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reflect_extension.go
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reflect_extension.go
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package jsoniter
import (
"fmt"
"github.com/modern-go/reflect2"
"reflect"
"sort"
"strings"
"unicode"
"unsafe"
)
var typeDecoders = map[string]ValDecoder{}
var fieldDecoders = map[string]ValDecoder{}
var typeEncoders = map[string]ValEncoder{}
var fieldEncoders = map[string]ValEncoder{}
var extensions = []Extension{}
// StructDescriptor describe how should we encode/decode the struct
type StructDescriptor struct {
Type reflect2.Type
Fields []*Binding
}
// GetField get one field from the descriptor by its name.
// Can not use map here to keep field orders.
func (structDescriptor *StructDescriptor) GetField(fieldName string) *Binding {
for _, binding := range structDescriptor.Fields {
if binding.Field.Name() == fieldName {
return binding
}
}
return nil
}
// Binding describe how should we encode/decode the struct field
type Binding struct {
levels []int
Field reflect2.StructField
FromNames []string
ToNames []string
Encoder ValEncoder
Decoder ValDecoder
}
// Extension the one for all SPI. Customize encoding/decoding by specifying alternate encoder/decoder.
// Can also rename fields by UpdateStructDescriptor.
type Extension interface {
UpdateStructDescriptor(structDescriptor *StructDescriptor)
CreateMapKeyDecoder(typ reflect2.Type) ValDecoder
CreateMapKeyEncoder(typ reflect2.Type) ValEncoder
CreateDecoder(typ reflect2.Type) ValDecoder
CreateEncoder(typ reflect2.Type) ValEncoder
DecorateDecoder(typ reflect2.Type, decoder ValDecoder) ValDecoder
DecorateEncoder(typ reflect2.Type, encoder ValEncoder) ValEncoder
}
// DummyExtension embed this type get dummy implementation for all methods of Extension
type DummyExtension struct {
}
// UpdateStructDescriptor No-op
func (extension *DummyExtension) UpdateStructDescriptor(structDescriptor *StructDescriptor) {
}
// CreateMapKeyDecoder No-op
func (extension *DummyExtension) CreateMapKeyDecoder(typ reflect2.Type) ValDecoder {
return nil
}
// CreateMapKeyEncoder No-op
func (extension *DummyExtension) CreateMapKeyEncoder(typ reflect2.Type) ValEncoder {
return nil
}
// CreateDecoder No-op
func (extension *DummyExtension) CreateDecoder(typ reflect2.Type) ValDecoder {
return nil
}
// CreateEncoder No-op
func (extension *DummyExtension) CreateEncoder(typ reflect2.Type) ValEncoder {
return nil
}
// DecorateDecoder No-op
func (extension *DummyExtension) DecorateDecoder(typ reflect2.Type, decoder ValDecoder) ValDecoder {
return decoder
}
// DecorateEncoder No-op
func (extension *DummyExtension) DecorateEncoder(typ reflect2.Type, encoder ValEncoder) ValEncoder {
return encoder
}
type EncoderExtension map[reflect2.Type]ValEncoder
// UpdateStructDescriptor No-op
func (extension EncoderExtension) UpdateStructDescriptor(structDescriptor *StructDescriptor) {
}
// CreateDecoder No-op
func (extension EncoderExtension) CreateDecoder(typ reflect2.Type) ValDecoder {
return nil
}
// CreateEncoder get encoder from map
func (extension EncoderExtension) CreateEncoder(typ reflect2.Type) ValEncoder {
return extension[typ]
}
// CreateMapKeyDecoder No-op
func (extension EncoderExtension) CreateMapKeyDecoder(typ reflect2.Type) ValDecoder {
return nil
}
// CreateMapKeyEncoder No-op
func (extension EncoderExtension) CreateMapKeyEncoder(typ reflect2.Type) ValEncoder {
