float64Codec{}
case reflect.Bool:
return &boolCodec{}
case reflect.Interface:
if typ.NumMethod() == 0 {
return &emptyInterfaceCodec{}
}
return &nonEmptyInterfaceCodec{}
case reflect.Struct:
return &structEncoder{typ: typ}
case reflect.Array:
return &arrayEncoder{}
case reflect.Slice:
return &sliceEncoder{}
case reflect.Map:
return encoderOfMap(cfg, "", typ)
case reflect.Ptr:
return &OptionalEncoder{}
default:
return &lazyErrorEncoder{err: fmt.Errorf("unsupported type: %v", typ)}
}
}
func createEncoderOfSimpleType(cfg *frozenConfig, prefix string, typ reflect.Type) ValEncoder {
typeName := typ.String()
kind := typ.Kind()
switch kind {
case reflect.String:
if typeName != "string" {
return encoderOfType(cfg, prefix, reflect.TypeOf((*string)(nil)).Elem())
}
return &stringCodec{}
case reflect.Int:
if typeName != "int" {
return encoderOfType(cfg, prefix, reflect.TypeOf((*int)(nil)).Elem())
}
return &intCodec{}
case reflect.Int8:
if typeName != "int8" {
return encoderOfType(cfg, prefix, reflect.TypeOf((*int8)(nil)).Elem())
}
return &int8Codec{}
case reflect.Int16:
if typeName != "int16" {
return encoderOfType(cfg, prefix, reflect.TypeOf((*int16)(nil)).Elem())
}
return &int16Codec{}
case reflect.Int32:
if typeName != "int32" {
return encoderOfType(cfg, prefix, reflect.TypeOf((*int32)(nil)).Elem())
}
return &int32Codec{}
case reflect.Int64:
if typeName != "int64" {
return encoderOfType(cfg, prefix, reflect.TypeOf((*int64)(nil)).Elem())
}
return &int64Codec{}
case reflect.Uint:
if typeName != "uint" {
return encoderOfType(cfg, prefix, reflect.TypeOf((*uint)(nil)).Elem())
}
return &uintCodec{}
case reflect.Uint8:
if typeName != "uint8" {
return encoderOfType(cfg, prefix, reflect.TypeOf((*uint8)(nil)).Elem())
}
return &uint8Codec{}
case reflect.Uint16:
if typeName != "uint16" {
return encoderOfType(cfg, prefix, reflect.TypeOf((*uint16)(nil)).Elem())
}
return &uint16Codec{}
case reflect.Uint32:
if typeName != "uint32" {
return encoderOfType(cfg, prefix, reflect.TypeOf((*uint32)(nil)).Elem())
}
return &uint32Codec{}
case reflect.Uintptr:
if typeName != "uintptr" {
return encoderOfType(cfg, prefix, reflect.TypeOf((*uintptr)(nil)).Elem())
}
return &uintptrCodec{}
case reflect.Uint64:
if typeName != "uint64" {
return encoderOfType(cfg, prefix, reflect.TypeOf((*uint64)(nil)).Elem())
}
return &uint64Codec{}
case reflect.Float32:
if typeName != "float32" {
return encoderOfType(cfg, prefix, reflect.TypeOf((*float32)(nil)).Elem())
}
return &float32Codec{}
case reflect.Float64:
if typeName != "float64" {
return encoderOfType(cfg, prefix, reflect.TypeOf((*float64)(nil)).Elem())
}
return &float64Codec{}
case reflect.Bool:
if typeName != "bool" {
return encoderOfType(cfg, prefix, reflect.TypeOf((*bool)(nil)).Elem())
}
return &boolCodec{}
case reflect.Interface:
if typ.NumMethod() == 0 {
return &emptyInterfaceCodec{}
}
return &nonEmptyInterfaceCodec{}
case reflect.Struct:
return encoderOfStruct(cfg, prefix, typ)
case reflect.Array:
return encoderOfArray(cfg, prefix, typ)
case reflect.Slice:
return encoderOfSlice(cfg, prefix, typ)
case reflect.Map:
return encoderOfMap(cfg, prefix, typ)
case reflect.Ptr:
return encoderOfOptional(cfg, prefix, typ)
default:
return &lazyErrorEncoder{err: fmt.Errorf("%s%s is unsupported type", prefix, typ.String())}
}
}
type placeholderEncoder struct {
cfg *frozenConfig
cacheKey reflect.Type
}
func (encoder *placeholderEncoder) Encode(ptr unsafe.Pointer, stream *Stream) {
encoder.getRealEncoder().Encode(ptr, stream)
}
func (encoder *placeholderEncoder) EncodeInterface(val interface{}, stream *Stream) {
encoder.getRealEncoder().EncodeInterface(val, stream)
}
func (encoder *placeholderEncoder) IsEmpty(ptr unsafe.Pointer) bool {
return encoder.getRealEncoder().IsEmpty(ptr)
}
func (encoder *placeholderEncoder) getRealEncoder() ValEncoder {
for i := 0; i < 500; i++ {
realDecoder := encoder.cfg.getEncoderFromCache(encoder.cacheKey)
_, isPlaceholder := realDecoder.(*placeholderEncoder)
if isPlaceholder {
time.Sleep(10 * time.Millisecond)
} else {
return realDecoder
}
}
panic(fmt.Sprintf("real encoder not found for cache key: %v", encoder.cacheKey))
}
type placeholderDecoder struct {
cfg *frozenConfig
cacheKey reflect.Type
}
func (decoder *placeholderDecoder) Decode(ptr unsafe.Pointer, iter *Iterator) {
for i := 0; i < 500; i++ {
realDecoder := decoder.cfg.getDecoderFromCache(decoder.cacheKey)
_, isPlaceholder := realDecoder.(*placeholderDecoder)
if isPlaceholder {
time.Sleep(10 * time.Millisecond)
} else {
realDecoder.Decode(ptr, iter)
return
}
}
panic(fmt.Sprintf("real decoder not found for cache key: %v", decoder.cacheKey))
}
type lazyErrorDecoder struct {
err error
}
func (decoder *lazyErrorDecoder) Decode(ptr unsafe.Pointer, iter *Iterator) {
if iter.WhatIsNext() != NilValue {
if iter.Error == nil {
iter.Error = decoder.err
}
} else {
iter.Skip()
}
}
type lazyErrorEncoder struct {
err error
}
func (encoder *lazyErrorEncoder) Encode(ptr unsafe.Pointer, stream *Stream) {
if ptr == nil {
stream.WriteNil()
} else if stream.Error == nil {
stream.Error = encoder.err
}
}
func (encoder *lazyErrorEncoder) EncodeInterface(val interface{}, stream *Stream) {
if val == nil {
stream.WriteNil()
} else if stream.Error == nil {
stream.Error = encoder.err
}
}
func (encoder *lazyErrorEncoder) IsEmpty(ptr unsafe.Pointer) bool {
return false
}
func extractInterface(val interface{}) emptyInterface {
return *((*emptyInterface)(unsafe.Pointer(&val)))
}
// emptyInterface is the header for an interface{} value.
type emptyInterface struct {
typ unsafe.Pointer
word unsafe.Pointer
}
// emptyInterface is the header for an interface with method (not interface{})
type nonEmptyInterface struct {
// see ../runtime/iface.go:/Itab
itab *struct {
ityp unsafe.Pointer // static interface type
typ unsafe.Pointer // dynamic concrete type
link unsafe.Pointer
bad int32
unused int32
fun [100000]unsafe.Pointer // method table
}
word unsafe.Pointer
}