return nil
}
// DecorateDecoder No-op
func (extension EncoderExtension) DecorateDecoder(typ reflect2.Type, decoder ValDecoder) ValDecoder {
return decoder
}
// DecorateEncoder No-op
func (extension EncoderExtension) DecorateEncoder(typ reflect2.Type, encoder ValEncoder) ValEncoder {
return encoder
}
type DecoderExtension map[reflect2.Type]ValDecoder
// UpdateStructDescriptor No-op
func (extension DecoderExtension) UpdateStructDescriptor(structDescriptor *StructDescriptor) {
}
// CreateMapKeyDecoder No-op
func (extension DecoderExtension) CreateMapKeyDecoder(typ reflect2.Type) ValDecoder {
return nil
}
// CreateMapKeyEncoder No-op
func (extension DecoderExtension) CreateMapKeyEncoder(typ reflect2.Type) ValEncoder {
return nil
}
// CreateDecoder get decoder from map
func (extension DecoderExtension) CreateDecoder(typ reflect2.Type) ValDecoder {
return extension[typ]
}
// CreateEncoder No-op
func (extension DecoderExtension) CreateEncoder(typ reflect2.Type) ValEncoder {
return nil
}
// DecorateDecoder No-op
func (extension DecoderExtension) DecorateDecoder(typ reflect2.Type, decoder ValDecoder) ValDecoder {
return decoder
}
// DecorateEncoder No-op
func (extension DecoderExtension) DecorateEncoder(typ reflect2.Type, encoder ValEncoder) ValEncoder {
return encoder
}
type funcDecoder struct {
fun DecoderFunc
}
func (decoder *funcDecoder) Decode(ptr unsafe.Pointer, iter *Iterator) {
decoder.fun(ptr, iter)
}
type funcEncoder struct {
fun EncoderFunc
isEmptyFunc func(ptr unsafe.Pointer) bool
}
func (encoder *funcEncoder) Encode(ptr unsafe.Pointer, stream *Stream) {
encoder.fun(ptr, stream)
}
func (encoder *funcEncoder) IsEmpty(ptr unsafe.Pointer) bool {
if encoder.isEmptyFunc == nil {
return false
}
return encoder.isEmptyFunc(ptr)
}
// DecoderFunc the function form of TypeDecoder
type DecoderFunc func(ptr unsafe.Pointer, iter *Iterator)
// EncoderFunc the function form of TypeEncoder
type EncoderFunc func(ptr unsafe.Pointer, stream *Stream)
// RegisterTypeDecoderFunc register TypeDecoder for a type with function
func RegisterTypeDecoderFunc(typ string, fun DecoderFunc) {
typeDecoders[typ] = &funcDecoder{fun}
}
// RegisterTypeDecoder register TypeDecoder for a typ
func RegisterTypeDecoder(typ string, decoder ValDecoder) {
typeDecoders[typ] = decoder
}
// RegisterFieldDecoderFunc register TypeDecoder for a struct field with function
func RegisterFieldDecoderFunc(typ string, field string, fun DecoderFunc) {
RegisterFieldDecoder(typ, field, &funcDecoder{fun})
}
// RegisterFieldDecoder register TypeDecoder for a struct field
func RegisterFieldDecoder(typ string, field string, decoder ValDecoder) {
fieldDecoders[fmt.Sprintf("%s/%s", typ, field)] = decoder
}
// RegisterTypeEncoderFunc register TypeEncoder for a type with encode/isEmpty function
func RegisterTypeEncoderFunc(typ string, fun EncoderFunc, isEmptyFunc func(unsafe.Pointer) bool) {
typeEncoders[typ] = &funcEncoder{fun, isEmptyFunc}
}
// RegisterTypeEncoder register TypeEncoder for a type
func RegisterTypeEncoder(typ string, encoder ValEncoder) {
typeEncoders[typ] = encoder
}
// RegisterFieldEncoderFunc register TypeEncoder for a struct field with encode/isEmpty function
func RegisterFieldEncoderFunc(typ string, field string, fun EncoderFunc, isEmptyFunc func(unsafe.Pointer) bool) {
RegisterFieldEncoder(typ, field, &funcEncoder{fun, isEmptyFunc})
}
// RegisterFieldEncoder register TypeEncoder for a struct field
func RegisterFieldEncoder(typ string, field string, encoder ValEncoder) {
fieldEncoders[fmt.Sprintf("%s/%s", typ, field)] = encoder
}
// RegisterExtension register extension
func RegisterExtension(extension Extension) {
extensions = append(extensions, extension)
}
func getTypeDecoderFromExtension(ctx *ctx, typ reflect2.Type) ValDecoder {
decoder := _getTypeDecoderFromExtension(ctx, typ)
if decoder != nil {
for _, extension := range extensions {
decoder = extension.DecorateDecoder(typ, decoder)
}
for _, extension := range ctx.extensions {
decoder = extension.DecorateDecoder(typ, decoder)
}
}
return decoder
}
func _getTypeDecoderFromExtension(ctx *ctx, typ reflect2.Type) ValDecoder {
for _, extension := range extensions {
decoder := extension.CreateDecoder(typ)
if decoder != nil {
return decoder
}
}
for _, extension := range ctx.extensions {
decoder := extension.CreateDecoder(typ)
if decoder != nil {
return decoder
}
}
typeName := typ.String()
decoder := typeDecoders[typeName]
if decoder != nil {
return decoder
}
if typ.Kind() == reflect.Ptr {
ptrType := typ.(*reflect2.UnsafePtrType)
decoder := typeDecoders[ptrType.Elem().String()]
if decoder != nil {
return &OptionalDecoder{ptrType.Elem(), decoder}
}
}
return nil
}
func getTypeEncoderFromExtension(ctx *ctx, typ reflect2.Type) ValEncoder {
encoder := _getTypeEncoderFromExtension(ctx, typ)
if encoder != nil {
for _, extension := range extensions {
encoder = extension.DecorateEncoder(typ, encoder)
}
for _, extension := range ctx.extensions {
encoder = extension.DecorateEncoder(typ, encoder)
}
}
return encoder
}
func _getTypeEncoderFromExtension(ctx *ctx, typ reflect2.Type) ValEncoder {
for _, extension := range extensions {
encoder := extension.CreateEncoder(typ)
if encoder != nil {
return encoder
}
}
for _, extension := range ctx.extensions {
encoder := extension.CreateEncoder(typ)
if encoder != nil {
return encoder
}
}
typeName := typ.String()
encoder := typeEncoders[typeName]
if encoder != nil {
return encoder
}
if typ.Kind() == reflect.Ptr {
typePtr := typ.(*reflect2.UnsafePtrType)
encoder := typeEncoders[typePtr.Elem().String()]
if encoder != nil {
return &OptionalEncoder{encoder}
}
}
return nil
}
func describeStruct(ctx *ctx, typ reflect2.Type) *StructDescriptor {
structType := typ.(*reflect2.UnsafeStructType)
embeddedBindings := []*Binding{}
bindings := []*Binding{}
for i := 0; i < structType.NumField(); i++ {
field := structType.Field(i)
tag, hastag := field.Tag().Lookup(ctx.getTagKey())
if ctx.onlyTaggedField && !hastag {
continue
}
tagParts := strings.Split(tag, ",")
if tag == "-" {
continue
}
if field.Anonymous() && (tag == "" || tagParts[0] == "") {
if field.Type().Kind() == reflect.Struct {
structDescriptor := describeStruct(ctx, field.Type())
for _, binding := range structDescriptor.Fields {
binding.levels = append([]int{i}, binding.levels...)
omitempty := binding.Encoder.(*structFieldEncoder).omitempty
binding.Encoder = &structFieldEncoder{field, binding.Encoder, omitempty}
binding.Decoder = &structFieldDecoder{field, binding.Decoder}
embeddedBindings = append(embeddedBindings, binding)
}
continue
} else if field.Type().Kind() == reflect.Ptr {
ptrType := field.Type().(*reflect2.UnsafePtrType)
if ptrType.Elem().Kind() == reflect.Struct {
structDescriptor := describeStruct(ctx, ptrType.Elem())
for _, binding := range structDescriptor.Fields {
binding.levels = append([]int{i}, binding.levels...)
omitempty := binding.Encoder.(*structFieldEncoder).omitempty
binding.Encoder = &dereferenceEncoder{binding.Encoder}
binding.Encoder = &structFieldEncoder{field, binding.Encoder, omitempty}
binding.Decoder = &dereferenceDecoder{ptrType.Elem(), binding.Decoder}
binding.Decoder = &structFieldDecoder{field, binding.Decoder}
embeddedBindings = append(embeddedBindings, binding)
}
continue
}
}
}
fieldNames := calcFieldNames(field.Name(), tagParts[0], tag)
fieldCacheKey := fmt.Sprintf("%s/%s", typ.String(), field.Name())
decoder := fieldDecoders[fieldCacheKey]
if decoder == nil {
decoder = decoderOfType(ctx.append(field.Name()), field.Type())
}
encoder := fieldEncoders[fieldCacheKey]
if encoder == nil {
encoder = encoderOfType(ctx.append(field.Name()), field.Type())
}
binding := &Binding{
Field: field,
FromNames: fieldNames,
ToNames: fieldNames,
Decoder: decoder,
Encoder: encoder,
}
binding.levels = []int{i}
bindings = append(bindings, binding)
}
return createStructDescriptor(ctx, typ, bindings, embeddedBindings)
}
func createStructDescriptor(ctx *ctx, typ reflect2.Type, bindings []*Binding, embeddedBindings []*Binding) *StructDescriptor {
structDescriptor := &StructDescriptor{
Type: typ,
Fields: bindings,
}
for _, extension := range extensions {
extension.UpdateStructDescriptor(structDescriptor)
}
for _, extension := range ctx.extensions {
extension.UpdateStructDescriptor(structDescriptor)
}
processTags(structDescriptor, ctx.frozenConfig)
// merge normal & embedded bindings & sort with original order
allBindings := sortableBindings(append(embeddedBindings, structDescriptor.Fields...))
sort.Sort(allBindings)
structDescriptor.Fields = allBindings
return structDescriptor
}
type sortableBindings []*Binding
func (bindings sortableBindings) Len() int {
return len(bindings)
}
func (bindings sortableBindings) Less(i, j int) bool {
left := bindings[i].levels
right := bindings[j].levels
k := 0
for {
if left[k] < right[k] {
return true
} else if left[k] > right[k] {
return false
}
k++
}
}
func (bindings sortableBindings) Swap(i, j int) {
bindings[i], bindings[j] = bindings[j], bindings[i]
}
func processTags(structDescriptor *StructDescriptor, cfg *frozenConfig) {
for _, binding := range structDescriptor.Fields {
shouldOmitEmpty := false
tagParts := strings.Split(binding.Field.Tag().Get(cfg.getTagKey()), ",")
for _, tagPart := range tagParts[1:] {
if tagPart == "omitempty" {
shouldOmitEmpty = true
} else if tagPart == "string" {
if binding.Field.Type().Kind() == reflect.String {
binding.Decoder = &stringModeStringDecoder{binding.Decoder, cfg}
binding.Encoder = &stringModeStringEncoder{binding.Encoder, cfg}
} else {
binding.Decoder = &stringModeNumberDecoder{binding.Decoder}
binding.Encoder = &stringModeNumberEncoder{binding.Encoder}
}
}
}
binding.Decoder = &structFieldDecoder{binding.Field, binding.Decoder}
binding.Encoder = &structFieldEncoder{binding.Field, binding.Encoder, shouldOmitEmpty}
}
}
func calcFieldNames(originalFieldName string, tagProvidedFieldName string, wholeTag string) []string {
// ignore?
if wholeTag == "-" {
return []string{}
}
// rename?
var fieldNames []string
if tagProvidedFieldName == "" {
fieldNames = []string{originalFieldName}
} else {
fieldNames = []string{tagProvidedFieldName}
}
// private?
isNotExported := unicode.IsLower(rune(originalFieldName[0]))
if isNotExported {
fieldNames = []string{}
}
return fieldNames
}